Smell - A Neglected Sense in Architcture

UNIVERSITY OF CAMBRIDGE PROGRAMME FOR INDUSTRY MASTERS OF STUDIES IN INTERDISCIPLINARY DESIGN FOR THE BUILT E NVIRONMENT ___________________________________________________________________________________________ JOCHEN RABE IDBE COHORT 6 Thesis 14,963 words SUPERVISOR: DR. DAVID CROWTHER OCTOBER 2001

SM E L L – A NE GLECTED SENSE

IN

A R C HITEC TU RE

Do we kn ow what t a o n t a (co mmo nly translat ed as beings, en tities, t he- thin gs-which ar e) means? W e woul d come closer t o th e matt er if we w ere t o conc ern o ur selve s with th e nos e, th e eye s and wit h h earing.

Heidegger, Martin Heraclitus Seminar 1966.

Smell – A Neglected Sense in Architecture Int roduct io n

1

INTRODUCTION _______________________________________ ERROR! BOOKMARK NOT DEFINED.

2

PHYSIOLOGY OF SMELL _______________________________________________________________ 4

2.1 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 3

HYGROTHERMAL CONDITIONS ________________________________________________________ OUTGASSING _____________________________________________________________________ SORPTION ________________________________________________________________________ FRICTION ________________________________________________________________________ MACROCLIMATE ___________________________________________________________________

17 18 19 20 23

SOURCES OF ODOURS _______________________________________________________________ 26

5.1 5.1.1 5.1.2 5.1.3 6

PROCESSING O DOROUS DATA • ODOUR DRIVEN BEHAVIOUR ________________________________ 10 NEUROPHYSIOLOGY OF SMELL ______________________________________________________ 10 PERCEPTION ____________________________________________________________________ 11 SMELL PERCEPTION AND LANGUAGE ___________________________________________________ 13 PHYSICAL DETERMINANTS OF SMELL PERCEPTION _________________________________________ 14 ODOUR MEMORY __________________________________________________________________ 15

PHYSICAL INFLUENCES_______________________________________________________________ 17

4.1 4.2 4.3 4.4 4.5 5

5 5 5 6 6 7 8

PERCEPTION OF ODOURS AND ITS IMPLICATIONS IN ARCHITECTURE ____________________ 10

3.1 3.1.1 3.1.2 3.2 3.3 3.4 4

MINING OF O DOROUS DATA ___________________________________________________________ NASAL C AVITY ____________________________________________________________________ OLFACTORY EPITHELIUM ____________________________________________________________ THE TRIGEMINAL NERVE _____________________________________________________________ ODORANT RECEPTORS _____________________________________________________________ COMBINATORIAL RECEPTOR C ODES FOR ODOURS ________________________________________ ADAPTATION _____________________________________________________________________

BUILDING MATERIALS _______________________________________________________________ 26 ODOROUS MATERIALS _____________________________________________________________ 26 ODOUR MEDIATING MATERIALS_______________________________________________________ 30 TREATMENT OF MATERIALS _________________________________________________________ 32

BUILT IMPACTS ON ODOURS IN ARCHITECTURE ________________________________________ 33

6.1 6.1.1 6.1.2

MICROCLIMATE ____________________________________________________________________ 33 INSIDE ↔ OUTSIDE _______________________________________________________________ 33 INSIDE ↔ INSIDE _________________________________________________________________ 35

7

HUMAN IMPACTS ON ODOURS IN ARCHITECTURE ______________________________________ 38

8

CONCLUSION ________________________________________________________________________ 39

BIBLIOGRAPHY __________________________________________________________________________ 44 APPENDICES ____________________________________________________________________________ 48

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Smell – A Neglected Sense in Architecture Int roduct io n

1

Introduction

Every surrounding smells. The one, the reader of this paper, experiences at the moment of reading also has an odour. Every human being breathes approximately 30,000 times per day1. 30,000 stimuli per day and yet almost no architect contemplates these as an intrinsic creative aspect of architecture.

There is excellent academic work done examining unpleasant or hazardous smells as one cause of Sick Building Syndrome (SBS)2 and service engineers and other specialists increasingly incorporate the results within their discipline to prevent negative influences. However, there is no academic work 3 to explore the meaning and the positive possibilities of odour in architecture. It is the aim of this paper to initiate a debate on this particular aspect of smell.

There is vast material on the temporary use of volatile oils and other odorants deriving from esotericism, hardly scientific and quite often painful to read. However, aromatherapy is nowadays widely accepted for its benefits for human physiology and psychology4, but no paper considers either the interaction of odorants with their direct surroundings or the odour of a building itself. This might be due to incomplete understanding of the sense of smell; but with the enormous efforts carried out in brain research an understanding of our senses has started to appear in the sphere of scientific knowledge, too5. Neurophysiologists need to understand the sources of information in order to understand its processing within the brain. Despite the concentration on vision in a visualised world, some remaining secrets of smell were uncovered very recently and together with the improved knowledge of the human brain, this embodies one objective of this paper, namely to explore the role of odours in our daily surrounding.

The Homo olfaciens is a product of biological as well as cultural evolutions and thus the examination of the cultural significance of smells will be another approach to understand its significance for architecture. Endless examples of the occurrence of odorants in architecture in a vast variety of cultures make a complete monograph impossible. Various different disciplines must combine to achieve a comprehensive understanding of the cultural background of odours in architecture, yet little work has been done till now6. Despite our incomplete knowledge and the complex nature of this issue, examples will yield conclusions about the nature of this phenomenon and will underline the importance of scent architecture. The term scent architecture is capable of many readings. This thesis will going to employ scent architecture in the sense of architecture, built according to the contemplation of smell as one out of five senses perceiving buildings. Scent architecture can be divided into two ways influencing smellscapes. Either a building itself smells or its design influences the parameters determining the quality and quantity of smell experience.

1 2 3 4 5 6

Infants ~76,000, children ~38,000 and adults ~28,000 breaths per day.

E.g. Fanger et al. (1988).

To my knowledge.

Cf. Price (1999) and Penoel (1990).

Cf. chapter 3.

It is rather astonishing that archaeology is perfectly aware of the enormous meaning of smells, especially in religious contexts, though no studies reveal the architecture’s part in this field.

Prof. Margareta Steinby, Professor of the Archaeology of the Roman Empire, All Souls College, Oxford and Prof. Henner von Hesberg, Director Institute of Archaeology, University of Cologne in personal conversations.

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Smell – A Neglected Sense in Architecture Physiology of Smell

2

Physiology of Smell

The sense of smell is a primal sense for humans as well as animals. In evolutionary terms it is one of the most ancient of senses. Smell (or Olfaction) allows vertebrates and other organisms with olfactory receptors to identify food, mates, predators and provides both sensual pleasure as well as warnings of danger. For both humans and animals, it is one of the vital means by which our environment communicates with us.

Odorants are volatile chemical compounds that are carried by inhaled air to the Regio olfactoria (olfactory epithelium) located in the roof of the two nasal cavities of the human nose, just below and between the eyes (Figure 2.A). The odorant must possess certain molecular properties in order to provide sensory reactions.

It must have a degree of water solubility, a sufficient high vapour pressure as well as some ability to dissolve in fat (lipophilicity) and surface activity7. For this reason, as we will see later on8, Fig. 2-A temperature and moisture are crucial factors for the performance (From Leffingwell, 2001). of odours in architecture. Without any moisture odorant molecules remain without a medium to travel and the nose would detect no smell9. On the other hand if it is too damp molecules diffuse less rapidly and therefore smells are perceived at a lower rate. An increase in temperature causes higher water solubilities, vapour pressures and rates of diffusion.

In theory the olfactory sense is able to distinguish among a practically infinite number of chemical compounds at very low concentrations 10. These extraordinarily low detection thresholds 11 reveal another essence of the sense of smell: Smell is a sense of distance. Sailors smell land before seeing it: smell is the most long-ranged of our senses 12 providing the outer detection line for relevant information from our environment, either alluring or warning. Thus motion is another important part of the nature of smell. Odours either attract or repel and this grants great possibilities to direct the attention and the motion of subjects within their surroundings. Due to the difficulty of comprehending odorous sensations 13 olfaction was named the subtle sense14 and together with its infinite diversity and in occurrence with the numinous element, religion, cults and myths were always associated with smell. To some degree temple architecture was always scent architecture.

7 8 9 10 11

12 13 14

Cf. Ohloff (1990), p11.

Cf. chapter 4.1.

Like in the desert and at the poles.

Cf. Malnic, Buck et al. (1999), p720.

Detection threshold of Damascone, a chemical responsible for the scent of roses: 0.009 ppb (part per billion) 1g per 1 million tons water; Ohloff (1992), p114.

All the more if vision is obstructed, as it happens quite often in natural as well as urban environments.

As discussed below in chapter 3.

Cf. Engen (1982), p1.

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Smell – A Neglected Sense in Architecture Physiology of Smell

2.1

Mining of Odorous Data

2.1.1

Nasal Cavity

Anterior naris Olfactory Epthelium Anterior naris

The nasal cavity as a whole consists of three parts: an anterior naris, a central chamber containing the epithelium and the receptors and a posterior naris through which air inhaled through the anterior naris exits into the nasopharynx behind the soft palate (Figure 2-B).

Odorants may reach the receptors through the latter route, for example when one is eating. Recent research revealed that ~ 5% of the air inhaled through normal breathing15 will pass through the olfactory cleft16. For higher flow rates, the figure is no more than 20%. Flow rate is an important factor in determining the strength of odours as everyone knows by instinct when sniffing intermittently to perceive an odour more precisely.

Fig. 2-B A Look inside the Nose and Throat.

2.1.2

Olfactory Epithelium

The olfactory region of each of the two nasal passages in humans is a small area of about 2.5 cm2 (0.38 inch2, Figure 2-C) containing in total approximately 50 million primary sensory receptor cells. This mucous layer, 60 microns thick, is a lipid-rich secretion that covers the surface of the receptors at the epithelium surface. Here the molecules interact with the olfactory receptors and produce the signals that our Fig. 2-C brain interprets as odour. Stem cells give rise to the olfactory receptor cells. No 2,5m cm2 other location in the mature nervous system exists wherein less differentiated stem or 0.38 inch2 cells replace neurons 17. Permanent reproduction18 secures quick recovery after pathological disorders and it might be assumed that this elucidates a remarkable significance of the sense of smell assigned by nature. Every human is provided with a fairly identical olfactory epithelium, which gives us a first hint that individual differences in olfactory sensitivity and preferences are located beyond the actual organ of smell. Notable noses are bred rather than born19.

15 16 17 18 19

About 250cm 3/sec per nostril; cf. Engen (1982), p19.

Cf. Kelly et al. (2000), p333.

Vokshoor et al. (2001), p1.

The olfactory receptor neurons turnover approximately every 40 days. Cf. Leffingwell (2001), p2.

Engen (1982), p5.

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Smell – A Neglected Sense in Architecture Physiology of Smell

2.1.3

The Trigeminal Nerve

We must also see that the olfactory epithelium contains another sensory system in the form of Trigeminal Nerve receptors. Whereas the olfactory receptor system20 is highly localized in humans, the trigeminal nerve21 provides a second set of nerve endings which are responsible for sensations of touch, pressure, pain and temperature in the areas of the mouth, eyes and nasal cavity.

Trigeminal nerve sensations involve experiences of pain and irritation and not olfaction in the physiological sense. Trigeminal information is processed in completely different ways without involving the Bulbus olfactorius (Figure 2.B) at all. Trigeminal stimulants produce effects described as hot, cold, tingling or irritating22. Thus the trigeminal system appears to be an alert system and the respective sensations contribute to SBS. Ohloff states that about 70% of all odours are said to stimulate the trigeminal nerve although, in general, the detection thresholds are several times higher23.

The physiological separation of trigeminal and olfactory stimuli enables a precise handling of odours. Whereas, for instance, propionic acid24 stimulates both, the trigeminal and the olfactory nerves, vanillin stimulates only the olfactory nerve25. Thus a precise separation of harmful and desirable odoriferous substances is possible26. Focussing on the latter this allows me to concentrate on the favourable aspects of odours in architecture without the consideration of SBS. 2.1.4

Odorant Receptors

In 1991, Linda Buck and Richard Axel discovered both the family of transmembrane proteins that were believed to be the odour receptors and some of the genes that encode them27. This was a seminal breakthrough in the understanding of the olfactory system. It is now estimated that there are approximately 1,000 odorant receptors (ORs) in humans that are encoded by a multigene family28. The number of genes specific to the olfactory system comprises 1-2% of the 50,000 to 100,000 genes thought to make up the human genome29. This number is second only to the

20 21 22

23 24

25 26

27 28 29

First cranial or olfactory nerve.

The fifth cranial nerve.

For example, leavo-menthol or (-)-menthol produces the trigeminal feeling of cold at moderate concentrations and hot at high concentrations in the nasal cavity. Other commonly encountered trigeminal stimulants include the chemicals allyl isothiocyanate (mustard, mustard oil), capsiacin (hot chilli powder, mace spray) and Diallyl sulfide (onion).

Ohloff (1990), p7; Cf. Yousem et al. (1997), p833-838.

