Does a cool roof apply to your building?
Three questions are enough to find out.
- Does the roof heat the building? A single-storey building with a large roof (warehouse, factory, store, sports hall, agricultural shed) receives most of its solar gains through the roof: this is the ideal case. A multi-storey building is only concerned on its top floor — which is often enough to justify the project in a residential block or an office building.
- Is the roof type compatible? Steel deck, bitumen membrane, EPDM, asbestos-free fibre cement, PVC older than 10 years: yes, after diagnosis. Asbestos-cement, recent PVC, paving slabs on pedestals, green roof, waterproofing at the end of its life: no, or not before other works.
- What do you expect? Air-conditioning savings (air-conditioned building), comfort and productivity (non-air-conditioned building), waterproofing that lasts, an answer to the French tertiary-sector decree, a contribution to a climate plan: a cool roof delivers on each of these fronts, but not in the same proportions.
The system applied is always the same — PrimaTherm® in 4 layers, 95 % solar reflectance, emissivity 0.89, SRI 120, Broof(t3) — and so is the method: no lifting equipment, site in operation. What changes is the issue at stake, the preparation and the way the result is measured.
Applications by building type
Industry
Workshops, factories, regulated sites, temperature-sensitive processes: heat under the roof degrades working conditions, makes processes drift and loads the chillers. A cool roof brings workshops back below 28 °C for several weeks a year and is applied without a crane or a production stop — a decisive argument on a site with a heavy prevention plan. Reference: Airbus Marignane, 5,900 m² of bitumen membrane with −29 °C measured at handover; other aerospace, rail and industrial sites appear in our projects. CEE: not eligible as such (the sheet is reserved for commercial tertiary buildings). See cool roof for industrial buildings.
Logistics
Platforms and warehouses of several thousand m², most often in single-skin steel deck, with little or no air conditioning: 35 to 40 °C in the aisles in summer, operators slowing down, heat-sensitive goods. The indoor gain is highest here (up to −6 °C felt), the works are phased cell by cell without blocking flows, and the roof is protected. For a property company with triple-net leases, the argument is asset value and tenant retention. CEE: not eligible on a non-air-conditioned warehouse. See cool roof for warehouses and logistics.
Retail and supermarkets
Single-storey, air-conditioned stores and hypermarkets with a cold chain: this is the profile where air-conditioning savings are the most direct (up to −40 % depending on the zone) and where CEE sheet BAT-EN-112 can apply, if the volume is heated and cooled by a heat pump. The works are carried out with the store open. See cool roof for retail and supermarkets.
Shopping centres
Large membrane flat roofs, numerous technical installations, continuous operation and a French tertiary-sector decree that applies in full. The cool roof is rolled out zone by zone, around air handling units and rooflights (PrimaTherm® LT lacquer), with the CEE premium as a possible lever under conditions. See cool roof for shopping centres.
Public buildings
Town halls, sports halls, media libraries, nurseries, administrative buildings: flat roofs everywhere, sometimes vulnerable users, an expectation of exemplarity and the French Green Fund (Fonds Vert), which can be mobilised according to prefectural priorities. No CEE with the current sheet, but a case that stands on its before/after measurements. See cool roof for public buildings.
Schools
Classrooms under the roof, heatwaves in June and September, air conditioning rarely possible: the cool roof is the simplest passive measure, applied during the holidays. A 1,000 m² school in La Rochelle (bitumen membrane, combined with photovoltaics) was treated by Hélios with the PrimaTherm® system. See cool roof for schools.
Hospitals and care homes
Vulnerable people, departments that never close, fire safety requirements (Broof(t3), CSTB report RA23-0010) and coordination: the cool roof is applied without lifting equipment, with water-based, low-VOC products, under a prevention plan drawn up with the facility. See cool roof for hospitals.
