222
In some ways, this process broke the environmental balance of the medieval
towns (which were designed keeping in mind local microclimate regulation) often
creating an artificial barrier around them, suffocating them, and contributing greatly
to raise the amount of impermeable surfaces to the detriment of permeable ones. In
recent years, the relationship between urban planning and architecture paid a price
for the rigidity dictated by Local Strategic Plans conforming to homogeneous and
repetitive rules rather than adapting to the peculiarities of the various land areas
(Samonà 1980). As a result, we are dealing with areas that are already rigid and
intensely anthropized, with a paucity of characterizing settlements, whose development in the near future may be expected to involve mostly the transformation of the
existing tissues. Our test focused on the connection between local climate, urban
structure and the emergence of the urban heat island effect, with the purpose of
providing land management guidelines for the near future (Musco et al. 2014).
Within this framework, we singled out a section of Padua’s metropolitan area for
analysis and planning, with the intent of applying the results of our tests to the rest
of Veneto’s central area. Often, the cause for urban heat islands are specific factors
(such as large paved areas), which are directly connected to widespread systemic
factors (such as the nocturnal dispersion of the heat absorbed by peripheral urban
tissues, or pollution from production areas, again located in the suburbs). Such a
plurality of causes leads to studying heat islands from different points of view,
which are both horizontal and vertical.
Oke’s model (2006) approaches this phenomenon by analyzing different urban
climate scales, where diverse climate events occur that influence each other:
– Horizontal scale: Microscale, Local scale and Mesoscale;
– Vertical scale (according to different UHI types): Air UHI (Urban Canopy Layer
UCL, and Urban Boundary Layer UBL), Surface UHI, and Subsurface UHI.
The Urban Boundary Layer (UBL) encompasses the urban cover layer above the
average height of buildings, whereas the Urban Canopy Layer (UCL), encompasses
the urban cover layer below the average height of buildings. After considering
the goals of our projects, namely to analyze the causes of this phenomenon at the
microscale level with the intent of coming up with accurate mitigation measures, we
proceeded by considering the heat island on the vertical scale encompassed between
ground level and the average height of buildings, that is, in the Urban Canopy
Layer.
This microscale level can help verify the relationship between urban form, roofing materials and UHI, with particular reference to the vegetative cover, soil permeability and albedo of materials. Within this context, the following factors influence
microclimate at different urban scales in a significant way: orientation of buildings,
surface covering, Sky View Factor (SVF), solar incidence, materials used, and shape
of buildings. For example, where building facades are too close to each other, temperatures are affected by the SVF, i.e., they heat up more than other facades located
on more open and ventilated roads (which are perhaps no more than thirty or forty
yards away).
F. Musco et al.
In some ways, this process broke the environmental balance of the medieval
towns (which were designed keeping in mind local microclimate regulation) often
creating an artificial barrier around them, suffocating them, and contributing greatly
to raise the amount of impermeable surfaces to the detriment of permeable ones. In
recent years, the relationship between urban planning and architecture paid a price
for the rigidity dictated by Local Strategic Plans conforming to homogeneous and
repetitive rules rather than adapting to the peculiarities of the various land areas
(Samonà 1980). As a result, we are dealing with areas that are already rigid and
intensely anthropized, with a paucity of characterizing settlements, whose development in the near future may be expected to involve mostly the transformation of the
existing tissues. Our test focused on the connection between local climate, urban
structure and the emergence of the urban heat island effect, with the purpose of
providing land management guidelines for the near future (Musco et al. 2014).
Within this framework, we singled out a section of Padua’s metropolitan area for
analysis and planning, with the intent of applying the results of our tests to the rest
of Veneto’s central area. Often, the cause for urban heat islands are specific factors
(such as large paved areas), which are directly connected to widespread systemic
factors (such as the nocturnal dispersion of the heat absorbed by peripheral urban
tissues, or pollution from production areas, again located in the suburbs). Such a
plurality of causes leads to studying heat islands from different points of view,
which are both horizontal and vertical.
Oke’s model (2006) approaches this phenomenon by analyzing different urban
climate scales, where diverse climate events occur that influence each other:
– Horizontal scale: Microscale, Local scale and Mesoscale;
– Vertical scale (according to different UHI types): Air UHI (Urban Canopy Layer
UCL, and Urban Boundary Layer UBL), Surface UHI, and Subsurface UHI.
The Urban Boundary Layer (UBL) encompasses the urban cover layer above the
average height of buildings, whereas the Urban Canopy Layer (UCL), encompasses
the urban cover layer below the average height of buildings. After considering
the goals of our projects, namely to analyze the causes of this phenomenon at the
microscale level with the intent of coming up with accurate mitigation measures, we
proceeded by considering the heat island on the vertical scale encompassed between
ground level and the average height of buildings, that is, in the Urban Canopy
Layer.
This microscale level can help verify the relationship between urban form, roofing materials and UHI, with particular reference to the vegetative cover, soil permeability and albedo of materials. Within this context, the following factors influence
microclimate at different urban scales in a significant way: orientation of buildings,
surface covering, Sky View Factor (SVF), solar incidence, materials used, and shape
of buildings. For example, where building facades are too close to each other, temperatures are affected by the SVF, i.e., they heat up more than other facades located
on more open and ventilated roads (which are perhaps no more than thirty or forty
yards away).
F. Musco et al.