A colourless sharp-smelling liquid carboxylic acid used for inhibiting the growth of mould in bread.

Chem. formula: C2H5COOH. Cf. Sobel et al. (1998), p8996.

Due to the abundance of different odorants there are unfortunately no comprehensive data of the odoriferous. substances subject in this separation.

Cf. Malnic, Buck et al. (1999), p713-723.

Cf. Malnic, Buck et al. (1999), p713.

Recently, Doron Lancet and co-workers at the Weizmann Institute of Science Crown Human Genome Center have constructed a database of human olfactory receptor genes by a highly automated data mining system to detect all OR genes present in the public databases. This non-redundant dataset includes 906 human olfactory receptor genes, of which >60% appear to be pseudogenes. For details and an interactive chromosomal distribution graph of OR gene distribution see http://bioinformatics.weizmann.ac.il/HORDE/humaneGenes/.

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Smell – A Neglected Sense in Architecture Physiology of Smell

receptors of the immune system. Up to now there has been no proof that the quantity of genes correlates with its importance for the human organism. Yet nature generally evolves highly efficiently according to the demands of the environment and it may argue the high number of odorant receptor genes suggests a remarkable biological significance of the sense of smell. Here nature offers an enormous number of registers to play on for anyone whose business is to create sensual environments.

2.1.5

Combinatorial Receptor Codes for Odours

Fig. 2.D In this model, the receptors shown in colour are those that recognise the odorant on the left. The identities of different odorants are encoded by different combinations of receptors.

However, each OR can serve as one component of the combinatorial receptor codes for many odorants. Given the immense number of possible combinations of Ors, this scheme could allow for the discrimination of an almost unlimited number and variety of different odorants. (From Malnic, 1999).

30

31 32 33

34

In March 1999 two teams of scientists30 seem to have unravelled the mystery of how the nose can interpret a plethora of different odours. It appears that the sense of smell in mammals is based on a combinatorial approach to recognizing and processing odours.

Instead of dedicating an individual odour receptor to a specific odour, the olfactory system uses an alphabet of receptors to create a specific smell response within the neurons of the brain31. As in language or music, the olfactory system appears to use combinations of receptors (analogous to words or musical notes, or to the way that computers process code) to reduce the number of receptor types required to convey a broad range of odours. As in genetic code where the four nucleotides 32 allow the creation of a nearly infinite number of genetic combinatorial sequences. Using a technique called calcium imaging33, researchers established which nerve cells were stimulated by a particular odour. Using this technique, it was shown that (1) single receptors can recognize multiple odorants, (2) a single odorant is typically recognized by multiple receptors and (3) that different odorants are recognized by different combinations of receptors, thus indicating that the olfactory system uses a combinatorial coding scheme to encode the identities of odours 34 (Figure II-D). This explains how ~1,000 receptors should permit the discrimination of a vast number of diverse odorants. Thus odour acuity is excellent and not - as most discussions of smell in comparison to sight and hearing like to state - dull. It is rather the ability to communicate the sense of smell which is dull, partly due to neurophysiological reasons and to an ascent of scent culture, as will be discussed below.

Buck et al. at Harvard Medical School and Hirono et al. at the Life Electronics Research Center in Amagasaki, Japan.

Cf. Malnic, Buck et al. (1999), p720.

Adenine, cytosine, guanine and thymine.

When an odorant molecule binds to its odour receptor, calcium channels in the membranes of the nerves open and calcium ions pour inside. This generates an electrical charge that travels down the axon as a nerve signal. Calcium imaging measures this influx of calcium ions; Malnic, Buck et al.

(1999), p714.

Cf. Malnic, Buck et al. (1999), p720-721.

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Smell – A Neglected Sense in Architecture Physiology of Smell

Buck and her colleagues also demonstrated that even slight changes in chemical structure activate different combinations of receptors. Similarly, it was found that large amounts of a chemical bind to a wider variety of receptors than do small amounts of the same chemical35. With changing distance to odorants concentrations differ and through this the sensual experiences. No discrete odour is approachable. Both natural and domestic environments very rarely provide stable conditions for a lasting smell sensation and therefore change is characteristic of smell. Moreover Buck’s research shows that smell not only provides a single piece of information about the existence and identity of an odorant. The nose encodes sequentially differing information in the course of sensing an odour.

The main point here is that the quality of perceived odour and thus the nature of the response to the odour may change. By this odorants seem to yield sequentially differing information, in effect they ‘talk’ to us. Ohloff reports on ancient Arabic mosques with musk added to the mortar (Samples E2-H2)36. In combination with its central position the scent was spread over its surroundings, luring worshippers to assemble in the temple. People followed the odorous – numinous – traces laid out in the city37. Approaching the temple the scent changed, from a first pleasant, luring whiff to an overwhelming sensation.

Adaptation

It is a common assumption that the sense of smell, more than other senses, is readily affected by adaptation as a result of fatigue from continued exposure to a stimulus. For example, a room one has just entered may have a noticeable odour, but it seems that the odour quickly disappears because receptors fatigue and decrease their rate of firing in the presence of odorant molecules in the mucus. Exposure to an odour may cause adaptation and thus reduce its perceived intensity but without its disappearance altogether (Figure 2.E).

It is interesting for the study of SBS that repeated stimulations of the trigeminal nerve are not subject to adaptation. On the contrary it leads to an increase in perceptual intensity, and this might counteract a possible decrease in perceived odour intensity by stimulation of the olfactory nerve.

35

36

37

Perceived Intensity

2.1.6

Duration of Adaptation in min.

Fig. 2.E Average judgments of intensity of 0.7 ppm hydrogen sulfide as a function of exposure. (From Engen,1982).

This may explain why a large whiff of the chemical indole smells putrid, while a trace of the same chemical smells flowery; cf. Buck (1999).

In the seventh century AD, musk was being traded with Arabs who valued it for its scent, and mixed it with mortar in the construction of their mosques, such as those at Kara Amed and Tabriz in Iran; cf.

Ohloff (1992), p33.

One has to consider that pleasant smells were rather rare in the cities at these days.

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Smell – A Neglected Sense in Architecture Physiology of Smell

However, sensory effects ascribed to adaptation may also be due to the related phenomenon of habituation. Without specific controls, it is difficult to know whether a decrease in the stimulating effectiveness of an odorant is due to adaptation or habituation. Adaptation describes changes in the receptors; habituation refers to a cessation of response to a novel or startling stimulus.

Summarising recent research on the physiology of the sense of smell, it can be concluded that the odorous environment speaks to us in a far more complex way than one would suppose. To participate in this communication with sophistication one has to understand both the process of accumulating odoriferous information and how it is processed in the brain, which will be discussed below38.

38

Cf. Engen (1982), p70 and Yousem et al. (1997).

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Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

3

Perception of Odours and its Implications in Architecture

Humans are the very determinant for architecture and hence smell as one of the humans’ five senses. As mentioned above the relevance of smells for the state or behaviour of humans is mainly determined beyond the olfactory epithelium and any effort to create scent architecture without the consideration of the cognitive processes would be futile.

3.1 3.1.1

Processing Odorous Data • Odour Driven Behaviour Neurophysiology of Smell

When an odour excites a neuron, the signal travels along the nerve cell’s axon and is transferred to the neurons in the olfactory bulb (Bulbus olfactorius) (Figure 3.A), the clearinghouse for the sense of smell. From here, odour signals are relayed to both the brain’s higher cortex39, which handles conscious thought processes, and to the limbic system, which generates emotions 40. The connections between the epithelium and the cortex are complex and by no means direct. It is interesting that the olfactory epithelium is only two synapses away from the hypothalamus; it is also interesting to speculate that this is consistent with the apparent importance of odour in emotionally driven behaviour.

Fig. 3.A Location of Major Limbic System Structures.

Yet it is important to understand that odours per se do not contribute to any specific state or behaviour41 (except pheromones 42). Odorous architecture does not cause any specific mood; it only initiates a response in the olfactory system. Odours may thus be considered as non-functional components of an object, but they may, however, become more powerful stimuli through association. But unless the stimuli possess some significance, they will be subject to adaptation and habituation. Yet what is significant, what neurophysiological processes turn the attention to significant information and how is it perceived and processed?

39

40

41 42

Olfaction is the only sense that has direct cortical projections without a thalamic relay nucleus.

Vokshoor et al. (2001), p3., Savic (2000), p311.

Neurons from the lateral olfactory tract project to the amygdala, septal nuclei, pre-pyriform cortex, the entorhinal cortex, hippocampus, the subiculum and hypothalamus. Many of these structures form the limbic system, an ancient region of the brain concerned with motivation, emotion and certain kinds of memory. The septal nuclei and amygdala contain regions known as the pleasure centres. The hippocampus is concerned with motivational memory. Doty (1995).

Cf. Engen (1982), p130.

Although the existence of human pheromones is still an open question, recent research suggests that observations of a sex-differentiated hypothalamic activation in humans by nonodorous concentrations of testosterone and oestrogen derivates provide a fundament for this hypothesis. Cf. Savic et al.

(2001); Sobel et al. (1999); Moran et al. (1995).

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Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

3.1.2

Perception

All living creatures only perceive what is useful to perceive43 and so do humans smell what is useful to smell. What is useful is determined by both biological as well as cultural evolution. Whilst the biological relevance of smells remains rather stable44 the cultural relevance changes according to sociological changes 45 or fashion.

Perception within an infinite spectrum of perceptible stimuli always means selection. To survive in a complex world, every being has to select the most useful data on a permanent base. These few data are the elements from which every individual forms a coherent idea of his or her world, and our primary perception tempts us to believe that this is all there is. Gaps are bridged with mental constructions, and only other individuals or artificial sensors reveal the abundance of information not perceived. Furthermore conscious perception is restricted by the capacity of the processes on which it is based. That the brain processes far more sensations than we know does not mean that they are redundant46. On the contrary, lots of our behaviour derives from unconscious mental activities, which do not enter our conscious memory47. When contemplating the roles of one’s senses, one is apt to think about odour in terms of detecting food, and hearing in terms of listening to speech, or, generally, the experience of conscious events.

But what kind of stimuli are registered by this selective attention, go on to enter consciousness and become memorable? Two major processes determine the infiltration into consciousness, the socalled bottom up and top down processes. Striking stimuli cause strong activities in the cerebral cortex, which address the mechanisms controlling attention from bottom up. On the contrary, it is possible to control attention deliberately. Conscious as well as unconscious processes influence this attention. Particular expectations alert particular modi operandi of the senses. Information from these senses receives preferred transmission, processing and entrance to consciousness and long-term memory, very much to the disadvantage of information deriving from the other senses.

The smell of smoke48, for instance, could induce strong bottom up processes if injected in the airconditioning as a fire alarm system. Even sleeping people’s attention would be raised although the reaction could be beyond the level of self-control needed for evacuation procedures. Another example for a bottom up stimulus would be the use of odoriferous doors. Swiss pine doors in contemporary glass-steel environments would draw attention to relaxation areas. In the course of time, any distinct scent of a door frequently perceived would be associated with the person or use connected to the room behind and thus could participate in the orientation of people within buildings. The easiest way to introduce the scent dimensions of a building deploying the top down 43 44 45

46 47

48

Singer (2000).

Safety, reproduction and nutrition.

Stoddart, for instance, argues that humans are characterised by having non-(body odour)advertised concealed ovulation and that this phenomenon arose in direct response to sexual interference between a bonded male and female from ‘extra maritial’ males and that its existence points to its origination within a multi-male group. Moreover he defines this development as the birth of perfumes masking the oestrus smells. Cf. Stoddart (1990), p166 and p 277ff..

Cf. Singer (2000).

Freud believed that some of the most important facets of life do not reach consciousness.

Cf. Goedde (1999).

A strong trigeminal stimulus.

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Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

route would be to label a building scent architecture. A large sign at the entrance would raise the visitors’ expectancy and sharpen the nose. Generally the neglect of the sense of smell in favour of vision results in low expectancies and simply due to untrained noses, even rich odoriferous environments are perceived to a restricted degree. It is characteristic that good taste nowadays is mainly coded visually49. Active and reflective training of the sense of smell is rather seldom in education and hence scent culture is lingering. However, not just smell culture suffers under the neglect of smell but the physiological pathways, too. Neurons undergo processes of permanent reconfirmation. Non-active neurons are eliminated50 and thus one could say that a variety of stimuli or a diverse environment enhance perception: Sana per varietatem.

People perceive what they expect to perceive and often a striking stimulus prevents the perception of the subtler and possibly more important stimuli. That is the neurophysiological foundation of panem et circenses and the breeding ground for all sensation societies e.g. our modern Big Brother society. A logical consequence is sensational architecture like, for instance, Frank O. Gehry’s Guggenheim Museum in Bilbao. Due to its striking visual stimuli, this type of architecture would be less suitable to be scent architecture and I wonder if Frank O. Gehry designed the scent of his building. As smell is easily dominated by vision and hearing bright and noisy environments either need extreme odoriferous stimuli or they are unsuitable for scent architecture altogether.

With gathering dusk and growing silence smell gains in importance51 and it is here that scent architecture should be most refined. Under this consideration it becomes obvious that crossings and bedrooms are the environmental climaxes for smell and it is here that scents retain their meaning.

