Short term and long term measurements of ventilation 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 were performed to determine the variation in ventilation rates due to variation in climate and variation in performance of the ventilation system. The monitoring was carried out in one-family houses and apartment buildings, which are representative of the Swedish housing stock. Three different ventilation systems were examined; passive stack, mechanical exhaust and mechanical exhaust-supply . The monitoring period was started with diagnostic tests to discover if the installed ventilation system was functioning as designed and to determine certain values. The airtightness was tested. The air flows in mechanical ventilation were measured. The actual monitoring phase included measurements in dwellings of overall and local (individual rooms) ventilation rates and boundary conditions. High cost and inconvenience prevent the use of continuous monitoring of these ventilation rates. A good compromise was found to be a combination of short-term continuous and long-term averaging tracer gas measurements. The main results were: - passive stack ventilation varies over time and is at times too low - exhaust ventilation is reasonably constant over time if the dwelling is not leaky, but is at times too low in individual rooms - balanced ventilation is almost constant over time if the dwelling is airtight. The paper presents and discusses the measurement techniques and the results from the measurements carried out during 1995.