Review and Critical Analysis of International UHI Studies

Another study in Japan simulated air temperature and building energy consumption and their
relationship with an urban climate. This simulation used combining a one dimensional
meteorological canopy and building energy use model [022].
An hourly building energy simulation model was presented in this paper for a case study in
Toronto, Canada. The model set out to calculate annual energy savings and peak‐power
avoidance after heat island mitigation measures were implemented. The model types used were:
the DOE‐2.1E which simulates a building’s energy use for the year, the input data was actual data
from the Toronto Weather for the Year Energy Consumption and to capture the temperature
changes from the reduction strategies a PSU/NCAR MM5 mesoscale meteorological model was
used. Nine building prototypes were modeled, the focus was on residential properties as that
building type was considered to benefit most from these countermeasures. The following
methodology was used to assess the potential effects: defined building characteristics; simulated
energy use using the DOE‐2.1E model and calculated savings for each reduction strategy;
estimated total roof area using existing data sources; and calculated metropolitan wide effects of
the strategies [033].
The following papers use models to estimate the effectiveness of UHI mitigation technologies; the
technologies under review are increased surface albedo; green roofs and urban green areas; and
urban form/planning. The types of models used are described in more detail below.
3.1.4 Surface Albedo
The Lawrence Berkeley National Laboratory (LBNL) have published numerous papers on the
modification of albedo surfaces to promote energy savings, reductions in urban temperatures and
the improvement of air quality. Four papers look at modeling for albedo specifically, all of which
are from LBNL and focus on the California region [015, 142, 064, 079]. Many papers look at a
number of mitigation options, predominantly albedo and shade trees, and attempt to evaluate the
most effective strategies using modeling and simulations. Of the 12 modeling studies that look at
more than one mitigation strategy, nine were for studies in North America and three in Asia. Of
the 12 studies, six focused on air quality as an output [028, 050, 104, 048, 012, 058] three on energy
use [022, 028, 168] six on temperature and urban climate [022, 050, 059, 092, 084, 058] and one on
health impacts [089]. Please note that some studies looked at more than one output.
A sample of the models used in this section were:
Energy simulation models of buildings were run to calculate the impacts of cool surfaces, these
simulations were fed with actual surface temperature and reflectivity data used in conjunction
with the as‐built drawings of the buildings. A cost benefit analysis was then conducted on the
simulation results [015].
For a global study of albedo modification and the potential global cooling and CO2 reductions
that could be achieved, a General Circulation Model (GCM) simulation was carried out. A GCM
simulation is used to estimate the changes in the average globe temperature by changing the
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