The control of the spectator’s selective attention is the secret of every magician and should be the architect’s too, comprising all senses.

But why did nature develop such a restricted, fragmentary perception? The answer: Simply for reasons of economy. It is highly uneconomical and a waste of capacity to process every possible piece of information and only in rare pathological cases one finds the so-called eidetic perception or photographic memory. Nowadays perception is understood as a highly active, hypothetically controlled process of interpretation52. The early stages of information processing are driven by fairly equal, genetically fixed brain operations. Hence one finds remarkable agreements on very basic stimuli. In correspondence to this Montcrieff as well as Engen found that there is excellent agreement between people of all kinds about really bad smells; they agree unanimously in their dislikes 53. Moreover there is a very good agreement between most people about the odours they like best, but the agreement is not nearly so perfect as is that about their pronounced dislikes 54 49

50

51

52 53 54

Even more if one considers that smell to a great degree makes up the perception of taste and that smell is 10,000 times more sensitive than taste. Cf. Montcrieff (1967).

Cf. Singer (2001), p3. These processes are most powerful during the formation of the brain and become less so in the course of one’s life. However, they never stop.

A 1-decipol (unit for perceived air pollution; cf. footnote 87) change in perceived air quality has the same effect on human comfort as a change of 1.2 dB in noise level. Fanger et al., (1993) p36.

Cf. Singer (2000).

Montcrieff (1966), Rules 5.

Montcrieff (1966), Rules 6.

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Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

which is probably due to the involvement of trigeminal stimuli. More complex stimuli involve higher cognitive activities in the cerebral cortex. Information is organised and interpreted in an increasingly abstract way and semantic parameters overtake figurative parameters 55. The higher the cognitive activities, the more they derive from former experiences and learning processes, or the higher the cognitive activities the more subjective they are. That is why different people perceive the same thing as different. The numerous determinants of individual smell preferences constitute a clear obstacle to the use of odours in architecture. The use of scent in architecture must correlate with the degree of privacy or publicity wanted for the respective building or room. However, as revealed above smell includes preferences beyond individuality, too, which allows for introducing odours even in public buildings.

The strategy of extrapolation from experience to cope with future challenges is fine as long as the environment changes only at a slow pace. As our Neolithic ancestors were living in a fairly consistent environment, the natural way of perception was a good instrument to survive. Since the beginnings of modern culture the human environment has been changing at an increasing rate and misperceptions with it. However, shelter and safety is a basic need humans desire and that is why they strive for familiar environments. A common language is the crucial instrument to communicate familiarities both by verbal language and architectural language. That is probably the reason why every stable and strong culture had its own sophisticated architectural language, and cultures in transition – as ours in these times of globalisation - much less so. Odours have not changed at this rate in the course of history and it is interesting that natural scents – familiar since the beginning of mankind – are by far the most-liked odours 56. In the course of cultural evolution the palette of odours was merely added. In conjunction with the involvement of the limbic system in the processing of odorous information – a system highly connected with memory, as we will see in the following – smell is a crucial mediator of this basic need in architecture, shelter and safety.

3.2

Smell Perception and Language

Functionally smell may be to emotion what sight or hearing is to cognition, and one could justify classifying the sense of smell in the more general rubric of motivation rather than information processing. The initial experience in smelling an odour may be hedonic, a feeling state rather than a sensation, whereas in vision the sequence may be the reverse. Thus naming odours is a difficult cognitive task 57 and it seems fitting to describe odour language as both idiosyncratic and impoverished. This is undoubtedly one of the reasons for the failure to achieve a universally acceptable odour classification system58. Nowadays the so-called headspace sampling together with the analysis of the samples via gas chromatography allow to win objective odour data. Yet due to the complexity of the data the specification of odour qualities on a day-to-day basis still relies on object related language, which might be compared with the measurement of colours before Newton’s research on this topic. However, to examine or even work with a modality you must name

55 56 57 58

Cf. Singer (2000).

Montcrieff (1966), Rule 1.

Cf. Montcrieff (1966), Rule 90.

Cf. Gschwind (1998).

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Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

it, you must have a language for it. Sophisticated communication of odour qualities is difficult even for notable noses and embodies a main obstacle for the employment of odours in architecture and its planning. To enrich the built environment by smell, it needs conscious training of the nose starting in the early childhood as done with all other senses.

3.3

Physical Determinants of Smell Perception

Physical influences determine the performance of smell perception. The human organism undergoes permanent change, which has a direct influence on smell. Sickness decreases smell sensitivity and in some cases as Alzheimer’s, Parkinson’s diseases, schizophrenia, multiple sclerosis and alcoholism olfactory dysfunction is even a very early symptom59. This reduced sensitivity might be the reason for the apparent neglect of the sense of smell and its potentials in the design of hospitals and their maintenance. On the other hand, aromatherapy is nowadays widely accepted for its benefits for human physiology and psychology60, and despite all hygienic and functional demands, I would recommend the use of scent architecture in hospitals. Sick people’s surroundings deeply affect their health and are of crucial importance for their recovery.

The perception of smells is highly dependent on a person’s physical state, yet there is little academic work done to narrow down preferences applicable to architecture. Whilst the smell of food might be luring if one is hungry it might be disgusting for others who have just finished a big meal. Thus the airflows of kitchens - as the most odorous or smelly place in buildings - and other rooms with ambiguous smell stimuli have to be controlled with great care.

The most powerful determinant of olfactory preferences is age; next comes sex, which also has a powerful effect; then comes temperament, which has only a slight effect, and finally intelligence, which has practically no effect61. Children are more tolerant of odours and smells. Babies are able to detect odours but the hedonic scale of odours is largely, possibly totally, a developmental phenomenon62. Due to this, adults have the greatest sensitivity and the most precise preferences.

Starting from the age of sixty, smell sensitivity decreases at an increasing rate63, which makes old people’s houses sometimes hardly bearable for sensitive noses 64. Men and women agree well about the smells that are very bad and those that are very good, but in the intermediate ranges there are significant differences between the olfactory preferences of the two sexes 65. However, it is difficult to consider these differences in architecture. Moods influence both the sensitivity of the sense of smell and a person’s smell itself. Kirk and Smith66 revealed that stress and fear produce distinctive smells recognised by opponents. Places involving stress and fear, as e.g. offices and 59

60 61 62 63 64 65

66

Alzheimer’s disease cf.: Kovacs et al. (1999); Parkinson’s diseases cf.: Wszolek et al. (1998), Doty et al. (1988); schizophrenia cf.: Kopala et al. (1994); multiple sclerosis: Doty et al. (1997); alcoholism cf.: Ditraglia et al. (1991).

Cf. Price (1999) and Penoel (1990).

Montcrieff (1966), Rule 66.

Cf. Engen (1982), p 22.

Hulshoff Pol et al. (2000), p463.

Less care for smell plus the smell of old people with insufficient hygienic efforts.

Cf. Montcrieff (1966), Rule 11. The smell preferences of women differ to a higher degree than those of men. This is due to hormonal changes during the menstrual cycle or pregnancy.

Cf. Kirk-Smith et al. (1983).

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Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

dental surgeries should be designed accordingly. Sexual arousal sharpens the nose67 and it would be interesting to examine whether this phenomenon has influenced the architecture of harems and brothels.

3.4

Odour Memory

Another important determinant of the meaning of the sense of smell in architecture is the ability to remember the perceived stimuli and thereby particular spaces or buildings. The short-term memory and the long-term, or episodic memory, determine what information is available for cognitive activities, at what time and for how long. Both memories are only available for consciously perceived information and hence memory is subject to the same restrictions as perception68.

The short-term memory processes stimuli of transitory relevance. The rather small capacity of this memory is amazing in consideration of its importance. Without short-term memory there would be no chronology, and temporal as well as spatial orientation would be impossible. Every luring or repulsive smell would be forgotten in the next moment. The human short-term memory is merely capable of storing 7 different contents and only mnemonic strategies can improve its performance69. Thus the short-term remembrance of events is based on not more than 7 parameters – often less – and dependent on extrapolation and probabilities, too.

Fig. 3.B Average percentage correct recognition of the ‚old’ stimulus in a pair of stimuli as a function of the rentention interval for pictures and odours. (From Engen, 1982), p106.

67 68 69 70 71 72

73

To recall information and its context after days, months or years it has to be transferred into the episodic memory. In contrast to the cognitive processes during recognition, the recall of information needs far more complex activities. The inscription of information in the episodic memory can take a remarkably long time: months or years 70. Evolution developed this type of memory to enable creatures to orient within their environment, to find sources of water and food or shelter. Primarily it was a memory for places and that is why it is helpful to imagine a particular place or particular qualities of a place first, to remember i.e. the things which happened in this place71. Odour might be one of these qualities and several writers describe its special connection to memory72. Yet odour is different to vision or hearing. It is not possible to recall an odour itself, only its existence73.

Engen (1982), chapter 8.

Cf. Singer (2000).

Cf. Singer (2000).

With the exception of traumatic experiences.

Cf. Singer (2000).

Nabokov wrote: She used a cheap, sweet perfume called 'Tagore'. Ganin now tried to recapture that scent again mixed with the fresh smells of the autumnal park, but, as we know, memory can restore to life everything except smells, although nothing revives the past so completely as a smell that was once associated with it. Nabokov (1970), cf. Engen (1982).

Cf. Engen (1982).

15

Smell – A Neglected Sense in Architecture Percep t io n of Odours and its Implications in Architecture

Time seems to play no role in odour memory. In comparison to vision there is a striking difference between the two modalities for tests of recognition in the course of time (Figure 3.B). In vision the performance is nearly perfect immediately after the test (99.7%) but in smell it is less than 70%. But as the retention interval is increased - that is, as the second part of the experiment is delayed from 1 day to 1 month, visual recognition memory declines rapidly, but odour memory remains virtually unchanged74. So if you want to engrave a particular room or building in someone’s memory, smell is the medium for it. Visual aspects of architecture might be the most discussed, yet scent architecture has an unspeakably deep mental dimension. However, its power is double-edged and as you can induce an almost eternal longing for a particular surrounding by a distinct scent it can also cause an everlasting disgust75.

In contrast to a computer the brain works on an associative basis, which is a highly economical way of storing information, though not perfect. As in perception, missing information in the memory is supplied by probabilities based on experience. Thus every remembrance means an act of construction and creation.

Again, the susceptibility of memory to experience becomes increasingly problematic with the increasing rate of changes of our environment. This is probably the reason for an inherent conservatism of humans and there is evidence that recognition of an odour enhances its pleasantness76.

It becomes obvious that evolution did not develop a system detecting and memorizing highly authentic images of our environments. The human brain is an efficient operation system with a clear preference for quantity over quality. Departing from traces of information, associative memories recombine complete contexts. A distinct memory is encoded in a similar modus as odours are for the olfactory receptors77. A particular set of information is represented by a dynamic state of a specific number of nerve cells spread all over the brain. Hence one nerve cell is participating in the memory of a variety of levels of information and due to the vast number of nerve cells, the brain’s capacity is almost infinite and the probability of forgetting something by a defect of single nerve cells is very low. Good news at first sight, but there are two problems in connection with this system. First the flood of new information overwrites old data and might cause a partial damage to the code of particular information. Missing bits either have to be associated or invented and diminish the objectivity of the data. Furthermore, selectivity decreases with the flood of new and especially similar information, a phenomenon observed by everyone who has learned two closely related languages78. Therefore if we miss information which was already part of our memory, we have not forgotten it, but we cannot remember it. Unfortunately the nature of the processes that bring information back to our consciousness remains very vague, but everyone knows that odour can be a powerful reminder of things far off in the past. It might be assumed that due to its close connection with the limbic system olfactory stimuli can release striking, long forgotten – or rather not remembered – memories, described as the Proustian Phenomenon79. That is why odours are capable of launching people into lands of dreams and myths.

74 75

76 77 78 79

Cf. Engen (1982), p107.

Recollection, that is recognition after previous experience, of odours is nearly independent of pleasantness or unpleasantness; it is no more easy to remember one kind than the other. Montcrieff (1966), Rule 11.

Cf. Montcrieff (1966), Rule 90.

Cf. chapter 2.1.5.

E.g. Dutch and German.

Cf. Chu et al. (2000). Marcel Proust described this phenomenon in Remembrance of Things Past, for

Continued next page

16

Smell – A Neglected Sense in Architecture Physical Influences

4 4.1

Physical Influences Hygrothermal Conditions

Moisture content in the air in g/m3

As for life in general, water (here moisture) and temperature Relative Humidity are the two crucial determinants for smell. Writing on odours in the built environment, authors have exclusively concentrated on scents in gardens 80. That is probably due to the obvious abundance of sources and the favourite hygrothermal conditions for smell. Especially during sunset and afterwards the warmth stored in soil and buildings and the rising relative humidity81 provide ideal conditions for the sense of smell. This is one reason why lots of animals start hunting in the twilight. Humans also took advantage of this as for example the Japanese in their incense ceremony, kodo82, which was performed at exactly this time of the day.

Mainly dry surroundings such as deserts and the poles Fig. 4.A provide adverse life and smell conditions and so do dry Relative humidity as a function of moisture buildings. Insufficient humidity causes dry mucous content in g/m3 and temperature.

