Buildings without installations by Alexandre McCormack

B r o e k b a k e m a

WITHOUT

SUMMARY 1 1.1 1.2

2 2.1 2.2 2.3 2.4

3 3.1 3.2 3.3 3.4 3.5

4 4.1 4.2

5 5.1 5.2

Problematic

Standards and Regulations Natural Ventilation

User expectations and comfort

Indoor Air Quality Daylight Acoustics The Principle of Alliesthesia

Methods and Principles

Ventilation Heating Cooling Daylight Building Materials

Examples

Historical Modern

Design Tools and Strategies

Parametric Biomimicry

Conclusions

PROBLEMATIC

1.1

Problematic

1.1.1 Standards and regulations As of today, many tools and regulations are used for building design to achieve the highest energy performance and living quality. These standards are based on years of scientific research, using mathematical models, empirical equations, statistics and other forms of data to back it up. It is clear that this information is not always democratically accessible, however they are sometimes seen by designers as bluntly expressed in the form of recipe books that do not give the chance to grasp the principles and notions that could be taken into account early in the design. Furthermore, the discussion between designer and engineer is not that of co-evolution in a design but rather a back and fourth, sometimes frustrating, process. The former may not understand the factors involved in a problem and the latter generally emits a polar end result according to the standards he abides to. There is a huge gap and many missing links between both ends of the design. Another aspect that must be pointed out, is the veracity of our building regulations is sometimes questionable. They are constantly evolving because of European standardisation and due to continuous, more detailed academic research. A closer look into European, American or British standards shows that there are indeed still a few questions to be raised around the subject. In a lot of cases. these questions are rather crucial and could imply indeed being a lot more flexible towards these standardisations to which we are converging. The aim of this booklet is to understand the basics of HVAC design in buildings, to question the way we are used to creating indoor climates and to further explore and possibly innovate new methods for HVAC systems. 1.1.2 Energy efficiency In order to reduce the environmental impact of a building, generally, the following three steps are taken. 1.1.2.1 Reducing the demands Overall, the energy used to ventilate, heat or cool to reach building comfort standards are very high in older buildings. Decreasing heat transmission losses and air infiltration are some of the first steps weâ&#x20AC;&#x2122;ve taken to reach passive house standards. The energy consumption has been significantly reduced in newer and renovated buildings. Comparing the energy savings over the embodied energy of the extra materials needed shows that this step is the most important. Reducing the energy demands by exploiting natural forces is one of the main aspects of this study.

1.1.2.2 Renewable energy source Environmental impacts of some energy sources are significant. if there is no further possibility of reducing the energy demands, an optimal source should be considered 1.1.2.3 System optimisation The final step is to choose the materials and HVAC systems wisely. However, the better step 1 has integrated sustainable strategies, the less systems to be optimised thereâ&#x20AC;&#x2122;ll be. 1.2 Natural HVAC Design As we converge towards more sustainable solutions, we begin to open eyes on nature and grow awareness on the existing strategies for more energy efficient technologies. We are moving towards exploiting naturally occurring forces to our own benefits. On the other hand, energy efficient buildings are becoming closed systems, where natural occurring forces around the buildings are considered more of a burden than anything else. The principal of naturally ventilated buildings is to use natural forces to drive air in the most energy efficient way possible. There are some other aspects that NVBs have to offer other than the evidently low energy use for ventilation. Humans have learned to adapt to the most extreme conditions and environments. Our physiological systems have been adapted through evolutional optimisation in order to withstand varying and variable climates. For millions of years, the Earthâ&#x20AC;&#x2122;s atmosphere has been the absolute referential for terrestrial bodies. All living creatures function directly or indirectly on the basis of climatic cycles and there is no reason that human psychology, behaviour and metabolisms should differ. Creating living spaces that are more open to the outside climate, allows us to reunite our mind nd and and bodies an b di bo dies es with wit ith the th he environment en e nv viiro ronm men nt in n which wh hiic we nest.

USER EXPECTATIONS AND COMFORT

An adequate interior environement implies a full understanding of the user and what we should expect from a building. Survival is most certainly the primary function of human habitat but an optimal environment is what we seek. Comfort contends to less strain on our physiology and psychology and thus leading to greater benefits that are both individual and social.

2.1

Indoor Air Quality

2.1.1 Parameters A thorough understanding of the factors involved in creating the ideal environment is crucial in building physics design. The parameters involved are either personal or environmental. 2.1.1.1 Personal factors 2.1.1.1.1 Metabolic rate It is dependent on the activity and physiological response of each and every individual. The reference value of the average metabolic rate of a person at light activity (reading a book for example) is 58W/m2 or 1 MET (Metabolic Equivalent of Task). It can vary among individuals and within an individual from 0.9 MET during sleep to 8 or 10 during vigorous activities (running). In buildings, we consider the metabolic gains to be 100W where we estimate a surface of 1.8m2 per person. 1 MET

8 MET

2.1.1.1.2 Clothing insulation The unit value is 1 clo and is the equivalent thermal resistance to 0.155 Kâ&#x20AC;˘mÂ˛/W. 1 clo corresponds to wearing trousers, a long sleeved t-shirt and a sweater. This factor is taken into account in the adaptive thermal model where it acknowledges the clothing to the external climate.

2.1.1.2 Environmental factors 2.1.1.2.1 Air temperature The equivalent to the dry bulb temperature. It does not take into account the thermal radiation in the surroundings. 2.1.1.2.2 Mean radiant temperature Measured temperature taking into account the ability of an object to absorb or emit radiant heat. Solar radiance on a body can dramatically increase the perceived temperature although the dry bulb temperature is much lower. Asymmetrical local thermal radiance from walls, ceilings or radiators can be a source of comfort as well as discomfort as it implies only certain parts of the body to experience heat or cold. An interesting study could be made on whether humans have a preference to local bodily heating. 2.1.1.2.3 Operative temperature Mean value of ambient air temperature and mean radiant temperature. High thermal inertia with a large heat capacity gives the equivalence of dry bulb temperature acting as a heat sink before starting to radiate. 2.1.1.2.4 Relative humidity High relative humidity causes greater difficulty for humans to auto-regulate themselves through evaporative cooling. It also creates a sensation of ambient moisture and moist clothes. On the other hand, low relative humidity causes great discomfort with effects such as throat, nose, skin, eye dryness and itchiness. The ideal range for relative humidity is 20% to 60%. Within this interval, humans cannot greatly detect the variations of relative humidity. Outdoor relative humidity conditions can vary considerably, however the tolerance to relative humidity is somewhat greater in naturally ventilated buildings.

2.1.1.2.5 Air velocity The perception of flowing air can have a significant role in comfort especially in naturally ventilated buildings. However the maximum value of the air speed must be adapted to the function of the room. VELOCITY (m/s)

MECHANICAL EFFECT

EFFECT ON HUMAN BEINGS

0,1

Minimum likely in domestic situations

May feel stuffy

0,25

Cigarette smoke indicates movement

Movement not noticeable except at low air temperatures

0,5

Flame from a candle Feels fresh at comfortable, but flickers air temperadrafty at cool temperatures tures

Loose papers may be moved; equivalent to walking speed

Generally pleasant when comfortable or warm, but causes constant awareness of motion; maximum limit for indoor activities

1,5

Too fast for desk work with loose papers

Drafty at comfortable temperatures; maximum limit for indoor activities

Acceptable only in very hot and humid conditions when no other relief is available Table 1 : Air velocity in buildings (Evans, 1980) 2

Equivalent to a fast walking speed

2.1.1.2.6 Colour Thermal comfort is not always defined by the sense of touch. Colour visualization can have an impact up to 3째C in difference with the predicted comfort scheme. Blue or green rooms can feel colder than red or orange rooms. 2.1.1.2.7 Olfactory comfort Emotional, psychological and physiological impacts are complex. Some food companies have demonstrated the influence of smell on people. In many cultures, smells in interior environments provides harmonious, calm and protective sensations.

2.1.2 Comfort Models Since there are large variations from person to person in terms of physiological and psychological satisfaction, it is hard to find an optimal temperature for everyone in a given space. Laboratory and field data have been collected to define conditions that will be found comfortable for a certain percentage of occupants. 2.1.2.1 Static comfort model PMV/PPD This model is based on statistical studies on the perception of thermal comfort. It was defined by people rating their comfort (Predicted Mean Vote) or dissatisfaction (Predicted Percentage Dissatisfied) towards a given air setting in a room. 2.1.2.2 Adaptive comfort model The static thermal model is used for very constant room temperatures developed by controlled mechanical HVAC systems. However it has been demonstrated that outdoor climate influences indoor comfort in the case of naturally ventilated buildings. The adaptive thermal model can only be applied strictly to naturally ventilated buildings or hybrid ventilated buildings. There are three main factors contributing to this differentiation over the static thermal comfort model : behavioural (opening windows, taking off clothesâ&#x20AC;Ś), psychological (contrast to an outdoor climate) and physiological (metabolic rates). Studies have shown that users have a wider range in the perception of comfort. The adaptive thermal model allows a greater interval for temperatures and relative humidity. It is clear that thermal stress with excessive heat or cold affects cognitive and physical productivity and is why it is crucial for buildings to provide a comfortable environment for its users. However, taking advantage of a more variable model could enlarge the technical possibilities and energy savings in a building. 2.1.2.3 Critics The adaptive comfort model has yet to consider change of perception (alliesthesia), the influence of colour and smell aswll as other factors that may rely more on human psychology and behaviour. Local thermal radiation has also to be considered, and is why the comfort model must only be a guideline when designing the appropriate natural HVAC system in a building.

