LCA comparison of roofing materials for flat roofs

Purpose

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.

Design/methodology/approach

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.

Findings

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.

Practical implications

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.

Originality/value

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.