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The environmental performance of several flat roof systems with different materials and insulation thicknesses is compared using life cycle assessment (LCA), with the aim to determine the roofing materials with the highest environmental performance. The paper aims to discuss these issues.

The calculations were carried out for an existing apartment block with a 300 m² flat roof. Five insulation materials with three different heat resistances each, five types of waterproof layers, three covering layers, and a green roof are assessed using LCA. Foreground data including maintenance are obtained from roofing companies, and background data are taken from Ecoinvent. ReCiPe is used as impact method. Energy losses through the roof are calculated using the energy software EPA-W.

Improving the insulation from 2.5 to 5 m²K/W leads to reductions of the damage scores from about 10 to 40 per cent. Polyisocyanurate and expanded polystyrene were found to have the lowest environmental damage, although the differences are small. Regarding the other layers, PVC mechanically fixed, ethylene propylene diene monomer (EPDM) mechanically fixed, EPDM glued and PVC with gravel ballast were found to have the lowest environmental damage of the materials assessed.

The outcomes of this study will aid building owners and construction and maintenance companies to choose renovation options for flat roofs with the lowest impact on the environment.

A smart choice of materials for a roofing system, with enough consideration of other aspects such as practical applicability, can thus significantly improve the environmental performance of the roof of a building.

We lay the flattering unction to our soul that our recent remark with regard to the possibilities of awakening public interest in the public library movement by means of wireless broadcasting has not fallen entirely upon deaf ears. It has just been arranged that the Honorary Secretary of the London and Home Counties Branch of the Library Association is to broadcast a lecture on Public Libraries at a date to be announced later. This will mark an important epoch in our march forward and we await the result with considerable interest.