Probabilistic assessment of the potential impacts of vent-free gas products on indoor relative humidity

Measured concentrations of combustion gases from the use of unvented gas fireplaces

“…Another modeling study employed stochastic methods to evaluate indoor moisture buildup because of unvented gas fireplace use (Whitmyre and Pandian, 2004). The authors concluded that under most conditions, when the appliance is used for less than four consecutive hours, the indoor air relative humidity is below the level required for fungal growth.…”

Probabilistic assessment of the potential indoor air impacts of vent-free gas heating appliances in energy-efficient homes in the United States

“…The duration of use midrange of 2 hr and range of duration of use of 1-4 hr is consistent with available data on how vent-free gas heating products are used. A 1995 survey of adult users of gas hearth products in British Columbia, Canada, found that 96% used their gas hearth products for 4 hr or less per usage (Whitmyre and Pandian 2004). A 1998 survey of gas log users in California showed a median use time of 2.3 hr (Wilson 1999).…”

“…The American Gas Association Research Division (AGAR) developed an indoor air quality model that simulates how indoor air quality varies with time in a well-mixed space heated by a vent-free gas appliance, for each of the Department of Energy (DOE) heating regions in the United States (see Figure 1). The model was validated at the AGAR facility in Cleveland and the Gas Research Institute (GRI) facility in Chicago (Whitmyre and Pandian 2004) and was determined to perform well in predicting the time profile and equilibrium level of indoor relative humidity associated with the use of vent-free gas products for supplemental localized residential heating. This model has been used previously to assess the impacts of vent-free gas heating appliances on indoor relative humidity Pandian 2002, 2004) and indoor air levels of NO 2 (Whitmyre and Pandian 2013).…”

“…The volume of the room of vent-free gas heating product use was adjusted for the volume of an adjacent interconnected room for modeling the "inside door open" scenario. The duration of use of the vent-free gas heater was varied over a range of 1-4 hr (midpoint of 2 hr) to reflect available use survey data (Gordon, Francisco, and Rose 2008;Whitmyre and Pandian 2004;Wilson 1999). The total modeled period of 4 hr includes time when the vent-free gas heating appliance is cycled off.…”