It is well known that cave houses provide a noise free and weather proof environment (cool during the summer and warm during the winter). These structures also shield one from man-made Electromagnetic radiation that is present everywhere. Furthermore, since most of the materials used in construction are local, the environmental impact is minimal. Shown below are some cave houses from around the world. Some are simple dwellings with the most basic necessities, while other have running water, electricity and wireless access.
Pakistan was hit by a devastating earthquake in October 2005. Soon afterwords the government of Pakistan formed the Earthquake Reconstruction and Rehabilitation Authority, commonly known as ERRA. ERRA created 11 training centers for reconstruction of private homes destroyed in the earthquake. One of the techniques promoted in this reconstruction effort was the so called "Bhatar" method of construction.
Bhatar consists of reinforced stone masonry where parallel horizontal timber beams are inserted into the stone masonry at regular intervals to ensure coherence of structure. This is a much more economical option than typical construction which requires transport of cement, bricks and steal to remote mountainous regions. The houses constructed in this fashion are not only earthquake resilient but also energy efficient since the stone masonry acts as an insulator to heat and cold.
After the devastating earthquake of 2005 which destroyed nearly half a million rural homes in Pakistan, there was an urgent need to build earthquake resistant homes. Thus came into being PAKSBAB which is the short form of Pakistan Straw Bale and Appropriate Buildings. So far PAKSBAB, from its limited resources, has build 27 homes in northern parts of Pakistan. These homes have been built using indigenous resources and by training the local people in construction of straw bale houses.
A typical straw bale house has an area of 576 square feet and costs $3000 on average. This turns out to be $5.2/square feet which is less than half the cost of brick and mortar houses. A typical home comprises of two rooms, a verandah and a kitchen and requires around 1200 hours of labour. So 6 people working for 8 hours daily can construct a straw bale house in 25 days!
The main advantages of straw bale houses over brick and mortar houses are highlighted below.
1. Energy efficiency, since straw is a good insulator
2. Non toxic products are used (light straw, clay and wood)
3. Cheap materials are used resulting in a cost that is half that of a regular house
4. Resistant to earthquakes
Straw bales required for the construction of these energy efficient and earthquake resilient homes are built using manually operated farm jacks and locally manufactured compression moulds. Furthermore the local industry is being encouraged to supply straw bales and other materials required for these projects. Additional appropriate building methods that PAKSBAB is promoting include passive solar, rainwater catchment, solar lamps, high-efficiency cooking and heating, and the use of natural building materials such as light straw clay, wattle and daub, and cob.