2. INTRODUCTION TO TERMINOLOGIES CLIMATIC DESIGN
CLIMATE WEATHER
Terminologies which doesn’t mean the same thing
• Short Term
• Limited Area
• Can change rapidly
• Difficult to Predict
“Weather is what’s happening outside your window right
now”
“Climate is the average of many years of weather
observation”
Long Term (Usually 30 years)
Wide Area
Seasonal Changes
Measured over long spans of time
Weather is the state of atmosphere at a particular place and
time as regards temperature, cloudiness, dryness, sunshine,
wind, rain etc.
Climate is the weather conditions prevailing in an area in
general or over a long period usually over 30-years.
3. INTRODUCTION TO TERMINOLOGIES CLIMATIC DESIGN
Introduction to TROPICAL Climate
CLIMATE
TROPICAL
CLIMATE
An integration in time of the physical states of the atmospheric environment, characteristic of a
certain geographical location.' As weather is the momentary state of the atmospheric environment at
a certain location, climate could be defined as 'the integration in time of weather conditions‘.
Tropical climates are those where heat is the dominant problem, where, for the greater part of the
year buildings serve to keep the occupants cool, rather than warm, where the annual mean
temperature is not less than 20°C.
4. CLASSIFCATION OF TROPICAL CLIMATES CLIMATIC DESIGN
CLASSIFICATION
OF
TROPICAL CLIMATES
The classification given below was suggested by
G A Atkinson in 1953. The basis of this
classification is given by the two atmospheric
factors which dominantly influence human
comfort:
WARM-HUMID
CLIMATE
Air temperature Humidity
Vegetation
Wind velocities
AIR TEMPERATURE HUMIDITY
Extreme Cause of Human
Discomfort
01.
HOT-DRY
CLIMATE
02.
COMPOSITE
CLIMATE
03.
Precipitation
Sky Conditions
Air temperature Humidity
Vegetation
Wind Conditions
Precipitation
Sky Conditions
Air temperature Humidity
Vegetation
Wind velocities
Precipitation
Sky Conditions
Day Temp: 27 and 32 °C
Night Temp: 21 and 27 °C
55 to almost 100% Annual Rainfall: 2000 to
5000 mm
30 m/s, usually one or two
prominent directions
Grows Quickly
Cloud Cover: 60 and 90%
Fairly Cloudy
Day Temp: 43 to 49 °C
Night Temp: 24 and 30°C
10 to 55% Annual Rainfall: 50 to
155 mm
Hot winds carrying dust
and sand
Sparse & Difficult to
maintain
Cloud Cover: Minimal; Clear
Sky
Day Temp: upto 27°C
Night Temp: 04 to 10 °C
20 to 55% Annual Rainfall: 500 to
1300 mm
Hot & Dusty Fine growth, Usually
destruction happens during
Heavy Monsoon season
Heavily overcast during
monsoon and clear during
Dry seasons
5. HOT-DRY CLIMATE
WARM-HUMID
COMPOSITE
TEMPERATE
COLD
TROPICAL
CLIMATE
ZONES
IN
INDIA
Gulf of Kutch, Rajasthan, Madhya
Pradesh, Southern part of Andhra
Pradesh , Gujarat
Goa, Mumbai, Vishakhapatnam,
Chennai, Kolkata, Puri, Tripura,
Kozhikode, Gulf of Kutch
Haryana, Punjab, New Delhi, Uttar
Pradesh, Bihar, Madhya Pradesh,
Chattisgarh
Parts of Karnataka
Jammu & Kashmir, Leh, Himachal
Pradesh, Uttarakhand, Sikkim & Parts
of Arunachal Pradesh
CLIMATIC ZONES OF INDIA CLIMATIC DESIGN
Source of Map: First green
6. DESIGN PARAMETERS FOR SHELTER APPLICATION CLIMATIC DESIGN
Nature & Characteristics of
the Climatic Zone
Form, Planning & Orientation
01
02
External Surfaces and Immediate
Surroundings
03
Roofs, Walls & Opening size Height
& Construction Material
04
Roof & Wall Materials & Surface
Techniques
05
7. Shelter for HOT & DRY CLIMATE Zone
• Hot-dry desert and semi-desert climates are characterized by very hot, dry air and dry ground.
• Day-time air temperatures may range between 27 and 49°C (normally higher than the 31 to 34°C skin
temperature), but at night it may fall as much as 22 degC.
• Humidity is continuously moderate to low.
• There is little or no cloud cover to reduce the high intensity of direct solar radiation.
• The dry air, low humidity and minimal rainfall discourage plant life, and the dry, dusty ground reflects
the strong sunlight, producing an uncomfortable ground glare. Local thermal winds often carry dust
and sand.
