Shelter for hot-dry climate

Application
1. Shelter For Hot-dry Climate,
Sub-group: Hot-dry Maritime Desert Climate
2. Shelter For Warm-humid Climate,
Sub-group: Warm- Humid Island Climate
3. Shelter For Composite Climate,
4. Shelter For Tropical Upland Climate,

APPLICATION
•Situation:
Two belts at latitudes between approximately 15 and 30⁰ north and south of
the equator.
•Example Cities:
Assuan, Baghdad, Alice Springs, Phoenix etc
Shelter For Hot- Dry Climate
Equator

APPLICATION
1.1 Nature of the Climate
Very hot, Dry air and dry ground.
1.1.2 Air Temperature:
•Daytime temperatures may range between 27- 49⁰C (higher than skin
temperature, 31- 34 ⁰C )
•At night it may fall as much as 22⁰C.
1.1.3 Humidity:
•Humidity is continuously moderate to low.
1.1.4 Sky Condition:
•Little or no cloud cover to reduce the high intensity of direct solar radiation.
•The clear skies permit a considerable amount of heat to be reradiated to
outer space at night.

APPLICATION
1.1.5 Vegetation:
•Minimal rainfall discourage plant life.
•Uncomfortable ground glare.
1.1.6 Wind:
•Local thermal winds often carry dust and sand.

APPLICATION
1.2 Physiological Objectives:
1.2.1 Daytime:
• Reduction of the intense radiation from the sun, ground and surrounding buildings.
• Basically a problem of protection.
• A knowledge of periodic heat flow characteristics of various constructions is needed
to select walls and roofs. This will-
 Maintain inner surface temperatures less than the Skin temperature.
 Allow the body to dissipate surplus heat
 Cool the indoor air by convection
Less than skin
Temp

APPLICATION
1.2.2 Night time:
• At night air temperature is low and surface temperature is high, so it can increase
effective temperature(ET).
• If ET is high it will be beneficial.
ET is High
Surface Temp.

APPLICATION
• Breezes can not be used as it is very hot and dusty. But if air is cooled and filtered it
will be pleasant.
• For low humidity evaporation is greater. Special arrangement is quite unnecessary.
•
1.3 Form & Planning:
• Out-door conditions are so hostile.
• Both the buildings and the external living spaces need to be protected.

APPLICATION
1.3.1 Enclosed & Compact Planning:
1. Enclosed, compactly planned and essentially inward-looking building is the most
suitable.
2. o accessibility of water, fuel and food
storage to points of use
o easily cleaned surfaces
o reduction of movement distances
o avoidance of unnecessary stairs
will benefit the occupants by
reducing physical movement,
effort and fatigue

APPLICATION
3. In hot-dry climates the tendency of –
•close groups of buildings
•narrow roads and streets, arcades,
colonnades
•small enclosed courtyards
to get the maximum amount of
shade and coolness

APPLICATION
1.3.2 Orientation:
• Surfaces exposed to the sun should be reduced .
• Larger dimensions of a building should preferably face north and south.
• Non-habitable rooms (stores, toilets, etc.), can be placed on the east and west for
thermal barriers
1.3.3 Shading:
• Projecting roofs, verandahs, shading devices, trees and utilization of surrounding
walls and buildings are familiar techniques for shading of roofs, walls and out-door
spaces.
• Use low thermal capacity materials for shading devices to ensure their quick cooling
after sunset.
• o Aligning buildings close to each
other
o East and west walls are placed close
together
mutual shading will decrease the
heat gains on external walls

APPLICATION
1.3.4 Roof:
• For shading of the roof the most effective method is to construct a second roof over
the first.
• It is imperative to separate it well from the main roof, to provide for the dissipation
of heat.
• Use a reflective surface on both roofs.
• The cost of a 'double roof', is very high. However, a simple ceiling, with a ventilated
roof-space would also be effective.

