Cut your cooling bill

Simple home design and eco-friendly choices can reduce utility bills and save energy

Summer heat not just singes us, but also burns a hole in our pocket with high electricity bills. Some simple ideas — while building a house or upgrading it — can help you save on utility bills. These solutions are also environment-friendly and do not compromise on your comfort.

Top reflections

One key factor that influences how hot your home becomes, is the roof. Good choice of roof material can ensure the space directly below the roof is cool, and cut power costs. For example, cool roof materials deflect sunlight and reduce the temperature of the roof.

This can save 15 per cent of energy use in a building. One of the cool roof materials include thermoplastic, which is said to reflect 80 per cent of sun’s rays, much higher than asphalt roof that only reflects under 30 per cent. Other similar materials include terracotta and clay tiles as well as white or light-coloured glazed tiles.

Another simple, but effective, idea is to paint the roof. A simple coat of white limestone paint can reduce the temperature inside the house by 3 degrees. This is not expensive and costs under ₹30 per square feet.

There are also special reflective coatings that can applied on the roof to reduce the heat flow into the building. The costs may be higher than a simple limestone coating, but may provide UV protection and/or water-proofing.

A white or reflective roof can potentially save 15 per cent of air-conditioning energy use in a house.

Green roofs

You can also reduce the heat from the roof while reaping additional benefits such as food or power.

For instance, you can create a green roof by growing plants on the terrace. These are good in urban buildings as they help reduce the heat due to concrete walls and lack of green cover.

Ensure the plants you pick do not wilt in the heat — take steps to protect and water them.

In general, these are more expensive than cool-roof solutions, and require expenses on an ongoing basis for maintenance.

Installing solar panels is another viable option, though it requires higher initial costs.

The panels absorb heat and generate power that can be used to reduce your grid electricity usage. Study data have showed that the ceiling of a building with solar panels can be 2-3 degrees Celsius cooler than that with an exposed roof.

The cost of solar panels, based on data from government solar calculator, is about ₹500 per sqft of roof space.

About 120 sqft of roof space can generate about 1kilo-Watt of power per hour.

Window to cool

While roof changes are effective for independent or low-raise houses, better windows can help reduce heat in all types of buildings. You can consider replacing any single-pane windows with double-glazed units.

These trap air in between them and thus reduce heat and energy consumption. There are also triple-glazed windows that can provide higher energy savings.

Another option is to use sun-control films on windows, similar to the ones used on car windows. These are simple plastic films that can be pasted on glass panes.

They can cut nearly 80 per cent of the heat coming through the windows and can save 5-10 per cent of your electricity bill. The advantage of this method is that it also reduces heat loss, saving power in winter.

You can also use blinds to reduce both light and heat coming through windows.

Besides regular blinds, there are also smart-blinds that use sensors to adjust the opening based on ambient conditions.

Smart saving

There are other smart solutions as well that can identify where power is wasted and save accordingly. For example, sensors can detect rooms that are not occupied and turn off cooling and light, saving power.

Some smart-home systems provide analysis such as the amount of power you would save by increasing the AC temperature by 2 degrees (This can save you typically over 10 per cent of the electricity used for cooling). These can entice behaviour changes to save power.

Newer models of fans — such as brush-less DC motor models — consume up to 60 per cent lesser power than regular fans.

Likewise, inverter ACs are about 7 per cent more power-efficient than non-inverter versions.

The writer is co-founder, Rana Investment Advisors.

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