In-situ Measurement of Ventilation and Impacts of Filtration on IEQ and Energy use of Residential Buildings

Abstract

Indoor environmental quality (IEQ) impacts of filters in residential HVAC systems is a strong function of many HVAC system- and building-specific parameters. Furthermore, the energy consequences of filters can be important, and the magnitude and the sign of these energy impacts are system-specific as well. These system- and building-specific parameters can vary not only over different residential buildings, but also over the lifetime of a filter in a given building. A primary building-specific parameter that varies greatly over time is outdoor ventilation air change rate (ACR). ACR is not only an important particle removal mechanism, and a source of variations in filter IEQ performance, but it also is an important contributor to energy use in buildings. This work first critically reviews the existing literature on filtration and then presents an integrated evaluation of the overall IEQ and energy performance of higher efficiency residential filters. It also further develops the understanding of how ACR varies over time and how it influences filtration performance in residences. Yearlong measurement results from particle removal performance analysis of four different high efficiency filters placed in 21 residences in Toronto, Ontario showed that there was more variation in filter performance between the same filter in different homes than there was between different filters in the same home. In addition, increasing system runtime (ontime fraction) could also lead to higher particle removal impacts of filters. Study of energy consequences of the same filters in the same homes showed that fan energy consequences of high efficiency filters are negligible and because HVAC runtimes were generally low (median = 9.6%) in this sample of homes, the difference between energy consumption of different types of motor fans at typical runtimes was small (less than 10 kWh per month). Yearlong ACR measurements showed that ACR is a temporally dynamic parameter with timescales of minutes that varies considerably over long-term periods (e.g., geometric mean = 0.47/h, geometric standard deviation = 3.44 in one of the residences studied). Overall, this dissertation provides new methods and data for assessing the ventilation performance and impacts of filtration on IEQ and energy use of residential buildings.