Analysis of the high-quality wooden facade in extreme climates

The project "Alpine base Schiestlhaus on the Hochschwab, which was opened in 2005, represents a lighthouse project for the "House of the Future" programme as the 1st shelter in zero-energy house quality. An energy-autonomous, highly thermally insulated building for use in extreme locations, equipped with an energy façade with solar collectors, a photovoltaic system, dry toilets with a wastewater treatment system, a drinking water cistern and a ventilation and extraction system with heat recovery represented a novel state of the art building at the time.

After more than 15 years in operation, however, damage to the exterior wall came to light that called into question the initially developed thermally insulated façade construction in its executed form with wooden panels and has made it necessary to renew parts of the façade's base as well as the airtight exterior shell, which is like a roof surface. In the original construction, the structure was designed as an air-tight wall construction with a standing air layer based on calculations carried out by the IBO (Austrian Institute for Building Biology and Ecology) in consultation with the Wood Research Institute, to prevent the penetration of moisture and snow in the weather conditions to be expected in this extreme location. The passive house windows made of wood-aluminium by Internorm were integrated into the façade in accordance with the standards valid at the time. These requirements could, due to the extreme climatic conditions, obviously not be met.

From a scientific point of view, a long-term durable highly insulating multi-layered wooden façade as an alternative to the typical construction made of solid wood and without thermal insulation that is usually used in these extreme conditions is nevertheless an important development. Based on an extensive investigation of the cause of the damage, a new wall structure was therefore to be developed as part of this analysis, which was subsequently to be tested and finally executed in a variant on the existing Schiestlhaus.

Within the framework of this project, analysis activities were carried out on the cause of damage as well as the development of new facade structures. The activity report subsequently covers the main investigations carried out within the framework of this project.

For future projects, it has become clear that a wooden façade in passive house design quality, which has been implemented for the first time in this type of project, cannot be implemented under these difficult weather conditions without continuous measurements. A metal façade on a wooden construction suitable for passive houses is an adequate alternative that meets both the extreme climatic and the high energy requirements.

Project lead

Univ. Prof. Architekt DI Dr. Martin Treberspurg - Treberspurg und Partner Architekten ZT GmbH

Treberspurg und Partner Architekten ZT GmbH
Univ. Prof. Architekt DI Dr. Martin Treberspurg
Penzinger Straße 58
A-1140 Wien