Design of Climate responsive sustainable building for Hot and Dry zone

Designed for: Girma Bitsuamlak PhD, PEng

CEE 9532 Building Sustainability

  

Designed by: Pradeep Kandasamy Natarajan

IntroductionLocation: Jaisalmer, Rajasthan, India

Climate: Hot and Dry

Site Description: Located in the centre of The Thar desert in Rajasthan.

Building Type: G+1

Design strategies:

• Consideration of the Traditional buildings throughout the design process.

• Orientation of the building components along the prevailing direction of wind.

• Shading and overhangs based on sun path diagram.

• Courtyards for the effective ventilation and for natural lighting.

• Provision of vents in the walls for effective ventilation.

• Design of roof based on Bernoulli's principle.

• Consideration of the Life Cycle Assessment of building materials and components.

Why Traditional Design?

Environmentally sustainable.

No mechanical equipment's necessary for cooling the building.

Reduction in Co2 emissions.

Uses the available energy efficiently

Zero energy homes

Resources available:

1.Wind rose diagram:

Based on the wind rose diagram:

• Windows are provided

• Wing walls are positioned

• Roof is designed

2.Night flush cooling:

• Temperature difference necessary for the night flush cooling is around 11°C to 17°C.

• In Jaisalmer the difference in temperature during the summer is around 15 to 16°C which is suitable for night

flush cooling.

3.Solar energy:The location of Jaisalmer makes it an advantage to use the solar energy effectively.

The average radiation value for a horizontal surface in Jaisalmer is 5 kWh/m2/day

4.Availability of sandstone:

Jaisalmer often called as Golden city because of the construction of the buildings using sandstone

Sandstone is abundant in cities near Jaisalmer, which reduces the transportation cost of the material.

Constraints for sustainable design strategies:

Since Jaisalmer is located at the centre of the desert, water is scarce in this region. Hence evaporative

cooling can not be adopted.

Trees can not be relied for shading the buildings, because survival of such trees are very rare in this

region.

Design Strategies:

1.Partitions:

• During the design phase care must be given in providing the partitions.

• Lesser partitions ensures the free movement of air inside the house.

2.Solar orientation and shading:

• The shading requirements of the building is calculated from the computer software Revit.

• Shading is provided in such a way that the overhang allows the winter sun inside and blocks the summer

sun.

• Each and every side of the building is analysed with the help of the sun path diagram using the software

and accordingly windows are placed.

• The effect of day lighting on the building can be studied with the help of the Illuminance effect of the

software.

• The width of the overhang is 5 feet.

Sun path diagram for different seasons:

3.Courtyard:

The courtyard serves the purpose of both natural ventilation and day lighting.

The hot air from the house escapes through the top of the courtyard to the exterior, due to the temperature

difference between interior and exterior portion of the building.

The effect of day lighting is measured with the help of the software.

Illuminance = Light Falling on a Surface

It is measured by Foot-candles(lumens/ft2)

An Illuminance Value of 30 Foot-candles is satisfactory for reading books whereas a value of 200 Foot-candles

is necessary for doing precise works.

The courtyards in a house gives a Illuminance value of 200 Foot-candles during the noon without the help of

any artificial lighting

May 21 at 12pm May 21 at 4pm

Courtyard:

4.Construction materials and components:

Walls: Sandstone is used for the construction of the building as of the local practice.

Sandstone which has a higher thermal mass value is suitable material for the hot climate.

Thermal mass of the walls are 42.57 kJ/K and the r value is 0.1155 m2K/W

Windows: The windows are selected in such a way that it allows the daylight to pass in and restricts

the heat from the exterior environment.

The window used is SGG ENVISION from saint gobain.

By using the particular product 4889 kg Co2 per annum is saved, equivalent to planting of 20 Trees.(ref:

saint gobain website)

5.Wing walls:

The Wing walls are placed on the west and south direction so as to use the pressure difference for

natural ventilation.

Wind flow diagram:The wind flow across the building is studied in order to make use of the natural ventilation.

6.Roof:

The roof is designed in such a way that it assist in enhancing the night flush cooling of the building.

Overhang is not provided in the north direction as the intensity of direct sunlight on the direction is less.

7.Adjustable louvers:

These louvers can be opened during the night to allow for night flush cooling and closed during very

hot days.

South view

North view

8.Vents in the wall:

Providing small vents along the top of the walls can improve the natural ventilation of the building as adopted in

the traditional structures.

South Direction:

• More number of windows in the south direction.

• Windows are placed at lower sill level in south direction.

West Direction:

• Less number of windows on the west side of the building.

• Picture shows the wing wall on the west side

North Direction:

• Curtain walls are provided in the north direction to allow for the natural lighting.

• More windows are provided to allow for free ventilation.

East Direction:

• Less number of windows are placed on the east side.

• Windows are placed at higher sill level.

9.Solar panels:50% of the electricity is to be obtained from the solar panels: 23x0.5=12(round off)Total number of modules required=32Area of one module=11.8ft2

Area required for the panels=32x11.8 =380ft2

Usable area of roof = 650ft2

Solar water heater:water requirement per day = 100 litres Required Temperature of water = 60°CAmbient temperature of water = 20°C Area required = 34ft2

DC loads Quantity Watts totalHours of operation Energy/day

Lights1 10 15 150 10 1500CFL

Lights2 5 6 30 5 150computers 2 200 400 12 4800Television 1 150 150 10 1500

Refrigerator 1 600 600 5 3000fans 8 100 800 15 12000

Television 1 150 150 15 2250                   Total watt hours 22950        Total kW hours 22.95

10.Life cycle Assessment:

LCA of sandstone, plain concrete and reinforced concrete were compared of which sandstone consumes less

energy than the concrete.

Results of the LCA of solar, wind and thermal power is analysed and based on the results the design is made.

At present the city receives the electricity from the thermal power plant, hence solar panel is included in the design.

A huge number of wind farms and solar farms are constructed in the desert on a plan to power the state from the sustainable energy.

MaterialEnergy

consumed(MJ/ft3)Sandstone 69

Plain concrete 95.46Reinforced

concrete 170.42

Summary:

An overview of the sustainability features:

Orientation of the building with respect to sun path and wind profile.

Selection of the materials, changes in the geometry of the building components.

Overhangs and vents in the wall.

Solar panels and electricity.

Conclusion:

Life cycle assessment of the materials will play a major role in determining the sustainability of the

building in future.

Sustainability is not a step ahead rather it is a step back, in the form of traditional buildings.

An awareness must be created among the common peoples regarding sustainability.