Cool roof for data centers

Heat in a data hall comes first from the electrical power drawn by servers, storage and networking. The roof adds a share that comes from outside: the solar radiation captured by the covering and passed to the spaces below. A dark roof absorbs that radiation and heats up sharply. A light, highly reflective surface sends most of it back. A cool roof acts on that external share, upstream of every cooling system. On an existing building, this lever touches neither the layout of the halls nor the air distribution.

Cooling levers work as a cascade. Free cooling uses outside air as long as its temperature allows. Adiabatic cooling, which uses water evaporation, takes over when that air gets too warm. Mechanical cooling handles what is left, during the tightest hours. The cool roof comes before that cascade. By reducing the heat taken in by the covering, it lengthens the periods when outside air is enough and runs the compressors less often. None of these systems is replaced; all of them are called on less.

The critical point arrives during a heatwave. Cooling demand climbs just as chiller efficiency drops and outside air is no longer enough. On those days, every degree avoided upstream relieves your cooling plant. A cool roof lowers the temperature under the roof by 8 to 10 °C and removes 7 to 8 °C of thermal load on the roof, from the first summer after application. The gain is passive and permanent: no consumption, no control, no wearing parts.

Data halls and technical rooms are mostly covered in steel deck or bituminous membrane. These roofs carry a lot of equipment: chillers, heat exchangers, cable trays. 80% of Covalba projects are on bituminous membranes over ten years old, hardened by UV and thermal shock. The survey then points to the right system: CovaTherm on a sound substrate, CovaSeal 20 when the waterproofing has to be renewed, CovaMetal 20 on a steel deck to protect from corrosion.

Tertiary and industrial buildings covered by the décret tertiaire (French tertiary decree) report their consumption on the OPERAT platform. They target -30% by 2030, -40% by 2040 and -50% by 2050. Reflective roof coatings fall under the CEE datasheet BAT-EN-112, reserved for tertiary and industrial buildings. On budget the gap is clear: €20 to €25/m² supplied and applied for a long-life cool roof, against €80 to €100/m² for a new membrane and around €150/m² for renewed insulation and waterproofing.

A hosting site never stops. The works are therefore carried out entirely from the roof: machines on the ground, hoses on the roof, no removal of the covering, no access to the halls. Duration runs from a few days to a few weeks depending on the surface. Areas under equipment are treated during your maintenance windows. The coating then protects the membrane from UV and pushes its replacement back 8 to 10 years. French labour law also requires employers to protect staff from heat, including in your control rooms, without setting a maximum temperature.