Airtight climate shells under real conditions Stages 1 and 2

The climate shell's airtightness system is absolutely crucial for near-zero energy houses, passive houses and plus houses to function as intended. Houses are built for decades of trouble-free use. It is therefore required that sealing systems do not lose their properties after a few years, but that the airtightness is preserved over a long period of time. To achieve airtightness, polymeric materials are normally used which are more sensitive to aging than most other building materials. The stability over time is determined by the composition and structure of the polymeric material as well as how it is manufactured and stored. Factors such as the surrounding environment are also important for the long-term properties. Since the products that ensure the airtightness are usually built into the construction, premature replacement can mean major and costly interventions in the buildings. Therefore, it is desirable to be able to evaluate in advance, in a laboratory environment, the durability of the various air sealing systems. For this, a testing method is needed.

The overall aim of this E2B2-supported research project is to develop a method by which whole systems of airtightness can be investigated. The goal is good air tightness and low energy consumption over a long period of time with the air tightness system of the future. As a continuation of the previous partial application, a method and test bed has now been developed to ensure that the materials and combinations of materials included in the climate shell have good tightness even after decades of use. The testing method has proven to work well. By, among other things, exposing the materials to temperatures of 60 °C to 80 °C, an intended service life of 25-50 years has been simulated. Construction site conditions matter In addition to the materials, the conditions of the construction itself, which are not always ideal, play a role in durability. Within the scope of the project, assembly of airtightness systems has therefore been done in environments chosen to mimic realistic construction site conditions.

Important results
• Since the systems that ensure the airtightness of buildings are built into the construction, their long-term durability is absolutely crucial. Switching is often expensive and complicated.
• By examining in advance the airtight materials and material combinations included in the climate shell, it is possible to choose a solution that also lasts in the long term.
• Although the three different makes of air tightness systems tested in the project have good air tightness, below 0.1 l/(s∙m²), accelerated aging in all cases shows an increasing air permeability.
• Construction site conditions, which can be anything but ideal, also play a role in durability. Changes in air tightness are noted when assembly took place in a cold, damp and dusty environment.
• Climate shells that deteriorate with age are a bad deal. An air leak that increases from 0.3 to 0.9 l/(s∙m²) drives energy use up by 15 percent.