Study of air infiltration energy consumption

Abstract

The influence of heat recovery on the energy impact of air infiltration, and the systematic error due to the steady-state method were studied both experimentally and theoretically. Two methodologies suitable for measurement of the overall heat loss factors in full-size houses have been developed and validated. Dynamic measurements of Infiltration Heat Exchange Effectiveness (EHEE), which expresses the air infiltration heat recovery as a fraction of the classical value of air infiltration energy consumption, showed that results from earlier steady-state measurements can be approximately applied to dynamic conditions when solar radiation is not present. However, this study has shown for the first time that IHEE is strongly dependent on air flow direction due to the impacts of air flow on the recovery or rejection of solar radiation energy. IHEE values greater than one and less than zero have been measured. These values are impossible in the absence of solar radiation. The results highlight the necessity of considering the air infiltration heat recovery and improving the current design methods for calculating the heating and cooling loads in buildings. The experimental and theoretical investigation show that steady-state methodology can: 1) be used without systematic error in the case of constant air flow 2) result in IHEE prediction error in a range of 1% to 8% when one-way dynamic air flow is present 3) cause significantly larger error when balanced dynamic air flow is present. The SSP (Single input and Single output data Pair) method can identify UA[0] of an enclosure using short term measurement data, typically a few hours long. It has overcome most of the typical problems in UA[0] identification, such as errors due to thermal storage, ground heat transfer, inter-correlated multi-inputs, and solar radiation. The STAM (Short Term Average Method) has also been developed, which makes it possible for the first time to determine both the UA and the solar aperture precisely under outdoor conditions from a two-day or a three-day test. These methods were developed and used to measure heat loss factors needed to determine IHEE values in this study.