Cool roofs are beneficial not only for keeping homes cool, but it is also cool on the pockets as it considerably lowers the cooling cost of buildings. As the effects of climate change have increased the global temperature, the need for cool roofs is growing very fast. Cool roofs are of different types like roofs installed with solar panels, roofs with a garden or vegetative growth, and roofs painted with reflective coating to bounce back sunlight. Solar panels have been in the news for the last few years, and many look upon it as the most dependable equipment to achieve sustainability.
But coating the roof with a white or shiny coating is a simple but highly effective and affordable solution to counter the solar heat and keep homes cool. These cool roofs also mitigate the effects of heat islands generated by traditional roofs that heats the surrounding air while absorbing almost the entire sunlight. Traditional or dark roofs, as people now call it, are soon to become a thing of the past as the clamor for cooler homes and cooler environment keeps growing. Dark roofs absorb heat energy at a high rate of almost 100 watts per square feet of the roof surface. The high rate of heat dissipation not only makes the building interior warmer, but the heat also passes into the surrounding environment outside the building and considerably increases the air temperature.
The working modality of painted cool roofs
Painted cool roofs are the easiest solution to control the building temperature and keep it within tolerable limits to ensure comfortable living. The white paint on the roof must have high reflective property so that it can adequately reflect the sunrays and minimize the chances of heat absorption by the roof. As a result, there is minimal temperature increase inside the building, and the amount of heat that radiates into the surrounding air is low. It results in a cool ambiance inside homes and reduces the use of air conditioners while keeping the carbon emissions low. Some roof coatings developed recently are so much effective that it can maintain temperature lower than the ambient temperature by reflecting 82% of solar energy. Once the roofing contractor Utah has installed the roof, you can get it painted and enjoy cool living.
Cool roofs are highly affordable because it does not involve any new installation except for painting the roof surface with some paint or coating. Cool roofs keep homes cool and help to save energy costs by reducing the use of air conditioners. Buildings with cool roofs consume 40% less energy for cooling during the peak summer months as compared to dark roofs, as revealed in various studies. Also, these roofs do not require any maintenance except for keeping the roof clean to maintain the whiteness of the painted surface. If the surface becomes dull, it will lower the reflective property and reduce the ability to keep homes cool. Moreover, cool roofs have a longer lifespan than traditional roofs, which also saves the cost of untimely roof replacement.
Reduce heat island index – Cool roofs prevent heat transmission into the building, and by keeping the roof surface cool, it ensures that the surrounding temperature remains close to the ambient temperature. By preventing a sudden increase of heat in localized areas, the chances of creating heat islands reduce significantly.
Lower emission of air pollutants – As the use of air conditioners reduces, it will reduce energy consumption, which in turn will reduce the use of fossil fuels. As a result, the harmful emissions of greenhouse gases like Nitrogen dioxide and Carbon dioxide will also decrease.
Better air quality – Reduced emission of harmful gases leads to improved air quality as the level of pollutants in the air remains low. Urban areas experience lesser smog formation due to the lowering of the smog-forming gases like carbon monoxide, nitrogen dioxide, ozone, and sulfur dioxide at the ground level. People can breathe easy and stay healthy.
Types of coatings for cool roofs
Painting the roof with ordinary white paint will not be effective unless it has high reflective properties. Here are some types of coatings that work well for cool roofs.
White roof coatings – These coatings are a mixture of white pigment and some polymeric materials that can reflect 70% to 80% sunlight. Applying several coats forms a thick layer that increases the reflective property and keeps surface temperatures very close to the ambient temperature.
Pigmented coatings – Unlike white coatings, these colored coatings come in various shades like red, blue, and green but can reflect only about 20% of sun rays. Improving roof and building aesthetics is a bigger reason for using this type of coating rather than deriving the benefits of cooling.
Roofing membranes – The membranes made from polyester, fiberglass, or felt blended with materials like synthetic rubber, asphalt, PVC, or other synthetic polymers are durable and flexible as well as waterproof. The top layer can either be a coat of pigments to increase the solar reflective property or covered with roofing gravel. The single-ply EPDM membrane is most popular and used for almost 40% low sloped roofs for commercial buildings because of its ability to withstand all kinds of climate. The membranes are available in white or black color and repairable.
Aluminum roof coatings – This type of coating is made of asphalt-like resin that contains aluminum leafing flakes. The resin imparts aluminum like looks to the coating, and it is hard to make out that it has asphalt underneath. The aluminum coatings have 50% solar reflective ability, and certain brands can offer a higher reflectivity of 70%. By using aluminum coatings, the indoor temperature can come down by as much as 15oF to 20oF.
Tiles – Tile roofs have a high reflective property and keep homes cool. Homes that have clay tile roofs are quite cool due to high thermal emittance (86%) and SRI above 50%. Tiles are 100% recyclable and extremely durable.
As the environmental uncertainties are growing, the world is becoming hotter, the popularity of cool roofs is spreading very fast.