2.1.3 Natural Ventilation Parameters

Indoor Pollution

Relative Humidity

Operative Temperature

Air Speed

INDOOR PARAMETERS

INDOOR AIR QUALITY

Wind Speed

Solar radiatian

Dry bulb temperature

Wet bulb temperature

HVAC SYSTEM Outdoor Pollution

Occupancy Rate

FUNCTION

Spaces

Metabolic Rate

USER PARAMETERS

BUILDING PARAMETERS

USERS

COMFORT Psychology

CLIMATE

OUTDOOR PARAMETERS

Clothing

2.1.4 Sick Building Syndrome (SBS) After the birth of artificially ventilated systems and the will towards more energy efficient buildings, ventilation rates were kept to the lowest values that were considered acceptable. In proportion to the time occupants spent indoors, multiple sickness symptoms have been linked to stagnant air. Asthma, allergies, headaches, eye and skin irritation, odour and taste sensations have been linked to poorly ventilated buildings. Ventilation became only necessary for regulating relative humidity for the prevention against fungus or organic matter formation in homes. With the apparearance of SBS, indoor pollutants became a major concern for ventilation. Energy efficient buildings are more airtight than ever, standards now give minimum air flow rates in adequacy with CO2 concentrations defining different levels of indoor air quality. 2.1.5 Indoor air quality indicators In theory, the aim is to find one or more indicators that are the greatest factor contributing to indoor quality and thus leading to a minimum acceptable criteria. Outdoor air is a reference value of air quality, nonetheless outdoor pollution levels vary between cities and even these could be a danger to health. Consequently, the question on whether indoor air quality should be absolute rather than relative to outdoor air can be raised. Perhaps standards someday will suggest greater air quality indoors than outdoors. In such an event, it would be admitting to failing on improving our cities environment.

2.1.5.1 Inhabitat 2.1.5.1.1 VOC, chemicals and noxious concentrations SBS has been commonly linked to the noxious components coming from cleaning chemicals and building materials. Asbestos has thought us to pay attention to the materials we use indoors yet indoor air quality classifications do not take building materials into account. Volatile organic compounds (VOC) such as formaldehyde is commonly found in paint, coatings, glues and glulam. Other VOCs such as Benzene can come from tobacco smoke and stored fuels, methylene chloride from aerosol spray paints, perchloroethylene from stored dry clean clothes and so onâ&#x20AC;Ś 2.1.5.1.2 Dust Dust in homes, offices, and other human environments contains small amounts of plant pollen, human and animal hairs, textile fibers, paper fibers, minerals from outdoor soil, human skin cells, burnt meteorite particles, and many other materials which may be found in the local environment. 2.1.5.2 Occupants 2.1.5.2.1 O2 concentrations Air is mainly composed of 79% of nitrogen and 21% of oxygen. The oxygen consumption of a human is approximately 0.0003 m3/h/pp (Loer SA, 1997). In order to keep oxygen levels maintained at 20%, the imported fresh air would only have to be 0.03 m3/h/pp or 0.0083 L/s per person. 2.1.5.2.2 CO2 concentrations At normal resting activity, a human emits approximately 0.03 m3/h/pp of carbon dioxide (University of Minnesota, 2009). Normal outdoor levels of CO2 are measured at 350 ppm. If we set maximum indoor concentrations at 1000 ppm, air would have to be renewed at a rate of 46.3 m3/h/pp or 12.85 L/s/pp. This is over 1500 times greater than the flow rate needed for oxygen supply.

2.1.5.3 Mathematical Box Model The concentration of a pollutant in a room with a constant air flow rate and an emission rate of the pollutant within the room leads to the following differential equation : dc/dt = q â&#x20AC;&#x201C; c.V. dc/(q-c.V) = dt (-1/V).ln(q-c.V) = dt (-1/V).ln((q-c(t).V)/(q-c(0).V)) = t c(t) = q/V(1-e^-nt) + c(0) c(t) = (q / nV) [1 - (1 / e^nt)] + (c0 - ci) (1 / e^nt) + ci c0 = carbon dioxide concentration in the room at start, t = 0 (m3/m3) c = carbon dioxide concentration in the room (m3/m3) q = carbon dioxide supplied to the room (m3/h) V = volume of the room (m3) e = the constant 2.718..... n = number of air shifts per hour (1/h) t = time (hour, h) ci = carbon dioxide concentration in the inlet ventilation air (m3/m3) The needed flow rate in a room to maintain a given concentration of pollutant in a room is : Q/(1-e^-Q) = q/(c-ci) with t = 1h and n = Q/V Because ventilation rates are relatively rather low, the equation can be approximated to a linear equation : Q = q/(c-ci).

Pollutant (Chemical production) In-flow

Out-flow

Emission

Deposition

Pollutant

Outdoor concentration (ppm)

Max. indoor Emission rate concentration (L/s/pers) (ppm)

Min.air flow (ppm)

(O2)

21000

20000

0,0083- 0,0001

0,0083-0,01

CO2

350

1000

0,0036-0,0167

7,91-12,85

Benzene

0,00106

0,00319

1,82709E-09

0,24

Formaldehyde

0,0057672

0,0374067

0.13-3,74759 E-07 0,11-3,29

An anecdotal comparison with the needed flow rates to achieve at least the actual mean value in dwellings shows that CO2 is the ultimate reference. In the case of formaldehyde, the flow rates vary considerably according to the sourceâ&#x20AC;&#x2122;s emission rate. When formaldehyde emissions are very high (11mg/m2/h), it would correspond to wet wooden floor finishing that would make the building anyway temporarily unusable. When using a formaldehyde component, it is important to highly ventilate. 2.1.5.4 CFD tools The previous calculation is based on a simplified model suggesting that emissions are instantaneously evenly distributed in the air. However, air is not always evenly flowing in a room and components vary in density. CO2 has a tendency to drop as it is heavier than air. Computational fluid dynamic tools are a lot more useful for visualising the distribution of contaminants in a room. This type of modelling shows how to ventilate but may also show whether the predicted ventilations rates in the simplified model can be lower or higher (local accumulation). 02 is not a pollutant but interesting in comparison to the flow rates. Rates depend on activity. Outdoor concentrations in Den Haag, Netherlands (European Environment Agency, 2013) The emission rate for Benzene was based on the estimated daily indoor intake of Canadians (Americans intake is nearly twice as high) (Harrison, Delgado Saborit, & Dor, 2010). Average indoor concentrations in France (World Health Organization, 2010) Emissions from plywood and cabinet door with acid-cured finish (California Environmental Protection Agency , 1997)

2.2

Daylight

2.2.1 Benefits of Daylight Although a lot of benefits are objectively speculations and that scientific studies such as those trying to relate artificial lighting to health problems are rather tedious, the relation between psychophysiology and daylight has been demonstrated on a positive basis. For example, cognitive performance increased up to 18% among young students in classrooms with natural daylight compared to those in artificially lit classrooms (Heschong, 2002). Light therapy for treating mood disorders has shown to be just as effective as pharmaceutical anti-depressants (Robert N. Golden, et al., 2005). The question around daylight has been substantial for the past decade and stronger positions around the benefits in buildings are being taken. On the other hand, a confusion still largely remains between theory and practice, between requirements, regulations and building design. 2.2.1.1 Circadian cycle In spite of the absence of empirical arguments, we can still agree that daylight is the form of light with which we have predominantly evolved for the past 300 million years. The circadian cycle is set by our biological clocks, itâ&#x20AC;&#x2122;s our natural rhythm between sleep and activity over 24 hours. The disruption of this cycle may be the cause of mood and sleep disorders. The impact of daylight on our bodies are multiple. It defines our circadian cycle via the stimulation of our retinal receptors. Full visual stimuli can only be achieved with the solar spectrum and would necessarily have an indirect effect on cognitive stimuli (attention and activity for example). Furthermore, our body takes advantage of sunlight to produce vitamin D which in return simulates the calcium metabolism. It also has an effect on hormones such as the amount of melatonin in our bodies that is regulating awakeness. Even if there is indeed a need for a further understanding of the effects of daylight on humans, it is clear that our bodies rely on it as a reference and likely uses it as a resource, a nutrient. Scientific research is backing up the logical theory and intuition behind the benefits of daylight. Recent studies have discovered that retinal cells other than cones and rods are directly linked to the part of the brain influencing our circadian system (Stein, 2011). Itâ&#x20AC;&#x2122;s an important lesson for designers to sometimes go back to the primary, even basic questions to be fully aware of what they are doing. Sunset and sunrise light spectrums do not contain the blue part of the spectrum. this is in fact the reason why they appear red. Since blue light principally effects the circadian rythm, daily transition activates or inhibits the production of melatonin in the body.

