Everything You Need to Know About Low-E Coatings

Key Takeaways

• Low-E Coatings : Thin metallic layers on windows that regulate heat transfer, keeping homes warmer in winter and cooler in summer.
• Hard-Coat : Best for colder climates, provides basic heat retention.
• Soft-Coat : Ideal for varied climates, offers better heat control and UV protection.
• Energy Efficiency : Reduces energy bills by improving insulation and blocking excess heat.
• UV & Glare Protection : Blocks harmful UV rays and reduces glare, protecting interiors.
• Choosing the Right Coating : Pick based on your climate—hard-coat for cold areas, soft-coat for warmer regions.

When it comes to selecting windows for your home, it's not just about aesthetics — energy efficiency is key. One of the most effective technologies available today is Low-E (low emissivity) glass coatings. As the demand for eco-friendly, energy-efficient solutions grows, Low-E coatings have become an essential feature in modern windows. But what exactly is a Low-E coating, and how can it improve the comfort and energy performance of your home? In this article, we’ll dive deep into how Low-E coatings work, their benefits, and help you choose the best one for your home.

What are Low-E Coatings?

Low-E coatings are thin, metallic layers applied to the glass surface of windows. These coatings are designed to regulate heat transfer, allowing natural sunlight to enter your home while blocking unwanted heat from escaping. Essentially, a Low-E coating reflects infrared radiation, which helps keep your home warm in winter and cool in summer. It’s the perfect balance of energy efficiency and comfort, providing both insulation and solar heat control.

The key function of Low-E coatings is to reflect long-wave infrared energy (heat) while allowing short-wave solar energy (sunlight) to pass through. In winter, this means that while sunlight can still warm your home, the heat inside stays trapped, reducing the need for heating systems. In summer, it helps block out excess solar heat, making your air conditioning system work less.

As a result, homes equipped with Low-E windows tend to stay more comfortable year-round, with lower energy bills and less reliance on heating and cooling systems.

How Do Low-E Coatings Work?

There are two types of Low-E coatings: hard-coat (passive) and soft-coat (solar control) . Both work to regulate energy flow through your windows, but they differ in terms of durability, effectiveness, and method of application.

1. Hard-Coat Low-E (Passive)

This type of coating is applied during the manufacturing process using a pyrolytic method. The coating is fused directly to the glass while it's still hot, creating a durable and long-lasting bond. It provides a basic level of energy efficiency and is ideal for colder climates, as it allows more heat from the sun to enter your home during winter.

2. Soft-Coat Low-E (Solar Control)

A more advanced coating, soft-coat Low-E is applied using a vacuum deposition process. It involves a series of layers that are applied to the glass at room temperature. This type of coating offers superior performance in terms of heat control and UV protection. It is perfect for homes in areas with both hot summers and cold winters.

Key Performance Metrics for Low-E Coatings

To determine the efficiency of Low-E windows, it's helpful to understand the different ratings used to measure their performance. Here are the key metrics you'll encounter:

1. Solar Heat Gain Coefficient (SHGC):

This measures how much solar radiation passes through a window. A lower SHGC means that less heat enters your home, which is ideal for hot climates. For colder climates, a higher SHGC can be beneficial, as it allows more sunlight to warm the home.

2. U-Value:

The U-value measures the rate at which heat is lost through the window. A lower U-value indicates better insulating properties. For instance, a window with a U-value of 0.2 will lose much less heat than one with a U-value of 1.0.

3. Visible Light Transmittance (VLT):

This metric measures the amount of natural daylight that passes through the glass. A higher VLT allows more light into your home, contributing to a bright and inviting space.

4. Light to Solar Gain (LSG):

The LSG ratio compares the amount of visible light passing through the window with the amount of solar heat gain. A higher LSG ratio means more natural light with less heat gain, providing the best of both worlds.

The Different Types of Low-E Coatings

1. LoE 8071
   This standard Low-E coating helps to keep your home warm during the winter by reducing the amount of infrared heat escaping through your windows. It’s effective for most windows in any home, offering a solid performance balance between insulation and solar heat gain.
2. CG-70
   A more advanced coating, CG-70 provides better insulation and reduces UV rays more effectively than LoE 8071. This coating is perfect for homes in regions with variable weather patterns, offering a blend of performance for both hot summers and cold winters.
3. SNX-628
   This coating offers high-performance insulation with the added benefit of up to 95% reduction of UV radiation. It's ideal for windows facing the sun, particularly south and west-facing windows, where UV rays are most intense.

Low-E Coatings Comparison Table

Low-E Coated Windows

There are several specific Low-E coatings that you can choose from:

• LoE 8071 : This is a standard low-emissivity coating that helps keep the heat inside and reduces UV rays from entering the home. It’s a versatile choice that can work in almost any room.
• CG-70 : This coating is more advanced and provides better performance than LoE 8071. It's great for most windows in your home.
• SNX-628 : This option reduces up to 95% of UV radiation and provides excellent insulation. It’s ideal for unshaded south- and west-facing windows, helping block out damaging UV rays while maintaining comfort.

Real Example: How Low-E Coatings Improve Energy Efficiency

Let’s say you live in an older home with single-glazed windows. During winter, your furnace runs constantly, trying to maintain a comfortable temperature. If you were to replace those single-glazed windows with double-glazed Low-E windows, you’d notice a significant difference. The Low-E coating would prevent the heat from escaping, meaning your furnace would run less often. In the summer, the same Low-E windows would block out excess solar heat, reducing the need for air conditioning. Over time, this would result in substantial energy savings.

Benefits of Low-E Coatings

1. Energy Efficiency:
   The primary benefit of Low-E coatings is their ability to reduce energy costs by preventing heat loss in winter and solar heat gain in summer.
2. Improved Comfort:
   Low-E windows help maintain a more stable temperature in your home, keeping it cooler in the summer and warmer in the winter.
3. UV Protection:
   Low-E coatings block harmful UV rays, which can cause fading of furniture, rugs, and curtains. This protection helps maintain the appearance of your interior.
4. Reduced Glare:
   By controlling the amount of sunlight that enters through your windows, Low-E coatings can reduce glare, making it easier to watch TV or work on a computer during the day.
5. Environmental Impact:
   Low-E windows contribute to a reduction in carbon emissions by improving the energy efficiency of your home, which reduces the need for heating and cooling.

Choosing the Right Low-E Coating for Your Home

When selecting Low-E windows, it’s essential to take your local climate into account. If you live in a colder region, a hard-coat Low-E may be the best choice for maximizing heat retention. In contrast, a soft-coat Low-E is more suitable for warmer regions where cooling is a priority.

At Canadian Choice Windows and Doors, we offer a range of Low-E coatings tailored to meet the needs of every home. Our standard option is LoE 189, which provides excellent insulation and UV protection without the higher cost of other coatings like LoE 270. We believe that every window should come equipped with Low-E coatings as standard to ensure optimal performance.