ABSTRACT: The size of spaces has been associated with the levels of energy use in buildings. Empirical evidence shows that many home spaces remain unoccupied for significant lengths of time; and that a significant proportion of UK homes are under-occupied. This paper discusses the potential for saving space heating energy through a design approach for a house with a seasonally adaptive fabric. The approach explores the ways in which architectural design can save energy by resolving the tension between spaces in buildings that are tied in unchanging patterns by static furniture and/or equipment; and those tied in changing patterns by varying occupancy. The key features of the Deciduous House are: a rigid fabric to accommodate rigid elements such as services; and an adaptive fabric with capabilities to seasonally minimise the heated space during the heating season; change its glazing ratio and U-Values; and optimise solar energy when it is in useful supply. The research uses TAS simulation to assess the performance of different configurations of a three bedroom house. The results show potential savings averaging 25.45%, 24.6% and 25.5% during peak winter when the house is used by four, three and two householders respectively. This is in comparison with a conventional base case layout used by similar householders; and with similar U-values meeting the proposed 2013 UK building regulations requirements.

Keywords: space heating energy efficiency, household size, under-occupancy, deciduous house.