The context
Saint-Laurent-d’Agny, south-west of Lyon, is the town where Hélios has its head office. Its school, like most school buildings built between the 1970s and the 1990s, suffers from the same problems in June and September: a dark bitumen membrane roof, classrooms under the roof that exceed 30 °C at the end of the day, and no air conditioning. The municipality chose the cool roof solution for 600 m² of roof, with the PrimaTherm® reflective system in four layers.
TODO-ENZO : période des travaux, mesures de température et photos après travaux à intégrer (envoi prévu après dépôt de la fiche).
The constraints
- A school: work scheduled outside the presence of pupils, access and storage areas marked out, water-based products with a low content of volatile organic compounds.
- A village centre: drums and pump on the ground inside the school grounds, only the hoses go up to the roof; no crane, no road closure.
- A bitumen membrane: PH169 primer blocking bitumen bleed-through, at 6 m²/L, before the reflective base coat in two passes and the anti-soiling topcoat.
What the municipality gains
A roof that stays between 25 and 35 °C instead of 50 to 70 °C in full sun, i.e. up to −30 °C on the surface, and classrooms that are more bearable during the hot hours without installing air conditioning. The system also protects the membrane from thermal shock and UV: the waterproofing renewal is pushed back accordingly. For a local authority, it is a quick response to heat episodes, compatible with the French Green Fund (Fonds Vert) as part of an overall summer-comfort project.
Further reading
- Cool roof for schools and public buildings.
- Cool roof in the Rhône and in Lyon.
- Cool roof on bitumen roofs — preparation and coverage rates.