2.2.1.1.1 Melatonin Produced in a specific part of the brain, melatonin is a hormone influencing the circadian cycle by causing a sense of drowsiness and lowering the body temperature. Melatonin production stabilises in an infant 3 months after birth and is delayed in teenagers allowing them to stay up later. Other than taking part in the circadian cycle, it may play a role as an anti-ageing component via its powerful anti-oxidant properties and could also take part as an immune system enhancer. Melatonin is exhibited via simulation of the retina with blue light (wavelength between 460 and 480nm). Perhaps, when considering the benefits of daylight, we may only need to take into account the effects of blue light. On the other hand, it may be the case that other benefits are also taken from broader light spectrums and should not be neglected. 2.2.2

Measurements

2.2.2.1 Radiometric unit Measures the power of light independently to eye sensitivity. The SI unit used is W/m2. 2.2.2.2 Photometric unit Takes into account the sensitivity of the human eye towards different wavelengths. The SI unit used is lux or lumens/m2. The conversion factor between radiometric values and photometric values is in function of the wavelength.

2.2.3

Daylight factor

- Ei : illuminance due to daylight at a point on the indoors working plane. - SC : Direct light (sky component) - ERC : light reflected from an exterior surface (externally reflected component) - IRC : light reflected from on interior surface (wall, ceiling, floorâ&#x20AC;Ś) (internally reflected component) - Eo : simultaneous outdoor illuminance on a horizontal plane from an unobstructed hemisphere of overcast sky.

Overcast sky Eo

ERC SSC

2.2.4

DF = (Ei / Eo) x 100%

IRC IRC

Visual comfort

2.2.4.1 Glare Glare is a subjective human sensation that describes light within the field of vision that is brighter than the brightness to which the eyes are adapted (HarperCollins 2002). 2.2.6 Artificial lighting vs natural daylight There seems to be very little differentiation in regulations and standards between quality and quantity of light. Regulations quantify the needed amount of light in an area but do not yet appear to consider the type of source. The question on whether the same quantity of light dependent on its quality, especially in the case of daylight, should indeed be raised. Some differences have been pointed out on what considerably effects visual comfort. -

Distribution of light (daylight more diffuse) Discriminating colour (spectral absorption) Flicker (headaches, tirednessâ&#x20AC;Ś) Sparkle (highlighting 3D objects enhanced with daylight) Variability (alliesthesia) Preference (affinity towards windows) Motivation Mood and satisfaction Circadian photobiology Noise

2.2.7

Glazing

2.2.7.1 g-value Materials and gases that compose high thermal performance glazing will absorb a certain amount of solar energy. The percentage of transmitted energy of glazing is defined by its g-value. A low g-value can be advantageous in lessening solar gains and preventing overheating due to excessive radiation. On the other hand, the spectrum of visual light is reduced and can have an impact on colour. The physiological impact has yet to be understood. It is possible that the benefits of daylight are partially cancelled out with low e-coated glazing (low emissivity). It is why maximizing the quality of daylight while providing the right visual and thermal comfort is important.

Blue light loss

azi zing ng 2.2.7.2 Blue light glazing h benefits b fi off daylighting, d lii h i i l glazing l i h does d In order to maximise the special that not reflect the blue light spectrum should perhaps be preferred in buildings. Anti-reflective glass allows a large spectrum of daylight to fully penetrate the material. However, in order to reduce the possibility of sun burns (UV light), shading must be set in place. Furthermore, special coatings in order to reduce infrared light can help reduce excessive solar gains. 2.2.8 Daylight and lighting visualisation tools Photon mapping and path tracing is possible with the help of tion. ARUP was able to predict an astonishingly large part of effects inside of the Sacremento Airport. Todayâ&#x20AC;&#x2122;s accessibility puter visualisation tools can contribute to a full understanding over daylight in architectural designs.

computerisathe daylight towards comand control

2.3

Acoustics

2.3.1 The auditory system Of our five senses, the auditory sense is the only one that is constantly in activity without the possibility to really inhibit. Consequently, the perception of acoustic comfort is a lot more relative than any other perception, where the reference point is constantly changing. Generally speaking, silence is seen as the acoustic optimum for rest and concentration. However, the notion of silence varies considerably inter-individually and intra-individually at a specific state and time. 2.3.1.1 2.3.2

Health and behavioural implications (Bluyssen, 2009) pain and hearing fatigue hearing impairment, including tinnitus annoyance interferences with social behaviour (aggressiveness, protest and helplessness) interference with speech communication sleep disturbance and all its long- and short-term impacts cardiovascular effects hormonal responses (stress hormones) and their possible conse quences for human metabolism (nutrition) and the immune system. Parameters

2.3.2.1 Pitch The frequency range of a human lies between 20Hz and 20 000Hz. As we get older, the frequency is range is diminished to 12 000 Hz. 2.3.2.2 Threshold The sound pressure is measured in decibels. A human can hear as low as 0dB and starts to experience pain at 140dB. The sound level that is equivalent to the average energy of noise recorded over a given period is the Equivalent Continuous Noise Level (LAeq). SRI (Sound reduction index) 2.3.2.3 Sensitivity Sensitivity to threshold depends on the pitch of the sound and is quantified by its loudness expressed in Phones. Human ears are particularly sensitive within the frequency of the human voice.

Figure 1 : Phons and the effect on the human ear (Boduch & Fincher, 2009) 2.3.2.4 Noise factors Any source of sound, loud or quiet, intelligible or not, can be considered noise when it induces a form of annoyance. However, factors contributing to noise can be generally established. 2.3.2.4.1 Loudness Since the sensitivity towards frequencies differ, some sources of sound are perceived less loud and less disturbing than others. 2.3.2.4.2 Intelligibility Sources that are information bearing are perceived as much more disturbing than unintelligible sounds (Boduch & Fincher, 2009).

2.3.2.4.3 Localisation Generally, the fact of locating or recognising the source will make a sound more acceptable. 2.3.2.4.4 Intermittency Continuous sources of sound are less likely to create a disturbance as it gives the possibility to familiarisation and an adaptation. On the other hand, sounds that are short and intermittent induce a more surprising effect and are much more likely to be unpleasurable. 2.3.2.4.5 Frequency spectrum Natural, familiar sounds are composed of a broader range of frequencies. This may be why pure tone sounds contribute more to annoyance than broadband sounds. 2.3.3

Material Properties

2.3.3.1 Mass Transmission of airborne sound through a partition is function of the mass law. It suggests that sound insulation of a solid element is proportional to its mass without any regard to absorption properties, where doubling the mass reduces transmission by 5dB. The mass law is used for materials with a density of 10 to 1000 kg/m2. 2.3.3.2 Isolation Sound isolation properties of a multiple layered wall can be calculated linearly by adding the sound insulation ratings of each layer. This leads to lightweight framed constructions leading to greater acoustic performance than what the mass law on its own would suggest. However best performance of materials are achieved by applying a cavity of at least 40mm between each layer. (Tata Steel, BCSA, SCI, 2014)

2.3.3.3 Sealing Sound being a wave, the physical properties of wave propagation will apply. This implies the diffusion of sound will make way through any gap. To achieve optimal performance from sound insulation materials, particular attention must be given towards sealing. 2.3.4

Airborne sound

2.3.4.1 Reverberation The reverberation time T is the time that takes the sound pressure to decay by 60 dB after reverberation. A sound created in a room with a long reverberation time will sound louder than the same sound created in a room with a short reverberation time. (Tata Steel, BCSA, SCI, 2014) 2.3.5 Flanking Sound transmission from one room to another is called direct transmission. However, other factors and principally leakages can lead to sound transmission from one room to another. Areas of weakness can have a disproportionately negative effect on overall performance in walls where a high dB rating is specified.

