Sustainable structural timber floors

Abstract

The recent developments in the building industry to build more sustainable should result in the use of light constructions with a low environmental impact. Timber is a suitable material for this purpose. To reduce the environmental impact of a building, an improvement in an often used structural element can have a significant impact on the sustainability. Floors are a large part of the material consumption of building. A challenge with lightweight timber floors is the vibrational performance of the floor due to walking humans. Conventional concrete floors are less sensitive to vibrations due to their large weight. The vibrations of the floor have influence on the comfort of the humans residing on the floor. Furthermore, concrete is generally seen as a less environmentally friendly material than timber. This raised the main research question of this thesis: How do vibrational performance levels influence the sustainability of several timber floor systems, considering multiple design configurations, compared to conventional concrete floor systems?

The floors used in this research are a CLT floor, LVL box floor, TCC floor, concrete cast in situ floor and concrete hollow core floor. For the research on the vibrational performance and sustainability of floors some methods for assessment are used. For the vibrational performance the assessment method from the renewed Eurocode 5: Timber structures is used. This assesses the resonant and transient vibration response of the floor and checks them with predetermined vibrational comfort criteria. For the assessment of the sustainability the environmental cost indication is used. This method assesses several environmental impact categories and weighs their impact onto the environment, separately the global warming potential is also assessed by the CO2eq emissions of a material.

The result gathered from the research show that timber floors are more sensitive to vibrational performance than concrete floors. Floors with a high vibrational performance need a significantly higher floor height than low performance floors. The influence of damping and floor configurations is important for the vibrational performance. The environmental impact of timber floors have an advantage when biogenic carbon is taken into account. Concrete floors can reach longer floor spans and for high performance floors have a lower increase of environmental impact than timber floors. For the environmental impact of a floor, reuse or recycling is important for the end-of-life scenario.

To draw a conclusion to the main research question; Vibrational performance of floors do effect the environmental impact of the floors. High performance floors have a significantly higher environmental impact than low performance floors. The environmental impact of concrete floors increases less for higher floor performances than timber floors. Timber floors are more sustainable within their technical feasibility. The floor configurations can mitigate vibrations and can thus reduce the environmental impact of the floors.