There is a need to improve building envelopes in many parts of the developing world. In cold climates, scarce fuel is consumed in an attempt to maintain reasonable indoor temperatures. In Northern Pakistan, traditional houses are made with stone walls while newer buildings, houses and schools, use uninsulated concrete block that has even lower thermal resistance. Evaluation and improvement of these buildings were undertaken with a regional non-governmental organization. Measurements were made of the thermal resistance of typical exterior walls. An energy analysis showed that using 1.0 kg of straw in an insulation board would save about 5 kg of firewood over a winter in a Pakistani school. Recent research has focused on development of an insulation that can be retrofitted over existing walls. The insulation board must be sufficiently strong to support itself during construction and resist damage at its surface. Several methods of containing and binding straw were examined; the most promising adhesive was commercially available methane di- isocyanate. Good mechanical properties were obtained at resin contents as low as 2% by weight. At densities of 128 and 160 kg/m3 (8 and IO lb/ft3), these boards have thermal conductivities of 0.039-0.041 W/m-K (R-values of 3.7 and 3.45 per inch), respectively. The boards have an estimated materials cost per unit thermal resistance that is roughly half the delivered cost of competing insulations available in Pakistan. Straw insulation boards have the added advantage that they can be made on site with semi-skilled local labor and local materials.
Improving building efficiency in developing countries: case study of insulation for Northern Pakistan.
USA, American Council for an Energy Efficient Economy (ACEEE), 1998, in: proceedings of "Energy Efficiency in a Competitive Environment", the 1998 ACEEE Summer Study on Energy Efficiency in Buildings, CD format, pp 5.141-5.152