Air Fantasies: Inflatable Pillow System for Climatic Façade Infill

AIR FANTASIES: INFLATABLE PILLOW SYSTEM FOR CLIMATIC FAÇADE INFILL

LUKAS VIRKETIS

University of Westminster - Department of Architecture Applied Technology and Environmental Modelling 2016-2017 4ARC626 / TS 3A

Tutor: William Mclean

BA(Hons) Architecture Applied Technology and Environmental Modelling 2016-17 This module employed a range of contemporary and historical case studies to investigate how climatic envelopes are conceived, modelled and analysed using both real and virtual prototyping.

AIR FANTASIES: INFLATABLE PILLOW SYSTEM FOR CLIMATIC FAÇADE INFILL

LUKAS VIRKETIS

University of Westminster - Department of Architecture Applied Technology and Environmental Modelling 2016-2017 4ARC626 / TS 3A

Tutor: William Mclean

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PHASE

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CONTENTS ABSTRACT IDENTIFICATION Introduction The problem The cause

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HYPOTHESIS Solutions

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ANALYSIS Solar study Sun-path/shadow analysis Heat radiation analysis

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PROPOSITION Building envelope system ETFE References Concept sketches and prototypes Design development Proof of concept Final proposal Technical drawings Detail drawings Visuals

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CONCLUSION Comments

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APPENDIX Bibliography

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ABSTRACT

‘Pollution is nothing but the resources we are not harvesting. We allow them to disperse because we’ve been ignorant of their value.’

Richard Buckminster Fuller This semester the module of Technical studies introduced the students with a range of contemporary and historical case studies to investigate how climatic envelopes are conceived, modelled and analysed using both real and virtual prototyping through a series of lectures. We were asked to produce a report, which would describe the environmental qualities of the site, prepare an environmental analysis of the chosen site, and finally design an enclosure system/facade element as well as demonstrate a ‘proof of concept’ through virtual analysis.

Ethylene Tetrafluoroethylene, ETFE, is plastic building material designed to be extremely lightweight, yet very strong. By taking advantage of its light-weight nature, excellent light transmission and thermal insulation properties, I have designed an ‘infill’ wall system for an airlock entryway, in order to solve an existing flaw at the University of Westminster which causes the decrease of the human comfort in the part of the building. Using a combination of ETFE plastic pillows, embedded within an aluminium frame, I tend to solve the occurred issue by performing solar studies and thus designing a site-specific proposal with a particular shape.

The report concludes the researched material through a range of crucial factors, such as performance, sustainability, simple construction and cost-efficiency, as well as argues the proposal itself by the professional architect specializing in similar projects.

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IDENTIFICATION identification

/ʌɪˌdɛntɪfɪˈkeɪʃ(ə)n/ noun

1. an act or instance of identifying; the state of being identified.

2. something that identifies a person, animal, or thing.

3. the association or linking of one thing with another.

INTRODUCTION SITE University of Westminster (Marylebone Campus) was chosen as the site of the project with an intention to use my personal experience and observation accumulated throughout the years, as the student (main user) of the University. While the southern facade entrance of the University is constantly used by the students as the cross section of a number of amenities (library, cafe, bookshop, etc.) as well as a link between the University building and the Hall of Residence Tower through an open air route, the decrease of thermal comfort (low temperature) in the inside of the building was identified by personal and other students physical observation, which led to assume the existence of the cross ventilation which caused the drop of internal temperature. In order to solve the identified flaw, further investigation is required.

FIGURE 1.1 (left page) University of Westminster, south west view FIGURE 1.2 (right page) University of Westminster, south west axonometric view

OBJECTIVE The task of the project is to identify the actual problem and the cause of it, rise the hypothesis of the probable solution, analyse the site through sun-path/ shadow and heat radiation studies, present the proposal and finally, make the conclusion by examining it by various arguments and comments.

CHILTERN HALL

HALLS OF RESIDENCE TOWER

THE SITE

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LUXBOROUGH TOWER

MARYLEBONE CAMPUS

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THE PROBLEM HUMAN COMFORT AND BODY HEAT Human comfort is achieved when the environment provides the appropriate conditions to avoid feeling too cold or hot. Human body temperature must remain at a constant 36.9 °C: we must lose heat at the same rate as it is produced or gain heat at the same rate it is lost. We lose heat mainly through the evaporation of perspiration. The body generates heat even while at rest. When internal body temperature is insufficient, the body starts to shiver, which in turn increases the production of body heat. Human comfort depends chiefly upon thermal comfort.

