eTheses Repository - University of Birmingham

0.61) and that of conventional gravel (with an albedo of 0.09), compared to the ambient
temperature. For this reason in warm climates buildings are often painted white.
A number of modelling studies have shown reductions in temperature over urban areas by
decreasing the surface albedo. For example Taha et al. (1988) showed, using one-
dimensional meteorological simulations, that for a typical mid latitude city in summer it is
possible to reduce local air afternoon temperatures by as much as 4 K by increasing the
surface albedo from 0.25 to 0.40. Seaman et al. (1989) showed that by increasing the
urban-rural albedo difference from 0.025 to 0.05 the UHI is weakened by 0.3 K. Sailor
(1995) used a 3-D meteorological simulation of Los Angeles, USA to show decreased peak
summertime temperatures of up to 1.5 K by increasing the surface albedo by 0.14
downtown, and 0.08 over the entire basin. Atkinson (2003) found a reduction in
temperature over the urban area of 0.3 K by increasing the urban albedo from 0.15 to that
of the rural surroundings (0.18).
Lower ambient air temperatures, achievable through an increase in albedo, also have
implications on air quality (Sailor 1995; Taha 1997) and can effect substantial energy
savings in areas where air conditioning is prevalent (Rosenfeld et al. 1998) since the direct
heat transfer from the building surface into the building is also reduced.
In the control simulation of the present study the albedo for all urban surfaces, i.e. roofs,
walls and roads, was set to 0.20 as suggested in the original BEP scheme code. This is a
typical urban albedo value (Taha (1997) suggested a range of 0.15 to 0.20 for US and
European cities). However, this value of 0.20 is equal to the albedo of the rural surface,
which is also set to 0.20 for the METRAS ‘Meadows’ urban class. For this reason a
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