Insulating paint: all you need to know

In the face of global warming, the effects of which are being felt worldwide, insulation is a key factor in the construction and renovation of buildings. Preserving their functionality and the comfort of those who live or work in them is of paramount importance. When major works are costly in terms of materials and manpower, and the results are sometimes hypothetical, it's best to turn to simpler solutions provided by modern science. Insulating paint is one such solution, or rather, a technological resin that can be applied to roofs at low cost. Known as "cool roof", let's take a look at how this solution works and what the results are.

Paint to protect against the sun's rays

Especially for large buildings, the roof is the most sensitive surface to heat penetration - or heat loss in winter. Particularly during heatwaves, the sun's rays can quickly make indoor temperatures uncomfortable, prompting action to be taken: installation of air conditioning, renovation of insulation, etc. Before considering costly interventions, it's a good idea to understand the warming phenomenon and consider a simpler but equally (or even more) effective solution: the application of a slightly special paint.

Solar radiation reaching a roof is broken down into three distinct rays:

• ultraviolet light, which causes sunburn but is fortunately mostly blocked by the ozone layer in the atmosphere;
• visible light, through which colors appear;
• infra-red light, the source of heat, which we all emit: thermal imaging cameras detect infra-red light, enabling us to see at night.

When we reach the roof, part of the heat radiated by these infra-reds is reflected back into the atmosphere. The lighter the color, the greater the reflection. The remainder is absorbed by the roof surface, some of which is re-emitted into the immediate environment in the form of infra-red, the rest being stored as heat.

The key here is to design the roof - or renovate it - in such a way as to optimize its reflection and thus the reflection of the heat received back into space. The immediate consequence is a reduction in building interior temperatures.

The impact of white on the roof: a long-standing idea

The first step is to lighten roofs, with white being the obvious choice as it has the highest albedo - meaning it reflects the maximum amount of solar radiation.

The Mediterranean basin has long understood the benefits of white. To protect homes from the heat, cities in Greece, the Maghreb and the Middle East are white, both roofs and walls. What's more, the sometimes rounded architecture also helps to protect the interior of buildings from the heat. The coating traditionally used is lime-based plaster, which is fragile and reapplied annually.

Applying a white coating to cool roof surfaces is therefore an old idea. The idea has made its way into the modern world ever since Nasa used a white coating to protect its space shuttles from the sun's rays. New York City is a pioneer in this field, having repainted no less than 10 million m² of roofs in white since 2010. The process has since spread throughout the world, in a conquest accelerated by the need to react to global warming.

However, it's not just a conventional white paint or coating: today's technology makes it possible to go (much) further, by developing products with reflective, insulating and protective properties. The result is resins that fall into the " cool roof " category.

💡 Read our complete guides to thermal insulation for buildings

The promise of a cool building in summer: does it really work?

The so-called "cool roof" resin increases the roof's thermal insulation and reflective capacity: 93% of solar radiation is thus reflected. As a result, the roof surface captures less heat, and is up to 30 degrees cooler for the same amount of sunlight.

The direct consequence is a reduction in temperature within the building, of between 3 and 7 degrees during heatwaves. Appreciable for everyone, and especially for the workers, who are expected to maintain their efforts even when temperatures rise!

In addition to comfort gains for indoor users, there is also a financial saving on energy consumption due to air-conditioning, up to a 30% reduction in the bill.

In some regions, or for certain types of building, this gain can make it possible to do without air conditioning altogether, or at least to undersize it. In such cases, the financial gain increases, with the added bonus of less expensive installation and less frequent maintenance.

The larger the building, the greater the benefits of cool roofing: industrial structures, commercial premises and agricultural buildings are the first to benefit from this technology. Goods or animals will benefit from this improvement in the same way as human beings, increasing the protective efficiency that is the raison d'être of buildings. This method can also be applied to insulation on existing steel trusses, improving not only the reflection of solar rays but also the durability of the roof.

There are a number of reasons for choosing a professional resin rather than paint to reinforce insulation. The first is its protective properties, enabling resins to preserve the roof from weathering and wear, with a predictable gain in life expectancy of a decade! The second is economical, as the paint has to be renewed every year, whereas the resin is applied for at least 10 years.

Discover Covalba's CovaTherm reflective paint.

Increased comfort, preserved productivity, energy and renovation savings: cool roofing is the answer to today's economic and climatic challenges. It's up to you!