Overheating and energy use in urban office buildings in a warming climate

Abstract

Buildings are responsible for one-third of the UK's greenhouse gas (GHG) emissions. The move to reduce emissions has resulted in recent stringent building regulations primarily aimed at reducing heating and associated energy use, often by improving the building fabric's airtightness. However, internal gains dominated, highly-insulated and airtight non-domestic buildings will likely overheat in the projected warming climate, requiring energy-intensive cooling, thus diminishing the effectiveness of heating efficiency focused regulations. This research investigated the effects of the warming climate on overheating and energy use and resulting emissions in representative urban office spaces in London in the present-day and projected future climates using hourly dynamic thermal simulations. Findings suggest that airtight and highly-insulated office buildings in the temperate UK will overheat in the 2050s. Heating demand reduces by at least 36% in the 2050s but electricity consumption and summertime space conditioning will increase by at least 13% and 55% respectively when hybrid cooling is adopted to ameliorate overheating. Despite the increase, a mixed-mode ventilation strategy is one of the ways of achieving overall energy efficiency while meeting benchmark overheating and emissions targets. Current heating-focused legislation needs to be re-evaluated to account for the effects of the warming climate and overheating risks.