Performance assessment of residential building envelopes enhanced with phase change materials

Abstract

Residential buildings in India account for ~22% of the national electricity consumption, of which one-third is used for space cooling; however, they are rarely constructed with energy-efficiency considerations. This presents an opportunity for reducing the energy consumption and associated greenhouse gas (GHG) emissions by design and construction of energy-efficient houses. Therefore, this investigation assessed the potential of PCM-enhanced building envelopes for reducing the cooling energy requirements of residential buildings in Delhi (capital of India). Through numerical simulations, we studied the impact of key PCM design parameters such as its thickness, position, melting point temperature and latent heat capacity on the proposed energy benefits, and compared them with those obtained with insulation-enhanced envelopes. We found that, applying a PCM layer on the roof reduced the summer heat gain by 12.6%–36.2%, whereas an insulation layer of the same thickness reduced heat gains by 41.0%–71.4% over the baseline construction. PCM-enhanced walls were also found to reduce the heat gain by 10.4%–26.6%, while insulated walls led to a heat gain reduction of 32.4%–64.0%. By extrapolating these results to city-scale, it appears that PCM/insulation-enhanced envelopes could reduce Delhi's annual electricity consumption and GHG emissions by 0.3%–1.5% and 0.2%–1.0%, respectively.