THERMAL COMFORT Thermal comfort can be defined as a condition of mind which expresses satisfaction with the thermal environment. It is assessed by subjective evaluation (ANSI/ASHRAE Standard 55). Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC (heating, ventilation, and air conditioning) design engineers. The main factors influencing thermal comfort are: - Temperature (dependant upon climate and ultimately upon solar geometry); - Humidity (high humidity levels reduce evaporation rates. When relative humidity exceeds 60%, our ability to cool is greatly reduced); - Air movement (a breeze or draught of around 0.5 metres per second provides an equivalent temperature reduction of around 3 °C); - Exposure to radiant heat or cooling sources (radiating surfaces are very important to our perception of comfort).

Due to large variations from person to person, it is difficult to satisfy everyone within the same thermal environment. However, on average the comfort zone for occupants is higher in the summer months (23 °C to 25.5 °C) than it is in the winter months (20 °C to 23.5 °C).

A quick survey of subjective evaluation of thermal comfort was assessed by approximately 20 users (students, bookshop and cafe staff) who were permanently using space, which stated the sense of cold air draughts, low temperature, higher humidity level - decrease of thermal comfort. Such primary study completed on the site gave a sense of direction of further investigation of the issue.

HEAT LOSS The decrease of internal temperature on the site presupposes the existence of heat loss. This happens when the heat energy is transferred from warmer internal spaces to colder outside areas by conduction through the walls, floors, roof and windows. It is also transferred by convection, for example, cold air can enter the building through gaps in doors and windows.

THERMOGRAPHIC INSPECTION Thermographic imaging camera was used in order to identify the heat loss. Such observation using the device, which forms an image using infrared radiation, helped to prove the existence of heat loss in the facade. The images, made by the camera, showed the heat loss mainly through the double doors, especially when they were in use by the people.

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FIGURE 1.3 (left page) Thermographic images made by the thermographic imaging camera FIGURE 1.4 (right page) Thermographic imaging camera in operation, directed towards the facade

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MARYLEBONE CAMPUS

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CHILTERN HALL

CAFETERIA

LIBRARY CAFE

BOOKSHOP

HALLS OF RESIDENCE TOWER

THE SITE LUXBOROUGH TOWER

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MARYLEBONE CAMPUS

CHILTERN HALL

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LIBRARY CAFE

BOOKSHOP

HALLS OF RESIDENCE TOWER

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THE SITE LUXBOROUGH TOWER

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THE CAUSE INSULATION Good insulation acts as a barrier to heat flow and is essential to keep buildings warm in winter and cool in summer. However, bad insulation (the infiltration of cold air into the building and exfiltration of hot air out of the building) is one of the main reasons for the heat loss. Because it typically happens through cracks in the building envelope, the existing glass door facade is causing air leakage through the double doors and joints between the facade frame and the glass.

FIGURE 1.5 (left page top) Diagram of human circulation throughout the ground floor and the site of the University of Westminster FIGURE 1.6 (left page bottom) Diagram of air leakage (heat loss) from/to the ground floor and the site of the University of Westminster

CROSS VENTILATION The problem of decreased human comfort is also caused by intensive human traffic flow (circulation) which creates the cross ventilation and causes heat loss through use of doors for passage.

Cross ventilation occurs where there are pressure differences between one side of a building and the other. Typically this is a wind-driven effect in which air is drawn into the building on the high pressure windward side and is drawn out of the building on the low pressure leeward side.

It is generally best not to place openings exactly across from each other in a space. While this does give effective ventilation, it can cause some parts of the room to be well-cooled and ventilated while other parts are not. This can be observed in the diagrams of human circulation and air leakage from/to the building.

Cross ventilation can be problematic during the winter when windows may be closed, particularly in modern buildings which tend to be highly sealed. Trickle ventilation, or crack settings on windows can be provided to ensure there is adequate background ventilation. Trickle ventilators can be self-balancing, with the size of the open area depending on the air pressure difference across it.

LOOKING FOR SOLUTION Some of these issues can be avoided or mitigated by careful siting and design of buildings. For example, louvres can be used where ventilation is required, but a window is not, and ducts or openings can be provided in internal partitions, although these will only be effective if there is sufficient open area, and there may be problems with acoustic separation.

In straight-forward buildings, cross ventilation can often be designed by following rules of thumb for the openable area required for a given floor area, depending on the nature of the space and occupancy. The situation becomes more complicated when cross ventilation is combined with the stack effect or mechanical systems, and thermal mass and solar gain are taken into consideration.

Modelling this behaviour can become extremely complicated, sometimes requiring the use of local weather data, software such as computational fluid dynamics (CFD) programs and even wind tunnel testing.

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HYPOTHESIS hypothesis /hʌɪˈpɒθɪsɪs/ noun

1. a proposition, or set of propositions, set forth as an explanation for the occurrence of some specified group of phenomena, either asserted merely as a provisional conjecture to guide investigation (working hypothesis) or accepted as highly probable in the light of established facts.

