Energy-saving windows for high-rise residential buildings

India is currently experiencing one of the fastest growth rates in high-rise buildings, particularly in the residential sector.  As a result, energy demand is expected to rise further in the coming years due to the combined growth of certain factors: population, urbanization, GDP, and consumer purchasing power. This, in turn, will lead to a dramatic increase in the demand for improved domestic comforts which will further lead to an increased demand for energy.

Today, residential buildings that use more energy to stay cool are a major cause of unnecessary carbon emissions. For a builder, one of the biggest challenges when constructing a high-rise residential building is to ensure low energy consumption while providing a comfortable indoor environment for the occupants. Can the two be achieved concurrently?

Of course, they can! By encouraging greater use of solar control glass for windows. A good solar-control glass is designed to reduce or prevent unwarranted solar heat from entering the building without sacrificing a comfortable environment for the occupants.

According to a report published in September 2014 by Global Buildings Performance Network (GBPN) titled Residential Buildings in India: Energy Use Projections and Savings Potentials, residential buildings are responsible for 22%* of the total energy consumed in India. Among the main factors that contribute to this energy consumption are:

Air-conditioning / heating

Artificial lighting

As windows contribute to a significant portion of the heat transfer in a building, the choice of glass plays a vital role in the total heat gain of the building. When choosing a glass for windows, a number of factors should be considered including, solar control, light transmission, color, sound insulation, safety properties, aesthetics, and thermal insulation. India being a tropical country with soaring temperatures in the summer, reduced solar glare and heat gain, transparency, and a comfortable indoor environment, are some of the primary concerns for architects and building occupants.

Sparkling Ice (ST 167), a variant of the Antelio-Plus range of glass from Saint-Gobain Glass, has been designed keeping these concerns in mind. With escalating energy costs, the superior benefits of Sparkling Ice certainly shine brighter.

Benefits of Sparkling Ice:

18% reduction in direct heat gain

Significant reduction in daylight glare

33% reduction in UV transmission

Reduction in  the consumption of air-conditioners

A uniform and sparkling building façade

Sounds ideal, doesn’t it? And it serves the two-fold objective of the builder – ensure low energy consumption while providing a comfortable indoor environment for the occupants. A win-win for both! Now, let’s get down to brass tacks.

Let’s assume the following costs and figures:

Flat area in sq. Ft.

Floor area per flat is 1800 sq. ft.

Window / glass area is 150 sq. ft.

Builder’s selling price

Rs. 3500 / sq. ft.

Costs – Clear glass Vs. Sparkling Ice (ST 167)

Clear glass basic price is Rs. 40/sq. ft.

Sparkling Ice ST 167 basic price is Rs. 70/sq. ft.

The difference in price is Rs. 30 / sq. ft.

The builder needs to make an additional investment of Rs. 4500 in the case of ST 167, which means an increase in investment of Rs. 4500/1800 = Rs. 2.5 / sq. ft.

When he finally decides to sell the flat, his selling price will increase from Rs. 3500 / sq. ft. to Rs. 3503 / sq. ft.

What’s in it for the house owner?

Lesser load on the air-conditioner

Increased comfort for the occupant

Interiors such as curtains and furniture are protected from fading

Increased savings in energy bills

A superior aesthetic appeal

Conclusion

Reference for statistics

* Residential Buildings in India: Energy Use Projections and Savings Potentials report, published by Global Buildings Performance Network (GBPN) in September 2014.