Infiltration effects on residential pollutant concentrations for continuous and intermittent mechanical ventilation approaches

摘要

The prevailing residential ventilation standard in North America, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 62.2, specifies volumetric airflow requirements as a function of the overall size of the home and the number of bedrooms; assumes a fixed, minimal amount of infiltration; and requires mechanical ventilation to achieve the remainder. The standard allows for infiltration credits and intermittent ventilation patterns that can be shown to provide comparable performance. Whole-house ventilation methods have a substantial effect on time-varying indoor pollutant concentrations. If alternatives specified by Standard 62.2, such as intermittent ventilation, are used, short-term-pollutant concentrations could exceed acute health standards, even if chronic health standards are met. A methodology is presented for comparing ASHRAE- and non-ASHRAE-specified ventilation scenarios on relative indoor pollutant concentrations. Numerical modeling is used to compare the maximum time-averaged concentrations for acute exposure relevant (1-h, 8-h, 24-h) and chronic exposure relevant (1-year) time periods for four different ventilation scenarios in six climates with a range of normalized leakage values. The results suggest that long-term concentrations are the most important metric for assessing the effectiveness of whole-house ventilation systems in meeting exposure standards and that, if chronic health exposure standards are met, acute standards will also be met.