(Everden, South, & Hines, 2013)

2.3.6 Auditory Comfort In natural ventilated buildings, occupants are more tolerable towards noises than in airtight and controlled buildings. A users auditory sensitivity is somewhat changed in analogy to indoor temperature. Occupants have a more flexible expectation towards higher noise in a more externally opened situation. The benefits provided by naturally ventilated buildings lead to a further comprise with acoustic disadvantages. Open plan offices for example, that favour natural ventilation, also provide users a greater awareness and tolerance to surrounding activities. There is also a behavior factor where customarily open windows lead to more tolerance to exterior noise. 2.3.6.1 Speech intelligibility Speech intelligibility is not only defined by contrast of loudness but also by reverberation. The effect of a delay in sound of speech makes it difficult for speaking and hearing. Reverberation has to be less than 0.6 seconds long for speech intelligibility. The difference between speech and background noise should not be no more than 35 dB. 60 dB is the loudness of normal speech and 66 dB for loud speech. 2.3.7 Sound control Sound acts the same way as water, where there are gaps, leakage will occur. Different strategies for acoustic control can be set such as taking into account the materials used in a room or the partitions. However, it is important to take note on where that control needs to take place. It has been noticed that workers in open offices are less prone to noise and speech privacy than in cubicle partitioned offices. The fact of allowing people to visualise the presence of others induces a change of behaviour in people. Workers are aware of their surroundings and therefore adapt their speech to the intimacy of their neighbour. There are two ways in decreasing sound pressure in a room. Either by letting sound flee through boundaries (opening a window) thus decreasing reflective surfaces or by by absorbing sound thus absorbing part of the energy and decreasing the reverberant sound pressure in the room. Speech privacy results in a lot more dissatisfaction than noise intrusion. (Sound Matters, 2011). 2.3.7.1 Zoning Spatial strategies towards acoustics can take place on the functional basis of the building. Once usage, behaviour and function patterns have been established, creating zones to best suit the users need for privacy or absence of distraction will facilitate control and reduce resources for acoustic room design.

2.3.7.2 Sound absorption Sound absorption describes the ability of materials to restrict the reflection of sound, doing this by converting the energy of sound into heat. The greater the sound absorption, the shorter the reverberation time or echo produced. Sound absorption is measured as a coefficient from 0 to 1.0 where 1.0 is the best rating. Sound loudness and propagation can be amplified with acoustic spatial reverberation. Surfaces will naturally have an impact on the acoustic quality of a room and is therefore an important factor to take into account. Each material has its own absorption properties but in general softer materials have a greater sound absorption coefficient. The surface will define the reflective properties of the material where for example, smooth concrete will reflect sound with very little energy absorption compared to carpet and or even more so to cotton. An anechoic room uses groups of parallel wedges oriented for the acoustic energy to reflectively dissipate between them. Sound

Absorption

Reflected sound

2.3.7.3 Sound masking The principle of sound masking is developed by some companies that aim in reducing the perception of noise by adding background noise. Essentially, this technology reduces the contrast of acceptable background noise with undesirable sounds, especially in working environments. It results in reducing the percieved noise loudness and therefore decreasing the earshot distance. The sound produced is a white noise ressembling blowing air and is noticed only when the system is turned off. In wind-ventilated buildings, natural sound masking could occur provided that the outside acoustics are classified as an acceptable background noise. In the other case, acoustic treatment would most likely need to take place.

2.4

The principle of alliesthesia

“Alliós” meaning “changed” and “Aísthesis” meaning “sensation”. This is an extremely interesting phenomena but very little studies or models have been established on the subject. The difference between the static thermal model and the adaptive thermal model can be explained by the effect of Alliesthesia (Candido & de Dear, 2012). All five of our sensations can take part in a positive or negative hedonic tone. Thermal alliesthesia for example is created by experiencing a difference in temperature. With traditional HVAC systems, although the temperature is within a very comfortable interval, thermal delight or positive thermal alliesthesia cannot be experienced. A good example of positive alliesthesia is the effect of temporary piercing sunlight through clouds, or a sudden breeze on a hot day. Exploiting versatile and adjustable features in buildings could be a fantastic aspect in user-building interaction. In the case of more “lively” buildings that change with the exterior climate, or can adapt itself, the play on change of perception could be directly integrated in the comfort these adaptive systems are based on. 2.4.1 Hedonicity Heschong (1979 pp 18) eloquently explains: “when the sun is warm on my face and the breeze is cool, I know it is good to be alive”. Whilst a reasonable critique, it is unreasonable to suggest that we should not, or do not, experience displeasure. Pleasure is more rare than displeasure simply because any stimulus experienced in excess becomes unpleasant (Cabanac, 1979). But the result of this uneven distribution is a heightened sense when we do experience pleasure - the greater the displeasure experienced, the stronger the resulting pleasure (Kuno, 1995). Furthermore, if we stay within a certain limit of extremes causing displeasure, we can create an environment more positively stimulating with hedonic experiences. 2.4.2 “Sensory waves” Sensory experience or qualia, is based on highly subjective interpretation, varying from individual to another. A fixed value defined for a group of individuals does not make sense where the inter-individual experiences may simply result in stimuli more or less on one side of a hedonic tone. However, creating a wave of values or settings allows occupants to experience alliesthesia where discomfort may not have time to set in and simply expresses itself in a hedonic response. The experience rests within a certain interval that continues to appeal yet creates the sensation of delightful experiences. In a hedonistic point of view, the definition of comfort today would not comply, as it is an absence of stimuli rather than a quantitive or qualitive maximisation of pleasure we have the potential to experience.

Perception 1

Neutral

Perception 2

Perception 1

Static comfort model

Perception 1

Neutral

Perception 2

Adaptive comfort model

Neutral

Perception 2

Hedonic comfort model

Figure 2 : Negative and positive alliesthesia (de Dear (2010))

2.4.3

Sensory hedonic experience

2.4.3.1 Auditory (Mental) There is a satisfactory and protective feeling of being inside a room when rain hits the window panels. Realising what is happening outside becomes a poetic reassurance. The change of perception becomes a projection in the mind, knowing the difference between what we could negatively experience enhances the postive experience that we have. Auditory experiences are also mostly mental alliesthesia rather than a physical sensation. Pleasant noises such as bird singing tells us it is the beginning of the day. The contrast of hearing rushing cars and sitting in the couch in front of the TV is a reminder of a relaxing moment. The absence of noise activity tells us the world is asleep. Mental alliesthesia enhances an experience that could easily be taken for granted. 2.4.3.2 Visual 2.4.3.2.1 Daylight The postive impact of daylight on our physiological of psychological health is far from being neglegible. However, alliesthesia with sunlight is also something we countinuously experience. Sunlight intensity in a partially cloudy climate continuously varies throughout the day. The sensation is positively recieved in both cases, relaxing the eye at low intensities or being stimulating and energising at higher intensities. 2.4.3.2.2 Spatial Spatial alliesthesia is certainly coupled with other senses such as feel and acoustic (blind people), but visual may be the strongest spatial reader of all our senses. Architecture in itself embraces spacial alliesthesia on different scales and in different ways. The fact of influencing the perception of space a person has on his environment is perhaps the greatest power a designer has.

2.4.3.3 Olfactory The constant presence of a smell, positively or negatively recieved will wear off the olfactory sensation. On the other, a change in smell is what induces stronger hedonic tones. The information recieved from olfactory senses is complex and is far from being binary. It can go from one postive hedonic tone to another positive hedonic tone simply by going from one subjectively nice smell to another. Different perfumed plants along a botanic garden path can have this impact. 2.4.3.4 Feel 2.4.3.4.1 Thermal As discussed previsouly, thermal alliesthesia is how we can explain the adaptive thermal model. 2.4.3.4.2 Touch Surfaces either hard or soft, smooth or rugged, “Warm” hot or cold, fragile or strong, each have their own interpretation, their own use. The fresh, cool feel of a concrete wall on a hot day induces positive alliesthesia. Softer insulating surfaces are preferred on cooler days but can create discomfort on hotter ones such as our backs on leather couches. Questions should be raised on the materials used in buildings that could provide this sense of comfort (example : wooden hand rail vs metal hand rail). The design of a chair could let the possibility of switching around the back to accustom a users liking.

“Fresh”

2.4.4 Cenaesthesia Perception is not just a single hedonic tone of just one unique sense : “perception is the fruit of all senses”. Willing to positively stimulate all our senses at a given moment would be difficult. Creating a positive hedonic tone for one or more senses, compensates or lets a greater tolerance toward a negative hedonic tone of another sense. For example, occupants have demonstrated to be more tolerant towards noise in favor of natural cooling by opening a window. In this case, thermal (and perhaps spatial too) alliesthesia give a more powerful postive hedonic tone than the negative hedonic tone of acoustic discomfort.