2. a proposition assumed as a premise in an argument.

3. the antecedent of a conditional proposition.

4. a mere assumption or guess.

SOLUTIONS WAYS TO REDUCE HEAT LOSS As the existing door facade, affected by air leakage and cross ventilation when the passage doors are being used, is already double-glazed, some of the most efficient ways to reduce heat loss will be presented and further described below.

One of the ways would be to install the revolving or automatic doors instead of the existing ones or to introduce an airlock entryway system (vestibule) by constructing a small infill next to the existing facade. Both options will be compared and tested for the chosen site.

MARYLEBONE CAMPUS

FIGURE 2.1 (below) Revolving door of the main entrance to the University of Westminster (axonometric drawing) FIGURE 2.2 (below) Airlock entryway (axonometric drawing)

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FIGURE 2.3 (top right page) Diagram comparing hot and cold air infiltration with and without an airlock entryway FIGURE 2.4 (bottom right page) Hypothetical airlock entryway in its context

AIRLOCK DOOR The simplest way, in terms of costs and installation, would be a revolving door.

It typically consists of three or four doors that hang on a central shaft and rotate around a vertical axis within a cylindrical enclosure. Revolving doors are energy efficient as they prevent drafts (via acting as an airlock), thus preventing increases in the heating or cooling required for the building. At the same time, revolving doors allow large numbers of people to pass in and out. However, it requires extra space to accommodate additional doors, due to the fire safety regulations as well as the Disabled Discrimination Act (DDA). Because of lack of space for this option, the concept of airlock entryway is going to be introduced instead.

AIRLOCK ENTRYWAY

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An airlock entryway (vestibule) has two airtight doors that reduce the amount of air infiltration and heat loss when the exterior door is opened. They create a buffer area to block the wind and improve energy efficiency. Double door airlock entries are common features in energy-efficient homes in cold climates, but they also reduce air conditioning costs in hot climates. The airlock entryway shown on the side includes two insulated doors connected with a structural frame (minimum distance between the doors must be at least 2 meters) and usually covered in glass, for daylighting and sun heat intake. Such option seemed the most appropriate in terms of its effectiveness in reducing heat loss along with cost efficiency.

THE PASSIVE THERMAL INFILL

Besides of the benefits of an airlock entryway, the final proposal should be a modified envelope or enclosure where the form and fabric of the infill would be arranged in a way to maximize the benefits of ambient energy flows.

As the airlock concept already creates the ‘greenhouse’ effect, which would reduce air leakage from the inside of the building, the form and geometry of the infill should be directed by the solar gain, allowing the maximum amount of sunlight into the building, while the fabric of the infill should dictate its ability to allow heat energy in winter months, and to present a barrier to heat flow in summer months through controlled insulation.

CAFETERIA

CAFE

In order to propose an efficient solution to the problem using inexpensive and sustainable methods, further climatic (solar) analysis is needed.

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LIBRARY

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without an airlock entryway

with an airlock entryway

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ANALYSIS analysis /əˈnalɪsɪs/ noun

1. detailed examination of the elements or structure of something.

2. this process as a method of studying the nature of something or of determining its essential features and their relations.

3. a presentation, usually in writing, of the results of this process.

4. a philosophical method of exhibiting complex concepts or propositions as compounds or functions of more basic ones.

SOLAR STUDY SOLAR GEOMETRY In order to formalize a building in relation to the sun, it is necessary to understand the sun’s path.

The earth orbits the sun in a counter-clockwise elliptical orbit once every 365.26 days. The earth spins counter-clockwise on its North-South axis once every day (this accounts for the fact that the sun rises in the East and sets in the West). The axis is tilted with respect to the plane of its orbit at an angle of about 23.4 degrees. The average distance from the earth to the sun is around 150 million km.

In relative terms, if the earth was a 2 pence piece (1” or 25mm diameter), then the sun would be an 8’ (2.4m) diameter disc around 300 meters away.

The equatorial plane divides the earth into halves, being the Northern and Southern hemispheres. The intersection of these planes is a line which is called the line of equinoxes. One half of this line is the vernal-equinox (spring) and the other half - the autumnal-equinox. At two points in the earth’s orbit this line intersects the sun making the start of the autumn or spring seasons. Perpendicular to the line of equinoxes is a line which contains the solstices. These are points which start summer and winter when they cross the sun.

To calculate the position of the sun on any given day at a certain place on earth, two angles must be specified: the solar azimuth and the solar altitude.

The altitude angle is the angle in a vertical plane between the sun’s rays and the horizontal projection of the sun’s rays. The azimuth angle is that angle on the horizontal plane measured from the south to the horizontal projection of the sun’s rays.