APPLICATION
1.4 External Spaces:
As the day-to-day activities take place out-of-doors. It is necessary to treat the external
spaces.
1.4.1 Enclosure of out-door spaces:
• Adjacent buildings, pavements and dry ground heat up quickly during the day and
reradiate the heat at night.
• Enclosure of out-door areas by walls which are themselves shaded will help to avoid
such effects, and at the same time keep out dust and hot winds.
1.4.2 Plants & Water:
• Trees, plants and water in the enclosed space will cool the air by evaporation.
• It help to keep dust down and provide shade, visual and psychological relief.

APPLICATION
1.4.3 Small Courtyard:
The best external space in this type of climate is a courtyard. The small courtyard is an
excellent thermal regulator in many ways .
•A pool of cool night air can be retained, as this is heavier than the surrounding warm
air.
•If the courtyard is small, breezes will leave such pools of cool air undisturbed.

APPLICATION
•High walls cut off the sun, and large areas of the inner surfaces and courtyard floor are
shaded during the day.
•Cooler air, cooler surfaces, the earth beneath the courtyard will draw heat from the
surrounding areas, reemitting it to the open sky during the night.

APPLICATION
1.5 Roofs, Walls & Openings:
1.5.1 Large thermal capacity material:
• Walls and roofs must be constructed of heavy materials with large thermal capacity.
• Morning heating-up period is started with little heat content .
• The heat stored during the previous day must be dissipated during the night.
1.5.2 Design of Openings:
1. During the day the absence of openings
would be most desirable, or as small as
possible, located high on the walls.
2. During the night the openings should be
large to provide adequate ventilation for
dissipation of heat.

APPLICATION
1.5.2 Design of Openings:
•Large openings, with massive shutters with thermal capacity could be a
technological problem.
•Can use shutters with a high thermal resistance, e.g. heavy shutters made of wood.

APPLICATION
1.5.3 Occupancy pattern:
•An office building occupied only during the morning and early afternoon, cannot
dissipate heat through ventilation at night.
•Massive roofs will be particularly effective for this purpose.
1.5.4 Separate Day & Night Room:
•Where night-time temperature does not fall below comfort zone, large thermal
capacity should be restricted to internal walls, partitions and floors.
•The outer walls and roof would need to have a high resistive insulation.
•Alternatively separate day and night rooms could be provided in the house.

APPLICATION
1.5.3 Ground Heat Storage:
•The ground is also a valuable means of heat
storage.
•Building should have maximum contact
with the ground.
•Ground- floors should be solid, not
suspended and in no case should the building
be built on stilts.
•If ground near the building is shaded at
day, but fully exposed at night sky, the
radiant heat emission is not obstructed.

APPLICATION
1.6 Roofs & Wall Surfaces:
•Surface treatment and the selection of surface materials influence in reducing the
heat load.
•Light coloured or shiny external surfaces reflect large amount solar radiation so less
heat will enter in building.
•Roof is the most critical part of the building surface as it receives the greatest
amount of solar radiation.

APPLICATION
1.6 Roofs & Wall Surfaces:
•It is also most exposed to the clear night sky and emits most heat to outer space.
•The selection of roof surface materials will have the greatest effect than walls.
•It will still be more advantageous to use a white surface.
•Dark coloured surfaces should in all cases be avoided.

APPLICATION
1.7 Ventilation & Airflow:
1.7.1 Day- time:
•During the day-time openings should be closed and shaded.
•Air intake openings should be located so that the coolest and most dust-free air is
taken.
•Internal heat gains can present quite a problem. Such heat sources should be
isolated and separately ventilated.

APPLICATION
1.7 Ventilation & Airflow:
1.7.2 Night- time:
•Ample ventilation at night is necessary where the stored heat is to be dissipated.
•Indoor air stream at night can be directed to pass the hottest inside surfaces.
•It is advisable to have the top of the openings level with the ceiling.
1.7.3 Double Roof:
•If double roofs or a separate roof and ceiling is used, the heat transfer from the
outer skin to the ceiling must be consider.
•This can be ensure by ample ventilation of the roof space.

APPLICATION
1.7.3 Double Roof:
•In separate roof and ceiling, the roof should be light and the ceiling should be
massive.
•Roof slopes should be orientated towards the prevailing breeze, and obstructions
which prevent the air flow should be avoided.

Shelter for hot-dry climate

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