Residential buildings
Top-floor flats, waterproofing to protect, reduced 10 % VAT on French homes over two years old, a vote at the owners’ general meeting and a prior declaration to the town hall. MaPrimeRénov’ does not cover cool roofs: the case rests on comfort and the value of the building. See cool roof for residential buildings.
Data centres
Every degree gained on the roof relieves the cooling, the first consumption item. Application coordinated with the technical teams, without interruption, and measurement on site rather than a PUE promise. See cool roof for data centres.
Agricultural buildings
Livestock under heat stress, storage of fodder and produce, buildings in single-skin steel deck or fibre cement (asbestos-free only): the indoor gain is immediate and the works are compatible with farm operations. On a cured-meat plant in Périgny (2,000 m² of steel deck, PrimaTherm® system applied by Hélios), the roof space went from 50 to 30 °C and cooling consumption fell by 35 %. No CEE with the current sheet. See cool roof for agricultural buildings.
Hotels and restaurants
Rooms under the roof, kitchens, air-conditioned dining rooms, guests who judge comfort: a commercial establishment, often air-conditioned by heat pump, so CEE eligibility to be checked. Works in the low season or early in the morning, without closing. See cool roof for hotels and restaurants.
Applications by roof type
The sector tells you what is at stake; the roof type tells you the preparation, the coverage rates and the points of attention.
Steel deck
The most common roof type in industry, logistics and agriculture, and the most favourable: PH169 primer at 10 m²/L, excellent adhesion, result visible from the first sunny day. Points of attention: fixings, condensation on single-skin decks, rooflights, rust areas; pre-coated and galvanised decks are not prepared the same way. See the cool roof on steel deck roofs guide.
Bitumen roofs
SBS, APP, slate-finished or aluminium-faced membranes: the hottest surface of a building, and the roof type of our largest reference, 5,900 m² in Marignane. Bitumen bleed-blocking primer at 6 m²/L, long-pile roller, repair of blisters and upstands before application. See cool roof on bitumen roofs.
Waterproofing membranes
Bitumen, EPDM after an adhesion test, PVC only beyond 10 years with the PH107PVC base coat, TPO on consultation. Absolute rule: a cool roof protects the waterproofing, it does not replace it. See cool roof on waterproofing membranes.
Flat roofs
Flat roofs of offices, schools, residential buildings and houses: slope and standing water, upstands, outlets, rooflights, accessible terraces. For homeowners, the online shop (in French) below 500 m², prior declaration to the town hall, reduced 10 % VAT on supply and application. See cool roof on flat roofs.
Photovoltaic roofs
The cool roof is preferably applied before the modules: a cooler roof under the panels (a gain of a few percent on output, variable depending on the installation), useful albedo for bifacial panels, waterproofing protected where it will become inaccessible. References: Saint-Jeoire and the La Rochelle school. See cool roof and solar panels.
Summary: main issue, CEE eligibility, typical roof type
| Application | Main issue | CEE BAT-EN-112 | Typical roof type | Result to expect |
|---|---|---|---|---|
| Industry | Working conditions, processes, regulated sites | No, as such | Steel deck, membrane | Up to −30 °C on the surface, −6 °C inside |
| Logistics | Operator comfort, goods, asset value | No if not air-conditioned | Single-skin steel deck | Maximum indoor gain, works cell by cell |
| Retail and supermarkets | Air conditioning, cold chain | Conditional | Steel deck, membrane | Up to −40 % air conditioning depending on zone |
| Shopping centres | Tertiary-sector decree, continuous operation | Conditional | Membrane, flat roof | Roll-out zone by zone, rooflights |
| Public buildings | Exemplarity, vulnerable users | No, as such | Flat roof, membrane | Green Fund to apply for, before/after measurements |
| Schools | Comfort in June and September | No | Flat roof, membrane | Works during the holidays |
| Hospitals | Continuity, fire safety | No, as such | Membrane, flat roof | Broof(t3), prevention plan |
| Residential buildings | Top floors, building value | No | Flat roof, bitumen | 10 % VAT, prior declaration |
| Data centres | Cooling | Depending on use | Membrane, steel deck | Measurement on site |
| Agriculture | Heat stress, storage | No | Steel deck, asbestos-free fibre cement | Roof space from 50 to 30 °C in Périgny |
| Hotels, restaurants | Guest comfort, air conditioning | Conditional | Flat roof, membrane | Works without closing |
The ranges (−30 °C, −6 °C, −40 %) are cautious maxima; the actual value depends on the climate zone, the insulation and the use of the building, and is calculated in the profitability study.
