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climatic area is quite different than designing one for the colddry areas of the far north. Typical input data for a robust thermal
model include general climatic and weather data for the specific
location of the building. This information necessarily includes
external temperature and humidity variations, sun angles, characteristic wind speeds and directions, cloud cover, and similar data
for the specific latitude and longitudinal location of the building.
The amount of solar radiation on a particular exterior window produces a heat load within a space, for example, and depends on the
exact angle of the sun in the sky, which in turn is latitude dependent. (The amount is also obviously dependent on the orientation
of the surface and the presence or absence of shading devices—
factors that would be reflected in the “building description” data
described in a moment.) Since values for this kind of environmental data vary according with time, analytical models can be
based on hourly, daily, weekly, or monthly data, with the precision
of obtained results varying accordingly. Other thermal loads for
spatial environments can be internally generated. Common lighting sources, for example, are significant contributors to the thermal
loads within a space. Other internal load sources include machines
(including computers) that give off heat and, of course, the occupants themselves.
It is also necessary to fully describe the geometric characteristics
of a building or space, including the exact location, area, and distribution of various types of material surfaces and constructions.
In a pragmatic sense, this description normally includes defining
how surrounding walls, windows, floors, and roofs are constructed.
Many walls, for example, use layered constructions of various materials, each of which must be defined. Roofs are invariably constructed differently than walls. Locations and areas must be carefully
defined and relevant material properties, such as thermal conductivities or emissivities, assigned to each. Locations of heating or
cooling sources (or special sinks) that affect the space must also be
defined—for example, locations of heating elements or air diffusers. Many instances involve multiple thermal zones that are interconnected. Each must be defined. For analyses that address energy
analysis as well, primary and secondary mechanical systems need
to be defined too.
A great number of types of analytical simulation programs are
in use, each with differing purposes. One general approach is
focused on energy analysis in relation to thermal loads. Based
on input data, simultaneous heat-balance calculations of radiant
and convective effects on interior and exterior surfaces are deterThe Thermal Environment
climatic area is quite different than designing one for the colddry areas of the far north. Typical input data for a robust thermal
model include general climatic and weather data for the specific
location of the building. This information necessarily includes
external temperature and humidity variations, sun angles, characteristic wind speeds and directions, cloud cover, and similar data
for the specific latitude and longitudinal location of the building.
The amount of solar radiation on a particular exterior window produces a heat load within a space, for example, and depends on the
exact angle of the sun in the sky, which in turn is latitude dependent. (The amount is also obviously dependent on the orientation
of the surface and the presence or absence of shading devices—
factors that would be reflected in the “building description” data
described in a moment.) Since values for this kind of environmental data vary according with time, analytical models can be
based on hourly, daily, weekly, or monthly data, with the precision
of obtained results varying accordingly. Other thermal loads for
spatial environments can be internally generated. Common lighting sources, for example, are significant contributors to the thermal
loads within a space. Other internal load sources include machines
(including computers) that give off heat and, of course, the occupants themselves.
It is also necessary to fully describe the geometric characteristics
of a building or space, including the exact location, area, and distribution of various types of material surfaces and constructions.
In a pragmatic sense, this description normally includes defining
how surrounding walls, windows, floors, and roofs are constructed.
Many walls, for example, use layered constructions of various materials, each of which must be defined. Roofs are invariably constructed differently than walls. Locations and areas must be carefully
defined and relevant material properties, such as thermal conductivities or emissivities, assigned to each. Locations of heating or
cooling sources (or special sinks) that affect the space must also be
defined—for example, locations of heating elements or air diffusers. Many instances involve multiple thermal zones that are interconnected. Each must be defined. For analyses that address energy
analysis as well, primary and secondary mechanical systems need
to be defined too.
A great number of types of analytical simulation programs are
in use, each with differing purposes. One general approach is
focused on energy analysis in relation to thermal loads. Based
on input data, simultaneous heat-balance calculations of radiant
and convective effects on interior and exterior surfaces are deterThe Thermal Environment