Retrofitting near to zero energy homes in a Mediterranean climate

Abstract

The present local built environment has a common thermal comfort problem namely that most dwellings have a great reliance on electricity for environmental control indoors. The main objective of this research work was to offer a practical and cost-effective working solution to this problem. The feasible energy–saving measures that can be retrofitted to an existing dwelling were designed and applied to an existing building; a top third floor flat in Birkirkara, Malta, thus converting it into a thermally comfortable minimum energy home. The indoor climate of the subject flat, its mirror image apartment and the Birkirkara microclimate were monitored for one year and the necessary tools to analyse this data were utilised: a psychrometric chart analysis with Malta’s defined thermal comfort zones. Compared to its microclimate and the mirror apartment, the results show that the subject flat managed to keep a constant and very comfortable indoor climate across both the hot and cold seasons. It is only for a small portion (a total of 9 out of 122 days – 7% in summer and 16 out of 121 days – 13% in winter) that the energy–saving retrofit measures did not fall within the thermal comfort zones limits. This case study also shows that the combined energy saving retrofit measures had a payback period of 15 years, which eventually pays off with a surplus of over €700.