METHODS AND PRINCIPLES

3.1

Ventilation

Ventilation is the process of exchanging indoor air with fresh outdoor air. The atmosphere in enclosed spaces can lead to increased concentrations of unwanted components that are unsuitable for ideal human living conditions. 3.1.1 Necessity The essential part of ventilation is the elimination of inside air components. provision of air for occupants respiration (activity) control of internal humidity (comfort and protection) dilution and/or removal of background pollutants (metabolic CO2, vapours, odours, emission from building, furnishing and cleaning materials, VOCâ&#x20AC;&#x2122;s) dilution and/or removal of specific pollutants from identifiable local sources: toilet and cooking odours, water vapour from bathing /cooking / washers & driers, tobacco smoke, combustion products from fuel burning appliances provision of air for fuel burning appliances and dilution of related emissions 3.1.2 Effects of CO2 Occupants experience drowsiness, sleepiness, headaches and other symptoms leading to a decrease in productivity. A study occurred in a school demonstrating the negative effects on cognitive skills at high CO2 levels. It is important that CO2 levels are kept low in high activity areas such as offices and schools. 3.1.3 CO2 as an indicator CO2 concentrations is considered a good indicator of indoor air quality. Ventilation rates based on these values would be largely sufficient for all the other aspects to be considered such as the elimination of Volatile organic compounds (VOCs) or relative humidity regulation.

3.1.4 Regulations Table 1-4 . EN classification of indoor CO2 concentrations above outdoor

Category EN151251

IAQ Level

CO2 concentration above outdoors [ppm]

Airflow pp l/s/pp

Airflow per mÂ˛ floor area [l/s/mÂ˛]

IDA1

High

350

1.4

IDA2

Medium

500

1.0

IDA3

Moderate

800

0.6

IDA4

Low

> 800

3.1.5 Calculations (EN regulations, BREEAM) The basic formula Q=G/(ci-co) gives us the needed ventilation rate Q to keep the levels of CO2 at an adequate level. G : CO2 production rate per person ci : maximum indoor CO2 levels co : outdoor CO2 levels In Rotterdam, the outdoor CO2 levels are close to 400ppm. To reach IDA1 with occupants at resting activity, the flow rate would have to be 11L/s per person. At normal activity, the ideal air flow rate reaches 19L/s. These values are higher than those suggested in European regulations stated in Table 1-4. BREEAM requires an airflow between 9.7 and 13.9L/s per person depending on the function of the building. 3.1.6 Disadvantages in ventilation The best environment is a non-polluted exterior environment. Therefore, on its own, ventilation is strictly beneficial provided we take into account other comfort factors such as thermal conditions. This is of course only true if the air input is of higher quality. On the other hand, air input of relatively low humidity (10%-20%) will also cause discomfort. This happens typically with direct ventilation in cold climates. Furthermore, ventilating a heated area leads to considerable energy loss and costs. This is the reason why ventilation is generally reduced to a minimum resulting in energy savings.

3.1.7 Bio-utilisation : using plants to increase indoor air quality Some plants can reduce indoor air pollution by their capacity in retaining volatile organic compounds (VOC). Furthermore, the presence of indoor plants in an office environment can reduce CO2 from 10% to 25% and and CO bup to 90%. Basic calculations show that humans produce 1kg to 2kg of CO2 per day. Knowing that an average forest has an intake of CO2 of 6tons/year per hectare, we can estimate how many square meters of forest is needed to neutralise CO2 emitted by breathing. The value was estimated to be a little over 1 hectare of forest per person which would be inapplicable to buildings. It can be pointed out that small plants grow faster and may have a faster intake of CO2. Studies remain unclear in the efficiency of interior plants recycling indoor air. 3.1.8 Natural air driving forces There are essentially two ways in creating an air flow in a building. One consists of exploiting thermal gradient and the other of naturally occurring exterior forces. 3.1.8.1 Thermal buoyancy A gradient occurs when there is difference between the density of exterior air and interior air. The difference in densities manifests itself in different air pressures thus creating naturally occurring air movement. The phenomenon in buildings is called the stack effect.

Infiltration

Heated air

3.1.8.2 Wind Natural occurring forces surrounding the building can be used to drive the air within. Wind going towards a building envelope creates positive pressure pushing air in the building whereas wind going outwards creates negative pressure pulling the air out. Computer fluid dynamics (CFD) is a modern tool for simulating complex wind flows and could be exploited early in a design for natural ventilation. Before considering wind as a natural ventilation force, statistical studies on wind direction and speed are crucial for the location of the design. If wind speed is too low in the specific area, a different strategy may have to be considered. If wind direction is not constant throughout the year, it will have to be thoroughly considered in the design.

3.2

Heating

3.2.1 Ventilation losses Ventilation losses are inevitable unless a closed environment with an air cleaning system is provided. As it has been demonstrated previously, achieving good indoor air quality implies renewing indoor air with fresh air. The total heat loss from ventilation is given by : Hv = [Ti-To].cp.qV.

To qVin

qVout

Ti : inside temperature (K) To : outside temperature (K) : volumetric mass of air (kg/m3) cp : calorific heat capacity (J/K) qV : air flow rate (m3/s)

3.2.2 Heat recovery system The efficiency of HVAC systems can be increased up to 80% with integrated heat recovery systems. The principle is very interesting but is hard to conceive for naturally ventilated buildings. Biomimicry could be a source of inspiration for a heat recovery system for naturally ventilated buildings. A heat recovery strategy could be implemented not only as a piece of technology but as the architecture itself. Studies demonstrate in fact that MVHR are not as efficient as they would suggest. They demand a considerable amount of energy to function. These systems under a satic comfort model have been compared to natural ventilated buildings under adaptive comfort models and have been demonstrated to be less energy efficient (Sassi, 2013). 3.2.3

Transmission losses

3.2.3.1 Physics There three ways transmission losses occur. Conduction is the process where atomic agitation is transfered to neighbouring atoms. Radiant energy does not need material to be transfered and is why solar heat can cross the spatial void and enter our atmosphere. Convection is applied to gas and fluids where the temperature gradient creates a flow.

Conduction Convection

Ti : inside temperature (K) To : outside temperature (K) d : material thickness (m) k : heat conductivity (W/m.K)

k Radiation

3.2.3.2 How do we reduce transmission losses? Using materials with low heat conductivity k and increased thickness d will increase the thermal resistance of a building. Materials can achieve good insulation properties by reducing the air convection and using air as an insulator (ex : fiberglass, woolâ&#x20AC;Ś). Internal radiant heat losses can decreased with reflective surfaces. 3.2.3.3 Is insulation necessary? Simple calculations can demonstrate very quickly the importance of lowering transmission losses. The Passivhaus system can only work with very high thermal performance. Seen as ventilation heat losses for quality indoor air is inevitable, exploiting internal heat gains is only feasible in well insulated buildings. Different strategies may be set in order to decrease the use of insulation such as thermal zoning based on biological homeostasis. 3.2.4 Occupants and electrical devices as heaters Buildings without heaters are now the case with PassivHaus constructions. The internal gains from occupants and electric devices (computers, lights, refrigerators, etcâ&#x20AC;Ś) are sufficient in efficiently insulated buildings. Solar gains are also exploited but must be countered on cooling days. In average, computers and humans produce 100W. An energy efficient lightbulb emits 10W. When the internal gains are summed up, they can compensate ventilation heat losses when the transmission losses are low.

3.3

Cooling

3.3.1 User Behaviour This an extremely important factor and can considerably reduce energy costs. The simple fact of having users adapt their clothing to the indoor environement leads to a greater tolerance scale to ambiant temperature. In the adaptive comfort model, clothes insulation is function of the exterior climate. This is pretty straight forward and consequently just relaxing the dress code during hotter days remarkably increases the temperature range slightly beyond 26 째C. Furthermore, giving users the choice of adapting their environment and customising it to their will is key to a naturally ventilated design. Simply opening a window for example or adapting shutters will allow a further tolerance on the inside temperature.

3.3.2 Ventilation This method consists essentially in getting rid of the heat accumulated in the air inside of a building. On the other hand, when integrating air speed in ventilation, the sensation of coolness can be substantially increased due to convection and evaporative cooling. 3.3.2.1 Hybrid ventilation systems Weather conditions vary so much that they can be unpredictable at times. Since naturally driven air is dependent on the exterior climate, most modern naturally ventilated buildings have backup systems. Mechanical fans are coupled with the principles of wind and buoyancy driven forces. Principally, hybrid ventilation systems are first designed to maximise the use of natural forces and secondly to assure the efficiency of the system all year round, under all climatic settings.

3.3.3 Thermal inertia Integrating thermal mass in a building reduces thermal fluctuations. Increasing thermal capacity in walls, floors and ceilings will decrease radiation. In fact, mass acts as a heat sink during hot days. During cooler nights, The building can be ventilated for heat to dissipate from walls.

3.3.3.1 Position of insulation The position of the insulation layer relative to the wall has an impact on the thermal mass. If the insulation is situated inside the building, thermal inertia cannot occur with the walls. On the other hand, the temperature will indeed rise a lot faster inside the building. This feature might be wanted in some cases, especially in very cold climates.

