141
trend of temperatures is either below (HDD) a predefined bioclimatic thresholds or
above (CDD). A markedly decreasing trend was present in HDD time-series, while
an opposite, less marked trend, appears for CDD.
Two main simulation tools have been applied to the pilot area in order to estimate
the effect of some mitigation measures from a quantitative point of view. These
simulations were aimed at assessing the effects of types of mitigation actions, and
not the effects of specific interventions.
The first model applied in the pilot area was RayMan, a simulation model able
to calculate short- and long-wave radiation fluxes inside a complex urban environment. Output from RayMan model consists in the values of several thermal indices
derived from human heat-balance model. RayMan calculates the mean radiant
temperature using a simplified radiation balance applied to a person which is
exposed to:
– direct solar radiation;
– long wave radiation from ground, building walls and vegetation
– reflected radiation from the same surfaces.
In the present study, RayMan model was applied on a car parking area inside the
Villaggio Artigiano. Firstly, the model was run for the actual situation in the domain
(reference run) in a typical summer day in August. Then, some changes were introduced in the model domain (scenario runs) and the net effects of the mitigation
measures on the thermal field and on the bio-meteorological conditions were estimated. A number of tests were carried out considering various combination of
vegetation, type of materials for pavements and facades, height of buildings. From
CDD 1980-2010
Year
CDD - urban
CDD - rural
1200
1000
800
600
400
200
0
1 9 8 0
1 9 8 1
1 9 8 2
1 9 8 3
1 9 8 4
1 9 8 5
1 9 8 6
1 9 8 7
1 9 8 8
1 9 8 9
1 9 9 0
1 9 9 1
1 9 9 2
1 9 9 3
1 9 9 4
1 9 9 5
1 9 9 6
1 9 9 7
1 9 9 8
1 9 9 9
2 0 0 0
2 0 0 1 2 0 0 2
2 0 0 3
2 0 0 4 2 0 0 5 2 0 0 6
2 0 0 7
2 0 0 8
2 0 0 9 2 0 1 0
Fig. 6.8 Long term trend of Cooling Degree Days (CDD) for the urban and the rural area
6 UHI in the Metropolitan Cluster of Bologna-Modena...
trend of temperatures is either below (HDD) a predefined bioclimatic thresholds or
above (CDD). A markedly decreasing trend was present in HDD time-series, while
an opposite, less marked trend, appears for CDD.
Two main simulation tools have been applied to the pilot area in order to estimate
the effect of some mitigation measures from a quantitative point of view. These
simulations were aimed at assessing the effects of types of mitigation actions, and
not the effects of specific interventions.
The first model applied in the pilot area was RayMan, a simulation model able
to calculate short- and long-wave radiation fluxes inside a complex urban environment. Output from RayMan model consists in the values of several thermal indices
derived from human heat-balance model. RayMan calculates the mean radiant
temperature using a simplified radiation balance applied to a person which is
exposed to:
– direct solar radiation;
– long wave radiation from ground, building walls and vegetation
– reflected radiation from the same surfaces.
In the present study, RayMan model was applied on a car parking area inside the
Villaggio Artigiano. Firstly, the model was run for the actual situation in the domain
(reference run) in a typical summer day in August. Then, some changes were introduced in the model domain (scenario runs) and the net effects of the mitigation
measures on the thermal field and on the bio-meteorological conditions were estimated. A number of tests were carried out considering various combination of
vegetation, type of materials for pavements and facades, height of buildings. From
CDD 1980-2010
Year
CDD - urban
CDD - rural
1200
1000
800
600
400
200
0
1 9 8 0
1 9 8 1
1 9 8 2
1 9 8 3
1 9 8 4
1 9 8 5
1 9 8 6
1 9 8 7
1 9 8 8
1 9 8 9
1 9 9 0
1 9 9 1
1 9 9 2
1 9 9 3
1 9 9 4
1 9 9 5
1 9 9 6
1 9 9 7
1 9 9 8
1 9 9 9
2 0 0 0
2 0 0 1 2 0 0 2
2 0 0 3
2 0 0 4 2 0 0 5 2 0 0 6
2 0 0 7
2 0 0 8
2 0 0 9 2 0 1 0
Fig. 6.8 Long term trend of Cooling Degree Days (CDD) for the urban and the rural area
6 UHI in the Metropolitan Cluster of Bologna-Modena...