The balance of the annual heating and cooling demand within the London urban heat island

In London, the urban heat island increases the average and peak air temperatures which in turn affect the demand for heating and cooling. To assess this, the simultaneous hourly air temperature in London has been measured continuously for a year at 80 locations, on a radial grid covering an area of 500 square miles. These have shown that central areas of London are significantly warmer than the surrounding areas (2 K warmer over the year). The measured data have been used as input to a thermal simulation model to assess the heating and cooling load of a standard air-conditioned office building positioned at different locations within the heat island. It is found that the urban cooling load is up to 25% higher over the year, and the annual heating load is reduced by 22%. Minimum CO₂ is emitted at a rural location. The net rate of increase of CO₂ with temperature is found to be 2.8%/K.