The Tlemcen house
The Tlemcen ecological house uses cellulose wadding and flagstone within a wooden framework. Wood's low thermal inertia, low construction cost, and low thermal transmission make it the material of choice. Double-glazed windows and airtight external doors aid insulation, and the south-facing living area enables collection of solar radiation. The house uses solar-powered heaters with exposed sensors on the south side, generates electricity via photovoltaic cells, and makes use of ground cooling. Heating the house is expected to use no more than 15 kilowatt hours per square meter per year (kWh/m2/yr), and the total energy demand is expected to be 50 kWh/m2/yr. That is a small number when compared with the total energy demand of 220 kWh/m2yr for a conventional house.
To put those numbers in perspective, consider the 2004 guide to energy efficiency in buildings published by the UK's Chartered Institution of Building Services Engineers (CIBSE). The guide cites energy consumption benchmarks for typical existing buildings as 417 kWh/m2/yr from fossil fuels plus 79 kWh/m2/yr from electricity, for a total of 496 kWh/m2/yr, or almost 10 times the energy requirements of the Tlemcen house. Even the CIBSE "good practice" standards of 247 kWh/m2/yr from fossil fuels plus 44 kWh/m2/yr from electricity, for a total of 291 kWh/m2/yr, are much greater than the energy goal's of the Tlemcen house.