Analysis of Passive Retrofitting Measures for Reduced Electricity Demand

The aim of this work is to determine the effective passive measures to enhance the thermal comfort of the building envelop. Passive measures are those measures which reduce electricity demand but do not require any electricity to operate. The building components such as walls, roof and window are exposed to solar radiation and outside air temperature. Heat is conducted from exterior environment into the interior of the building envelop through these channels, wherein majority (approx. 60%) is conducted by walls and roof. Envelop insulation is considered as an efficient retrofitting measure to reduce heat gain from walls and roof. In this study, a techno-economic model has been investigated to obtain optimum insulation thickness (OIT) for the residential buildings in the three climate zones of India. Four types of commonly used insulation materials analysed are: expanded polystyrene (EPS), extruded polystyrene (XPS), fiberglass and polyurethane foam (PUF). The effect of cooling design temperature and the coefficient of performance (COP) of air conditioners on the insulation thickness were also investigated. Fiberglass is observed as the most cost effective insulation material, considering life cycle performance of the insulation material for all the climate zones. It was also concluded that air-conditioner with higher COP can potentially reduce the insulation cost.