Dwelling conversion and energy retrofit modify building anthropogenic heat emission under past and future climates: A case study of London terraced houses

Abstract

Energy demand per capita is expected to increase in smaller dwelling units in the UK and Europe as less energy is shared due to the trend of few people per household. To meet the demand for more smaller units, a popular retrofitting approach is to split up existing large dwellings. As this type of dwelling conversion (DC) affects both household size (HHS) and residents energy use behaviours, building thermal performance and anthropogenic heat emission (QF,B) to outdoor environment are impacted. Here, using the UK time use survey (TUS) activity information, we compare implications of DC to energy conservation measures (ECM) for terraced houses in both baseline and future London climates. Our results show that ECM can substantially reduce both heating energy demand and QF,B during colder seasons, whilst due to the absence of space cooling in UK residential buildings the ECM ineffectively diminishes summer demands. Further to this, the increased occupancy density resulting from DC increases summer peak QF,B by 53.8% at 17:00, which could intensify canopy-layer urban heat island effects. Although climate projected for the 2050′s should result in a decreased wintertime QF,B, the potential increase in summertime space cooling energy demand will see an associated increase in summertime QF,B. Occupancy patterns need to be considered as part of retrofitting assessments and climate change impacts considered their influence on HVAC usage schedule. The role of occupancy behaviour extends beyond retrofit strategies themselves, to larger urban extents (e.g. planning, policy making, urban weather/climate feedbacks) to ensure both energy saving and urban heat mitigation.