Quantitative correlation between buildings air permeability indicators: Statistical analyses of over 400,000 measurements

Abstract

Several building airtightness databases were created in many European countries thanks to the development of commissioning tests. However, comparing building performance across countries can be challenging, as various indicators are used to measure the air permeability of buildings depending on the specific application and the nation’s regulation. This paper examines the comparison of air permeability indicators used in various countries and seeks to establish default conversion equations between these indicators. To do so, a statistical analysis was conducted on the French database. The most frequently used indicators are the specific air leakage rate per envelope area and the air change rate at a reference pressure of 50 Pa in most countries and 4 or 10 Pa in a few other countries. The compactness appears to be a relevant geometric parameter for characterising the relationship between the air permeability indicators, as it encapsulates both the shape of the building and its contact with adjacent buildings. Correlations between the different indicators have been calculated according to the building type and compactness. Thus, this study concludes that indicators can be reliably estimated by knowing the building type and geometry. A general correlation is provided with a higher estimation error if the geometry data is missing.