AIR CONDITIONING ENERGY USE IN HOUSES IN SOUTHERN ENGLAND

As a result of increasing summer temperatures in the UK, it is likely that more dwellings in the future will have air conditioning installed to meet the occupants comfort requirements. This trend will inevitably increase the energy demand for cooling. This study, using computer simulation, estimates the likely increase in domestic cooling energy, under a number of scenarios. Three typical house types, detached, semi-detached and terrace were modelled and cooling energy consumption calculated based on information collected from a previous field study carried out by the authors and from the literature. The energy consumption data for the 3 dwelling types were then summed over the housing stock and adjusted for the level of air conditioning ownership to provide an estimate of the total cooling energy demand in southern England.The study shows that the annual cooling energy needed for a typical sitting room of 18 m2 is 100 kWh, and 180 kWh for a similarly sized bedroom. Simulations indicate that currently the total annual cooling energy needed by domestic air conditioners is around 50 GWh, with resulting emissions of 6 kilotonnes of carbon, for southern England, at current ownership levels, if units are installed in both the sitting room and main bedroom. This is estimated to be 0.012% of the total UK energy consumption of 402 TWh. However, this cooling energy could increase to 210 GWh per year (25 kilotonnes carbon), if ownership increases to 10%. Set-point temperatures also have a major impact, with a 2 oC decrease increasing consumption by 45%, while a 2 oC increase gives a 28% reduction. It was also found that using a mixed mode approach to cooling the bedroom, where windows were opened late at night and in the early morning, decreased the cooling required ten-fold. This would be a worthwhile mode of operation for use in climates, such as in southern England, where ambient temperatures at night often fall below the set-point of the air conditioners.