Special applications: rooflights, equipment, technical areas
A roof is never just a flat surface. Polycarbonate rooflights and skydomes, which often account for 5 to 10 % of an industrial roof, let heat through as well as light: the PrimaTherm® LT semi-transparent lacquer treats them (one coat reduces gains by around 25 %, two coats by around 50 %). Equipment — air handling units, chillers, extractors — is protected during the works and the system is applied right up to its bases; a chiller surrounded by a cooler roof draws in less hot air. Walkways and maintenance areas receive load-spreading plates or gratings. These additional items are priced line by line in the proposal.
What does not apply, and why we say so
- Asbestos-cement (buildings built before 1997): no intervention.
- PVC membrane less than 10 years old: the plasticisers are still migrating; wait, or choose a white membrane if the roof is being replaced.
- Terrace on paving slabs on pedestals: the membrane is already in the shade.
- Green roof: it cools by evapotranspiration; only bare technical areas can be treated.
- Waterproofing at the end of its life: replacement first, cool roof afterwards. See cool roof coating or membrane.
- Pitched tile or slate roofs: outside our scope without a specific study.
- Outside the weather window: 12 to 35 °C, dry surface, no rain within 4 h — April to October depending on the region.
How we qualify an application
The free roof study answers within 48 h from three pieces of data — area, building type, postcode — with a satellite measurement, a probable identification of the roof type and a first qualification of the incentives. The technical visit confirms the roof type, its condition, access and the adhesion tests required. The proposal then details the system, the coverage rates, the phasing and the handover measurements. The sectors and roof types hubs give you the entry point by business or by roof; the projects show the result on demanding sites, and the French city pages (for example cool roof in Lyon or cool roof in Marseille, in French) give local lead times and references.
Frequently asked questions
On which buildings is a cool roof most effective?
On single-storey buildings with a large roof, where the roof is the first source of solar gains: warehouses, factories, stores, sports halls, agricultural buildings, flat-roofed schools. The indoor gain there reaches up to −6 °C under a poorly insulated roof. On a multi-storey building, only the top floor is concerned.
Can a cool roof be applied to every roof type?
To most of them: steel deck, bitumen membrane, EPDM, asbestos-free fibre cement, PVC membrane laid more than 10 years ago. Not on asbestos-cement, not on recent PVC, not under paving slabs on pedestals, not on a green roof, not on waterproofing at the end of its life. The diagnosis decides case by case.
Which sectors are eligible for the French CEE premium?
Only commercial tertiary buildings whose volume is heated and cooled by a heat pump, under sheet BAT-EN-112 of the French energy-savings certificates (CEE): shops, shopping centres, hotels, restaurants, commercial offices. Industry, non-air-conditioned logistics, agriculture, schools and residential buildings are not eligible as such. MaPrimeRénov’ does not cover cool roofs.
What result should be expected for each application?
On the surface, up to −30 °C everywhere (50–70 °C down to 25–35 °C). Inside, up to −6 °C felt depending on insulation. On air conditioning, between 15 and 40 % reduction depending on the climate zone. On a non-air-conditioned building, the value lies in comfort, productivity and the protection of the waterproofing.
How do I know which page matches my building?
Start from the sector (what you do in the building) for the issues, constraints and incentives; then from the roof type (what the roof is made of) for preparation, coverage rates and points of attention. If in doubt, the free study qualifies both within 48 h from a satellite measurement.