The Measured Energy Impact of Infiltration in a Test Cell

Abstract

Infiltration is customarily assumed to increase the heating and cooling load of a building by an amount equal to the mass flow rate of the infiltration times the enthalpy difference between the inside and outside air—with the latent portion of the enthalpy difference sometimes neglected. Calorimetric measurements conducted on a small test cell with measured amounts of infiltration introduced under a variety of conditions show convincingly that infiltration can lead to a much smaller change in the energy load than is customarily calculated; changes as small as 20 percent of the calculated value have been measured in the cell. The data also suggest that the phenomenon occurs in full-sized houses as well. Infiltration Heat Exchange Effectiveness (IHEE), ε, is introduced as a measure of the effectiveness of a building in “recovering” heat otherwise lost (or gained) due to infiltration. Measurements show that ε increases as: (a) flow rate decreases; (b) flow path length increases; (c) hole/crack size decreases. There is a clear correlation between large values of ε and large values of the exponent, n, so fan pressurization results may be useful in predicting ε for buildings.

3D heat and air transport model for predicting the thermal resistances of insulated wall assemblies

“…After that model was benchmarked by comparing its predations against the model of Buchanan and Sherman [16], and experimental data [19], it was used to investigate the thermal performance of the diffusive building envelope. In that study [18], numerical simulations were carried out to determine the contribution of air infiltration to the heat gain/loss through the "diffusive layer" representation of the building envelope.…”

A Numerical Study on the Impact of Wind Gust Frequency on Air Exchanges in Buildings with Variable External and Internal Leakages

“…From the 1970s onwards, its impact on energy performance has been recognized in the literature, e.g., [1]. Several studies have presented estimations of the heat load fraction in a building that takes place due to infiltration [2][3][4][5][6][7][8][9][10]. In addition, infiltration has been verified as playing an important role in the internal environment and in the indoor air quality [11][12][13][14].…”

Developing an Enhanced Model for Combined Heat and Air Infiltration Energy Simulation

“…Claridge et al (1985) reported a calculated overall house energy loss factors 50% above those obtained through regression analysis of recorded experimental house data; indicating a "Heat Recovery" in infiltration energy. Other similar work includes Claridge and Bhattacharyya (1990) who measured infiltration loads equivalent to as low as 20% of those calculated using classical infiltration calculation methods. Classical methods for calculating the additional energy load due to infiltration, including computer models and hourly simulation programs, assume a load increase due to infiltration equal to the infiltrating air mass flow rate times the inside-outside air enthalpy difference.…”

“…The heat load is therefore calculated as a summation of the heat loss due to conduction and the heat loss due to infiltration (Claridge and Bhattacharyya, 1990;Claridge and Liu, 1996). A handful of combined heat loss models where therefore proposed to account for this interaction between conduction and infiltration; including Anderlind (1985), Liu (1987), Bailly (1987) and Arquis (1986).…”

“…-0 < R < 1 Claridge and Bhattacharyya (1990) introduced a new non-dimensional factor representing the effectiveness of heat recovery resulting from the heat exchange between infiltrating/exfiltrating air and the walls. This factor is known as the "Infiltration Heat…”