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close this bookClimate Responsive Building - Appropriate Building Construction in Tropical and Subtropical Regions (SKAT; 1993; 324 pages)
View the document1. Foreword
Open this folder and view contents2. Fundamentals
Open this folder and view contents3. Design rules
close this folder4. Case studies
View the document4.0 Preliminary remarks
View the document4.1 Experiment in Ghardaia, Algeria
View the document4.2 Simulation in Ghardaia, Algeria
View the document4.3 Buildings in Shanti Nagar, Orissa, India
View the document4.4 Experiments in Cairo, Egypt
View the document4.5 Buildings in the Dominican Republic
View the document4.6 Buildings in Kathmandu, Nepal
View the document4.7 Buildings in New Delhi, India
View the document4.8 Movable louvres for a school in Kathmandu, Nepal
View the document4.9 Mountain hut in Langtang National Park, Nepal
Open this folder and view contents5. Appendices
 

4.1 Experiment in Ghardaia, Algeria

The main points:

• With controlled ventilation (night ventilation only) full advantage can be taken of the lower night temperatures.

• The ventilation during nighttime has only a minor effect on the daytime temperature.

• The gypsum construction keeps the temperature at a very even level.

Source: Research project by Lund University, (LCHS) and CNERIB, Algeria, carried out by Hans Rosenlund and Djamel Ouahrani. [ 101, 157 ]

4.1.1 Geographical location and climatic characteristics

Ghardaia lies in an extremely hot and arid region in the desert of Algeria, 600 km from the coast, at an altitude of 500 m above sea level and a latitude of 31.5o North.

The climate is hot and dry in the summer with temperatures variation between a maximum of around 45°C and a minimum of 20°C, thus giving a large diurnal temperature swing. Winter temperatures vary between a maximum of 24°C and a minimum of 0°C. Solar radiation is intense throughout the year with a maximum of 700 W in winter and 1000 W in summer, measured on the horizontal surface.

4.1.2 The project

In 1981, an experimental building was erected in Ghardaia. The purpose of the building was to measure the influence of different parameters on the indoor climate. The building contains two identical rooms, where one room can be manipulated while the other is kept as reference. A series of tests was conducted.

The building has walls of gypsum blocks, 40 cm thick; a roof of gypsum mini-vaults, 8 cm thick, resting on concrete beams and covered with 5 cm thick concrete plaster; and a concrete floor resting on the ground.

A characteristic feature of the building is the ventilation box consisting of a raised roof with an upper window.


Fig 4/1 Plan, section and elevation of the experimental building

4.1.3 Influence of night ventilation

One experiment was to monitor the influence of night ventilation. In the reference room the window and roof ventilator were kept closed, whereas in the experimental room they were opened during nighttime. The effect of the night ventilation is clearly seen as a remarkable drop in temperature when the window was open. During the night the indoor temperature approaches the outdoor one. This means that the number of air changes per hour is important.


Fig 4/2 Influence of increased night ventilation, measured air temperatures in the middle of the rooms

4.1.4 Performance of gypsum

During the daytime the temperatures in both rooms vary only slightly, which means that with this type of construction the cool of the night can hardly be maintained during the next day. The temperature is remarkably even throughout the day. This can be explained by the properties of the massive gypsum construction, which has medium thermal storage capacity but rather good thermal insulation value. Therefore, the exchange of heat between the air and the surface is small and, when the windows are closed, the indoor temperature is even. This structure performs in a similar way to the mud house documented in chapter 4.4.

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