NATURE OF
THE
CLIMATE
FORM
&
PLANNING
PLANNING
• An enclosed, compactly planned and
essentially inward-looking building is the
most suitable.
• For this reason in hot-dry climates the
tendency is to have close groups of
buildings, narrow roads and, streets,
arcades, colonnades and small enclosed
courtyards, in order to get the maximum
amount of shade and coolness.
DESIGN PARAMTERS FOR SHELTER: HOT & DRY CLIMATE ZONES CLIMATIC DESIGN
8. Shelter for HOT & DRY CLIMATE Zone
ORIENTATION
• Surfaces exposed to the sun should be reduced as much as
possible. Site conditions permitting, the larger dimensions
of a building should preferably face north and south, as
these elevations receive the lowest heat loads from solar
radiation.
• Non-habitable rooms (stores, toilets, etc.), can be effectively
used as thermal barriers if planned and placed on the east
and, especially, the west end of the building.
NORTH
SOUTH
WEST EAST
FORM
• Projecting roofs, verandahs, shading devices, trees and
utilization of surrounding walls and buildings are familiar
techniques of solving this problem.
• The most effective method is to construct a second roof over
the first. Since the outer roof, gaining heat through radiation,
will reach a very high temperature, it is imperative to separate
it well from the main roof, to provide for the dissipation of
heat from the space between the two roofs, and to use a
reflective surface on both roofs.
Reflective
surface on
roof
DESIGN PARAMTERS FOR SHELTER: HOT & DRY CLIMATE ZONES CLIMATIC DESIGN
9. Shelter for HOT & DRY CLIMATE Zone
EXTERNAL
SPACES
COURTYARD PLANNING
• Adjacent buildings, pavements and dry ground heat up quickly, causing both a painful glare and reflected
heat radiation towards the building during the day, and at night they will reradiate the heat stored during
the day.
• 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.
• Trees, plants and water in the enclosed space will cool the air by evaporation, help to keep dust down
and provide shade, visual and psychological relief.
• The best external space in this type of climate is a courtyard. Here a pool of cool night air can be retained,
as this is heavier than the surrounding warm air. If the courtyard is small (i.e. the width is not greater than
the height), even breezes will leave such pools of cool air undisturbed. The small courtyard is an excellent
thermal regulator in many ways.
DESIGN PARAMTERS FOR SHELTER: HOT & DRY CLIMATE ZONES CLIMATIC DESIGN
10. Shelter for HOT & DRY CLIMATE Zone
ROOF,
WALLS &
OPENINGS
• Walls and particularly roofs must be constructed of heavy materials, with a large thermal capacity.
• Thus the design of openings is governed by two requirements:
1. During the day the absence of openings would be most desirable, or at least openings as small as
possible, located high on the walls.
2. During the night the openings should be large enough to provide adequate ventilation for the dissipation
of heat emitted by the walls and roof
• If so, the next best thing would be the use of shutters with a high thermal resistance, e.g. heavy shutters
made of wood. If these are kept closed during the day, the heat inflow is retarded, and if opened at night,
the heat dissipation is not obstructed.
• The ground is also a valuable means of heat storage, the building should have maximum contact with the
ground, i.e. ground- floors should be solid, not suspended, and in no case should the building be built on
stilts. The heat will then be conducted from the building fabric to the ground.
DAY TIME NIGHT TIME
Closed Shutters
DESIGN PARAMTERS FOR SHELTER: HOT & DRY CLIMATE ZONES CLIMATIC DESIGN
11. Shelter for HOT & DRY CLIMATE Zone
ROOF
&
WALL SURFACES
• Light colored or shiny external surfaces will reflect a large part of the incident solar radiation, thus much
less heat will actually enter the building fabric.
• Although a bright metal surface, such as an aluminium sheet, and a white painted surface both will have
an absorbance around 0.2 the latter will have an emittance value about eight times as high as the bright
metal (0.8 as opposed to 0.1). If we consider that a white surface will not remain very bright for long, its
absorbance may increase to 0.3, and if we compare this with a polished aluminium sheet, which may have
an absorbance of only 0.1, it is seen that the aluminium will absorb much less heat.
• Dark colored surfaces should in all cases be avoided. White versus bright metal surface Bright aluminium
Where radiant loss is possible (for example to sky) a white surface gives less net gain.
WHITE PAINTED SURFACE BRIGHT METAL SURFACE
DESIGN PARAMTERS FOR SHELTER: HOT & DRY CLIMATE ZONES CLIMATIC DESIGN
Out-door conditions are so hostile in this climate, that both the buildings and the external living spaces need to be protected as much as possible from the intense solar radiation and the hot, dusty winds.
