Recycling and End-of-Life Scenarios for Timber Structures

Abstract

In consideration of sustainable buildings, closing life cycle loops becomes more and more important. Up to now reuse and recycling is taken rarely into account in building processes. With rising consumption of wood for energetic use recycling of material becomes more important.

Up to now there are various studies in EU market ([1], [2], [3]), which quantify the usage of wood in market shares. Explicit calculations on recycling of wooden material in the building sector have not yet been done. In general the demand for reclaimed wood products in the building sector will rise due to the fact that the preferred option has to be the reuse and the recycling of reclaimed wood. The thermal use of wood is the last option in the cascade of use. On this option the refinement of reclaimed wood for innovative products as well as the broadening and enhancement of the cascades of reuse and recycling is strongly needed for the timber construction industry. Long-term and resource efficient use of wood from premium quality (like laminated wood, plywood, timber frame construction) is necessary to ensure sustainable construction with wood. In the process of planning new wooden construction the dismantling and reuse / recycling of the products has to be considered too.

In this paper outcomes of the woodwisdom-net research project ECO2– wood in carbon efficient construction – as well as calculations on wood consumption of wide-span timber structures and investigated case studies on a very detailed level are brought together to show the state of art and theories to improve resource efficient usage of wood. Aim is a realistic estimation of theoretical scenarios for end of life and their influence on planning processes as well as the influence on life cycle assessment according to EN 15978. In another approach the total demolition of an old wooden house in the Alps was evaluated. It is a typical example for a long-used construction with numerous repair intervals, changes, and additions. This leads to a wide variety of fractions and often to a contamination of wood from preservatives. The fractions of the demolished house mainly consist of small bits and pieces dedicated to different recycling options than wide span structures. The different waste wood fractions in strength, scale, and size will tolerate certain processing options with an emerging range of recycling products.

A better management of its renewable resources supports the material supply of the wood sector to ensure a long-term availability of solid wood products at reasonable prices. This will allow preservation and also gain market shares now and in the future.