(From Minke, 1994). membranes and can result in chronic damage to the respiratory tract including the olfactory epithelium. Thus ideal physical conditions entail favourable conditions for the occurrence of odorous sensations in architecture. Yet not all forms of life are welcome in buildings. Mould and dust mites appearing in conjunction with excess moisture are severe problems in architecture.

The medically recommended humidity within buildings is ~50% relative humidity (RH)83. Inhabitants still feel comfortable at 30% RH at ~25°C up to 70% RH at ~18°C84. The recommended temperatures differ according to room function, varying from 15°C in toilets to 24°C in bathrooms 85. Permanently used rooms as offices or living rooms should be ~20°C warm. Within these conditions the nose itself provides ideal hygrothermal conditions for the olfactory epithelium by warming and humidifying the inhaled air to 32°C and 88-98% RH through the surfaces of the nasal cavity86.

To find the ideal hygrothermal conditions for architecture one must consider primarily health aspects. High humidity is favourable for the occurrence of scents but it has problematic consequences, too. High temperatures impede breathing and increase transpiration. In the

80

81 82 83 84 85 86

full text see Appendix III. E.g. Sanecki KN, The fragrant Garden, London, Batsford, 1981; Squire D, The scented Garden, London, Salamandr, 1988; Perry F, Scent in the Garden, Exeter, Webb & Brown, 1989.

For the relation of absolute - and relative humidity see Figure 4.A. Cf. chapter 6.1.2.

Cf. Buss (1987), p114.

Cf. Buss (1987), table 5.6.2, p178.

Cf. Buss (1987), p165-166.

Prof. G. Mlynski, ENT Department University of Greifswald, in personal consultation.

17

Smell – A Neglected Sense in Architecture Physical Influences

operative temperature range a 1°C change in perceived air quality was found to have the same effect on human comfort as the change in perceived air quality of 2,4 decipol87.

Moreover moist house-dust can carry pathogens and mould and house-dust mites proliferate in moist and warm surroundings. Research reveals, however, that bathrooms and kitchens, usually regarded as the moistest rooms in buildings, are less susceptible to mould than bedrooms 88. Due to the lasting human input of humidity, such rooms provide more stable conditions for mould than bathrooms and kitchens, with only short peaks of high humidity. To get going mould needs at least 80% relative humidity on the surface of building materials, 12 hours a day on 5 consecutive days.

Like mould, dust mites proliferate in stable humid and warm conditions 89. If the relative humidity is kept below 70%, however, adult mites survive for short periods only.

Therefore optimum hygrothermal conditions for scent architecture can be achieved without negative impact on the inhabitants or the architecture itself. It follows that in seeking areas to rehabilitate or to reintroduce odours in architecture one has to look for rooms with clean air90, relative humidity levels of 50-70% at temperatures from 15ºC to 24ºC according to the intended use91.

4.2

Outgassing

Outgassing can be defined as a form of evaporation of volatile compounds contained in solid materials 92. The outgassing rate is highly influenced by a material’s vapour permeability and the adhesion or volatility of the contained substances.

Since homes are now constructed tightly sealed in order to conserve energy, outgassing from building materials is more potent, either harmful or pleasant. Due to the focus on negative impacts of outgassing as part of SBS there is little information on outgassing rates of building materials’ scents. The use of solid wood93 will not only mitigate a potential indoor air quality problem; it also has the potential to reintroduce scents of materials on a long-term base. Temperature and thickness are decisive for the rate and duration of outgassing. Surfaces that are heated, e.g. when they are exposed to the sun, or near a heater or other sources of heat, increase the outgassing rate and have a shorter scent performance of materials. Nowadays buildings face an average lifespan of ~75 years (with a decreasing tendency) and thus scent architecture beyond short lived, 87

88 89 90

91 92

93

Decipol = An empirical unit of indoor air pollution introduced by the Danish environmental scientist P.O. Fanger in 1988. One olf is defined as the air pollution produced by one standard person, and one decipol is the perceived air pollution level in a space having a pollution source of strength one olf and ventilation at the rate of 10 litres/second with unpolluted air. Measurements are recorded by human observers using protocols laid out by Fanger and his colleagues. Fanger (1988), p155-157.

Cf. Richter (1999), p19.

Cf. Crowther (1997), Table: Temperature and humidity needs of the house-dust-mite.

Generally high ventilation rates of clean air are followed by a higher satisfaction with air quality. Cf. Fanger (1990-91), p42.

Peaks can be higher for short periods (in bathrooms, saunas, etc.).

Outgassing rate = Quantity of gas evolving from a unit area of a solid surface in unit time, measured in torr litre / sec and outgassing rate is in torr litre / cm2 sec.

Instead of plywood, particleboard or medium density fibreboard partially made with toxic glues and outgassing urea formaldehyde.

18

Smell – A Neglected Sense in Architecture Physical Influences

fashionable interior design considerations must seek for adequate materials and construction methods. Obviously any material’s rate of outgassing finds its maximum after cutting or drying up to the average hygrothermal working conditions of a new building. Yet the curve of decrease does not necessarily reach zero. Again no research has been done on how long materials smell and to what degree the scent of old buildings participate in their particular atmosphere but alpine log cabins, several decades, sometimes over 100 years old, panelled with Swiss pine94, or the Arabian musk mosques 95 prove that odorous materials are capable to perform over a building’s full lifespan.

The cost of using solid unsealed materials is higher than for conventional materials. An additional option to prevent harmful outgassing is to seal the particleboard, interior plywood, or medium density fibreboard (MDF) components with an appropriate finish. This should be done prior to installation since it is necessary to reach all edges and surfaces. An increase in costs brings into question, whether to choose solid materials right from the start and not having allergens or toxics 96 behind a thin layer of sealing.

Providing desirable indoor climates does not mean merely to exclude hazardous gases. As discussed earlier on humans need diverse sensual stimuli, and to include the sense of smell in the design of buildings it needs exact data on the particular scent performance of materials in terms of intensity and duration. Yet even having these data it will be a difficult task to achieve the full control over every odorant and its interaction with others and the complex, permanently changing climate conditions of buildings. These will be discussed below.

4.3

Sorption

Sorption97 (adsorption and desorption) phenomena are operative in most natural physical, biological and chemical systems. The process of adsorption involves separation of a substance from one phase accompanied by its accumulation or concentration at the surface of another98.

The adsorbing phase is the adsorbent, and the material concentrated or adsorbed at the surface of that phase is the adsorbate99. Physical adsorption is caused mainly by van der Waal’s forces and electrostatic forces between adsorbate molecules and the atoms which compose the adsorbent surface. Thus adsorbents are characterized first by surface properties such as extension area and polarity. A large specific surface area is preferable for providing large adsorption capacity, but the creation of a large internal surface area in a limited volume inevitably gives rise to large numbers of small sized pores between adsorption surfaces. The size of the micropores determines the accessibility of adsorbate molecules to the internal adsorption surface, so the pore size distribution of micropores is another important property for characterizing adsorptivity of adsorbents 100. In general large pores ad- and desorb faster but less deep as small pores, an important rule of thumb 94 95 96 97 98 99

100

The Swiss pine, Pinus cembra, contains a high density of resin ducts.

See chapter 4.1.2.

E.g.: Chlorinated hydrocarbons, aromatic hydrocarbons, Aliphatics etc..

Latin: sorbere = to swallow.

Slejko FL (1985) and Suzuki M (1990).

Adsorption is thus different from absorption, a process in which material transferred from one phase to another (e.g. liquid) interpenetrates the second phase to form a solution.

Cf. Slejko FL (1985) and Suzuki M (1990).

19

Smell – A Neglected Sense in Architecture Physical Influences

for the evaluation of the odour mediating performance of building materials as discussed later on (Figure 4.B).

The current methods of predicting indoor humidity are lacking because they neglect moisture ad- and desorption by building materials and furnishings, even though several researches have shown sorption effects to be significant. Experiments demonstrated that peak indoor humidity can be reduced by 20%, while the lowest humidity can be increased by 10% RH101.

Sophisticated use of materials with sorption qualities can improve the perceived indoor climate102.

Through sorption materials store surrounding smells and according to their sorption qualities they are either short- or longterm memories of smells and everything associated with them in buildings.

Fig. 4.B Sorption curves of 11.5 cm thick internal walls at 21°C and an increase in RH from 50% to 80% on both sides over 16 days (from Minke, 1994).

1 Loam (low percentage of clay) ρ1800, 2 Loam (high percentage of clay) ρ1900, 3 Loam with straw ρ1400, 4 Loam light ρ700, 5 Loam light ρ550, 6 Pine ρ450, 7 Aerated Concrete ρ400, 8 Gas Loam light ρ750, 9 Perforated Brick ρ1500, 10 Light Brick ρ800, 11 Brick ρ1800, 12 Sand-lime Brick ρ2200, 13 Concrete C15 ρ2200.

4.4

Friction

Another crucial phenomenon for the emergence of odours in architecture is friction. Almost everyone knows by instinct that to prove the quality of herbs one has to rub the leaves between the fingers. Odorous molecules are activated and released to the air or stick to the surface rubbing against the odorant. Human interaction with buildings activates space and from touching architecture its specific odours are made perceivable. Every step and grip has the potential to include the sense of smell in architecture and offers architects a chance to include another sensual dimension.

101 102

Teischinger (1990), pp249.

Minke gives the example of a house in Kassel, Germany, with the walls built from clay. Measurements revealed a RH of ~ 50% RH ±5%, in the bedrooms 55%-65% due to lower temperatures.

Cf. Minke (1994), pp. 23.

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Smell – A Neglected Sense in Architecture Physical Influences

The elements of architecture most stressed by human use are stairs and floors. Due to kinetic energy more than the full weight of a person rubs against a few square centimetres of material and easily releases odorous molecules from even sturdy materials 103. Yet modern floor materials do rarely have odorous potentials and if, it is either by chance or covered under layers of varnish.

Timber floors would have potential to interact with human steps, yet other practical requirements can easily spoil that potential. First of all the architect has to choose odorous timber104.

Odoriferous timber smells because of the included essential oils and resins, which make it resistant to fungi and rot. Such timber has a highly dense distribution of micropores. Thanks to this, the process of outgassing is slow which means the smell lasting. At the same time the small micropores give such timber high stability and make it hard. Thus odorous timber belongs to the most durable types of timber and it is not by chance that Noah’s Ark is said to be built from cypress timber105, together with the Cedar of Lebanon the most often mentioned plant in the Bible.

Modern hygienic standards try to achieve surfaces of almost antiseptic quality. Apart from the negative impacts of such overtidyness 106 this often leads to the use of synthetic seals which themselves give off harmful chemical compounds. Moreover in sealing timber with all sorts of varnishes one seals their odour, too107.

A disadvantage is that most of these timbers cost considerably more than pine or even oak, which are commonly used for timber floors. Yet this is no reason to exclude their odorous potentials from architecture. As discussed above human perception is nowadays understood as a highly active, hypothetically controlled process of interpretation108 based on processes of selection109. Thus it is not necessary to cover a whole room with olive wood (Sample A1) to achieve an Italian atmosphere. It would be enough to have the threshold made from untreated olive timber to set up this atmosphere for anyone entering the room. Moreover this sensation is subject to adaptation, its intensity decreasing considerably after a few breaths anyway. Thresholds are highly used elements in architecture, thus they are subject to high loads of friction energy. These thresholds would be very robust, durable and odorous and would age beautifully over decades.

Another potential disadvantage is that friction is by definition followed by attrition. Attrition followed by a dangerous decrease in functionality is unacceptable. However, attrition does not necessarily include negative impacts on architecture. Contemporary architecture rarely considers the ageing of a building and its materials from an aesthetical standpoint. Steps, beautifully worn in centuries of use and displaying history (e.g. in Oxbridge colleges) are almost unthinkable nowadays. Concrete floors or steps mixed with musk or other odorants, or wooden steps made of durable odorous timber could meet the requirements of functionality, durability and smell.

103 104 105

106 107 108 109

E.g. asphalt.

Please find a list of odorous timber in chapter 5.1.1.

Cupressus sempervirens, cf. Bible, Book Moses 6.14, German universal translation (1980). Most of the English translations give gopher wood (Cledrastis lutea) as the Ark’s timber.

The hypothesis that antiseptic surroundings increase the probability of allergies is gaining support.

Cf. chapter 5.1.3.

Cf. Singer (26.09.2000), p3.

See chapter 3.

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Smell – A Neglected Sense in Architecture Physical Influences

Thus to reintroduce scents in architecture the architect has to look for elements frequently or heavily used. Every building, every room has paths and areas of typical use. Doors are the needles’ eyes in architecture through which everybody has to go to. Windows are also much frequented, unmovable elements. Light, fresh air and vistas lure the inhabitants to use them. Windows are of great interest with respect to odours in architecture because of the transition of indoor and outdoor climates, which will be discussed below110. For the provision of optimal functionality most architects develop connectivity or circulation patterns. This is an ideal basis for the creation of scent architecture, too. More precise patterns comprising the friction between architectural components and all extremities as well as the torso and the head would provide a helpful tool to apply odorous materials at exactly the right position.