The LadyBug plug-in for Grasshopper (Rhinoceros 5.0) was used to perform sun-path/shadow study and heat radiation study which is demonstrated in the following pages.

SUN-PATH/SHADOW STUDY The study explored the sun-path of the site at summer solstice, equinox and winter solstice, demonstrating the position of the sun at every hour of the day as well as indicating the falling shadow. This helped to identify particular hours of the day when the site is covered in shadow and when the sun directly targets the site. The sun-path/shadow analysis showed that the average hour when the sun directly hits the site is 12:00 (solar noon). This helped to exercise the heat radiation study, which would help to identify the particular angle of the sun, which is needed, in order to propose the right angular shape of the design of the airlock entryway.

HEAT RADIATION STUDY The study explored the sun’s heat radiation of the site at summer solstice, equinox and winter solstice. This helped to understand the heat distribution on the surfaces of the site, which, due to the fact of the changing angle of the sun, was different. The information received from the sun-path/shadow study set the solar noon (12:00) as the basis to get the correct angle, needed to propose the right angular shape of the design of the airlock entryway.

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FIGURE 3.1 (right) Grasshopper (Rhinoceros 5.0) interface while using LadyBug plug-in

SUN-PATH/SHADOW STUDY

SUMMER SOLSTICE - JUNE 21 London, United Kingdom Latitude: 51.5074° N, Longitude: 0.1278° W Active sunlight: 05:00 - 20:00 24

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HEAT RADIATION STUDY

SUMMER SOLSTICE - JUNE 21 London, United Kingdom Latitude: 51.5074째 N, Longitude: 0.1278째 W Azimuth: 178.71째 Altitude: 61.9째

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SUN-PATH/SHADOW STUDY

EQUINOX - MARCH/SEPTEMBER 21 London, United Kingdom Latitude: 51.5074° N, Longitude: 0.1278° W Active sunlight: 07:00 - 18:00 26

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HEAT RADIATION STUDY

EQUINOX - MARCH/SEPTEMBER 21 London, United Kingdom Latitude: 51.5074째 N, Longitude: 0.1278째 W Azimuth: 177.50째 Altitude: 39.0째

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SUN-PATH/SHADOW STUDY

WINTER SOLSTICE - DECEMBER 21 London, United Kingdom Latitude: 51.5074° N, Longitude: 0.1278° W Active sunlight: 09:00 - 15:00 28

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HEAT RADIATION STUDY

WINTER SOLSTICE - DECEMBER 21 London, United Kingdom Latitude: 51.5074째 N, Longitude: 0.1278째 W Azimuth: 180.23째 Altitude: 15.1째

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SUN-PATH/SHADOW ANALYSIS

SUMMER SOLSTICE - JUNE 21 Active hours between 10:00 and 13:00.

Approximately 4 hours of direct sunlight targeted to the site.

EQUINOX - MARCH/SEPTEMBER 21 Active hours between 11:00 and 13:00.

Approximately 3 hours of direct sunlight targeted to the site.

WINTER SOLSTICE - DECEMBER 21 Active hours between 12:00 and 13:00.

Approximately 2 hours of direct sunlight targeted to the site.

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HEAT RADIATION ANALYSIS 61.9°

SUMMER SOLSTICE - JUNE 21 Azimuth: 178.71° Angle of the sun (altitude) at solar noon (12:00): 61.9°

EQUINOX - MARCH/SEPTEMBER 21 39.0°

Azimuth: 177.50° Angle of the sun (altitude) at solar noon (12:00): 39.0°

WINTER SOLSTICE - DECEMBER 21 Azimuth: 180.23° Angle of the sun (altitude) at solar noon (12:00): 15.1°

15.1°

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PROPOSITION proposition /prɒpəˈzɪʃ(ə)n/ noun

1. a statement or assertion that expresses a judgement or opinion.

2. a suggested scheme or plan of action, especially in a business context.

3. a project, task, idea, etc. considered in terms of its likely success or difficulty.

BUILDING ENVELOPE SYSTEM CHOOSING THE SYSTEM One of the most important steps in designing an airlock entryway, after the completion of the solar study, is to decide what kind of envelope systems will be used. The high transparency for the maximum amount of sunlight along with thermal insulation properties will remain primary criteria, however, the proposed materials will also be tested through their cost-efficiency, simplicity in construction, durability and maintenance, as well as sustainability.

THERMAL MASS Thermal mass is the ability of a material to absorb heat energy. It acts as a ‘thermal battery’ or ‘heat sink’, as it stores and re-radiates heat.