Indoor

Insulation inside

Outdoor

Insulation in the centre

Insulation outside

3.4

Daylight

3.4.1 Daylight regulations BREEAM recommends a minimum of 1.5% to 3% daylight factor depending on the buildings function. Visual comfort is quantified in regulations rather than qualified. The international guidelines are not taking into account the daily benefits of natural daylight but do encourage a minimum amount of daylight most likely in order to achieve energy savings on indoor lighting. Introducing more glazing in a building lowers the overall thermal performance due to greater transmission losses. It is crucial to implement intelligent configurations to find a compromise between daylight and heating losses. 3.4.2 Vertical windows The advantages of vertical windows are clear, they provide a good view and is an easy solution for daylight in multiple level buildings. However, they can cause glare and give an unnatural feel due to penetration of sun rays leading to discomfort at times. Glare can be avoided with shutters or 3.4.3 Zenithal daylight We never look directly at the sun, and sunlight is mostly horizontal at the beginning and end of the day when itâ&#x20AC;&#x2122;s intensity is low. We are psychologically and physiologically used to sun coming down on our heads. Under active circumstances, we naturally turn our backs to the sun, or protect direct sunlight on our eyes with hats or sunglasses. Zenithal daylight penetration into buildings introduces the natural position of the sun and most likely enhances the benefits of natural daylight. The intensity of light is considerably higher in the sky and is why skylights are much more daylight efficient than vertical windows. Furthermore, we have the tendency to look down on horizontally planes to work, making downwards lighting a lot more comfortable. 3.4.4 Diffused daylight In difference with direct light, diffused light is omnidirectional. Itâ&#x20AC;&#x2122;s created by distributing light uniformly in different directions. Consequently, this causes an altered image of the light source but in return has the advantage of reducing glare when the light source is overpowering such as the sun. However, for the same illuminance (energy per unit area) the luminance (direct light) is reduced causing a decrease in the effect of contrast resulting in a diminished visual distinction of details. Luminance is the really the quantification we see, as we only get direct light to the eye. Contrast is the ratio between the lowest and highest luminance measured from an object and is why even with high illuminance, contrast can still be lower.

OUTDOOR

lux

Sunlight

100 000

Full Daylight

10 000

20 0000

5000 2000 1500 Overcast Day

1000 750 500 250 150

Very Dark Day

Twilight

Deep Twilight Full Moon

INDOOR ACTIVITY

Very special visual tasks of extremely low contrast and small size Very prolonged and exacting visual tasks

Visual tasks of low contrast and very small size for prolonged periods of time

Detailed Drawing Work, Very Detailed Mechanical Works

Normal Drawing Work, Detailed Mechanical Workshops, Operation Theatres

Supermarkets, Mechanical Workshops, Office Landscapes Normal Office Work, PC Work, Study Library, Groceries, Show Rooms, Laboratories Easy Office Work, Classes

Warehouses, Homes, Theaters, Archives

100

Working areas where visual tasks are only occasionally performed

Simple orientation for short visits

Public areas with dark surroundings

0,1

Starlight

.001

Overcast Night

.0001

3.4.5 Shading systems The type of shading, the colour, the position to the glazing, the type of glazing are setting that will affect the efficiency of the shading system. The choice of the system depends on whether it is destined to reduce glare or solar gains or both. Generally speaking, exterior shading is better for preventing overheating and can be oriented to make optimal use of solar gains in function of the season.

3.5

Acoustics in naturally ventilated buildings

Naturally ventilated buildings deal with low air flow and thus need to have little air flow resistance. The architectural impacts are for example larger faĂ§ade openings. Consequently, noise insulation is decreased and leads to the main reason why acoustics is a crucial aspect in naturally ventilated building design. 3.5.1 Natural sound masking In addition, a controlled increase in background noise levels can provide masking noise within the space, a problem previously identified with passive cooling systems. This benefit, however, is dependent on the acoustic character of the external noise being used to provide masking.â&#x20AC;? 3.5.2 Noise mapping Using todayâ&#x20AC;&#x2122;s digital tools, it is possible to predict the acoustical impact of the environment on a building. This implicates developing design strategies to prevent the excess of exterior noise leading to discomfort in naturally ventilated buildings. Airtight buildings may be less subject to acoustic discomfort coming from outside, on the other hand, taking into consideration noises early in a design could lead to using less resources in resolving acoustical burdens. 3.5.3 Acoustic attenuators in naturally ventilated buildings Many companies are now developing passive technological systems to deal with acoustical disadvantages in more open buildings. There are essentially three type of natural ventilation systems, each with their advantages and disadvantages : acoustic Louvre, splitter attenuation, acoustically lined bend. Many systems are a combination of different acoustical strategies (Chilton, Novo, McBride, Lewis-Nunes, & Johnston, 2012).

3.5.3.1 Acoustic Louvre An acoustic Louvre is angled composed of horizontal blades with a metal upper side and an acoustically absorbent underside. These are generally weatherproof to some extent.

3.5.3.2 Splitter attenuator It is composed of blades aligned with the airflow direction. The inside of the surrounding chamber and both sides of the blades are acoustically absorbent. These are the same as in-duct attenuators used in mechanical ventilation systems. Note that a lined, straight duct would be classified as a splitter attenuator with no splitters. 3.5.3.3 Acoustically lined bend or plenum Any chamber or duct that has an acoustically absorbent lining and provides an offset or change-of-direction to the airflow path. 3.5.3.4 Questions and critic These technologies are limited to a type of design, mainly faĂ§ade ventilated buildings. It seems to be a post-design solution. The question raised is whether it is possible to adapt architecture in itâ&#x20AC;&#x2122;s very early stages towards wind and buoyancy driven air currents. Instead of technology to be implemented in the building for ventilation, what if the building becomes the ventilator and technology itself. If wind were to shape architecture what would it look like? If acoustics, wind, air buoyancy, daylight were to shape architecture, what would it look like?

3.6

Building Materials

Choosing the right materials is important for good indoor quality. VOCs emitted by toxic materials lead to sick building syndrome. To assure a healthy indoor environment, building materials and construction details must take some particular attention in the design. 3.6.1 Biases First of all, it should be clarified that “natural” materials are not necessarily healthier than man-made materials. Certain types of wood can be naturally extremely toxic, and even asbestos is sourced from natural rock formation. Generally speaking, the most “inert” and stable materials are the least problematic in indoor environments. There are a lot less risks into triggering allergies or emitting dust and volatile compounds. On the other hand, man made materials such as concrete, even though they are somewhat stable, are potentially dangerous during the building process. Before hydration, cement is a reactive component and anhydrid cement can indeed proceed to react within the lungs leading to physiological problems. Lime has been used for thousands of years but is a highly nocive building compound to work with before carbonatation takes place. When establishing the health risks of a building material, the safety for workers during the construction process should also be taken into account in addition to its exposure during its occupation. 3.6.1 Formaldehyde based materials 3.6.1.1 Paint Formaldehyde is classified as a probable carcinoogenic and has also been directly associated to sick building syndrome. Even though it’s naturally present in air, it becomes a health risk when the concentration levels increase. Paints temporarily emit high concentrations of formaldehyde when they are applied and are drying. It’s important to increase the ventilation rate during the application of paint. There are some non-toxic alternatives for paints that do not contain formaldehyde, ammonia, crystalline silica or ethylene glycol. Although, they are generally only suitable for indoor use as they tend to be less durable or resistant than classic paints. 3.6.1.2 Glue based materials Composite wood materials contain glue which is generally a source of high formaldehyde emission levels. Glulam or chipboards are some examples of which the use indoors need to be considered aswell as their classification for health standards. However, it has been reported that glue laminated wood only use moisture resistant adhesives being phenolic and or melamines (not urea) resulting in low fornaldehyde emission levels.

3.6.2 Pressure treated wood Arsenic is present in nature at low concentration levels. However it becomes poisonous at higher concentrations. At the beginning of the 20th century, wood was treated with arsenic to prevent rot. Studies have demonstrated that itâ&#x20AC;&#x2122;s possible to be contaminated by CCA (Chromated Copper Arsenate) pressure treated wood where arsenic has the possible to resurface. Itâ&#x20AC;&#x2122;s important to diagnose the presence of arsenic in existing building and seal off arsenic. The contamination is through direct contact, hand to mouth, unlike respitory contamination with volatile organic compounds. 3.6.3 What Asbestos has taught us Todays legislations prohibit the use of asbestos in buildings but a hard lesson was taken. The use of new materials may seem unharmful at first but the carcinogenic effect takes place 10 to 15 years after being exposed. Regulations, classifications and testing are helping to prevent negative health effects of newly exploited materials. However some studies warned about the effects of Asbestos years before it was officially banned. Whistle blowers were simply shut off by the capitalistic outcome around the asbestos market. Designers must be well informed about the products they are willing to use in buildings, especially if their main concern is about the wellbeing of the occupants.

