Building Envelope Specification
The most basic definition of a building is a man-made structure that isolates the interior from the outdoor environment. The portions of the building that separate the building’s interior from the outdoor environment (e.g. walls, roofs, floors) are often
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Building Envelope Specification
2.1 Building Envelope The most basic definition of a building is a man-made structure that isolates the interior from the outdoor environment. The portions of the building that separate the building’s interior from the outdoor environment (e.g. walls, roofs, floors) are often referred to as the building envelope. The envelope protects the interior from rain, snow, wind, and excessive heat or cold; helping to make the interior a safe, comfortable, and productive environment for its occupants. Often, a building’s interior is conditioned with Heating, Ventilation and Air Conditioning (HVAC) to maximize occupant comfort. There are many important considerations when designing a building envelope. The envelope must be sufficiently strong to support itself. It must effectively keep water or other unwanted environmental materials from damaging the building or its contents. It must be secure enough to keep unwanted pests (or people) out of it. It must be visually appealing. These aspects are all very important and there are numerous texts devoted to each of them. As this book is devoted to building energy modeling our focus will be on the transfer of energy through the building envelope.
2.2 Weather As noted weather personality Willard Scott once said, “Everyone complains about the weather, but nobody ever seems to do anything about it.” It should come as no surprise that weather drives a significant portion of energy transfer into and out of a building. An office building in Alaska will be subject to very different environmental conditions than an office building in Florida. It is also well known that, while the actual weather conditions occurring at any given time are difficult to predict, a location’s general climate may be described in a meaningful way. © Springer International Publishing AG, part of Springer Nature 2018 L. Brackney et al., Building Energy Modeling with OpenStudio, https://doi.org/10.1007/978-3-319-77809-9_2
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2 Building Envelope Specification
Because weather varies from year to year, a methodology for combining measured weather data from multiple years into what is referred to as a “Typical” Meteorological Year (TMY) has been developed.1 TMY data attempts to represent both the annual average weather as well as a range of weather extremes that a given location experiences. This makes TMY data more useful in predicting future energy use than Actual Meteorological Year (AMY) data for a particular year. TMY data for many locations may be downloaded in EnergyPlus Weather (EPW) format from https://energyplus. net/weather. EPW files are a key input for any OpenStudio Model, representing the ambient conditions a building is exposed to. The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) categorizes a location’s climate into one of several climate zones based on TMY data for that location.2 ASHRAE climate zones are codified with a climate zone number ranging from 0 for extremely hot through 8 for sub-arctic along with a sub-type
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