Climate and Architecture

Arch 331

Dr. Abdelrahman Elbakheit

References

. . , عوف بن سعيد الرحيم عبد سعيد د المعمارى التصميم و المناخية 1العناصر 2. . الموسوى , عبود هاشم د المناخ و العمارة

Main climates on Arabian Countries:

Hot Dry (Desert): الصحراوى الجاف الحار المناخ

Hot Humid (Equatorial): االستوائى الرطب الحار المناخ

Tropical Marine Hot Humid: الساحلى المدارى الرطب الحار المناخ

Tropical High Land: للمرتفعات المدارى المناخ

Mediterranean Warm Temperate: , المتوسط االبيض البحر مناخ الدافئ المعتدل المناخ

1. Hot Dry (Desert):

- Covers most of Arabian areas, Arabian Peninsula and North Africa.

- Long Summer (five-six Month), short Winter (three –four Month) the rest temperate weather.

- High diurnal daily range of temperature. Specially summertime with temperature range 20 º.

- Daily Max. 45º and above.

- Daily Min. 25º.

- Difference in high temperatures in summer and winter can be 30 º due radiation concentration in summer compared to winter.

- very low rain, some areas may have between 55-155 mil annual rain.

1. Hot Dry (Desert):

- Famous for Hot Dry dust winds in different times of the year( mainly Summer) known with local names, ,الخماسين رياح و القبلى رياح و الشكوك و السموم و الطوز

2. Equatorial Hot Humid:

- Very rear in Arabian lands and is confined to the southern parts of Sudan.- Temperature varies due to rainfalls from (18 º -38 º) in rainy autumn to dry summer

respectively.- Yearly mean temperature is 25 º.

- Daily and yearly diurnal temperature is very small compared to other climates, not more than 3 º. Mainly due to:

- High relative humidity year round.- Lower evaporation rates.- Heavy green vegetations for more than 7 months.

- Long rainy season of 7-months, form April to October or November.- Heavy vegetations.

3. Tropical Hot Humid (Coastal) climate:

- Arabian Gulf coasts, and Arabian peninsula coast on the red Sea.

- Two seasons , very Hot and relatively moderate.

4. Tropical High Land climate:

- High land of 900- 1200 m above sea level.- South and west of KSA, Yemen, east of Sudan.- Rainy in Summer, and cold in winter.- Max. mean 20°-32° in summer.- Min. mean 06°-26° in winter.

5. Worm temperate: Mediterranean climate:- In coastal areas of the north Africa and western parts of Alsham.

3. Climatic Design:

- Building design with climatic influence deals mainly with ways and means to moderate these elements to suit human comfort.

4. Bioclimatic chart:

- developed in 1963 to study the relationship between climate elements and human comfort.- Climate Elements: Solar Radiation, Air temperature, Air Movements and Humidity..- From the Bioclimatic chart the limits of human comfort can be establish as well as the times

and conditions that can be treated with other helping mechanisms.

- When air temperature is 24º and relative humidity 70%, a person needs 1.5m/s air speed to be in the comfort level.

- When air temperature is 10º and relative humidity 56%, a person would need solar radiation about 78 Watts to be in the comfort level.

5. Psychometric Chart:

- Developed in 1979 as a tool to study air properties and their interaction with human comfort and with other climate elements.

- The idea of comfort varies according to subjective (persons health, mood, activity etc..) and objective reasons ( temperatures, relative humidity, etc…).

- For hot Dry regions we can describe the comfort condition to be under temperature from (22º-27 º) and relative humidity from (20%- 80%)

6. Climatic Building design for Hot Regions :

Concentrates to the right of the comfort zone in the psychometric chart and we have two main hot climates, Hot Dry and Hot Humid.

First for hot dry: - Protect the interior from direct solar gains in summer by proper orientation, shadows and

shades- Use of insulation materials in walls and roofs.- Protect the external skin of the building by shading, double roofs and curtain walling.- Use high thermal mass materials to delay heat propagation from outside to inside.- Use of light colours for the exterior of buildings- Use of over night cooling to reduce day time heat gains- Use evaporative cooling from added water surfaces and from vegetations and fountains.

Secondly for Hot Humid:

- Protect the interior from direct solar gains in summer by proper orientation, shadows and shades.

- Maximise natural ventilation to reduce high humidity.

- Eliminate the use of water surfaces that increase humidity such as vegetations , fountains and ponds.

7. Climatic Building design for Cold Regions :

Concentrates to the left side of the comfort zone in the psychometric chart

- Maximize direct solar gains in winter through windows or the thermal mass.

- Use constructions with high thermal mass to store heat daytime for night time, by exposing the thermal mass for sun radiation.

- Old Thermal mass materials are stone and mud, new ones are Concrete or transparent water tanks.

- Protect the building from cold wind.

- Use of insulation to store heat inside buildings for longer periods.

Thermal Mass:

- The use of thick walls construction in vernacular architecture with high thermal mass has proven its suitability in hot dry climates.

- It has the advantage of delaying heat propagation form the external surface of the wall to the inside of buildings daytime.

- If the difference between Max. and Min. temperatures is 20º, with 30cm thick mud construction, then the inside will be cooler by 10º than the outside and the maximum temperature inside will be after 12 hours from that of the outside.

Night Cooling :

The use of night cooling to eliminate the heat inside building is effective only in areas with high temperature differences between daytime and night time.

- Use of night cooling through opening windows night time and closing them daytime.

- Reduce the hot air entering into the building daytime by the use of wind catchers.

- Use of light colours in the exterior surfaces of the building.

- Not effective in Hot Humid areas because of low difference in daily Max. and Min. temperatures. It is better to have low mass in the building envelope (roofs and walls) and to maximize natural ventilation day and night. Use high insulation material and avoid reflections from ground and surroundings.

Climatic design for Riyadh City:

- Riyadh is located at 24º 43’ N and 46 º 44’ E. With summer months from June to September.

- Temperatures in Summer, Daily Max. (45 º -42 º) Daily Min. (24.5 º -22.5 º). High diurnal range, 20 º.

- Relative humidity corresponding to temperatures, (5% -6%) and ( 33.5%-39%) respectively.

- High solar radiation 813 – 929 W/m2.

- The high diurnal range and low humidity levels can be the main factors to influence the deign and choice of materials in this climate.

Cold months, December, January and February :- Can be cold night time and therefore may need heating, daytime can make use of solar

radiation and storing heat in the thermal mass, water, etc….

Moderate months, March, April, October and November :- Cool at night and low humidity, so natural ventilation is well suited, can be slightly hot day

time. Can make use of vegetations and water surfaces for cooling.

Hot Months, May, June, July August and September:- Can be very hot with low humidity day time, therefore can make use of evaporative cooling,

thermal mass, wind catchers, etc….