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Indoor Air Quality
The National Institute of Standards and Technology (NIST) used the AJLC as a test-bed for new methods of measuring and modelling ventilation and indoor air quality. This research advanced knowledge about how alternative "green" design strategies can be better employed in new building ventilation systems.
NIST conducted indoor air quality monitoring research on the Center between March 2000 and June 2001 . The three primary objectives of this study were:
- to develop and refine measurement methods for evaluating indoor air quality and ventilation in buildings
- to evaluate indoor air quality design approaches
- to evaluate and demonstrate the use of a computational modeling tool, CONTAM, for indoor air quality design
Several issues related to energy efficient architecture and general building air quality monitoring make this study relevant to the Center and other buildings like it.
One of the potential problems with energy efficient buildings is that they end up being sealed so tightly that indoor air pollution becomes a problem resulting from the lack of air exchange. One way to get around this problem is to design buildings that emit low-VOC (Volatile Organic Compounds) that require less ventilation. If air quality is inherently better because of low harmful off-gassing, then less air exchange is needed. Currently, however, individual indoor air pollutants are seldom considered in the planning of ventilation systems. Instead, a prescribed volume of outdoor air, based on the building's occupancy or square footage, is used for designing ventilation. This one-size-fits-all approach does not allow buildings like the Lewis Center to take advantage of designing innovative systems or low-emitting materials. Therefore, an alternate design approach based on the actual contaminants produced indoors may be desirable for green buildings. For example, the Center has very low off-gassing of VOCs because its paints, adhesives, carpets and other materials are nontoxic. However, the building was designed with a very high air exchange rate (100% entirely new fresh air is circulated through the building every 4 hours). The study indicates that a much lower air exchange rate might be sufficient. This could save energy associated with heating the fresh air delivered to the building.
The NIST experiments involved:
- automated measurements of building ventilation rates and indoor VOC pollutant levels
- tests to measure the building envelope airtightness
- collection of related data including weather conditions and mechanical system on/off status
Data generated from this building were used to create and calibrate an air quality model with the CONTAM modeling tool. This model will enhance the capabilities of designers of future green buildings, as well as provide a means of evaluating the benefits of innovative technologies including the use of low-emitting materials.
The data gathered from automated measurement of volatile organic compounds (VOCs) for three week-long periods during the study was used to compare various methods of collecting and analyzing pollutant data. View the report below:
Transient Analysis of VOC Concentrations for Estimating Emission Rates
Andrew Persily, Cindy H. Reed and Steven J. Nabinger
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