Better housing enhances the quality of life of the residents and leads to higher productivity as well as income generating capabilities. Therefore the affordable housing design should aim to provide a healthy and comfortable environment to the residents. It is of vital importance to build houses that minimize the use of energy, water and mineral resources during their life cycle.

• In 2001, India introduced the Energy Conservation Act which led to the development of a first generation Energy Conservation Building Code (ECBC) for building the sector. Recently, the ECBC has been further revised.
• Ministry of New and Renewable Energy (MNRE) offered capital subsidy incentives for purchase and installation of solar water heating and solar lighting equipment in houses.

Design Philosophy:

The design philosophy of affordable housing should incorporate key performance metrics such as indoor air quality, thermal comfort and energy performance index. Affordability should be determined based on the entire life cycle costs. The housing design must also incorporate climate responsive design and encourage the use of local building materials for construction.

Design approach:

Energy efficient buildings are typically designed using either of the two approaches:

1. Prescriptive approach: Specifies requirements for each building components.
2. Performance approach: a detailed energy stimulation of the building using stimulation models is performed to assess whether the building meets or exceeds the overall performance criteria for the building.

Prescriptive approach is most suitable approach for affordable housing design and construction.

Efficient Envelope:

Housing should be designed to minimise the heat gain inside the building. High reflectance roof is one of the cost effective technologies to reject solar radiation falling on the building. Further, wall, window and roof materials with higher thermal resistance will reduce heat gain inside the building. Reduction in the heat gain improves thermal comfort inside the building and reduces the need to operate active cooling systems. Higher visible light transmission (VLT) leads to more daylight and reduces the energy consumption of artificial lighting. Use of skylight is also an effective approach to achieve suitable daylight inside the building. Integration of solar lighting and water heating can significantly reduce the energy consumption.

External shading devices:

External shading devices can be cost effective approach for affordable housing to reduce direct solar radiation and heat gain for the windows. Well designed ventilation can also use outdoor air to provide cooling whenever the environmental conditions are favourable.

Low Energy Technologies:

In extreme climatic conditions, low energy cooling technologies are required in the affordable housing design to keep the residents thermally comfortable and healthy. Evaporative cooling is one of the cost-effective technologies. Integration of solar water heating and lighting can significantly reduce the energy consumption. Energy Management System (EMS) is a very effective measure of energy use of affordable housing. EMS can lead to energy savings and provide necessary energy benchmarks information for the future design of affordable housing.

These good quality affordable housing with green technologies can play a significant role in securing the well-being and economic growth of the country.