If you’re thinking about installing a rooflight (also called a skylight) or upgrading an existing one, “Low-E glass” is a term you’ll almost certainly encounter. But what exactly is Low-E glass, and is it worth choosing for your rooflight?

In this post, we’ll break down what Low-E glass is, how it works, the key benefits, potential drawbacks, and whether it’s the right choice for your home.

What Does “Low-E” Mean?

Low-E stands for Low Emissivity. Essentially, Low-E glass is engineered to reduce the amount of infrared and ultraviolet light that passes through glass without significantly reducing visible light.

That means:

• You get natural daylight coming in…
• …but less unwanted heat transfer through the glass.

Low-E glass achieves this through a very thin, microscopic metallic coating on one or more surfaces of the glass. The coating is almost invisible, it doesn’t noticeably change the appearance of the glass, but it has a big impact on performance.

How Low-E Glass Works

To understand Low-E glass, it helps to know how sunlight and heat normally behave with windows:

• Visible light is what you see, the daylight that makes a space bright.
• Infrared radiation is heat energy, this warms a room.
• Ultraviolet (UV) light is invisible and can cause fading of fabrics and finishes.

Low-E glass is designed to:

1. Let in visible light freely so your space stays bright and naturally lit.
2. Reflect infrared heat back to its source, which helps keep heat inside in winter and outside in summer.
3. Reduce UV transmission, which protects interiors from fading over time.

This balance is achieved by the special Low-E coating. Depending on the type of coating and how many layers are used, the glass can be optimized for different climates and performance goals.

Types of Low-E Coatings

There are two main categories:

1. Hard-Coat Low-E

• The coating is fused to the glass during manufacturing.
• Typically more durable.
• Often used in colder climates where heat retention is a priority.

2. Soft-Coat Low-E

• Applied after the glass is made.
• Generally offers better performance (lower heat transfer).
• Slightly more delicate and usually needs to be sealed within double or triple glazing to protect the coating.

Rooflight manufacturers use different Low-E coatings depending on the performance needed, so it’s worth asking what kind they use if you’re comparing products.

Benefits of Low-E Glass in Rooflights

Now that we know what Low-E glass is, let’s explore why many homeowners choose it.

1. Improved Energy Efficiency

Low-E glass significantly reduces heat loss in winter and limits heat gain in summer compared to ordinary glass. That means your home stays more comfortable year-round, and you may spend less on heating and cooling.

2. More Comfortable Living Spaces

Rooflights without Low-E glass can create intense sunlight at certain times of day, which can feel warm and glaring. Low-E glass helps moderate solar heat, reducing hot spots and creating a more comfortable environment.

3. Better Protection Against UV Damage

Up to 40% of fading in fabrics, finishes, and furniture is caused by UV radiation. Low-E glass blocks a significant portion of UV light, helping protect your interior finishes.

4. Increased Visible Light with Lower Heat

One of the biggest strengths of Low-E glass is that it lets in plenty of daylight, which is one of the main reasons people install rooflights, without bringing in as much unwanted heat.

5. Condensation Reduction

Because Low-E glass helps maintain more consistent interior surface temperatures, it can also reduce the likelihood of condensation forming on the glass – a common issue in winter.

Drawbacks & Considerations

While Low-E glass offers many benefits, there are a few points you might want to consider before you decide:

1. Higher Upfront Cost

Low-E glass generally costs more than standard glass. That said, the energy savings over time can help offset the initial price difference.

2. Slight Tint or Appearance Change (in Some Cases)

Some types of Low-E coatings can give glass a very slight tint or reflective quality. Most people don’t notice it in daily use, but it’s worth seeing samples if aesthetics are important to you.

3. Not All Low-E Glass Is the Same

The performance of Low-E glass varies depending on the coating technology, the number of panes in the glazing unit, and how the window is oriented. So, specifying Low-E glass isn’t enough on its own – you want to understand the actual performance ratings too.

Performance Metrics to Look For

When comparing rooflights with Low-E glass, here are key numbers you’ll see:

U-Value

• Measures how well a material resists heat transfer.
• Lower values = better insulation.
• For rooflights, a lower U-value means less heat escaping in winter.

Solar Heat Gain Coefficient (SHGC)

• Tells you how much solar heat passes through.
• A lower SHGC means less heat gain from sunlight, good for warm climates; in cooler areas, a slightly higher SHGC can help solar warmth.

Visible Light Transmittance (VLT)

• The percentage of visible light that passes through.
• Higher VLT means brighter rooms.

Balanced performance – low U-value, appropriate SHGC for your climate, and high VLT – is what makes Low-E rooflights so effective.

Should You Use Low-E Glass in Your Rooflight?

For most homeowners, the answer is yes. Especially if:

• You want better thermal comfort.
• You live in a climate with cold winters and warm summers.
• You value energy efficiency and lower heating/cooling costs.
• You want to reduce UV fading and glare.

Low-E glass is a straightforward upgrade that generally pays off in comfort and performance.

However, there are a couple of scenarios where you might choose otherwise – for example:

• If you live in a very mild climate where heat gain/loss isn’t a major concern.
• If you want maximum solar warming in a cold, dark location, and you’re less concerned about heat retention.

Even in those cases, nearly all modern rooflight manufacturers recommend some form of Low-E coating because it still improves year-round comfort and reduces energy waste.

What Is Low-E Glass, And Should I Use It in My Rooflight?

Low-E glass is one of the smartest upgrades you can make in a rooflight. By letting in plenty of natural daylight while reducing heat loss, unwanted heat gain, and UV exposure, it improves comfort and energy efficiency without sacrificing brightness.

While it costs more than standard glass, the long-term comfort, performance, and energy savings usually make it worth the investment – especially in climates with seasonal temperature swings.

At Lantern Superstore, we specialise in high-performance rooflights designed to enhance comfort and efficiency. Our Low-E glass blocks up to 99% of harmful UV rays, helping to minimise glare from your rooflight. Speak to our team today on sales@lanternsuperstore.co.uk to explore Low-E glass options and find the perfect fit for your project.