A lot of heat energy is required to change the temperature of high density material like concrete, brick and tile. They are therefore said to have high thermal mass. Lightweight materials such as timber have low thermal mass. The more dense the material (i.e. the less trapped air) the higher its thermal mass. A high mass building needs to gain or lose a large amount of energy to change its internal temperature. In winter, allow thermal mass to absorb heat during the day from direct sunlight or from radiant heaters and it will re-radiate this warmth back into the building. In summer, allow cool night breezes and/or convection currents to pass over the thermal mass, drawing out all the stored energy. During the day, protect thermal mass from excess summer sun with shading and insulation if required .Good thermal conductivity –the material must allow heat to flow through it. For example, rubber is a poor conductor of heat, brick is good, concrete is better. Low reflectivity –Dark, matt or textures surfaces absorb and re-radiate more energy than light, smooth, reflective surfaces.

Correct use of thermal mass for the airlock entryway would moderate internal temperatures by averaging diurnal (day/night) extremes, however, due to the need of direct sunlight for the inside of the building, the use of thermal mass wouldn't give wanted result, as the glass has low thermal mass.

THERMAL INSULATION Besides thermal mass, thermal insulation can be predominantly used in order to keep heat in or out of the building, as the glass is relatively good insulator.

Bulk-insulation mainly resists the transfer of conducted or convected heat, relying on pockets of trapped air within its structure. Its thermal resistance is essentially the same regardless of the direction of heat flow through it. Bulk insulation includes materials such as glass fibre, wool, cellulose fibre, polyester and polystyrene. All products come with a U value –the thermal transmission per sq.m per degree of temperature difference between inside and outside.

Reflective-insulation mainly resists heat flow due to its ability to re-radiate heat. It relies on the presence of an air layer of at least 25mm next to the shiny surface.

The thermal resistance of reflective insulation varies with the direction of heat flow through it. Products are known as ‘reflective foil laminates’.

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ALTERNATIVE TO GLAZING It appears, that even though glass, as the traditional material, is the only capable to provide translucency along side with its thermal insulation properties, ETFE (ethylene-tetra-flouro-ethylene) is an efficient and relatively cheap solution for architecture in the places, where glass is impossible to use or expensive (translucent roofs and atriums).

FIGURE 4.1 (below) Table of characteristics of ETFE film and glass

The quantity of materials (steel and aluminium) required for covering with ETFE is less, than is required for glass covering. As the material is many times thinner and lighter than glass, it allows to produce much larger spans than those that apply in classical structures. A rectangular pillow may reach the width of about 4 m, and the length is almost unlimited. The load-bearing structure may be minimized thanks to the increase of the spans and the use of lighter junctions.

In terms of insulation properties, ETFE film is used in the two or three layer model and can be a great source of insulation for the inside of the structure.

ETFE is highly resistant to chemical damage, as well as being resilient to wild weather. The film can retain well its strength for over 20 years whilst also retaining its transparency with its self-cleaning capabilities.

LIGHT TRANSMISSION/TRANSPARENCY Transmission of light is the moving of electromagnetic waves (whether visible light, radio waves, ultraviolet, etc.) through a material. This transmission can be reduced, or stopped, when light is reflected off the surface or absorbed by the molecules in the material.

Excellent transmission of light, as one of the key factors of the airlock entryway, can be easily achieved by using glass (single or double-glazed), high transmition as well as transparency - properties which makes ETFE an especially valuable solution for building greenhouses, scientific botanical centres, winter gardens, sports facilities.

CONCLUSION The research proves that ETFE cushions are a better choice material than glass, because of its high transparency, great ability to protect from over-heating (using multiple layers), as well as it is more affordable and requires lighter structure.

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ETFE INTRODUCTION The second half of the XX century was the beginning of active development of membrane technologies, which can now be characterized as a real break through in the field of membrane architecture. Membrane materials are used in building construction, along with traditional materials (stone, glass, metal, wood). Because of its exceptional durability and UV resistance, ETFE (ethylene-tetra-flouro-ethylene) was initially developed for the space industry. However, the leading architects and engineers all over the world started to apply the innovative technology for today's buildings. The diversity of objects starts from facilities for the Olympic games and government buildings to objects of commercial purpose or even small scale facade and roof enclosures.

FIGURE 4.2 (right) ETFE cushion envelope consisting of a bending-stiff grid made of rectangular profiles and 261 foil cushions with an edge length up to 2,8m and a diagonal length up to 4,1m.