Touching architecture by hand involves little friction. Thus fewer odorous molecules are set free, yet the molecules released are closer to the nose and might stick to the fingers. Doors, windows and railings are most frequently touched by hands, and again timber is a favourable material for that purpose. Sash windows made from odorous timber without any or with appropriate sealing could be excellent components of scent architecture due to the friction of its parts and between the window and the hands close to the nose. Closer looks at old parts of buildings show exactly, where the users support themselves, where the pull or push occurs. Newel posts are excellent elements for that purpose, because most people use them. Especially at turning points of the stairs’ direction, most of the kinetic energy of this turn is transferred to the top of the newels.

Simultaneously the floor just below the newels is subject to high friction. Here the feet, or shoes twist without any forward movement and cause high friction. However, other materials, such as metals are used quite a lot and are subject to the same phenomenon with respect to their odorous potentials.

Contents might contribute considerably to scents released by friction. All sorts of fabric in the form of curtains, chairs, sofas, beds etc. could be included, however, their smell performance is mostly restricted due to their synthetic nature or might be even dangerous through outgassing of allergens or other toxic substances. An exception to this rule and an excellent example for scent architecture in a very sophisticated interaction with its surrounding micro- and macroclimates is the Indian khus, a screen woven from the roots of vetiver, discussed in the chapter on odorous building materials.

For maximum precision of scent design in architecture the suggested enhanced circulation pattern would have to be added by a time scale. As we shall see in the next chapters macro- and microclimates are crucial for odours in architecture and differ considerably between a typical working day, the weekend, standard types of weather conditions, seasons etc.. It would thus be interesting to have a map of all surfaces of a typical building giving the frequency of use over different periods of time together with their respective loads. Where there is touch, there could be odour. A main disadvantage for the use of friction for scenting a building is that where there is touch, there is dirt. Thus an insightful use and maintenance is essential.

110

Cf. chapter 6.1.1.

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Smell – A Neglected Sense in Architecture Physical Influences

4.5

Macroclimate

Climate is of crucial importance for scent architecture. External hygrothermal conditions have no influence on the physiological performance of the nose111 yet are decisive for the occurrence of odorous molecules. Temperature and moisture being the two most important climatic smellparameters, in extreme climates at the poles or in deserts rarely occur smells. Hence, Arabic gardens – sheltered from the adverse climate by high enclosures and a roof of palm leaves – were odorous oases, too. Fountains and the transpirations of the plants provide an ideal microclimate for odours and these scents contributed greatly in the paradisical impression they induced in the visitor.

Generally one could say that warm climates such as those around the Mediterranean are favourable for the performance of odours and quite often one finds more sophisticated scent cultures in these areas. The Andaman Islanders 112 have constructed their calendar on the basis of a distinct succession of odours, naming the different periods of their year after the fragrant flowers that are in bloom at different times 113.

As we will see later a wide range of odours derive from natural materials and they tend to be best liked114. Plants adapted to hot climates cover themselves with clouds of vaporised moisture. By this they achieve natural ventilation through the cooling effect of evaporation. Simultaneously they have to attract insects for pollination and must resist fungi and other pests, for which warmth and moisture are favourable, too. Essential oils and resins achieve both tasks.

Yet Central Europe provides satisfactory odour climates, too. To evaluate their inherent potentials one has to examine climatic cycles and their influences on temperature and humidity. Because odours being subject to adaptation sudden climate changes are of special interest.

Despite high averages of relative humidity the winter is poor in hygrothermal alterations and thus constitutes the off-season for odours. Fairly constant cold temperatures enhance this phenomenon.

Even if the sun is shining it does not have the strength to alter the temperature and humidity significantly (Figure 4.C / Winter). Dry indoor climates decrease the odorous potential of architecture even more, yet due to modern insulation standards and thus sealed facades the level of humidity is kept on a higher level. Nevertheless the winter causes a reduced interaction of indoor and outdoor climate.

111 112 113 114

Cf. chapter 4.1.

The Andaman Islands lie off the coast of Burma in the Bay of Bengal.

Cf. Classen et al. (1994), p95.

Cf. Montcrieff (1966), Rule1.

23

Smell – A Neglected Sense in Architecture

Relative Humidity [%]

Temperature [ºC]

Physical Influences

Winter

Spring

Summer

Autumn

Figure 4.C Temperatures and relative humidity during typical days of the different seasons.

(From Wettinet, 2001).

After months of privation spring introduces striking climate changes and I wonder to what degree hedonistic escapades can be traced back to the nose115. The earth is still saturated with water and in comparison with the summer sun the spring sun dries up the air to a lesser degree, but already releases additional humidity from the ground at full height and strength (Figure 4.C / Spring).

Whilst in winter the outdoor climate is mostly locked out, spring allows opening up buildings to their surroundings. This brings back not only the scents of nature from outside, but revives odorous materials inside the architecture as well. The summer is the driest season of the year, yet rich in odours. Due to high amplitudes of temperature and humidity the nose comes across striking hygrothermal changes and with it odours (Figure 4.C / Summer). In the morning high humidity, rising temperatures and eventually direct sun provide ideal smell conditions 116.

Smell – the subtle sense – is easily dominated by the other senses 117. Therefore summer evenings have an ideal combination of parameters. First of all higher relaxation, darkness and less noise make individuals more susceptible to smells. Moreover humidity reappears due to falling air temperatures, rising relative humidity and less or no direct evaporation by the sun. The ground releases gently the stored thermal energy and with it its odours. The autumn is characterised by a similar phenomenon, yet not on a daily but a yearly basis. In our central European climate the late summer and autumn provides a favourable combination of relative humidity and warmth (Figure 4.C / Autumn) and probably everybody knows the slightly morbid scent of rotting leaves pointing towards winter. Generally one could say that humid conditions of ground temperature higher than air temperature are favourable for the occurrence of odours.

115 116

117

Cf. footnote 42.

It is at this time of the day that herbs reach the highest concentrations of essential oils and thus the best time to harvest them.

Cf. chapter 3.

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Smell – A Neglected Sense in Architecture Physical Influences

Sociological differences influence macroclimates relevant for odours in the daily life as well. Cities are vast thermal storages with the consequence of smaller amplitudes in temperature and humidity.

Due to higher temperatures in cities there is less relative humidity118. Moreover the built environment generally absorbs 5-50% less precipitation depending to its density119, which causes low percentages of absolute humidity.

Cities themselves have typical smells. My hometown Hamburg is characterised by its smell of the river Elbe. Not the water itself is responsible for this slightly musty smell of algae and the whiff of sea air. In Hamburg the river Elbe is still a tidal stream confined with artificial banks made from rocks. These rocks expose a high surface area to the permanent process of ebb and flow and considerable amounts of water are evaporated from the rocks, which are covered with algae and sludge. Due to Hamburg’s vicinity to the North Sea and the Baltic Sea a permanent fresh wind distributes this smell throughout the city120.

Finally, humidity and temperature change very quickly due to weather. Sudden weather changes can strongly interact with the microclimate of buildings. Pliny describes the scent of earth after a shower as that divine breath of hers, of quite incomparable sweetness, which she has conceived from the sun121. It is obvious that the odorous potentials of the direct surroundings of a building and the skin of the building are heavily dependent on weather conditions. Scent architects need to be fully aware of typical meteorological data, like main wind directions and wind force, average precipitation, sunshine hours etc.. An abundance of divine breaths can be caught by architecture as will be examined in the chapter Built Impacts on Odours in Architecture.

118 119 120

121

Munich 7.9.81: 55% RH in the city centre and 90.4% of the city; Cf. Fezer, F. (1995).

Cf. Fezer, F. (1995).

Probably the scent of London’s centre is affected by the tidal activities of the Thames, too, although due to the bigger size of the city and the smaller river less so.

Cf. Pliny, Natural History, vol 5, k 17, translation by H. Rackham, Heinemann, London, 1961.

25

Smell – A Neglected Sense in Architecture Sou rces of Odours

5

Sources of Odours

5.1

Building Materials

Outgassing and sorption are the keys to the understanding of how materials transmit smells. The less porous materials are the less they ad- or desorb odorous molecules and consequently the less they smell. Dealing with scents as one inherent dimension of architecture one has to focus on lasting smell phenomena. Few materials have the ability to outgas their natural smell over the full lifespan of a building, yet by permanent ad- and desorption even materials without an inherent scent as, for instance, plaster do have considerable impacts on the smells of buildings. Small micro pores and large internal surfaces cause long ad- and desorption processes and primarily organic materials as timber, leather, fibres etc. meet these requirements. Created as highly permeable materials, animal skins, timber, roots etc. keep their physical sorption qualities after death. The production of aromas is limited to the respective lifetimes. Thus one has to separate building materials into materials actively participating in the scent of architecture and materials mediating odours.

5.1.1

Odorous materials

Natural materials are the best liked olfactorily 122. Synthetic chemicals are much less liked123. The pleasantness of the odours of natural products is partly due to their complexity. Trace constituents modify and improve the quality of their odours124. It is not yet possible to build up copies of natural odorous products 125, which are so well liked, from synthetic materials. Always the natural product is preferred126.

Timber is the most frequently used organic material in architecture. Moreover it is probably the most important actively smelling constituent of scent architecture. All timbers have a typical wooden scent, but most of them only for short durations 127. Probably the most striking example of contemporary scent architecture, the Swiss pavilion at the world exhibition in Hanover in 2000128,

122 123 124 125

126 127

128

Montcrieff (1966), Rule1.

Montcrieff (1966), Rule1.

Cf. Montcrieff (1966), Rule2.

Nature not yet reproducible. E.g. the scent of Rosa damascener is a composition of ~500 different chemicals, more than 260 still not known; Ohloff (1990), p154 Montcrieff (1966), Rule3.

Terpenes (a large group of unsaturated cyclic hydrocarbons) found in the essential oils of plants, especially conifers, as constituents of the typical wooden scent, are known to be irritants in high doses.

Future outcomes of research on the allergenic potential of terpenes should be considered using timber in architecture.

The pavilion was built by the Swiss architect Peter Zumthor. To my knowledge it is actually the only existing contemporary example of architecture which underwent an active scent design. The architects claim to have designed the whole scent palette of the building (Zumthor P et al., KlangkĂśrperbuch, Birkhauser, 2000), yet personal conversations revealed that the scent design was restricted to the use of odoriferous timber (Douglas fir (Pseudotsuga menziesii caesia) and larch (Larix decidua)).

26

Smell – A Neglected Sense in Architecture Sou rces of Odours

was subject to exactly this problem. Built from piles of two different timbers 129 the pavilion’s scent had a considerably higher intensity at the opening than shortly before the closing of the exhibition three months later130. Timbers of short-lived scent qualities are of minor interest for this study and unfortunately most of the construction timbers as fir (Picea abies) or pine (Pinus sylvestris) do have this disadvantage. Only under great stress the surface of these timbers is damaged or cut and sealed odorous molecules are released. High attrition excludes the use of these timbers from scent architecture. At least these timbers can be beneficial to indoor climates or act as short-term smell memories through their rather quick sorption qualities 131.

However, several timbers have both lasting smell and durable constructional qualities as compiled in Table 1. The scent of these timbers, although distinctively wooden, can differ considerably132.

Cedars provide the most famous timber for scent architecture and numerous temples 133 and palaces 134 were built with cedar wood. The Lebanese cedar135 represents the primus inter pares, and the history of this timber is full of myths and legends. Due to the plant’s impressive appearance (Figure 5.A) and its timber’s scent and durability the Lebanese Fig. 5.A Cedar has long symbolised strength, dignity and Cedar of Lebanon, greatness. There seems to be a divine element Cedrus libani. connected with cedars spread over several unrelated cultures. For example Japanese Shintoism is deeply related with these divine trees 136.

Cedar, or sugi trees line the path to several Shinto shrines 137. The shrines were built from cedar, too, and are still subject to a unique rite called Shikinen zotai, a periodic rebuilding. In the shikinen zotai rite, buildings in religious precincts are razed and rebuilt periodically in certain ceremonial years. At Ise the rite is held every 20 years 138 and I wonder if the outgassing of the cedar timber 129 130 131 132 133 134

135 136

137

138

Cf. footnote 128.

Observed by the author in similar weather conditions.

Cf. chapter 4.3.

E.g. Brazil Cedar (Sample B1) and Florida Cedar (Sample C1) 1st and 2 nd temple at Jerusalem. Nave, roof and tiles, cf. Bible 2 Chronicles 3:1-17.

Solomon also sent this message to King Hiram at Tyre: Send me cedar logs like the ones that were supplied to my father, David, when he was building his palace. 2 Chronicles 2:3, Bible, The New Living Translation.

Cedrus libani.

The Nihonshoki (Chronicles of Japan) describe a myth, which explains how the land of Japan became a green land. One day, Susanoo-no-mikoto, the deity who founded the culture of Japan, pricked one of his beard hairs and transformed it into a cedar tree. He also pricked one piece of hair from his breast, one from his buttock, and one of his eyebrow, to make each of them respectively a cypress tree, a black pine tree and a laurel tree. And he ordered his offspring deities, Itakeruno-mikoto, Ohyatsu-hime, and Tsumatsu-hime to spread these trees in order to make the whole land green. Cf. Shinto-Online Network Association (2001) The word Shinto is composed of two characters, the first (Shin) means god and the second (To) means road or path: In other words the way of the Gods.

