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

Energy demand per capita is expected to increase with smaller dwelling units in Europe, as less energy is shared linked to the trend of fewer people per household. To meet the demand for more smaller units, a popular retrofitting approach is to split existing large dwellings. As this type of dwelling conversion (DC) affects both household size (HHS) and therefore the likely energy use behaviour of residents, building thermal performance and anthropogenic heat emission (QF,B) to outdoor environment are impacted. Here, the UK time use survey (TUS) provides activity information to allow comparison of the implications of DC to energy conservation measures (ECM) for terraced houses in both past and future London climates. Our results show that ECM can substantially reduce both heating energy demand and QF,B during cold 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 due to 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.