FIGURE 4.3 (below) Junction of clamping plates section 1. ETFE cushion 2. Extruded aluminium clamping plate 3. Extruded aluminium retaining profile 4. Plastic edge bead to fabric membrane 5. Supporting structure 6. Plastic air supply tube 7. Main air supply tube 1

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BENEFITS USING ETFE

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Fabrics used as roof membranes have the advantage of being light in weight, strong in tension and durable, and have the ability to be cut to different shapes and joined together economically, which is difficult to achieve so easily with metal and is very expensive to achieve with curved glass. Roof membrane fabrics are used in tension structures, either by stretching the material, or pressing the membrane, between structural supports or, alternatively, by supporting the material pneumatically in inflated structures. Although large scale self-supporting inflatable roof structures are in use, particularly for covering sports stadiums, they remain structurally stable only while air is being supplied to the pillows. If the air supply is interrupted, the complete rood structure deflates. In smaller scale applications, air-filled cushions remain in place when the air supply fails or is switched off when used as non-loadbearing panels. This type, where ETFE sheet is used to make panels formed a air-filled cushions, provides highly transparent, lightweight and resilient roofs that have thermal insulation values similar to those of double glazed units.

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CUSHIONs/AIR-SUPPLY/STRUCTURE ETFE cushions usually consist of a minimum of two layers of ETFE sheet which are set back to back to form a flat panel and are sealed at the edges. The void within the cushion-shaped panel is inflated with air to a pressure, depending on the cushion size and the manufacturer's proprietary system, to provide structural stability to the panel. The air supplied by electrically powered fans to cushions from rubber pipes or flexible plastic pipes that are connected to the underside of the cushion near the clamping assembly. The increased air pressure stretches the outer membrane, giving ETFE cushions their characteristic curved shape. Cushions typically have two or three layers that form inside chambers. The three layer cushions provides a U-value of around 2.0 W/m2K, which is similar to a double glazed unit used in glass roofs. Cushions made from two layers of ETFE sheet ar also used but the thermal insulation performance is reduced considerably.

Thermal insulation performance can also be improved by increasing the number of air chambers within the cushion by adding further layers of ETFE membrane.

The cushions are held in place by clamps that form a frame around the cushions in the manner of glazed roof-lights. The clamping frames are then supported by a mild steel structure formed typically as box section of tubes.

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REFERENCES EDEN PROJECT (NEAR ST AUSTELL) Architects: Nicholas Grimshaw & Partners, London

FIGURE 4.5 (below) Sectional details of the dome

The Eden Project is a popular visitor attraction in Cornwall, England. Inside the two biomes are plants that are collected from many diverse climates and environments.

FIGURE 4.6 (below) Domes of the Eden Project

The complex is dominated by two huge enclosures consisting of adjoining domes that house thousands of plant species, and each enclosure emulates a natural biome. The biomes consist of hundreds of hexagonal and pentagonal, inflated, plastic cells supported by steel frames.

The building skin stretches across the staged microcosm like a second sky. The lightness of the material make one forget the huge dimensions of the domes.

The covered biomes are constructed from a tubular steel (hex-tri-hex) with mostly hexagonal external cladding panels made from the thermoplastic ETFE. Glass was avoided due to its weight and potential dangers. The cladding panels themselves are created from several layers of thin UV-transparent ETFE film, which are sealed around their perimeter and inflated to create a large cushion. The resulting cushion acts as a thermal blanket to the structure. The ETFE material is resistant to most stains, which simply wash off in the rain. If required, cleaning can be performed by abseilers. Although the ETFE is susceptible to punctures, these can be easily fixed with ETFE tape. The structure is completely self-supporting, with no internal supports, and takes the form of a geodesic structure. The panels vary in size up to 9 m (29.5 ft) across, with the largest at the top of the structure.

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ALLIANZ ARENA (IN MUNICH) Architects: Herzog & de Meuron, Basel

FIGURE 4.7 (below) Sectional detail of the pillow facade

The Allianz Arena is a football stadium in Munich, Bavaria, Germany with a 75,000 seating capacity. Widely known for its exterior of inflated ETFE plastic panels.

FIGURE 4.8 (below) Allianz Arena pillow facade

By day the skin, which is divided up into diamond-shaped cushions, appears shiny, transparent and homogeneous. Yet behind there are different load-bearing systems: cantilevered steel lattice girders form primary structure of the roof, while the secondary support structure for the roof and vertical façades, structurally separate from the primary frame, is a rhomboid grid of steel girders, with field diagonals varying from 2 x 7 metres to 5 x 17 metres. The 65,000 m2 skin is made up of 2,874 individual ETFE cushions, each one matched by only one other of identical geometry. The cushions are fixed in aluminium profiles that clamp the weatherstrip edge to the secondary construction. The gutters between the cushions are sealed with flexible plastic profiles and welded at the junctions.

Twelve air-pumping stations keep a constant internal pressure in the cushions, raising it as required depending in wind and snow loads. The lower part of the facade is printed with a pattern of dots that intensifies towards the bottom to give a semi-transparent look. On the upper part, by contrast, the cushions ‘covers’ are made of white ETFE. To avoid too much shading of the turf, the cushions on the southern part are fitted with transparent ETFE sheeting, which allows virtually all the UV portion of sunlight to permeate, thus giving good growing conditions for the grass.

