Measured Cooling Season Results Relating the Impact of Mechanical Ventilation on Energy, Comfort, and Indoor Air Quality in Humid Climates

摘要

In Florida, residential whole house mechanical ventilation is not required by code and market penetration of ASHRAE 62.2 compliant mechanical ventilation systems is poor. There is concern amongst regional builders and contractors around implications of mechanically introducing humid outside air compared to the indoor air quality benefits, which many feel are not adequately documented or demonstrated. These implications include impact on energy use, comfort, durability, and cost. This paper describes results from a study in Gainesville, FL relating the impact of ventilation on these parameters. Ten homes built and occupied in the 2009-2010 timeframe with HERS Index < 65 have been under evaluation since June 2013. All ten homes were built with a central fan integrated supply ventilation system (CFIS) delivering an average of 35 cubic feet per minute (cfm) of outside air during heating/cooling operation only, and average 3.6 ACH50. As part of this study, a bathroom exhaust fan in each home was replaced with a larger capacity fan capable of exhausting a continuous 60 cfm on average, approximating ASHRAE 62.2-2010 requirements. The homes were divided into two cohorts: 6 homes that alternate between the CFIS ventilation system and the continuous exhaust ventilation system every 2 weeks, and 4 homes that operate one of the ventilation systems exclusively (2 homes per system). Monitoring of temperature, relative humidity, CO2 concentration, and space conditioning energy use occurs continuously, while concentrations of formaldehyde, acetaldehyde, TVOC, and NO2 are measured seasonally. Results spanning late June through mid-October 2013 are presented and discussed.