Last in 1992.

27

Smell – A Neglected Sense in Architecture Sou rces of Odours

might be one reason for it besides religious concerns. This might be even more probable because the shrines often keep precious written relics, either written on silk or paper. Moths and other insects endanger both materials and cedar is well known for being a natural insecticide.

Unfortunately there is no study on outgassing time spans of materials. However, it might be assumed the scent of cedar to last for 2 decades. Other fragrant timbers are cypress, thuja, olive, some species of pine, palisander etc.

NAME

BOTANICAL NAME

FAMILY

ORIGIN

Cupiuba Californian Cedar Atlas Cedar Lebanese Cedar Yellow Cedar Cypress Juniper Florida Cedar Thuja, Red Cedar Cerejeira, Amburana Palisander Angelim vermelho Brazil Cedar

Goupia glabra Calacedrus decurrens Cedrus atlantica Cedrus libani Chamaecyparis nootkatensis Cupressus sempervirens Juniperus communis Juniperus virginiana Thuja plicata Amburana cearensis Dalbergia nigra Dinizia ssp Cedrolus odorata (deciduous tree!)

Olea europea

Ceastraceae Cupressaceae Cupressaceae Cupressaceae Cupressaceae Cupressaceae Cupressaceae Cupressaceae Cupressaceae Fabaceae Fabaceae Mimosaceae Meliacea

Bolivia Florida Lebanon, Syria, Turkey Lebanon, North Africa East Asia Southern Europe Europe, Asia Florida NW of North America South America SE of Brasil South America Brasil

Oleaceae

Pinus ponderosa Pinus cembra Pinus rigida Amyris balsamifera

Pineceae Pineceae Pinaceae Rutaceae

North Africa, Southern Europe America Alpes SE North America New Guinea

Olive tree Ponderosa Pine Stone Pine Pitch Pine Torchwood, Sandelwood

SAMPLE #

C1 D1

B1 A1

Table 1 Collection of odoriferous timbers.

Other organic odorants relevant for scent architecture are fibres. Although not a classic building material and rather part of the furnishing fibres can be included in scent architecture with great sophistication, as exemplified by the Indian khus (Figures 5.B.1-2). There is no air conditioning in rural India. The natives discovered that the roots of the khus plant, known as vetiver grass 139 in the West, could be woven into mats, like curtains. These are hung over the open doors and windows 140 and sprinkled with water every few hours. Any breeze that passes through a khus mat produces cooling by evaporation, repels insects and fills the rooms with a pleasant scent.

Vetive r blin ds, that len d To burning su mme r noons The s cente d chill Of winter nights.

Bihari (1595-1664)

139 140

Vetiveria zizanioides.

The ideal position, as we will see later in the chapter 6.

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Smell – A Neglected Sense in Architecture Sou rces of Odours

Fig. 5.B.1-2 Khus in India.

Unfortunately I do not know whether vetiver fibres could be woven industrially and rather as a light and permeable fabric than a coarse mat. If so, there would be a sun-shading market to invade and even the most technical buildings could be surrounded by a scented breeze. Again there is unfortunately no information on how long khus smell or how often they have to be changed. Due to the wide use of khus in Southern India it might be assumed that vetiver mats are rather cheap. Other uses for fragrant fibres could be screens exposed to previously determined airflows, wall hangings, rope handles or thatching (Figure 5.C).

Originally tar is a natural material141, too, and was used in architecture from the late 19th century onwards as damp proof coating on floors, walls and plinths. Nowadays most of this material is produced synthetically as a by-product of oil refining.

Fig. 5.C Beside the traditional use as road or pavement surfaces 142 Seaweed thatching, asphalt invades the interior in form of prefabricated slabs Laesoe Island, Denmark.

(Sample J1). Floor surfaces made from these asphalt slabs do have the typical scent of tar. Despite being originally natural this scent is not generally perceived as pleasant. To some it is very pleasant, for others disgusting. The latter reaction might be due to the typical association of this scent with streets. By lifelong experience the scent of tar is connected to roadworks and thus considered as being unacceptable for architecture. Moreover asphalt is known to be allergenic143 and thus reveals that what smells good, is not necessarily good for you.

141 142 143

Distilled from wood or coal.

Average size 25 x 25cm.

Cf. Lynch RM, Kipen H. (1998).

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Smell – A Neglected Sense in Architecture Sou rces of Odours

The smell of vulcanised rubber is subject to a highly associative perception, too. Everybody knows bicycle shops or garages with piles of new tyres and that is why the same material used as doormats creates the association with these places 144. As we can see from this, memory does have a considerable impact on the perception of scent architecture as already discussed145.

Metals have few scent qualities. Only under special circumstances metals can smell, as rust or Corten steel do have a typical smell or brass and silver if touched. Despite being more or less scentless metals do have importance for scent architecture. For a differentiated use of odours in architecture, nonodorous areas are as important for odorous areas as pauses in music. Due to these qualities, smell laboratories are covered with aluminium panels.

The smells of plastics are generally perceived as unpleasant and outgassing may contribute in SBS phenomena. Plastics have to be applied with care in scent architecture.

Finally one has to take into consideration that the scent of some materials is actually the scent of their typical companions. For instance, the scent of weathered stone is often that of moss, lichens or algae or the scent of linoleum is close to beeswax, which is one ingredient of the floor polish146.

5.1.2

Odour mediating materials

Masonry has few inherent smells, yet most mineral building materials mediate odours. Construction sites have the characteristic smell of fresh concrete, which disappears when the material is set and dry. Stone does not smell. However, stones can participate in scent architecture indirectly by the choice of surface. Water evaporating from flamed granite smells differently than water turning to vapour from the polished material. As with all other materials the size of external surface is decisive for their smell performance as well.

The most precious potential for the use of mineral materials in scent architecture are their odour mediating qualities. Lime mortar was estimated by the ancients for exactly this quality, which was utilised by adding fragrances to the mortar. Pliny wrote: At Elis there is a temple of Minerva in which, it is said, Panaenus, the brother of Pheidias, applied plaster that had been worked with milk and saffron (Samples E5-H5). The result is that even today, if one wets one’s thumb with saliva and rubs it on the plaster, the latter still gives off the smell and taste off saffron147 148.

Another striking example deriving from the 15th century still can be sniffed in the mosque of Sefa Camisi in Turkey. Here the mortar was mixed with musk (Samples E2-H2) and thus the temple is known as Misk (Musk mosque). Males rate the musky smell of musk significantly better than do 144

145 146 147 148

For instance, the entrance of the University of Applied Sciences in Hamburg is carpeted with such rubber mats. The smell is rather unpleasant, yet due to the focus of the University on technical subjects it might induce adequate associations in visitors.

Cf. chapter 3.4.

Recent improvements of linoleum make polishing unnecessary.

Cf. Pliny, Natural History, Vol10, bk36, translation by H. Rackham, Heinemann, London, 1961.

At the time of Pliny the Elder (23 or 24 – 79 AC) the temple of Minerva at Elis must have been approximately 500 years old. The temple itself was never found, but Pheidias lived in the mid-5thcentury BC and so did his brother.

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Smell – A Neglected Sense in Architecture Sou rces of Odours

females. Muskiness appears to be a sex attractant for males 149. At that time mosques were reserved for men and it would be interesting to know, if the Muslims were consciously aware of this phenomenon and for what reason the musk was added. In any case, this is a fascinating interaction of scents, architecture and culture. Essential oils won from flowers were added to mortar and plaster150, too, but there is no knowledge what fragrance was used in what type of mortar or plaster (Rose-oil samples E4-H4) in what thickness.

The quality of mediating odoriferous molecules is a result of sorption as well as water vapour permeability. Materials with both a high permeability and a high sorption coefficient as, for instance, clay, actually show a lower permeability to water vapour under dynamic circumstances, because the water is adsorbed before it has diffused far151. Thus loam has a small active depth for moisture exchange and would be best for scented plaster. On the contrary lime mortar has little sorption qualities and a mediocre permeability and thus a great active depth for moisture exchange.

Thick layers of lime mortar could store greater amounts of odoriferous molecules and thus perform longer. Finally the performance of scented walls or floors depends on the adhesion and the detection threshold of the fragrance used and the ventilation rate employed. Unfortunately no research has been done on this subject and the samples added to this paper allow only a first impression of how different scented materials smell.

Although primarily used for interior design, I would like to include leather in this discussion due to its outstanding scent qualities. Leather comprises both smell qualities: It has a distinct and wellliked scent152 and is an ideal mediator of odours by ad- and desorption. Due to its natural microstructure, leather can store scent for years and in 18th century France screens were covered with scented goat leather153. However, the natural scent of leather154 was appreciated, too, and was and is used for wallcoverings and all sorts of furniture. Over the years the natural leather scent decreases but because of its excellent mediating qualities leather stores the accumulated scent of the respective room or building. Due to the traditional leather, bindings this scent is the olfactory character of old libraries. To evoke this character in the times of paperbacks, some recently built libraries deliberately use leather in their interiors 155.

149 150 151 152 153

154 155

Cf. Montcrieff (1966), Rules 17 + 46.

Ohloff (1992), p123.

Padfield (2001).

Partially deriving from the tanning process.

Scented leathers were in fact the start of the perfume industry in Grasse, France, in the 16th century. In 1759, high taxes finally put an end to tanning. Manufacture of perfumed leather goods gave way to the production of perfumes alone. Cf. www.cannes-on-line.com/Anglais/histarrpaysuk.html, observed 10.10.2001.

Partly as a result of tanning.

E.g. British Library.

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Smell – A Neglected Sense in Architecture Sou rces of Odours

5.1.3

Treatment of Materials

A crucial determinant for the use of odorous or odour mediating materials is the treatment of the surfaces. Paint, oil, wax, etc. all seal materials and with it their scent.

Humble trials on a very restricted selection of materials 156 suggest that different sorts of timber behave differently under different seals. Olive wood almost completely remains its olfactory qualities if treated with oil. In contrast Florida cedar, which has one of the strongest odours among timbers, loses its scent.

Generally, untreated materials would be best for scent architecture157, yet functional, hygienic or aesthetic considerations might force the architect to resort to sealing substances 158. As shown in figure 5.D paint not necessarily deprives materials of their permeability altogether, however, it would be useful to have an exact knowledge about the smell of these substances and how they impair the odoriferous molecules of materials 159. However, one has to keep in mind that merely some litres of paint can spoil the scent of materials very easily.

Without paint 2x lime, curd cheese, water 2x Chalk-glue paint 2x Linseed oil 2x Biofa dispersion paint without solvents 1x Biofar glaze with pigments without primer 1x Biofar glaze with pigments with primer 2x Acrylic paint 2x Plastic dispersion paint 2x Latex (for indoor + outdoor use) 2x Environm. Dispersion paint without solvents 2x dispersion paint (for indoor use only)

Fig. 5.D Influence of paints on the sorption performance of 1.5 cm thick, loam plaster samples under the influence of an increase in RH from 50%-80%. Paint according to DIN53778, Thickness 100±10µm. (From Minke, 1994).

156

157 158

159

See samples A1-C6 (Appendix I), Olive wood (Olea europea), Florida cedar wood (Juniperus virginiana) and Brazil cedar wood (Cedrala odorata), untreated, treated with oil, wax, lacquer (incl. solvents) and weathered (untreated) for 4 month.

Cf. chapter 4.2.

Uncoated materials are not necessary less hygienic than sealed materials. For instance, bathrooms covered with clay are more hygienic as bathrooms covered with tiles. Excess moist adsorbs quickly in the walls and thus mould and bacteria are deprived of their breeding ground. In the following the walls desorbe the moist again, preventing mould proliferating within the walls.

There is a general lack of data that quantifies the rate of moisture transfer, especially for surface coatings and furnishings. Virtanen et al. (2000), p2.

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Smell – A Neglected Sense in Architecture Buil t Impacts on Odours in Architecture

6

Built Impacts on Odours in Architecture

6.1

Microclimate

To trace scent in architecture one has to look for change. Although it is not obvious architecture is subject to permanent change, either as a result of the surrounding climate, its use or aging. Most of these changes include changes in the hygrothermal or friction conditions and thus smell. I have already discussed climate and weather conditions, but in the following I will have a closer look at its interaction with architecture and hygrothermal peculiarities of microclimates within buildings.

6.1.1

Inside ↔ Outside

Openings in the shell of buildings greatly influence odours in architecture. A prime example could be perceived at Vaux le Vicomte160, if kept in original condition. The two central rooms – the vestibule and the salon - divide the palace in two fairly symmetrical parts. In the times of its completion the three entrances as well as the three exits to the garden were permanently open to the outside (Figures 6.A.1-2).

Fig. 6.A.1-2 Vaux le Vicomte, Cross Section and Front Elevation.

(From Montclos, 1997).

The openings could be closed, but only with railings 161. By this the scents of the gardens circulated right through the palace. Simultaneously this layout provided natural ventilation enhanced by the funnel-shaped façades and long lanes cut into the forests leading in straight lines towards the palace from both sides 162.