At night, 1,058 facade cushions are lit up by fluorescent light inside.

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CONCEPT SKETCHES AND PROTOTYPES

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DESIGN DEVELOPMENT

AIRLOCK ENTRYWAY The concept of airlock creates a 'greenhouse' effect which helps to avoid cross ventilation as well as hot air exfiltration from the inside, and cold air infiltration to the inside of the interior of the building. However, such shape does not provide enough sunlight.

ANGLED SHAPE The walls of the airlock directed perpendicular towards the sun helps to get the maximum amount of light. However, it increases the intake of solar radiation which may cause over-heating in summer months, but is preferred in winter months.

ETFE CUSHION SYSTEM The walls covered in cushions using multiple layers of ETFE film helps to control the intake of solar radiation throughout the year, and does not dramatically reduce the amount of sunlight.

The diagram on the right illustrates the developed concept and proves the effect of the proposed design.

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PROOF OF CONCEPT Solar radiation

Triple-layer

Light Double-layer

Single-layer

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FINAL PROPOSAL AXONOMETRIC DRAWING

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EXPLODED AXONOMETRIC DRAWING 1. Supporting structure / structural steel 2. Extruded aluminium retaining profile 3. ETFE cushions 4. Extruded aluminium clamping plate 5. Door frame 6. Double doors 7. Glass

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GROUND PLAN scale 1:50

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ROOF PLAN scale 1:50

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ELEVATION scale 1:50

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SECTION scale 1:50

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FACADE ELEVATION scale 1:10

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FACADE SECTION scale 1:10 1. ETFE cushion 2. Extruded aluminium clamping plate 3. Extruded aluminium retaining profile 4. Plastic edge bead to fabric membrane 5. Supporting structure / structural steel 6. Plastic air supply tube 7. Main air supply tube 8. Metal flashing

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FACADE SECTION DETAIL scale 1:2

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VISUALS PERSPECTIVE

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PERSPECTIVE IN CONTEXT

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PHASE

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CONCLUSION conclusion /kənˈkluːʒ(ə)n/ noun

1. the end or finish of an event, process, or text 2. a judgement or decision reached by reasoning 3. a proposition concluded or inferred from the premises of an argument.

COMMENTS ARCHITECTS' COMMENTS As part of my RIBA Mentoring scheme this year, I had a chance to visit one of the architecture offices in London, which surprisingly had a small scale project near Borough Market in London, in which they successfully have used ETFE pillow system. The architect of the firm, who was working on the project, introduced me with it: ‘It was primarily designed as the temporary roof structure for traders during construction works, with an intention to dismantle it when needed, [as it was located within a conservation area, which involved remodelling the listed buildings along the route, and replacing others with modern retail and office buildings]. Because the refurbishment never took place, the pillow structure still stands to this day.’

The architect continued, that the client chose the ETFE cushion system as the lowcost solution forthe short life structure, and probably would not have considered it as fot the permanent structure. As the professional who not only has more experience in technical side of the architecture as well as his knowledge of the practical side this type of system, I was eager to ask him for some comments on my proposal: ‘The great side of usng ETFE in your project is its cost-efficiency, sustainability, leightweight covering which also has solar shading attributes, which are lacking in glass. However, I have to point out some of the things related to your proposal that you should consider: In terms of costs, it was a good choise to use ETFE systems instead of glass, as the glass is more expensive, and requires stronger structure which also increase the total cost. Also, to make the structure even less costly, bigger pillows could be introduced. In our project, we have used at least 7 metres in length, [as its maximum sizes can reach up to 10 metres long]. Equally, this would reduce the tube net system which would need to inflate less pillows, which eventually it would reduce the price of the structure.

As the ETFE cushions in our project were used as the equivalent to the roof, there was no fear of them being damaged by people’s activity or vandalism. However, in your case, the front facade of the structure can be easily damaged. This could be solved if the glass would be introduced for the front, but leaving the cushions on the angular roof side.

The instalation of the electornics and tubes inside the steel structure is possible, but as far as we have tried to do that in our project, it made it difficult to install them inside the steel tubes, especially, when in your case the structure is quite slender.

The engineering and production side of it is not a big problem as it is a small scale project, on the other hand, if you would consider designing bigger scale structures, like the one in Shanghai, [the Water Cube] those would need structural egnineers and people who would specialise in these systems.

In overall, besides the lack of ventilation in the summer time, which could be easily solved through electronic ventilation fan or simple openings on the roof, as the multiple layer cushions might not be enough to prevent the inside from overheating, the proposal itself and the research that supports your design strategies are very convincing and seems to work quite well, most importantly solving the issues identified on the site.’

