FIELD VALIDATION OF ALGEBRAIC EQUATIONS FOR STACK AND WIND-DRIVEN AIRINFILTRATION CALCULATIONS

Explicit algebraic equations for calculation of wind and stack driven ventilation were developed by parametrically matching exact solutions to the flow equations for building envelopes. These separate wind and stack effect flow calculation procedures were incorporated in a simple natural ventilation model, AIM-2, with empirical functions for superp osing wind and stack effect, and for estimating wind shelter. There we re three major improvements over previous simplified ventilation calcu lations: a power law pressure-flow relationship is used to develop the flow equations form first principles, the furnace or fireplace flue i s included as a separate leakage site, and the model differentiates be tween houses with basements, slab-on-grade, and crawlspaces. Over 3400 hours of measured ventilation rates from the test houses at the Alber ta Home Heating Research Facility were used to validate the prediction s of ventilation rates and to compare the AIM-2 predictions to those o f other ventilation models. The AIM-2 model had bias and scatter error s of less than 15% for wind-dominated ventilation, and less than 7% fo r buoyancy (stack-effect) dominated cases.