Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 Internal environment in ETFE foil covered building enclosures James Ward and John Chilton School of Architecture, Design and Built Environment Nottingham.

Similar presentations


Presentation on theme: "1 Internal environment in ETFE foil covered building enclosures James Ward and John Chilton School of Architecture, Design and Built Environment Nottingham."— Presentation transcript:

1 1 Internal environment in ETFE foil covered building enclosures James Ward and John Chilton School of Architecture, Design and Built Environment Nottingham Trent University Alex Heslop and Lance Rowell Architen Landrell Associates 16 September 2010TensiNet 2010 Sofia

2 Outline Introduction Thermal/optical properties of ETFE foil Design considerations for ETFE-covered enclosures – Visible light transmission and quality – Internal environment Overheating Ventilation Glare Noise levels Conclusions 16 September 2010TensiNet 2010 Sofia 2 Photo: Alastair Gardiner

3 Introduction 16 September 2010TensiNet 2010 Sofia 3 A recent conference paper highlighted: “Limited research regarding the modelling of ETFE in building applications and limited availability of information on material properties...” It also pointed out that: Previous ETFE studies have focused mainly on structural properties and related issues, while little research has been carried out in order to determine energy transmission properties and characteristics in terms of environmental building design. Source: Poirazis, Kragh and Hogg (2009)

4 Thermal/ optical properties of ETFE foil 16 September 2010TensiNet 2010 Sofia 4 Source: Dyneon™ Fluorothermoplastics Product Comparison Guide (2009)

5 16 September 2010TensiNet 2010 Sofia 5 The properties of ETFE 80 µm clear100 µm clear150 µm clear200 µm clear100 µm white200 µm white light transmittance light reflectance solar direct transmittance solar reflectance solar absorbence total solar transmittance short-wave shading coefficient long-wave shading coefficient total shading coefficient UV transmittance to 380 nm UV transmittance to 400 nm mean solar gain factors sample thickness (mm) Source: ETFE Foil Cushions as an Alternative to Glass for Roofs and Atria Source: (2000)http://www.building.co.uk/clear-choices/1600.article

6 Design Considerations ETFE foil is increasingly seen as the ‘wonder’ material for lightweight structural enclosures. Some issues that affect architectural design decisions are: – Visible light transmission and quality – Internal environment Overheating Ventilation Glare Noise levels 16 September 2010TensiNet 2010 Sofia 6 Photo: Alastair Gardiner

7 Light transmission and quality Transmittance depends on the wavelength of incident radiation but for ETFE foil is fairly consistent over the visible spectrum nm. This provides interior colour rendering close to that of natural daylight. Ultraviolet light transmission (below 380nm) is higher than for glass and polycarbonate. This has benefits for solaria and swimming pools and also for greenhouses. Infra-red transmittance is also high for wavelengths up to about 7000nm. 16 September 2010TensiNet 2010 Sofia 7

8 Measured transmittance ETFE 200μm samples 16 September 2010TensiNet 2010 Sofia 8

9 Measured long-wave infrared transmittance of 200μm ETFE sample 16 September 2010TensiNet 2010 Sofia 9 Courtesy: Professor Wayne Cranton, NTU

10 Internal Environment ETFE cushions are still a relatively new solution for covering courtyards and atria. Poor performance is sometimes inappropriately ascribed to the system rather than other aspects of the design. Basic properties of the ETFE foil can be modified by fritting and low- emissivity coatings. 16 September 2010TensiNet 2010 Sofia 10

11 Fritting to modify transmittance 16 September 2010TensiNet 2010 Sofia 11 Frit Ref #DescriptionInk Trans %Coverage %Trans % n/aClear 200μ ETFEn/a087 1Large dots Static lines Camo Clouds Med dots Med dots Large dots Hex Inverse Camo Chequered237539

12 ‘Intelligent’ fritting 16 September 2010TensiNet 2010 Sofia 12 Lancaster University, ISS Building, 2009 Architect/Designer: Wilson Mason Main Contractor/Customer: John Turner and Sons

13 Overheating The U-value and solar heat gain coefficient, or g-value, for glass and ETFE are often quoted as being quite similar. 16 September 2010TensiNet 2010 Sofia 13 U-value (W/m 2 K) g-value 6mm monolithic glass Double Glazing Unit (DGU) High Performance DGU Layer ETFE Cushion (with frit) 3 Layer ETFE Cushion (with frit) 4 Layer ETFE Cushion (with frit) Glass and ETFE cushion thermal/solar data as cited in Poirazis, H., Kragh, M. And Hogg, C. (2009)

