Comparative Performance of Two Ventilation Strategies in a Hot-Humid Climate
Martin, Eric; Chasar, David; McIlvaine, Janet; Amos, Bryan; Fonorow, Ken
Ventilation; Hot Humid Climates; Buildings
ASHRAE Standard 62.2, 'Ventilation and Indoor Air Quality in Low-Rise Buildings,' is the most commonly referenced residential ventilation standard in the United States. It is currently required by ENERGY STAR Version 3 (V3), the 2012 International Energy Conservation Code, the U.S. Department of Energy's Zero Energy Ready Home Program, many state weatherization programs, and many other home performance programs. The standard calls for ventilation levels that are perceived by some builders and contractors to cause indoor moisture issues in hot-humid climates unless mitigated by supplemental dehumidification systems, which increase overall energy consumption. Therefore, many high-performance home builders in a hot-humid climate use a supply ventilation strategy that delivers outside air only in conjunction with operation of the home's central heating and cooling system (runtime ventilation [RTV]), which results in ventilation air exchange rates that are significantly lower than ASHRAE 62.2.In 2012 and 2013, Pacific Northwest National Laboratory (PNNL), Florida Solar Energy Center (FSEC), and Florida Home Energy & Resources Organization (Florida HERO) began a collaborative effort to evaluate the impact of two different ventilation strategies on interior comfort conditions, space-conditioning energy use, and certain indoor air contaminant concentrations. Specifically, this report compares the builder-standard RTV system to an ASHRAE 62.2-compliant ventilation system using a continuous exhaust fan. The ASHRAE 62.2-compliant system was selected to represent the most likely ventilation system builders would employ were they required to comply with the ASHRAE 62.2 requirements because it is the least cost solution in most instances. Relevant parameters were measured in 10 homes in Gainesville, Florida, along with corresponding outdoor conditions, to characterize the impact of the two differing ventilation strategies. The study design grouped the homes into two cohorts: flip-flop homes and control homes. The first cohort of homes consisted of six of the 10 homes that were flip-flopped between the two ventilation strategies approximately every two weeks. The second cohort of homes consisted of two homes that remained in the RTV configuration throughout the study period and two homes that were maintained in the CEV configuration throughout the study period. This study design allows for the effects of individual occupants, inconsistencies between the homes, as well as the impact of climate, outdoor concentrations, or other biasing variables to be identified and accounted for in the analysis.This report provides information about the data collection method and results from more than one year of data collection during a period from summer 2013 through summer 2014. Indoor air quality was sampled in three discrete periods with the first occurring in August/September 2013 (summer 1), the second occurring in March/April 2014 (winter/mixed), and the third occurring in August 2014 (summer 2).
Hot Humid Climates; Buildings - Ventilation
Florida Solar Energy Center and Widder, Sarah, "Comparative Performance of Two Ventilation Strategies in a Hot-Humid Climate" (2017). FSEC Energy Research Center®. 91.