People also bring in rain and snow on theirĪsthma is understood to be a chronic disease of the airways characterized by an inflammatory response involving many cell types. Moisture in buildings comes from both outdoor and indoor sources: rain, snowmelt, groundwater, construction materials, plumbing systems, kitchens, shower rooms, swimming pools, and wet surfaces such as mopped floors ( Figure 3.1). Moisture also significantly affects the comfort and health of occupants (Lstiburek and Carmody, 1994 Achenbach, 1994 Tye, 1994 Deal et al., 1998). It is generally accepted that more than 75 percent of all building envelope (foundation, walls, windows, roof) problems are caused by excess moisture. Unfortunately, moisture problems in buildings are common in all climates of the United States. However, excess water or moisture in a building can lead to structural failures and health problems when materials stay wet long enough for microbial growth, physical deterioration, or chemical reactions to occur (IOM, 2004). It is a common cause of absence from school and from the workplace as well 14 million days of school loss were recorded in 1994-1996, 3.4 days per child with asthma (Cox-Ganser et al., 2005).Īs long as a building is properly designed, sited, constructed, operated, and maintained, excess moisture can be managed effectively. Asthma affects 8 to 10 percent of the population and even larger proportions of children in certain cities or in poor urban populations. It is common practice in the envelope design, consulting, and commissioning fields to focus on ‘control layers’ when considering the envelope.Building Envelope, Moisture Management, and HealthĮxcess moisture or dampness and mold growth in buildings have been associated with some upper respiratory symptoms (nasal congestion, sneezing, runny or itchy nose) and respiratory diseases, especially asthma, in children and adults (IOM, 2000, 2004). Therefore, the building envelope includes all the assemblies that make up the foundation walls and slab, exterior walls (including doors, windows, louvers, vents, etc.), and roof. The assembly also includes any air gaps and voids since it contributes to the envelope’s control function. For example, a typical exterior wall assembly consists of the exterior siding, building wrap, sheathing, studs, insulation, interior drywall, and paint. Speaking of a tent, while some building envelopes consist of only one component (at a particular section), most envelopes consist of multiple materials formed into various parts (components) combined in various assemblies to function as systems. Materials, Components, Assemblies, and Systems (Think about that tent you tried to pitch in the middle of the blizzard of 06). It was likely also built to resist specific forces (like those imparted by snow, wind, and gravity) since if it were unable to do so, it would not control the passage of moisture, air, and heat for very long. These functions include but are not limited to protecting the occupants and contents on the interior by controlling the passage of moisture, air, and heat. Meaning, unless you are living in a cave or other naturally formed burrow-like environment, the envelope enclosing your space was purposely built in the way it was to fulfill specific functions. The envelope is intentionally constructed of particular assemblies to separate the interior environment from the exterior. If you want our full answer on this question, please refer to our article here. Yes, we believe the building enclosure is the same as the building envelope, and while we prefer the term enclosure over envelope, we use both. This post’s title could well have been “What is the building envelope, and is it the same as the building enclosure?” since this is a ubiquitous question. In short, it is the physical assembly that separates the inside from the outside. The building envelope is the part of the building that physically separates the building’s interior environment from the exterior environment. References, Credits, and Further Reading.Materials, Components, Assemblies, and Systems.From what is the building envelope made?.
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