160 161 162

Vaux le Vicomte, Melun, France, palace of Nicolas Fouquet, minister of finance to Louis XIV. Cf. Pérouse de Montclos (1997), p72.

It would be interesting to examine the air flows within and around the building to speculate whether ventilation strategies were part of the design and to what degree of sophistication. And for those sceptics arguing that you would freeze to death in such a building: The palace was built primarily for

Continued next page

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Smell – A Neglected Sense in Architecture Buil t Impacts on Odours in Architecture

Due to neurophysiological reasons163 and adaptation the first sensation is of crucial importance for the perception of a new setting. Thus thresholds are the most interesting elements for odours in architecture. Entrances and exits mark usually the most eminent thresholds in architecture as described by the French poet Jean Pellerin: La po rte me flai re, elle hésite 164.

(The door scents me, it hesitates.)

Probably the classical entrance sequence of a Roman domus, vestibule165 – fauces 166 – atrium (Figure 6.B), was also favourable to set up a smell buffer between the exterior and the interior to keep the stench of the streets outside the house. Lucretius’ description of the habit to anoint doorposts with unguents, reveals the Roman sophistication in scent architecture, too167.

Fig. 6.B Roman Domus • Casa del Menandro, Pompeji.

(From Wallece-Hadrill, 1994)

Po Nowadays entrances still work as sluices, yet more for safety and insulation reasons and therefore there is less mixing of the macro- and the microclimate. Hence the perceived difference between the inside and the outside might be even more striking and has to be handled with care. Due to human physiology it might be enough to provide the desired stimuli by choosing the right material for the doorframe or just its parts at the height of the nose. This is the reason why department stores often place their leather departments and perfumeries, or supermarkets their bakeries, close to the entrances. For a refined design of scent architecture it would be interesting to examine the exact airflow patters of different doors. Is a revolving door scooping scents onto the streets as heralds of the internal atmosphere and/or vice versa? What is the difference between doors opening to the outside or to the inside? What is best for welcoming visitors in one’s olfactory privacy? Do sliding doors provide the sharpest atmospheric threshold or do they create olfactory boredom? With this knowledge together with the overall view of the main airflows in the whole building, an architect could work precisely with the given microclimates.

163 164 165 166 167

summer use.

Cf. chapter 3.1.2.

Bachelard (1994), p223.

Not in the example.

Fauces (lat.) = corridor.

Cf. Lilja (1972), p91.

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Smell – A Neglected Sense in Architecture Buil t Impacts on Odours in Architecture

Fig. 6-C.1-3 CFD-Simulations of air movements for three different window scenarios • No heating, no wind, outside temperature 10°C. (from Gritzki, 2001).

Due to research driven by energy concerns there is more to find about the airflow patterns around windows (Figures 6.C.1-3). Manual ventilation is still a widely used168 and preferred ventilation strategy, although difficult to get right from energy saving considerations. Typical airflow patterns can show us the exact position of the strongest airflows and by this the most relevant areas for a scent friendly design. It would be very helpful to use these simulations to find the exact position and form for windows and the respective airflows in order to direct the carried odours as closely as possible to the nose, wherever it is. The simulations shown above illustrate that it would be useless to concentrate on the upper parts of a window to include odours in the design of buildings in central European colder climates 169. On the other hand ground covers or sills in front of windows and doors seem to be the ideal elements to focus on. Due to the favourable exposure to the sun and the rain they are subject to permanent hygrothermal changes and their scents are directly taken into the building. However, Computational Fluid Dynamics (CFD) in architecture is still in its infancy. Precise simulations for entire buildings and additional parameters as wind pressure, solar gains, heaters, use or air conditioning systems are not yet possible, but quick progress is probable, driven by the great efforts undertaken to develop sustainable and environmental friendly architecture. However, even without CFD it is easy to predict that the side of the building exposed to the main wind and thus rain direction does have a different scent potential from that opposite to it. Thanks to the sun north walls smell differently to south walls and indoor climates will be considerably affected by the decision whether to green a façade or not. Winter gardens humidify adjacent indoor climates, too. Due to the position right between the outside and the inside and the plants kept within, it is the winter garden’s nature to be rich in odours.

6.1.2

Inside ↔ Inside

As for the interaction of outdoors and indoors, thresholds are of crucial importance for consideration of purely internal climate phenomena. In contrast to the latter the interior of buildings entail horizontal as well as vertical thresholds. Different floors do have different climates; generally speaking the higher up the warmer and drier. Therefore stairs or elevators might lead to considerably different hygrothermal conditions 170. The impact of internal doors on the atmosphere 168 169

170

In Germany > 70%; cf. Richter (1999), p69.

Reverse temperature conditions would cause reverse flow patterns, yet windows would be probably shut to keep the cool air inside.

Different odorous materials around elevator doors might facilitate orientation or set up specific

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Smell – A Neglected Sense in Architecture Buil t Impacts on Odours in Architecture

within a building depends highly on the ground plan and the difference between the adjacent rooms. German building regulations prescribe certain arrangements of rooms and contribute by this to the smell aspects of architecture. Toilets must open only onto corridors and never onto kitchens or other rooms for permanent use. These regulations are based on a fairly negative assessment of these rooms, which might be controversial. Indeed, smells do occur in toilets. On the other hand, the lavatory is the last retreat of modern life and Tanizaki Jun’ichiro valued welldesigned toilets as the last temples. Even he admits that traditional Japanese toilets, small buildings situated in the shade of trees and shrubs, connected with the main building with roofed passages and fairly open to the surrounding winds of the garden cannot be an example for modern dwellings or office buildings. However, there are things to learn. First it should be appreciated for its private and contemplative atmosphere. Generally toilets do have a silent and darkish atmosphere and give way to a higher smell sensibility. Lavatories should be separated from bathrooms with opposite demands on hygrothermal conditions. Hot and humid air worsens bad smells and spreads them all over adjacent rooms. Decent ventilation strategies cope with these smells easily and open the design to more sensual alternatives beyond the obligatory white tiles.

Even Jun’ichiro fails to install a wooden toilet and floor, but why not use timber material as wall covering?

Generally the zoning of the layout is of great importance and the more precisely the space is subdivided the more diverse odour architecture can be. By contrast open ground plans allow less different odour scenarios and bear the risk of uncontrolled mixing. Corridors might be to odours in architecture what bread is for wine tasting. As said above smell is the most long-ranged sense in obstructive surroundings. Thus scent architecture enables to layout scent traces to lure people long before vision gets hold of the thing led to. Swimming pools are an ambiguous example for this reason because often when you enter houses including a pool you instantly smell its existence, even if it is far away. The negative aspect of this is that chlorine does tend to have an unpleasant smell. To benefit from this phenomenon one must be perfectly aware of the airflows to avoid odours out of place. In addition to zoning scent architects have to consider the rooms’ volume and ventilation rate171 according to the amount and intensity of odorant materials used. Vestibules, for instance, are usually small in size but due to their position in the building rather high in ventilation rates. Thus odoriferous materials applied to these rooms should be higher in intensity or exactly at the position where the noses pass by.

Fireplaces are architectural features rich in odours and besides their heating function they are the remnants of the popular censers of the ancient172. Burning odorous timber as e.g. cedar or applewood173 can fill rooms with pleasant smells and over the course of time the scent adsorbs in

171 172

173

olfactory corporate identities.

Total amount of air exchange per time unit, either naturally or mechanically ventilated, or both.

E.g. most Roman houses had several censers spread all over the building. In most cases one was placed at the front door in order to protect their homes from the malignant emanations of the world outside. Cf. Classen (1994), p19. … Applewood will scent your room, With an incense like perfume … (from: The Log Fire, traditional rhyme).

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Smell – A Neglected Sense in Architecture Buil t Impacts on Odours in Architecture

the surrounding structures and contents. Thanks to this rooms with wood burning appliances often have a sweet and spicy scent, even without a fire burning.

As already given above humid conditions of ground temperature higher than air temperature are favourable for the occurrence of odours. Thus underfloor heating together with a permeable floor covering made from odoriferous screed or wood in e.g. bathrooms would grant excellent possibilities for scent architecture174.

The art of kodo175 took part after sunset, and as discussed earlier relative humidity rises and the earth still has enough thermal energy to take scents to the receptive nose. Moreover darkness blurs the supremacy of vision. When we want to think hard, to listen to the inner voice or compose the tightly constructed key sentence that will express the very core of our thinking, is there one of us who hasn’t had his thumb and forefinger pressed firmly against his eyelids 176? Less light means more vision as well as more odours. People instinctively stand still and close their eyes if they want to perceive an odour as intense as possible. Scent architecture should dwell in the twilight, either at places where people stay from dusk until dawn or in the darker areas of a design.

174

175

176

Underfloor heating together with high sorption qualities would prevent permanent excess moist and thus mould and germs (cedar wood would even enhance this effect being bactericidal itself). Due to the heating the floor material’s outgassing rate would be higher. The odoriferous material or odorant used would have to be highly adhesive and low in detection threshold.

Kodo = scent hearing. Kodo was introduced by shogun Ashikaga (15th century) in Japan as one ritual on the spiritual way to perfection. Ten different mixtures of fragrances were burnt in little bowls with the aim to recognise the first three in a following round. Due to adaptation the nana soku, the art of the seven inhalations, was a crucial part of the ceremony. Cf. Ohloff (1990).

Bachelard (1994), p181.

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Smell – A Neglected Sense in Architecture Hu ma n Impacts on Odours in Architecture

7

Human Impacts on Odours in Architecture

Civilisation determines odours at every level of the built environment. The most global smells are probably the exhausts from patrol and diesel engines. Due to the natural origin and the dependency on local climate conditions there is no equivalent global scent. The scent of resin is probably the most widely known scent to humankind but it varies a lot according to the components of the specific timbers.

Cities do have characteristic smells and a striking example of this is New York. Due to restricted space and high rents apartments usually do not have washing machines and driers. Hence the high density of laundries in the city, which are mostly situated in the souterrains ventilating hot and humid exhaust directly into the streets close to the nose of the passer-by. That is why a characteristic smell of New York is that of softener177.

Moreover different types of buildings have characteristic smells according to their use. The scent of incense is associated with catholic churches by more than a billion people178. Old libraries combine the scent of leather, paper and glue whilst recent libraries have a scent of paper made with higher concentrations of acid. Hospitals are flooded with disinfectants as most medical practices. Schools do often smell of musty sponges and supermarkets of fruits and vegetable deliberately situated in the entrances. Most recent office buildings are stripped from olfactory stimuli due to air-conditioning systems, which often even contribute to SBS phenomena. This technology concentrates on quantities rather than qualities and turns the whole building into an olfactory mishmash or deprives architecture of the olfactory dimension completely. Again airflow simulations will give insight to the influences of air-conditioning systems as the first step to reconcile the quantities and qualities of odours in architecture.

The smells of rooms are influenced by their use in the same way. The living room is probably used less than the bedroom, yet with more pungency. Bathrooms release scents of all sorts of shampoos and soaps, but only for very short periods in the morning and in the evening. Kitchens are full of lovely odours if you are hungry. If not, the same smells might have repulsive effects.

Therefore a precise scent design down to the last square metre is a rather complex thing. To approach this complexity it would be very helpful to have a three-dimensional map of airflows as suggested above together with a map of the expected use. These maps would allow one to control bad smells as well as to direct scents to wherever the nose is. Modern lifestyles entail the separation of where people live and work and buildings are used very differently over a day or a week. Moreover these buildings are subjects to considerable climate and weather changes. Thus a comprehensive mapping of airflows and typical patterns of use would need measurements over the course of typical living situations.

177

178

Typical smell associated with Paris: The smell of the metro, a mixture of burnt rubber from the wheels of the metro, asphalt and urine enhanced by the warmth produced in the tunnel system.

Number of Catholics worldwide in 1997: 1,018,257,000; cf. International Fides Service.

38

Smell – A Neglected Sense in Architecture Conclusion

8

Conclusion

Scent architecture is a rather difficult task. The subtlety of the sense of smell correlates directly with the difficulty of realizing its inherent creative potentials in day-to-day architecture. In order to plan, execute and maintain scent architecture, everybody participating in these processes has to be aware of its peculiarities.

The architect eager to include smell in his work will first encounter communication problems with the client. How to communicate a sense difficult to grasp with the conscious mind and without the possibility to simulate smellscapes in advance? Even more if the sense by which to do so is untrained and neglected? This paper is only a first attempt to overcome these obstacles.

Conscious training of the nose has to be started in early childhood to stop the decline of odour culture. However, even if there is an awareness and understanding of this dimension of man’s sensual existence it will be difficult to work out the preferences wanted for a particular building.

Every building is frequented by people with different odour preferences, yet whose preferences are to be decisive? Smell has both objective and subjective dimensions, and the planner in cooperation with the client has to work out the degree of individuality wanted and thus the adequate degree of scent architecture. Hence scent architecture could have a place in modern office buildings, too, although limited to basic and generally accepted stimuli. Tailor-made scent architecture must be restricted to private houses or buildings with rather specific uses, such as e.g. museums or churches. However, due to the high fluctuation of occupants caused by the modern living standards it might be even problematic to create scent architecture according to highly subjective preferences. The scents might stay longer than the occupant who desired them.