3.7

Fire Safety

3.7.1 Open plan issue Fire safety can be seen as a concern for naturally ventilated buildings. One of the main reasons is due to larger open spaces and a reduction in compartmentalisation. Most fire safety regulations restrict buildings to volumetric units in order to avoid an easy propagation of fire through the whole construction. 3.7.2 Reverse stack effect In the case of buoyancy air driven ventilation, it is possible that at certain moments of the day, especially in the morning, there is a reverse stack effect due to lower temperatures inside compared to outside. This stituation makes smoke much harder to escape the building until the fire creates enough heat for the stack effect to occur. 3.7.3 Water sprinkler cooling In the way as the reverse stack effect, fire sprinklers can cool smoke making the air density lower. The smoke will not make its way out through the top openings in a naturally ventilated building. 3.7.4 Double skin In the case of double skin faรงade buildings, the void can act as a shaft for fire to propagate to higher floors.

EXAMPLES

4.1

Historical

4.1.1 Windcatchers Natural wind forces were used to create air flow providing a cooling effect and sensation. Horizontal openings would let wind in creating positive pressure or would drive inside air out at negative pressure.

4.1.2 The Chimney Effect The heat in a chimney drives the air upwards and out of the building by stack effect thus creating negative pressure indoors. Renewed fresh air would naturally been drawn into the building by infiltration since older buildings are not airtight.

Infiltration

Heated air

4.1.3 Egyptian dual-courtyard Two courtyards are placed on either side of a building and connected by a tunnel. One courtyard thrives with vegetation to cool it down and the other is empty which allowing it to become hot. Through stack effect, the hot air in the empty courtyard is driven upwards out of the hot courtyard, pulling the cool air in the other courtyard through the tunnel and into the building. This ancient technique has most likely been based on speculation, very lit-

Cool courtyard (evaporative cooling)

Hot courtyard (Solar radiation)

4.1.3 Japanese reflective surfaces White or gravel surrounds traditional japanese architecture in order to enhance daylight penetration from underneath the roof overhangs. Moreso, the principle can also be found in traditional buildings by the side of rivers or ponds. Extreme care is taken with these reflective surfaces as daylight is praised in Japan.

Karesansui or â&#x20AC;&#x153;Dry Gardensâ&#x20AC;?, Ry an-ji, 15th century

4.1

Modern

Can we sense the day indoors? Diffused light from the ceiling provides intimacy yet gives a very natural perception of thel luminosity throughout the day. The circadian rythme naturally takes place while the energy demands of artificial lighting are significantly reduced.

Daylight House, Yokohama, Japan, 2011 - Takeshi Hosaka Architects

Can we tune a building to achieve the right acoustics?

The singing ringing tree, Lancashirem England, 2006 - Mike Tonkin and Anna Liu

Can we heat, cool and ventilate without HVAC systems? A very simple climatical analysis and approximation demonstrates the feasibility of modern natural ventilation. “2226” also proves that alternative construction methods, differing from generic insulation materials, can provide the necessary insulation requirements for passive building standards.

Stationary climate analysis : 18 °C inside, 7 °C outside

Walls : 2 Portotherm bricks - Thermal resistance 4,16 + 2.94 = 7.10 m2.K / W - U-Value : 0.14 W / m2.K Note : low embodied energy building, high termal efficiency

Transmission losses Ventilation losses 17 000 W 14 000 W Internal heat gains (Lights, computers, people...) 33 000 W

2226, Lustenau, Austria, 2013 - Baumschlager

Open plan typology for easy air flow Building compactness for less heat dissipation Ventilation automated by software CO2 detectors Solar gain control

Can old methods be applied today? Looking at archaic principles such as windcatchers as also proven to be effective in colder countries such as Norway. Combined with a solar heated transition space, natural ventilation has been demonstrated to be effective.

Grong Primary School, Norway 1998 - Letnes Architects

Is cross-ventilation still effective by todays standards? Simple technical aspects on facades and architectural strategies such as open plan make even simple cross wind ventilation possible for cooling. However, to answer todays standards, a hybrid back-up system is likely needed.

Riccarton School and Library, New Zealand, 2006 - Warren and Mahoney

Can the opeation of nature be a source of inspiration? Hybrid ventilation became highly effective when coupled with strategies inspired by termites. Using stack effect and fan/vent activation mimicking the principles of a termite mound led to reducing the impact for installations and the use of energy for cooling.

Eastgate Center, Zimbabwe, 1996 - Mick Pearce / ARUP

Can the form of nature be a source of inspiration?

Observing compass termite mounds shows that form and orientation can be a brilliant solar strategy towards heating and preventing over-heating. Due to a perfect north-south orientation, the sun heats the facades in the morning and evening. During the hottest hours of the day, the surface of radiation is simply limited thus reducing the risk of overheating.

Davies Alpine House, London, 2006 - Wilkinson Eyre Architects

Is living outside in a building possible? Open air schools were designed for children prone to tuberculosis at the beginning of the 20th century. Although it would be uncomfortable for a great time of the year, being outside has its benefits even in schools.

Openluchtschool (Open Air School), Amsterdam, 1930 - Johannes Duiker

5 DESIGN TOOLS AND STRATEGIES A building without installations is a building that is an installation. Exploitation of natural driving forces. Parametric design.

DAYLIGHT

FACTOR

1. Spatial distribution - Functions - Maximise zenithal daylight - Diffuse daylight - Horizontal daylight for visual comfort 2. Form finding 3. Heating properties

STRATEGIES

ACOUSTICS 1. Context - Implantation - Adapt position and openings 2. Functional distribution (zoning) - Private zones - Grouping noisy zones 3. Background Noise - Reduce noise contrast (silence is noise) - Explore possibilities to naturally induce background noise 4. Correction

EXAMPLES

- Japanese reflective surfaces - Daylight House - Davies alpine house

- Singing, ringing tree

ALLIESTHESIA

- Solar radiation on body - Luminosity on the retina - Hormonal change

- Silence and busy

DIRECTION/ PLANE

COMMENTS INSPIRATION

-z

Important factor to form finding Architectural decisions. Structural biomimicry.

(x, y) To take into account at the beginning of the design but possible to correct in the last Architectural decisions. Passive engineering strategies.

HEATING 1. Functional Distribution - Divide areas into organs - Most functional organs to least functional - Define temperature interval for each organ

VENTILATION 1. Wind - Climatic data - Direction and Speed - Spatial distribution - Compatibility calculations - Form finding

2. Insulation disposition - Reduce transmission losses - Transfer heat between spaces

2. Stack Effect - Spatial distribution - Heat induced spaces - Strategy - Wind plane bending - Compatibility 3. Electrical and metaboli- calculations cal heaters - Occupancy rate 3. Acoustics - Preliminary calculations - Compatibility 4. Solar Gains - Favorise adaptive solar strategies - Coupled with daylight

- 2226 - Openluchtschool - Davies alpine house

Windcatchers Chimney effect 2226 Eastgate Centre

- Real fresh air sensa- Cool and warm spaces tion - Warmer surfaces (touch) - Natural fluctuations

+z No installations as long as transmission losses are locally countered.

(x, y), bendable to z The aim is to have a fully functional passive system.

Biomimicry formfinding. Biomimicry homeostatic scheme / ARUP principle. Old ventilation principles.

COOLING 1. Ventilation - Spatial distribution - Cooled air (underground, shaded sides). 2. Shading - Minimise solar gains - Reponsive and adaptive systems 3. Thermal Inertia - Reduce thermal fluctuations - Night-time cooling 4. Heat dissipating surfaces - Liberate heat between spaces

- 2226 - Eastgate Centre - Breeze / air speed - Shade experience - Cooler surfaces (touch)

(x, y), -z, +z Closely related to ventilation strategy. Biomimicry cooling systems (heat transient spaces).

5.1

Parametric Scheme

The scheme acts on different scales. A single room, a group of rooms or the building as a whole can be looked at as one single functional unit in the scheme. 5.1.1 Building Information Model A scheme generalising most aspects of optimal building physics design can be a better tool for designers than written guidelines. Being able to virtually break down the geometry allows to treat each aspect gradually as the design sets in place. As we move towards building information modelling (BIM), dividing data and architectural aspects allows each actor to contribute and process iteratively. Direct Sunlight

Circadian cycle Function

Daylight intensity

W Bouyancy vector

Wind Plane (vector) N

VERTICAL PLANE - Daylight - Spatial Distribution - Heating - Circulation - Wind Bending - Ventilation

HORIZONTAL PLANE - Cross Over Wind - Functional Distribution - Heating - Circulation - Acoustics

3.5.1.1 Flexibility We should not forget about the flexibility and plasticity of the design parameters. Wind is unidirectional, yet the plane can be bent and reinforce the buoyancy vectorial forces.