Duncan Holmes Architect/Studio Associate at Jestico + Whiles

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FIGURE 5.1 (below) Jubilee Market structure (part of the Borough Market Viaduct project)

PERSONAL COMMENTS This semester, with the help of lectures, readings and comments made by the professionals, I had a great opportunity not only to explore a chosen site, identify its flaws and find solutions how to fix the issue, but also introduce my own proposal, argue its reliability using technical terms and solar analysis software, describe it through diagrams, simple technical and complex detail drawings.

Overall, the project enabled me to understand the importance of environmental analysis and how to successfully use it to shape the design of the proposal and achieve wanted aims in order to solve the problem.

Talking about the material used for the project, I got to know the advantages of ETFE cushion systems, because before the project, I was not aware of such an incredible alternative to glazing, which insulation properties, excellent light transmission and transparency, as well as being cost-effective, sustainable and fairly simple to use, changed my opinion towards it. Even the name of the report, 'Air Fantasies', evidently states my initial reaction to the material - an experimental material, only used for temporary structures.

In terms of the architect's comments on my proposal, I understood the importance of costs and simplicity in construction design, as these factors are one of the main obstacles in architecture. Even though I partially based the chosen material because of its cost-efficiency and sustainability, the proposal could have been designed with bigger triangular cushions, which would minimize the structural frame needed to support the pillows and eventually would cost even less.

In order to prevent the pillows being damaged by accidents and vandalism, the front facade wall could be replaced with glass, as it would provide more sunlight and heat radiation in winter months, and would barely influence thermal factors in summer moths, due to its angle.

In the case of overheating of the chamber inside the structure in summer months, a number of openings could be introduced which could be open to ventilate the space.

To sum up, the project gave me an opportunity to design the structure using valid arguments and studies in order to prove its functionality and construction, which resulted to further understand the importance environmental factors as well as the technical side of the architecture.

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APPENDIX

BIBLIOGRAPHY THEORY Henry Sanoff, Participatory design: theory & techniques, (North Carolina: North Carolina State University, 1990) Hensel Achim Menges; Michael Weinstock, Emergent technologies and design : [towards a biological paradigm for architecture], (New York: Routledge, 2010) Fred Scott, On altering architecture, (London: Routledge, 2008) Nils Peters, Jean Prouve, 1901-1984: the dynamics of creation, (London: Taschen, 2013) Frei Otto; Bodo Rasch, Finding form, (Stuttgart: Axel Menges, 1995) Richard Nicholls, Low Energy Design, (Oldham: Interface Publishing, 2002) Mareike Krautheim; Ralf Pasel; Sven Pfeiffer; Joachim Schultz-Granberg, City and wind : climate as an architectural instrument, (Berlin: DOM Publishers, 2014) Nick Dunn, Digital fabrication in architecture, (London: Laurence King Publishing, 2012) ENVIRONMENT/CLIMATE G. Z. Brown Mark DeKay, Sun, wind & light : architectural design strategies, (New Jersey: Wiley, 2014) BUILDING ENVELOPES/SKINS Andrew Watts, Modern construction envelopes, (Vienna: Springer, 2011) Mayine Yu, Skins, envelopes, and enclosures concepts for designing building exteriors, (New York: Routledge, 2014) Christian Shittich; Werner Lang; Roland Krippner, Building skins, (Basel: Birkhauser, 2006) Scott Murray, Translucent building skins material innovations in modern and contemporary architecture, (New York: Routledge, 2013) Victoria Ballard; Bell Patrick Rand, Materials for architectural design, (London: Laurence King Publishing, 2006) MATERIALS Michael F. Ashby; Kara Johnson, Materials and design : the art and science of material selection in product design, (Oxford: Butterworth-Heinemann, 2014) Michael Stacey, Component Design, (Oxford: Architectural Press, 2001) Marc Dessauce, The inflatable moment : pneumatics and protest in ‘68, (New York: Princeton Architectural Press, 1999) Annette W. LeCuyer, ETFE: technology and design, (Boston: Birkhauser, 2008)

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STRUCTURAL DESIGN Pete Silver; William McLean; Peter Evans, Structural engineering for architects : a handbook, (London: Laurence King Publishing, 2013) William McLean; Pete Silver, Air structures, (London: Laurence King Publishing, 2015) William McLean; Pete Silver, Introduction to architectural technology, (London: Laurence King Publishing, 2008/2013) J. E. Gordon, Structures : or why things don’t fall down, (New York: Da Capo Press, 2003) Frank Ching, Building construction illustrated, (New Jersey: Wiley, 2014) Adriaan Beukers, Lightness : the inevitable renaissance of minimum energy structures, (Rotterdam: 010 Publishers, 2005)

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Š 2017, Lukas Virketis

Š 2017, Lukas Virketis