durability

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.

An airtight building envelope ensures not only the energy-efficiency of a building, but also a damage free construction. Important to achieve optimal airtightness are the planning, implementation and materials. Long-term airtightness requires efforts in all three aspects. Airtightness products are being tested under lab conditions but these results cannot be transferred one-on-one onto buildings.

The airtightness just after the end of a building phase is assumed to be relevant criteria for high energy performance. Testing on site the initial performance of the airtightness via the blower door test has become nowadays a common practice but generally implemented before the occupation of the building. But a lot of questions are still remaining targeting the sustainability of the performances.

In timber frame construction in Europe air barrier systems are typically realised at the interior side of the building envelope. Yet in some applications such as renovation projects it can be easier to provide the air barrier layer at the exterior. This way, the air barrier system – typically board materials in which the joints are sealed with tape – is exposed to outdoor weather conditions. The aim of the present article is to investigate the impact severe climatic conditions on the airtightness of typical taped joints.

During field measurements on the airtightness of passive houses, ventilations system’s roof penetrations showed to be one of the major leakage paths, as they were not sealed using the appropriate, durable techniques. Therefore, a series of laboratory measurements was conducted on wood-frame walls to study different air sealing solutions. The use of special airtight gaskets is compared to less advanced sealing methods such as sprayed polyurethane foam and the use of pieces of tape.

The airtightness just after the end of a building phase is assumed to be relevant criteria for high energy performance. Testing on site the initial performance of the airtightness via the blower door test has become nowadays a common practice. This test is generally realized at the end of the construction works. What about the influence of ageing on the airtightness? Many questions exist on the durability of this initial performance.

The aim of the project was to evaluate how the air tightness of buildings changes over time and how the sealing materials are affected during the expected life length of 50 years. The project was divided into two parts were one was laboratory tests of different products with accelerated ageing, and the other part were evaluation of older existing buildings. The laboratory test was conducted in a temporary room with lightweight construction in wood and different sealing products. The room was then heated to 80 °C and had changing relative moisture content in the air.

This paper presents results of a study concerning the hygrothermal and durability performance of timber construction wall and bottom slab assemblies built in “passive house technology” for habitable basements of floating houses. Highly-insulated basement systems made of solid timber boards were developed, simulated and monitored and with regard to hygrothermal performance and furthermore, the probable durability investigated. The results of the simulations will be compared with in-situ measurements, which are carried out at an test set-up.

In this paper we present a series of leakage tests on extremely airtight dwellings (ACH50 < 0.6 upon completion) in which the durability of the airtightness and the measurement uncertainty involved are assessed. In literature, repeatability and reproducibility issues have been discussed by several authors, along with influences of weather. It remains unclear, however, to what extent the available uncertainty intervals are relative or absolute.