Bending wind plane towards the top. Coupling to bouyancy force. East Wind

Direct Sunlight Di

Circadian cycle Function

Daylight intensity

W Bouyancy vector

Wind Plane (vector) N

5.2

The heat 3D grid

5.2.1 Classification Temperatures are defined over the grid according to the function of each space. This grid is broken down into principles that are easily layered on top of the basic scheme. Room temperatures are set based on the adaptive thermal model. The hedonic comfort model is applied by modifying air velocity, experiencing the of change of temperatures between rooms, temporarily opening or closing shutters for visual stimulation, etc... Each room is classified in function of itâ&#x20AC;&#x2122;s usage, needed energy, internal gains, on whether it over-produces energy or needs energy, 5.2.2 Thermodynamic distribution Architectural functionality is primordial, but when it is possible, thermodynamic distribution of functions leads to exploiting energy producing spaces for rooms in need of heat. The heat grid is viewed as a superposition of multiple layers that represent the levels in a building. As heat passes from bottom to top, positive energy spaces should be placed under negative energy ones. An example would be facilities such as computer rooms placed under a library. 5.2.3 Spatial insulation distribution (see also biomimicry principle) It may be possible to reduce the amount of insulation needed if rooms theirselves become insulators. This means that the theoretical concentric heart of the building is where the functions with the most in need of insulation are placed. The surrounding (theoretical0 concentric circles act as transient heating spaces or insulators for the inner spaces. An example would be corridors, a gymnasium and other intermittently used spaces in the outer circle and classrooms in the inner circle.

+ +

5.3

The course of the sun

5.3.1 Daylight distribution The heat grid takes closely into account the function of the building. However daylight is an very important factor when we consider all its psychological and physiological benefits (as it has been previously discussed). Each room, having its own use and function, should be attributed a qualitive or quantitive daylight need. As we know, providing daylight to every room in a multiple storey building is nearly impossible, especially if we consider certain aspects around intimacy. Furthermore, a conflict between spatial insulation distribution and daylight distribution can be encountered and is where the designer must already start making choices and drawing smart strategies to integrate both in function of what he considers most important for the building. Architecture is not an iterative process and is why parametricism could indeed be an interesting tool for such considerations that sometimes defy the single human thinking process. 5.3.2 Orientation Once again, primarily considering functionality, daylight and thermodynamics is the most optimal way in linking planar orientation. The initial design decision on orientation will strongly impact energy consumption (overheating or solar gains), comfort (glare, radiation, daylight) and material needs (shading, glazing...). 5.3.2.1 Building occupation and thermodynamics Offices and schools are examples of buildings that generally work only during the day. The internal gains from occupants and electrical devices could be sufficient to provide the necessary heat during the day (provided transmission losses are low). To illustrate a possible orientation strategy, deciding on opening the building towards the east can help â&#x20AC;&#x153;awakeâ&#x20AC;? and heat with the morning solar radiation before it takes over its autonomous course through the rest of the day. Direct Sunlight

Direct Sunlight

Function

Optimal zenith

Bouyancy vector

Wind Plane (vector)

Bouyancy vector

Wind Plane (vector) N

5.2

Biomimicry

5.2.1 Inspiration from nature Life started to appear over 3.5 billion years ago and has since then evolved throughout a long iterative and selective process. Each step is an optimisation according to the specimens environment and its rivals, survival and energy minimisation. Biomimicry is about observing and borrowing some of nature’s principles that have resulted out of a complex and longing evolution and implementing it in a design. Inspiration of nature over invention from scratch can lead to more efficient designs and strategies. 5.2.1 Architecture in its environment Creating architecture based on natures concepts suggests taking into consideration the possible interactions it encounters. Biological systems have developed continuously adaptive responses to their varying surroundings in order to maintain a relatively stable performance. Developing a homeostatic building implies a symbiotic system with its users and an adaptive design to an ever changing climate. In the recent years, our tools have allowed a better insight on the complexity that relies in natures design. Creating an ideal environment for humans suggests a better understanding and control over our physiological parameters. An ecosystem is a community of living organisms (plants, animals and microbes) interacting as a system in conjunction with the non-living components of their environment (such as air, water, mineral soil). In respect to nature’s design, it does not make sense creating a rigid system interacting with a varying environment as this would imply significant energy costs when it may not be needed. Taking advantage of the environments forces is one of the first steps in reducing energy costs. In fact, if the building was seen as an organic system, this simple strategy could be translated as an ecosystem. It’s the principle of a community of living organisms (plants, animals and microbes) interacting as a system in conjunction with the nonliving components of their environment (such as air, water, mineral soil). 5.2.2 Adaptable systems The way organisms work depend on what scale we are looking at. A cell is fulfilled with “active vents” set in their membranes that respond to change of gradients or to molecules in their evironement. When we look at a group of cells, it becomes a much more complex system with highly specific and differentiated functions that can only work as whole. Whatever perspective we observe nature, there is always a responsive system that is clocked and bearing a large amount of sensors that are key to survival.

5.2.2 Homeostasis Heat transience in animal biological systems The whole system in warm blooded animals is based on based energy conservation and protecting vital organs. In the human body, vital organs are kept at a very controlled and relatively constant temperature. Three categories can be made for almost every animal biological system : - Functionality : corresponds to vital organs that are an absolute necessity before any living creature can serve its purpose. - Service : corresponds to its own service or the service of another such as mobility, purpose, tasking, etc... - Environment: where the system takes place, exchanges with, communicates... Observation of many animals shows that the principle of energy conservation and efficiency takes place in these 3 categories. Warm blooded mammals are intelligent designs in the case of thermal homeostasis. Servicing parts of animals are not vital, but they also become regulators for functional parts.

FUNCTIONALITY

SERVICE

ENVIRONMENT

5.2.3. Blood flow Some basic and simplified models on how a body regulates its temperature by vasodilatation and vasoconstriction can be a source of inspiration on how heat could be distributed in buildings. Vital organs 5.2.3.1 Excessive cold : Vasoconstriction Blood is drawn away from the surface in order to reduce heat dissipation, a thicker insulating coat naturally occurs. The muscles in the members are reduced in performance but vital organs are protected and remain functional. In humans, this is principle is combined with shivering in order to produce extra heat. 5.2.3.2 Local heat (Solar radiation) : Partial vasodilatation Asymetrical bodily heating in a relatively cold environment makes blood flow to surface on the parts that are heating. Some animals use this as a heating strategy bringing cooler blood to the surface and sending back warm blood to the rest of the body. The system can also be reversed for a cooling strategy, evaporating the heat at the cooler parts. 5.2.3.2 Excessive heat : vasodilatation Generally, when the body is subject to excessive heat, vasodilatation is associated to other cooling strategies. Humans combine it with evaporative cooling by sweating. All organs and muscles are fully functional and, generally, at its best performance.

Conditions

Cold outside

Hot outside

Cold inside

Constriction

Dilatation

Hot inside

Dilatation

Dilatation +

5.2.4 Examples There are many examples in nature how animals deal with thermal extremes. Only a few here are illustrated to show how they could be a source of inspiration. 5.2.4.1 Elephants s Their highly vascularised large ears allows blood to cool down by evaporative cooling effect enhanced with water and flapping. In addition, their large bodies act as thermal inertia and bear large heat dissipation surfaces on their skin. Buildings could have heat dissipation surfaces. 5.2.4.2 Toucans beak Their disproportionally large beaks actu-ally acts as a transient heat exchanger. gh h The blood flow varies consistently through the beak acting as a heat regulator by dissipation. e Part of a building could act as an active transient heat exchanger. 5.2.4.3 Hiibernation A few mammals such as bears simply slow their metabolism in response to extreme cold in Winter. Some buildings can be put in daily hibernation such as offices or schools when they are not used during the night. 5.2.4.4 Penguin feet Many animals have a counter heat exchanger principle but could be defined as most extreme in the penguins feet. If the general flow of air in a building could also exchange heat in the same way.

6 CONCLUSIONS

5.2

Designer guidelines

Design There is no ultimate solution or automatic applicable strategy, design is a chaotic arborescent process. Inspiration Opening up to nature as a source of inspiration is without a doubt a great way for setting a plausible sustainable strategy. Knowlegde The laws of physics and the parameters by which we depend on are not a burden but a tool for architecture. Intuition Sustainable architecture also accounts for the pleasure it induces, this becomes highly complex and recalls for a designers intuition. User oriented thinking Give users more freedom. Give the building more adaptability. Innovation Classic HVAC systems are an easy solution but not a necessary one. Seek into alternative and innovative strategies that could reduce the ressources needed. Think tank The broader the knowledge of the design team the more possibilities can be explored. Collaboration with different actors from the very beginning can possibly avoid encountering problems later.

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