Ever noticed how rooms on the top floors absorb the most amount of heat, making you feel as if you’ve entered a hot furnace on a summer afternoon?
Why Go White?
Painting the roof of your home in white is the simplest and most effective way to keep your home cool. Unlike using an air conditioner, it doesn’t cost a bomb and comes with absolutely zero hassles or bills. In fact, you can paint your roof white for as low as INR 500 (depending on the size of your roof). Also, there are no running costs or damages to the environment. On the contrary, white roofs can help reverse global warming too (I will get on that later).
How Much Cooler?
A white reflective roof can bring down the temperature of the rooms by a good 10 to 15 degrees Celsius. The best part is, your top floor will feel as cool as the floors below.
How Does It Work?
Physics (don’t worry, I’ll explain in a non-boring way if it isn’t your favourite subject) – an object is white because it reflects all the light that falls on it, whereas an object is black because it absorbs all the light falling on it. Heat and light from the sun travel together. So, when an object is dark, it gets more hot when it gets exposed to the sun. Painting the roof white will reflect the light and the heat that falls on it and hence will prevent it from getting hot. The surface temperature of a dark grey concrete roof can be around 20 degrees Celsius more than that of a similar white roof.
How To Do It?
Clean your roof, get a brush and paint your roof white.
1.Cooler interiors = lesser load on air conditioning = up to 40 percent lesser electricity bills.
2. Longer roof life due to less expansion and contraction.
3. White roofs reflect the long range infrared heat waves directly back to the atmosphere. Darker surfaces absorb the heat and emit short range heat waves to the surroundings which can’t escape the atmosphere and hence contribute to urban heat island effect in your city. Hence, if you paint your roof white, you will save money and also reduce your city’s temperature. If all roofs are painted white (Santorini, Greece anyone?), global warming can be easily reversed.
4. Looks great in the moon light – one of my favourite reasons too 🙂
What Type Of White Paint?
Any white paint or surface will help bring down the temperature. Some highly reflective paints that have a high SRI (Solar Reflective Index) value perform slightly better, but it is better to choose longevity over performance here.
1.The most common paint for white roof is limestone paint (choona) which is mixed with fevicol adhesive and applied on the roof. Limestone is the cheapest option (INR 500 for a 1000 square feet space) but it doesn’t last long once the rains set in.
2. White cement paint is slightly better that way. The degradation is slower in the rain, so it helps during the hot monsoon days too. You will have to paint every year before summers. It costs around INR 1000 for a 1000 square feet roof.
3. Elastomeric paint is one that can last around five years. This paint is a stretchy rubber-like substance that clings on to your roof better than the other options. This paint is also used to waterproof surfaces, hence it will help elongate the life of your roof. It also performs better, as it lasts throughout the year, plus there is no hassle of repainting again every year. The downside is the cost as it starts at INR 10 per square feet.
4. White ceramic tiles are a great option if you are looking for a permanent solution that will last as long as your house. Tiles can protect your roof better and give you an usable roof space. They are also great for waterproofing the roof if you are planning to make a terrace garden. Tiles are expensive, and good vitrified ones start upwards of INR 50 per square feet. If you are willing to spend, this is the best option, as vitrified tiles will absorb less water, while cheaper and regular ceramic ones can bulge and break. Go for bigger sizes with lesser joints and make sure the tiles are sparkling reflective white. Some tiles come with SRI values.
Where Can I Buy?
Most paints and brushes are available at your nearest paint shop. You can also buy them online, specially elastomeric paints which are not very widely available. For tiles, visit your nearest flooring store.
I live in the twin city of Cuttack-Bhubaneswar where air conditioners have become a necessity for most part of the year, thanks to global warming. Summer temperatures touch 45 degrees every year. We have been painting our roof white every year for the last 15 years and it works wonderful. I have experimented with different types of paint (other than elastomeric) and I recommend the cement paint if you are on a budget. If you are willing to spend, go for vitrified tiles.
And as always, if you have any questions or tips, please put them in the comments section below 🙂