Thermal Performance of Ancient Underground Dwellings in Tunisia MONCEF KRARTI, Ph.D. Joint Center for Energy Management CEAE Department, CB 428 University of Colorado at Boulder

2 Presentation Outline Why Underground Dwellings Ancient Underground Dwellings Tunisian Troglodyte Dwellings Field Measurements Summary and Conclusions

3 Why Underground Dwellings ADVANTAGES –Protection from stressful climates –Reduced maintenance cost and energy cost –Preservation of land –Increased safety from vandalism –Reduced noise problems DISADVANTAGES –Claustrophobia (Lack of windows) –Poor Ventilation

4 Ancient Underground Dwellings Earth-Sheltered House in Northern China (Semi- Arid Climate) Underground Settlements in the Cappadocia Area (Center of Turkey) Troglodyte Dwellings in Southern Tunisia (Arid and Hot Climate)

5 Tunisian Troglodyte Dwellings l HISTORY: Developed by the berbers (first known inhabitants of north Africa). As early as 500 BC and as late as 1900 AC. l LOCATION: Matmata plateau north of the Sahara desert (altitude = 500 m.). l ADVANTAGES – Easy soil to excavate (free of stones) – Shelter against invaders attack – Protection from hot and arid climate

6 Tunisian Troglodyte Dwellings l Types: – (a) Vertical design with central patio – (b) Horizontal design on mountain slopes

7 Floor plan of one section of the Marhala Hotel in Matmata

8 Field Measurements l Parameters Measured: Air temperatures and relative humidity both outdoors and indoors l First Field Study: Golany (1982) using Psychrometer l Present Field Study: Krarti (1997) using sensors and a data acquisition system

9 Monthly Soil temperature Variations at Various Depths

10 Hourly dry-bulb temperature measured during 1982 for winter

11 Hourly dry-bulb temperature measured during 1982 for summer

12 Hourly dry-bulb temperatures measured during summer 1997

13 Indoor temperature variation with height at 1 p.m. in the back and the front of the room (site 6)

14 Thermal conditions in various rooms in the Marhala hotel at 3 p.m. of July 24, 1997

15 Comparison of indoor environment for typical winter and summer days in a subterranean dwelling and a conventional above-ground house in Matmata

16 Summary and Conclusions Field measurements indicated that the troglodyte dwellings provide more comfortable environment than above-grade houses in the Matmata region throughout the year. The optimum depth for the dwellings is 10 m. as discovered by the first inhabitants of Matmata. Design of Matmata dwellings needs to be improved to correct for lack of ventilation and natural lighting.