Sol-air temperature and daylight illuminance profiles for the UKCP09 data sets

To provide information on climate change, the UK Climate Impacts Programme (UKCIP) provided the latest UKCP09 data to a resolution of 5 km square grids for the UK. Those data sets were used in this study along with the historical measured data for two locations-Bracknell (London) and Edinburgh-to critically analyse the likely changes that may occur in the sol-air temperature and daylight illuminance profiles. These parameters have an important bearing on the design and function of buildings and building services. Drastic increment of sol-air temperature was found for the projected data sets. An increase of as much as 20.1 degrees C of sol-air temperature for dark-coloured surface was found for Edinburgh and 13.3 degrees C for Bracknell. These increments may be due to the compound effect of change in the constituent variables that are used to calculate sol-air temperature, i.e. solar radiation, wind speed and dry bulb temperature. A sensitivity test was carried out to see the effect of each variable on sol-air temperature. An increasing trend of daylight was also found in the data sets. This is attributed to the changing clarity of the sky condition. The predictions indicate a radical change in the characteristics of solar climate, i.e. from the present diffuse fraction of total irradiation of 0.37 which indicates mild turbidity to a drop of 0.13 indicating clear skies with exceptionally low turbidity. (C) 2010 Elsevier Ltd. All rights reserved.