It is illusionary to create a holistic scent architecture which is as thoroughly controlled as the visual dimension of buildings. The smell of a building is subject to an interaction with a complex nexus of external influences (as macro- and microclimate, use etc.) which are beyond the control of planners or occupants. Even though visual stimuli are by no means constant and influenced considerably by external influences, too, they are always fixed to the physical existence of things. Odours are released by physical things as well, yet are invisible and are perceived often far from their origin.

From this derives the mysteriousness of smell, the difficulty to orient by odours and to control their effects within buildings.

The execution of scent architecture entails the same communication difficulties. The inclusion of smell in architecture requires an awareness of the smell qualities of every constituent in the building. Concerning the look of the individual parts making up a building this is everyday practice, but smell considerations are restricted to the exclusion of SBS phenomena. However, even if an architect is willing to make the effort, it will be difficult to get the relevant data. As long as there is no universally valid classification and thus a language for smells the planner will have to rely on his own experience or on a variety of rather vague classifications already existing179, probably unknown 179

Cf. Gschwind (1998).

39

Smell – A Neglected Sense in Architecture Conclusion

to the manufacturer and the contractor. Because of this, and due to many hasty alterations unavoidable in the course of a plan’s execution, the architect is unlikely to gain full control over every element’s smell and its participation in the overall smell of a building. Moreover there are probably very few clients who are willing to pay the architect for this additional amount of work.

Thus many architects will be reluctant to consider the smell of their building.

Air-conditioning represents another problem for scent architecture. It might be possible to set scent accents at spatial transitions of air-conditioned buildings, yet the inside of the building itself will be an olfactory mishmash. There is evidence that unchanging lighting and heating conditions in buildings make occupants sleepy and thus inefficient180. There is no reason to believe that uniform smellscapes do not contribute to this phenomenon. Everybody knows the frequent desire to breathe fresh air even in well air-conditioned buildings. CFD and the suggested circulation pattern comprising the physical interaction between occupants and architecture in accordance with typical living situations, applied together with new ventilation technologies aiming at a more differentiated control of microclimates, will improve the chances to include scents in architecture, even in airconditioned buildings.

Such expertise would enable precise interventions without great costs. Cedarwood beams or cypress panelling are neither affordable nor sustainable181. However, scent architecture need not be costly. On the contrary, a few drops of e.g. Muscone, a synthetic substitute for musk, in mortar or concrete182 are rather cheap. Even the use of expensive timbers does not necessarily entail great costs because it is enough to have small quantities in the right places to influence the whole indoor climate and to awake the occupants’ attention.

Scent architecture is also restricted by other constraints of modern life. It will be difficult to reintroduce unsealed materials in an over tidy society. Certain areas have to fulfil maximum hygienic requirements. There are, however, many areas were a less clinical approach would enhance health and atmosphere.

The sealing of materials avoids decolourisation and soiling. To call the same phenomenon by another name one could use the words aging183 and patina. There is a fine line between dirt and patina and it needs exact knowledge of how and when aging takes place to reintroduce unsealed materials. However, patina reveals the historic dimensions of a building and thus should be considered right from the start.

Scent architecture needs perseverance and makes maintenance difficult. Subtle architecture aimed at the subtle sense needs a subtle understanding and use. Yet most of us have untrained noses and little knowledge about this sense. Scent architecture can be easily spoilt by a pot of paint or 180 181

182 183

Cf. footnote 50 or Baker (1996).

Lebanese Cedar timber is currently not available at all because there are only very few examples left in the Lebanon.

Samples G2, H2.

Weathered samples: A5-C5.

40

Smell – A Neglected Sense in Architecture Conclusion

dominated by contents with own smells. To avoid such inadequate use and generally to overcome the neglect of smell, it is vital to develop better communication skills through training and further research in universally valid and intelligible classification systems of smells.

Every surrounding smells. The one, the reader of this paper, experiences at the moment of reading also has an odour. And there is no escape:

The ov ens, The sten ch I coul dn’t repeat The sten ch.

You h ave to breathe.

You can wip e out What you don’t want to see.

Close you r eye s.

You don’t w ant to hea r, don’t want to ta ste.

You can block out all the sens es except s mell. 184 Fig. 8.A New York, Ground 0.

One cannot escape smell, and the smell of burnt and decomposing human flesh described in the poem above traumatised thousands of New Yorkers from the 11th September 2001 onwards (Figure 8.A). One has to breathe and thus to smell and one has only partial conscious control of the often emotional reaction to smells. Therefore smell embodies a potential rival to reason and causes the fear of anarchy.

Nevertheless smell is part of our daily life and of all aspects of the built environment. The examples given above indicate the danger of using smells. Scent architecture must be used with great care and sophistication. The more powerful scents can be to improve surroundings, the more disastrous mistakes can be. This is probably the reason why negative impacts of smell as part of the SBS are well researched. Scent architecture must strictly exclude any smells or scents including trigeminal stimuli. In contrast to purely olfactory stimuli, trigeminal stimuli are not subject to adaptation, but sensitisation. Up to now the use of scents in architecture was risky. However, due to the achievements of recent research on smell and its influences on the human physiology and psychology it is becoming less so.

184

Hyett, In evidence • Poems of the liberation of Nazi Concentration Camps; in Classen (1994), p175.

41

Smell – A Neglected Sense in Architecture Conclusion

Scent architecture beyond the mere design of buildings without unpleasant or hazardous smells might be considered over-refined or even superfluous. Indeed, almost the entire built environment proves that one could live without scent architecture and that it is not an integral part of contemporary architecture. However, there is evidence for the positive influence of varied smellscapes 185, and in the endeavours to develop buildings with maximum comfort smell should be considered. Every building has a form which is more or less designed beyond its mere function and every building has a smell, which up to now has been an accidental by-product. Due to the obstacles given above, holistic scent architecture seems almost impossible and only very special occasions as, for instance, a scent museum would justify the considerable efforts needed. Due to the high sophistication required for the implementation of odoriferous building material it is probable that scent architecture will be primarily done indirectly. As in sight, the odorous top note of a building, as a manifestation of the individuality of its occupants, is made up by the smell of the people living in it, their furniture, clothes and belongings anyway. However, the basic note comes from the built structure itself; either by the provision of favourable microclimates or zoning – as an equivalent of the acoustics of buildings for hearing - or actually by materials actively participating in the smellscape of a building.

In the time frame beyond the immediate experience, smell is the most powerful sense. Scent architecture is superior to all other senses in terms of memory and if one wants to engrave a particular room or building in someone’s memory, smell is the medium for this. Also, the smell of a building acts as its memory. Smell provides the most vivid information about activities undertaken in buildings long before, and notable noses have a remarkably deep insight in the history of buildings and their occupants. Due to the direct connections to the limbic system, the feeling of being home is strongly mediated by the sense of smell as probably everyone has experienced on coming home after a longer absence. As already mentioned, safety and shelter is a basic need of humans. The smell of a building cannot actually give physical shelter and safety as thick walls can, yet the scent of home is strongly associated with these qualities and thus induces the feeling of safety and shelter. However, as for the immediate perception of smell, smell memory bears an equal risk of failure. A stinking house will be inscribed in the perceiver’s memory as firmly or even more firmly as a house of pleasant smells.

Smell is one of our five senses. There is no pure scent architecture as there is no purely visual architecture. Scent architecture must be considered in conjunction with all the other senses and vice versa. For instance, a more differentiated approach to light in buildings would be favourable for smell. The mere praise in contemporary architecture of transparency and translucency in order to gain the best lighting186 is not enough. It is the differentiated design of light and dark which is necessary and, as pointed out above, scent architecture works best in the shade or dark.

Smell is an interspatial sense and thus closely tied to movement. Due to adaptation scents are mainly perceived moving from one room to another or within rooms with changing microclimates.

185 186

Cf. footnote 50.

The Economist reported on research undertaken to develop transparent concrete!

Cf. Economist (22 nd September 2001).

42

Smell – A Neglected Sense in Architecture Conclusion

Whilst vision allows perceiving lasting stimuli one has to trace scents which decline shortly afterwards 187. Smell is the messenger under the senses and due to its intangibility one is tempted to name it the Hermes of the senses.

The nature of smellable spaces is a complex issue, which involves a variety of instinctive and conscious responses. These are layered on deep physiological, cultural and contextual issues which structure our level of involvement in the world. It is through this involvement that activity, ritual, and subsequently perception become structured and by this disclose the latent meaning of the space. If sufficient research and attention were given to this subject, perhaps some reawakening of our primordial modes of attachment to the world would occur and provide us with a greater awareness of the inherent meaning of our architectural environment.

“Do w e know what t a o n t a (co mmonl y t ransl ated as being s, entities, the-thing swhich ar e) means? We woul d c ome clos er to the matte r if we we re to con cern ou rsel ves with the nose, the eyes an d with hea ring.“ Heidegger, Martin Heraclitus Seminar 1966.

By listening to our instinctive, primordial being we can begin to address the complexity of the issue raised here and an understanding of smellable space may ensue. However, due to the restricted cognitive access to smell in the day-to-day world smell will surely retain a whiff of mystery. The oracle at Delphi announced its prophecies through a scented cloud emerging from a crevice. In western cultures, scented environments do not have this imaginative power anymore, yet scent architecture has been and will always be architecture full of wonders.

187

It would be interesting to examine to what degree odours could enhance orientation in labyrinths.

43

Smell – A Neglected Sense in Architecture Bibl iogr a phy

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Smell – A Neglected Sense in Architecture A pp e nd ices

Appendices

Appendix I Table of different wood samples with different coatings.

Untreated

Olive wood

Oil

Wax

Laquer

Weathered (4 month on top of a dashboard)

ATW® Holz-Öl / Seidenmatt

ATW® Holz-Wachs / Seidenmatt

Glasurit® Bootslack / Hochglanz

A1

A2

A3

A4

A5

B1

B2

B3

B4

B5

C1

C2

C3

C4

C6

Saffron

(Olea europea)

Brazil Cedar (Cedrolus odorata)

Florida Cedar (Juniperus virginiana)

Thuja

D1

(Thuja plicata)

Appendix II Table of different masonry samples with different fragrances added.

Untreated

Muscone

Swiss Pine

Rose Oil

Firmenich® #962195

Oil of Pinus cembra

Oil of Rosa damascena

Gypsum

E1

E2

E3

E4

E5

Loam

F1

F2

F3

F4

F5

Mortar

G1

G2

G3

G4

G5

Concrete

H1

H2

H3

H4

H5

Asphalt-slab

J1

DASAG® Naturasphaltplatte schwarz

(top polished)

48

Smell – A Neglected Sense in Architecture A pp e nd ices

Appendix III Many years had elapsed during which nothing of Combray, save what was comprised in the theatre and the drama of my going to bed there, had an existence for me, when one day in winter, as I came home, my mother, seeing that I was cold, offered me some tea, a thing I did not ordinarily take. I declined at first, and then, for no particular reason, changed my mind. She sent out for one of those short, plump little cakes called "petites madeleines," which look as though they had been moulded in the fluted scallop of a pilgrim's shell. And soon, mechanically, weary after a dull day with the prospect of a depressing morrow, I raised to my lips a spoonful of the tea in which I had soaked a morsel of the cake. No sooner had the warm liquid, and the crumbs with it, touched my palate than a shudder ran through my whole body, and I stopped, intent upon the extraordinary changes that were taking place. An exquisite pleasure had invaded my senses, but individual, detached, with no suggestion of its origin. And at once the vicissitudes of life had become indifferent to me, its disasters innocuous, its brevity illusory-this new sensation having had on me the effect which love has of filling me with a precious essence; or rather this essence was not in me, it was myself. I had ceased now to feel mediocre, accidental, mortal. Whence could it have come to me, this all-powerful joy? I was conscious that it was connected with the taste of tea and cake, but that it infinitely transcended those savours, could not, indeed, be of the same nature as theirs. Whence did it come? What did it signify? How could I seize upon and define it? ‌ And suddenly the memory returns. The taste was that of the little crumb of madeleine which on Sunday mornings at Combray (because on those mornings I did not go out before church-time), when I went to say good day to her in her bedroom, my aunt LÊonie used to give me, dipping it first in her own cup of real or of lime-flower tea. The sight of the little madeleine had recalled nothing to my mind before I tasted it; perhaps because I had so often seen such things in the interval, without tasting them, on the trays in pastry-cooks' windows, that their image had dissociated itself from those Combray days to take its place among others more recent; perhaps because of those memories, so long abandoned and put out of mind, nothing now survived, everything was scattered; the forms of things, including that of the little scallop-shell of pastry, so richly sensual under its severe, religious folds, were either obliterated or had been so long dormant as to have lost the power of expansion which would have allowed them to resume their place in my consciousness. But when from a long-distant past nothing subsists, after the people are dead, after the things are broken and scattered, still, alone, more fragile, but with more vitality, more unsubstantial, more persistent, more faithful, the smell and taste of things remain poised a long time, like souls, ready to remind us, waiting and hoping for their moment, amid the ruins of all the rest; and bear unfaltering, in the tiny and almost impalpable drop of their essence, the vast structure of recollection.

Marcel Proust; Remembrance of Things Past; translated by Scott CK, in: Moncrieff (1966), p54-58.

49