The airtightness of new buildings has significantly improved in the last two decades thanks to building energy performance regulations. However, until now, low knowledge is available about the evolution of buildings’ envelope airtightness. This work deals with the durability of buildings airtightness, and focuses on ways to better characterize it. This study is part of the French research project “Durabilitair” (2016-2019) that aims at improving our knowledge on the variation of buildings envelope airtightness through onsite measurement and accelerated ageing in laboratory-controlled conditions. During a past AIVC conference, a publication of the Durabilit’air project has presented and discussed the state of the art on characterizing buildings’ airtightness durability. Final results from the Durabilitair mid-term and long-term time scales field measurement campaigns are presented in a companion paper of this conference.
This paper focuses on the assessment of the durability of airtightness products in controlled conditions through the development of a laboratory experimental protocol for characterizing the accelerated ageing of building airtightness assembled products. The overall objective is to define and develop an experimental protocol capable of testing and quantifying the airtightness evolution of assembled airtightness products samples and comparing the relative ageing of the samples.
The state-of-the-art showed that there is no standardised protocol to characterise in laboratory-controlled conditions the durability of product assemblies regarding airtightness performance. As a matter of fact, due to the diversity of airtightness products, it is difficult – and even, perhaps impossible – to define an accelerated ageing universal protocol that would be equivalent to a known amount of years of natural ageing. From the light of the state of the art results, we defined the exposure conditions of a relative ageing test, through thermal, humidity and pressure variation cycles. We developed a 1 m3 environmental chamber and exposed three different 1 m2 samples of assembled products to the defined exposure conditions cycles.
The tested samples represent three different treatments of airtightness of the joints between windows and walls: 1) impregnated foam; 2) sealant with backing foam and 3) adhesive and membrane complex. During each exposure cycle, we have measured the evolution of the airtightness of the sample.
The ageing tests of the samples 2 and 3 showed a significant degradation of the airtightness performance after the ageing cycle, whereas air permeability of sample 1 could not be assessed by our experimental protocol. The choice of the samples and the experimental conditions are described and discussed. We conclude that modifying the duration and the characteristics of the exposure cycles (humidity, temperature and pressure) would certainly allow more differentiating results in future works.