FT NEWS

The torrid Indian summer sun beats down on the roofs of buildings, which heat up and radiate that heat into the homes that are immediately below the roof. This results in a considerable amount of heat gain in the upper floors of the building, making them uncomfortable, even unbearable, to live in. The rise in indoor temperatures contributes to greater air conditioning requirements and higher electricity costs, and increased discomfort in areas that are not air conditioned, such as the kitchen and bathrooms. Here are some techniques to drop the temperature by some degrees on your roof.

1. Grow a roof garden
One of the best ways to keep the roof cool is by growing your own rooftop garden with green grass and potted plants. The green roof shades the building from direct sunlight while the mud within the potted plants and the lawn absorbs most of the heat that hits the roof.

Before going for a roof garden, make sure that the roof is properly waterproofed so as to prevent any type of water seepage through the external walls or roof slab, which may cause damage to the building.

2. Paint the terrace white
Heat gain can be considerably reduced by turning the roof into a reflective roof surface. How?

• Paint the concrete floor with cool roof paints. These paints provide good thermal insulation by reflecting the sun’s rays and keeping the indoors cool. Brands such as Dr Fixit have such products on offer.
• A cost-effective way to keep the roof cool throughout summer is by coating the floor with white lime wash, locally known as chuna. One drawback with using lime wash is that it gets washed away during the monsoon season, hence reapplication is required every summer.
• For a more permanent solution one can install white ceramic or porcelain tiles on the roof.

3. Add shade
The roof slabs are made of concrete, which is a very dense material – it retains heat for a very long time and then transfers it to the indoors. The temperatures can be controlled by creating shade on the rooftop because shaded areas are cooler than the surroundings.

• Go for high walls or trellises along the perimeter of the roof, like in the photo here; this is an interesting way to shade the roof.
• Introduce design features, such as pergolas with creepers, to create shade.

4. Go for heat-resistant flooring

• Go for flooring materials such as wooden deck tiles or terracotta tiles that do not absorb or transfer as much heat to the lower floors and are comfortable to walk on even during the peak summers.
• Brands like Johnson Endura have introduced cool roof tiles that reflect most of the solar heat. These tiles work as an insulator that prevents heat from entering the top floor rooms.

5. Install solar panels
Alternatively, one can cover the roof with solar panels. The solar panels comprise photovoltaic cells, and block the heat from hitting the roof, as in his example. Instead, these panels capture the sun’s energy and convert it into electricity.

Note that the whole roof can be covered with solar panels only in multi-storied buildings or apartment complexes where the roof is primarily used for building services.