HVAC duct work is generally installed once the building has walls and a roof, but before windows are installed. It is our project team\'s understanding that the building would not be considered to have indoor air at this time, but since this inquiry deals with the indoor air distribution system, we want to be certain that we will comply with the credit requirements. In climates with freezing temperatures over the winter months, water based duct sealants (which comply with VOC limits) are not acceptable for use due to the fact that they will crack when frozen. Oil-based sealants (which do not comply with VOC limits) are required in freezing weather until the building is enclosed and thermally controlled. It is not clear to this project team whether or not SSc4.1 would apply to sealing the duct work. When, during the construction process, does SSc4.1 start to apply, and does SSc4.1 apply to duct sealants?
Duct sealants must be included under this credit. The VOC limit requirements of EQc4.1 for adhesives and sealants apply to all phases of construction. The LEED-NC v2.1 Reference Guide states on page 276 that this credit applies to products and installation processes that have the ability to adversely affect indoor air quality on site: and those that are exposed in interior spaces accessible by occupants (meaning all space within the weatherproofing layer of the building envelope). The VOCs from this product will offgas long enough to effect the building\'s indoor air quality. In addition, installers are immediately exposed to the product\'s emissions. Applicable Internationally.