How Different Types of Glazing Impact Solar Heat Gain in Buildings

Untreated Glass & Solar Heat Gain: What Every Indian Homeowner Should Know

Scroll through architectural magazines or global design feeds, and you’ll notice a recurring visual – expansive glass facades, large picture windows, and seamless indoor–outdoor connections framing spectacular views. These images are aspirational, even romantic.

What they rarely show, however, is the other side of large openings – especially in India.

In most Indian cities, large openings often come at a cost: excessive heat gain, glare, increased radiation exposure, fading of interiors, and higher cooling loads. With a majority of the country falling under hot-dry and hot-humid climatic zones, “hot” remains the one constant that designers cannot ignore.

The good news? With the evolution of glass technology, glazing today is no longer just about transparency. The right type of glazing can significantly control solar heat gain while preserving daylight, views, and comfort.

Let’s understand how different glazing solutions impact solar heat gain in buildings, and how each can be used effectively in the Indian context.

1. Regular (Untreated) Glass

Glass Windows with Shading Devices to Reduce Heat Gain

Plain or untreated glass offers good visual connection with the outdoors but also maximum solar heat gain. It allows a large portion of solar radiation to enter interiors, resulting in warmer indoor temperatures and increased dependence on air conditioning. Acoustic insulation is also minimal.

If untreated glass must be used, heat gain can only be mitigated through design strategies rather than material performance, such as:

• Smaller window openings

• Orienting openings towards the North or shaded sides

• Horizontal and vertical shading devices like overhangs and fins

• Traditional elements such as jaalis or perforated screens

•  Dense plantation or green buffers in front of glazing

From a safety standpoint, any external glazing should at least be toughened glass, ensuring impact resistance and reducing the risk of injury in case of breakage.

Best used when: Budget constraints exist and passive shading strategies are thoughtfully integrated.

Also read Tempered Glass - A Modern Solution for Strength and Safety

2. Laminated Glass

Laminated Glass for Sound Control and Enhanced Safety

Laminated glass consists of two glass panes bonded together with a PVB (polyvinyl butyral) interlayer, which plays a critical role in improving performance.

Compared to regular glass, laminated glass offers 

• Better thermal insulation, reducing direct heat transmission

• Enhanced acoustic insulation, particularly useful in urban environments 

• Safety, as the PVB holds the glass together even when broken, preventing shards from failing

While laminated glass alone does not eliminate solar heat gain, it performs significantly better than plain glass. When combined with external shading devices, solar load can be further reduced.

Best used when: Safety, sound control, and moderate heat reduction are priorities, especially in residential and mixed-use buildings.

Also read Elevate Your Space with Laminated Glass: A Guide to Safety and Style

3. Double Glazing (Insulated Glass Units – IGUs)

Double-glazed units (DGUs) in Facades for Noise reduction and Thermal Comfort

Double glazing introduces a more performance-oriented solution. It consists of two panes of glass sealed together with an air or gas-filled gap, creating an insulated glass unit (IGU).

This configuration 

• Significantly improves thermal insulation, reducing heat gain and heat loss 

• Enhances acoustic performance 

• Improves overall indoor comfort

For Indian conditions, it is important that both panes are toughened, ensuring durability and safety. Double glazing becomes especially effective when paired with solar control coatings, but even as a basic system, it offers a marked improvement over single glazing.

Best used when: Thermal comfort and noise reduction are important, particularly in commercial buildings, offices, and high-rise residences.

4. Solar Control Glass

Solar Control Glass minimises UV-radiation and Solar Heat Gain

When it comes to addressing solar heat gain holistically, solar control glass stands out as a comprehensive solution.

Designed specifically to tackle high solar radiation, this glass:

• Allows optimal daylight to enter interiors 

• Reflects and reduces up to 70% of solar heat 

• Minimises UV radiation, protecting interiors from fading 

• Helps maintain lower indoor temperatures compared to outdoor conditions

Solar control glass typically features a pyrolytic or coated surface that reflects unwanted heat while retaining visual comfort. Ideal for tropical climates like India, it is available in contemporary colours, varied thicknesses, and aesthetic finishes, making it suitable for both residential and commercial architecture.

Importantly, the solar control coating can be applied on toughened glass, offering the best of performance, safety, and design flexibility. Similarly, solar control glass can be used in insulated glazing as well to further enhance the performance of the glazing unit.

Best used when: Large glazed areas, façades, skylights, or west- and south-facing openings are unavoidable.

Also read How Solar Control Glass Drives Energy Efficiency In Net-Zero Buildings?

Choosing the Right Glazing: A Climate-First Approach

In Indian architecture, glazing should never be a purely aesthetic decision. Orientation, climate, usage pattern, and building type must guide material selection. From passive shading strategies to advanced solar control glazing, the right combination can dramatically reduce heat gain while preserving the joy of light and views.

Large windows don’t have to mean uncomfortable interiors if the glass is doing the right kind of work.