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Façade Design in Green Building Rating Systems Ommid Saberi Associate Director Head of Sustainability and Energy
16/02/2014
What will be covered?
What are the green building regulations and rating tools in the Middle East?
How do the rating systems deal with Façade design from different sustainability angles?
Comparison of the detailed requirements of each system. Challenges facing the market in the Middle East Some technical glitches on façade sustainability Conclusion
Green Building Regulations and Rating Tools
Estidama PBRS V1
2010 Abu Dhabi
DGBR V1
2014 Dubai
GSAS Design Assessment
v2.0 2013 Doha
Estidama – Relevant Requirements – Mandated 2010
RE-R1: Minimum Energy Performance IDP-1: Life Cycle Costing (LCC) IDP-4: Building Envelope Verification LBi-2.1: Material Emissions : Adhesives & Sealants LBi-7: Daylight & Glare LBi-8: Views LBi-9: Indoor Noise Pollution RE-2: Cool Building Strategies SM-4: Design for Disassembly SM-6: Design for Durability
Dubai Green Building Regulations – Relevant Requirements – Mandated 2014
304.03 Light Colours on the Outside of Buildings 304.04 Orientation of Glazed Façades 401.05 Openable Windows 403.01 Acoustical Control 404.01 Low Emitting Material: Paints and Coatings 405.01 Provision of Natural Daylight 405.02 Views 501.01 Minimum Envelope Performance
Requirements 501.02 Thermal Bridging 501.04 Air Loss from Entrance and Exit 501.05 Air Leakage
Global Sustainability Assessment System – GSAS – Relevant Requirements
Energy [e.1] Energy Demand Performance Materials [M.6] Design for Disassembly Materials [M.7] Life Cycle assessment (LCa) Indoor environment [Ie.2] Natural Ventilation Indoor environment [Ie.5] Daylight Indoor environment [Ie.6] Glare Control Indoor environment [Ie.7] Views Indoor environment [Ie.8] Acoustic Quality (30dB for classrooms, 40dB for
offices) Indoor environment [IE.9] Low-Emitting Materials Cultural & economic value [Ce.1] Heritage & Cultural Identity
Energy Performance – Reduction of Heat Gain
Building Fabric Item Estidama DGBR GSAS Above-Grade Wall Construction 0.3 W/m2oK 0.57 W/m2oK 0.42 W/m2oK
Vertical Glazing Ratio (gross window-to-wall) 40% 40% N/A
Vertical Glazing Type and U-value, 2 W/m2oK 2.1 W/m2oK 1.82 W/m2oK
Vertical Glazing SHGC 0.3 0.35 0.42
Vertical Glazing Light Transmittance
N/A Min 0.25 N/A
Air Leakage Rate, 2l/s/m2 at 75Pa 10m3/m2 of façade at 50pa
1.1 m3/h/m2 at 4Pa
Façade design
Windows and Shading Item Estidama DGBR GSAS
Openable Windows N/A Yes N/A
Shading Devices N/A South and west glazed areas
Shading Reduction Factor
Façade Color N/A Light colors N/A
Façade design
Item Estidama DGBR GSAS Life Cycle Costing Yes Yes Building Envelope Verification Yes
Material Emissions Yes Yes Yes Daylight & Glare Yes Yes Yes Views Yes Yes Yes Acoustic Yes Yes Yes Cool Building Strategies Yes Design for Disassembly Yes Yes Design for Durability Yes Heritage & Cultural Identity Yes
Challenges
Still mechanical and electrical systems are the main contributors to energy saving so façade gets less attention
Energy saving is achieved mainly by a better MEP design rather than a good façade design.
Undermining the value of a good façade design.
1 Solution should be to educate the market about the comfort benefits of a
good façade design as well as energy saving Also to set specific requirements for heat gain through facade
Challenges
Compliance with the regulations does no guarantee a good design Simply because they are checklists and does not replace a good designer Complying with code is becoming a replacement for innovative design
A LEED platinum Rated Building
2 Solution is to ensure each design has its own innovative aspects and
communicate the message to wider stakeholders
Challenges
The image of a building is becoming more important than comfort or energy use Buildings are designed for images from outside rather then for comfort inside Energy intensity is still a new concept and in the Middle East buildings are compared
to ASHRAE baseline. Not challenging enough to drive innovation.
3
Challenges
Challenge of not being challenged enough, challenge of living with business as usual
Can we design a façade that give us 20kWr/m2 of heat gain How can we will be challenged from technical point of view?
4
Challenges – A well shaded hotel 4 Solar gain & Infiltration gain & External conduction gain (MWh) MWh kWh/m2 Jan 01-31 -6 - 1 Feb 01-28 3 0 Mar 01-31 25 3 Apr 01-30 64 8 May 01-31 110 14 Jun 01-30 131 17 Jul 01-31 151 19 Aug 01-31 151 19 Sep 01-30 123 16 Oct 01-31 97 12 Nov 01-30 42 5 Dec 01-31 10 1
Summed total 903 114kWh/m2 Total façade area (m2) 7925
Technical Glitches - Which one has higher solar gain? Why?
Façade 1, Windows are not shaded but uses a glazing which has SHGC of 0.25.
Façade 2. Windows are shaded and glazing has SHGC of 0.55 and total SHGC of window including the shading is 0.25.
1 2
Technical Glitches - Which one has better indoor comfort? Why?
Façade 1, Windows are not shaded but uses a glazing which has SHGC of 0.25.
Façade 2. Windows are shaded and glazing has SHGC of 0.55 and total SHGC of window including the shading is 0.25.
1 2
Technical Glitches - Which one has better indoor comfort? Why?
Façade 1, Windows are not shaded but uses a glazing which has SHGC of 0.25.
Façade 2. Windows are shaded and glazing has SHGC of 0.55 and total SHGC of window including the shading is 0.25.
1 2
Technical Glitches – Flexibility and Human Interaction
Technical Glitches – Flexibility and Human Interaction
Technical Glitches – Flexibility and Human Interaction Technical Glitches – Flexibility and Human Interaction
Technical Glitches – Flexibility and Human Interaction Technical Glitches – Flexibility and Human Interaction
Technical Glitches – Air Infiltration
Technical Glitches - Infiltration requirements
Technical Glitches – Air Infiltration
HVAC design & energy models
0.25ACH?
Technical Glitches - U values – Target vs Reality
Design stage U values = Center of pane U value (0.25W/m2oK) Reality is average U value (0.4W/m2oK)
Technical Glitches - Openable Windows
Higher infiltration
Higher occupant comfort and satisfaction
Emergency ventilation Passive cooling in winter
Fresh air
Conclusion
Green building codes are covering a good portion of sustainability issues on façade design and performance.
The mandated elements related to facade in the codes are rather limited.
In the middle east there are still challenges for designers, manifactureres and contractors to overcome to create a standard product.
Attention to façade must not be ignored due to dominance of HVAC systems.
Innovative sustainable design should not be replaced by green cods.
