Selection of phase change material and establishment of thermophysical properties of phase change material integrated with roof of a building using Measure of Key Response index: Proposal of a new parameter

•PCM selection and effect of its thermophysical properties is established.•A new term is proposed i.e. Measure of Key Response index (MKR index).•Numerical simulations of PCM integrated roof in three climatic zones of India are carried out to establish the usefulness of MKR index.•The melting temperature and thermal conductivity of PCM play a significant role in the selection of PCM.