An envelope airtightness predictive model for residential buildings in Spain

Abstract

The need for airtightness control is a reality given its impact on buildings' energy use and Indoor Air Quality (IAQ). For the past few years, this fact has resulted in energy performance regulations establishment that involves airtightness requirements in many countries in Europe and North America. In this sense, efforts should not only be focused on new buildings, but also existing ones. Considering that around 90% of the built stock in the EU is expected to still be standing in 2050 and that almost 75% of the buildings are energy inefficient, attention must be paid to retrofitting actions.

Airtightness predictive models have become useful in the decision-making process and to estimate input values in energy performance simulation tools. So far, several predictive models have been developed in different countries. However, specific construction systems and practices lead to a lack of consensus regarding the impact of different factors on airtightness performance. Therefore, the applicability of existing models is limited to their specific contexts.

This paper presents a predictive model for envelope airtightness, which was developed from a database that contains a fully characterised representative sample of the residential building stock in Spain. A General Linear Model (GLM) was considered to assess significant variables related to the age of the building, typology, building state, construction system, and dimensions. As a result, a predictive model is presented and validated. Overall, even if some limitations were identified, the relevance of the model proposed is warranted from the statistical point of view. The airtightness predictive model presented offers a procedure for airtightness estimation of residential buildings in Spain.