the design of ecological buildings – lighting and shading international seminar on green housing,...

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

20021

The Design of Ecological Buildings: Shading and Lighting

Professor Yan ChenProfessor Les Norford

Department of ArchitectureMIT

Traditional shading technology New shading technology

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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What not to do - Beijing housing: vegetation but not much shading

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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What not to do - Balconies are enclosed and no longer provide shading

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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What not to do – worst case

Which way is south? Where is the window shading?

Can occupants possibly be comfortable without air conditioning?

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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The Earth’s Comfort Zones Around the world people have developed energy-efficient building forms that are suited to the climate conditions of their particular location – a form of ‘solar vernacular’.

They have developed simple solutions to the environmental challenges set before them: heat, cold , rain and wind. These solutions have been developed using a limited range of indigenous building materials, all of them renewable

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Climate Zones: Architecture

Boston Beijing

Ice Caps

Tundra

Mountain

Continental

Marine-West coastal

Mediterranean

Subtropical

Rain Forest

Savannas

Steppes

Deserts

40-42 N

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Mediterranean Climate

•Closest to the ideal climate - warm but dry with mild winters. People must protect themselves from the intense heat of summer and extreme light by shading and thermal mass.

•Life slows down in summer, as cooling is not always affordable.

•Arcades and verandahs create microclimates merging the bright outside with the cold dark indoors

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Shading by Buildings - Italy

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Marine West-coastal climate

•Not too hot, not too cold – the oceans have a calming influence on the temperature on land. The strong winds and rain that come with the cold winter make this a good environment for people to work in, as long as they have warmth and protection

•A balance is required between daylight and insulation – large windows allow natural lighting and ventilation.

•The low embodied energy of Georgian houses, using brick, wood and glass, has proved very sustainable for over 200 years

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Subtropical Climate

•A pleasant climate for most of the year, but summers are humid so ventilation is a necessity.

•The Japanese and Chinese developed systems of dynamic walls to create buffer zones between inside and outside, providing more comfortable summer spaces.

•Houses in the southern US use the porch as a buffer zone. In Japan the sliding screens allow maximum cross ventilation. Chinese roundhouses contain a protected fully sustainable community

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200211

Solar Shading

Villa Shodhan, Ahmadabad Unite Building, Marsailles, France

•Shading devices and roof gardens provide excellent shade and comfort for south facing walls

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200212

Window shading inMumbai, India

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200213

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Even newer buildings have at least some window shading

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200215

A school in Gujarat, India – note the depth of the facade

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Solar Shading

•Protective shading in Brazil. Adjustable louvers between fixed vertical concrete fins

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200217

Housing in Zimbabwe – another deep façade and a good use of pre-

cast concrete

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200218

New facade technologies

• many new high rise buildings in Europe are experimenting using double skin wall technology- allowing natural ventilation and adjusting to summer and winter climate conditions

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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How about a very different type of high-rise building for a hot and humid tropical climate?

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200220

Back to Beijing - vegetation helps reduce indoor temperatures

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Vegetation and shading from overhanging surfaces – looks cool and comfortable

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Awnings and plants

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Detailed View of Shading # 1:Osuna Housing, Seville, Spain

Notice strong solar orientation of the buildings on the site.

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

200224

Shading – relatively few windows on the west facade

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Winter sun for daylighting and solar heat

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Summer sun is blocked

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Detailed Look at Shading #2: Solar Village 3 Athens, Greece

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Align most buildings to face North-South

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Site orientation

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Shading system

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Note depth of south facing façade

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Shading Design

1. Determine when shading is needed

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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2. Determine elevation and azimuth of sun when shading is needed

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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3. Choose a shading device – fixed ….

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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… or movable

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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In hot climates, south-facing windows are best because they bring in the least heat

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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4. Determine size of shading device

Example: movable south-facing shading

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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A word about lighting

• Relatively easy to do with houses because room sizes are small

• Still important– Reduces energy for lighting– May reduce energy for cooling– Meets human needs for sunlight and contact

with nature

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Assessing lighting inside a Shanghai apartment

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Use simulation to estimate indoor illuminance

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Developers and designers can get help from the research community

• Encourage and support research to find new ways of determining energy-efficient designs

• Conduct design competitions in which carefully documented estimates of energy use are a key part of submittals

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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A new technology: automatically trading off cost of windows and insulation

against energy use

• Consider a Beijing apartment, with north and south exposures

• Vary window size, glazing type, and wall construction in each of the two walls

• Compute construction cost and operating energy

• Search for lowest operating energy for a given construction cost

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Search procedure

• Use the DOE-2 energy calculation program to estimate yearly energy use for heating, cooling and lighting

• Use a genetic algorithm to automatically search for the best trade-offs between operating energy and construction cost

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Trading off cost of windows and insulation against energy use – results of an automated search

Beijing - Pareto front [First and last generations]

0

1000

2000

3000

4000

5000

6000

2 3 4 5 6 7 8 9 10 11 12

MWh

Co

st

($)

Gen 1

Gen 100

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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What’s best? Construction details

• The most expensive but most efficient construction uses:– Large south-facing and small north-facing

windows– Lots of insulation in both walls, but more in the

north-facing wall

• All of the optimal trade-offs use double-glazed windows

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Repeat for east-west apartment

Beijing East/West case- Pareto front [1st and last generations]

0

1000

2000

3000

4000

5000

6000

7000

2 3 4 5 6 7 8 9 10 11

MWh

Co

st

($)

Gen 100

Gen 1

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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East-west apartment

• Higher energy use than an apartment facing north-south, as expected

• The most energy-efficient solution has windows of about 2 m2 in the east and west walls, compared to about 8 m2 in the south wall and 0.8 m2 in the north wall

The Design of Ecological Buildings – Lighting and ShadingInternational Seminar on Green Housing, Guangzhou, China, June

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Conclusion• Developers and designers can make buildings

more comfortable and efficient, by setting high goals and working with government organizations and building scientists.

• Better control of sun and light need not be costly and can provide a distinctive and pleasing form to buildings as well as save energy for lighting and cooling.

• Researchers should be encouraged to generate new designs and to pin point trade-offs between energy use and cost.