Multizone calculations and measurements of air flows in dwellings.

A study of the reliability of systems by considering the ability of different systems to maintain a required air flow rate over time is included in a subtask of IEA Annex 27 "Evaluation and Demonstration of Domestic Ventilation Systems". Measurements and calculations were performed to determine the variation in ventilation rates due to variation in climate and variation in performance of the ventilation system. Dwellings with passive stack, mechanical exhaust and mechanical exhaust-supply ventilation, representative of the Swedish housing stock, were studied. Diagnostic tests were carried out, to discover if the installed ventilation system was functioning as designed and to determine certain values e. g. characteristics of inlets and outlets. The airtightness was tested. The air flows in mechanical ventilation were measured. The continuous monitoring included measurements in dwellings of overall and local (individual rooms) ventilation rates, and measurements of boundary conditions, during three different periods. The ventilation rates were monitored using tracer gas; passive techniques for monthly averaging and constant concentration for hourly averaging. The measured ventilation rates were simulated using COMIS, a multi-zone air flow network model. The simulated and measured average total outdoor ventilation rates agree reasonably well, while there can be disagreement for hourly rates and individual rooms. This paper presents and discusses the measurements and the calculations and compares the two.