14 16 September 2010TensiNet 2010 Sofia 14 ETFE Atrium Roof Thickness (mm) Transmittance (%) Layer Description Clear Float60.78 Cavity12 Clear Float60.78 Shading DeviceNone EN-ISO U-value: glass only (Wm -2 K -1 )1.9 EN-ISO U-value: inc. frame (Wm -2 K -1 )1.9 G-value (BS EN 410):0.30/0.74 Example of design data assumed by building services consultant for ETFE covered new-build atrium in the UK, May Values are often taken to be interchangeable even though the physical characteristics may be different.

15 16 September 2010TensiNet 2010 Sofia 15 Kingsdale Comprehensive School, London, where, with the use of intelligently fritted three-layer cushions designed to reduced transmittance to as low as 5%, when necessary, and the provision of extensive high-level cross-ventilation, summer temperatures at high level were kept below 35°C, compared to up to 45°C predicted by initial thermal modelling. [Source: Building Services Journal, 09/04, CIBSE, London, 09/2004, pp ]

16 16 September 2010TensiNet 2010 Sofia 16 Nottingham Boys High School 2009 Architects: Maber Architects, Nottingham ETFE cushion system: Architen Landrell Associates Ltd Nottingham Boys High School 2009 Architects: Maber Architects, Nottingham ETFE cushion system: Architen Landrell Associates Ltd

17 16 September 2010TensiNet 2010 Sofia 17

18 16 September 2010TensiNet 2010 Sofia 18

19 16 September 2010TensiNet 2010 Sofia 19

20 16 September 2010TensiNet 2010 Sofia 20 Nottingham Boys High School 2009 Architects: Maber Architects, Nottingham ETFE cushion system: Architen Landrell Associates Ltd

21 Ventilation As with glazed atria, appropriate ventilation is essential. Also, care must be taken in planning of occupied spaces to avoid the potential stratified layer of hot air immediately under the roof. 16 September 2010TensiNet 2010 Sofia 21

22 16 September 2010TensiNet 2010 Sofia 22

23 Glare Although translucent, ETFE foil does not have the transparency of glass. In the following example, due to the orientation and the configuration of the enclosure (enveloped with ETFE foils) under strong sunlight it created an internal environment that was uncomfortable to remain in for any extended period of time. This is chiefly due to light levels far in excess of any of the adjoining rooms or corridors (glare) and, in summer, the elevated internal temperature. 16 September 2010TensiNet 2010 Sofia 23

24 16 September 2010TensiNet 2010 Sofia 24 William Smith Building, British Geological Survey 2008/9 Architects: Maber Architects, Nottingham ETFE cushion system: Vector Foiltec

25 16 September 2010TensiNet 2010 Sofia 25

26 Noise levels Due to the taut drum-like nature of tensioned ETFE and ETFE cushions; in heavy rain there is a chance that a level of noise is reached that could be considered unacceptable in occupied areas under the cushion array. This may be addressed with the application of an external mesh to attenuate the noise created by rain droplet impacts. 16 September 2010TensiNet 2010 Sofia 26

27 16 September 2010TensiNet 2010 Sofia 27

28 28 Conclusions Unlike for glazing, there are few readily identifiable sources available for universally applicable information pertaining to ETFE foil cushions. Given the bespoke nature of most ETFE enclosures it is difficult to designate standard values This leads to three possibilities: – Test each configuration for each enclosure. – Designate a standard cushion profile and for it construct ISO testing specifications based on existing specifications for physical and theoretical determination of attributes. – Increase knowledge of the properties of ETFE cushions to ensure ‘thermal models’ take into account the varying profiles and account for them September 2010TensiNet 2010 Sofia

29 29 Conclusions The current understanding of the thermal/optical properties of ETFE foil is somewhat limited. The environmental performance of spaces such as atria enclosed by ETFE cladding is also sometimes poorly understood. There is a clear need for further research in both of these areas September 2010TensiNet 2010 Sofia


Download ppt "1 Internal environment in ETFE foil covered building enclosures James Ward and John Chilton School of Architecture, Design and Built Environment Nottingham."

Similar presentations


Ads by Google