With the growing concern for our planet’s health, we all need to play our part in preserving Earth’s valuable resources. One way to reduce our carbon footprint and mitigate the effects of climate change is through energy conservation.

By choosing energy-efficient solutions for our homes, we not only contribute to a brighter and greener future for generations to come, but by embarking on an energy-saving journey, it can help keep your house cooler in extreme heat.

So, what makes a window energy efficient? And how much money can you save on your energy bills by installing energy-efficient windows?

Before we get into that, let’s explain the science of energy efficiency in windows.

What are energy-efficient windows?

Energy-efficient windows (also known as high-performance windows) are windows that have been specifically designed to minimize heat transfer, keeping your house cooler in extreme summers by reducing the amount of heat that enters your home through the windows.

To quantify the energy efficiency in windows, three measurements are used:

  • U-factor is a measure of how well a window insulates, this is done by measuring the rate of heat transfer through the window. The lower the U-factor, the more energy efficient the window.
  • Solar Heat Gain Coefficient (SHGC) measures how much solar heat is transmitted through a window. A lower SHGC means that the window will let in less solar heat, which can help to keep your home cooler in the summer.
  • Visible Transmittance (VT) measures how much visible light is transmitted through a window. A higher VT means that the window will let in more visible light, which can help to brighten your home.

Window manufacturers typically show the energy efficiency of their products using an energy-rating scale that range from A++ to E, with A++ being the most energy efficient.

The science behind energy efficiency in windows

The science here is rooted in the principles of heat transfer. Heat can be transferred through three mechanisms: conduction, convection, and radiation.

  • Conduction is the transfer of heat through direct contact. When heat is transferred through conduction, the molecules in the warmer material collide with the molecules in the cooler material, transferring their energy.
  • Convection is the transfer of heat through the movement of fluids. When warm air rises, it is replaced by cooler air, which is then warmed up. This process continues, creating a current of warm and cool air.
  • Radiation is the transfer of heat through electromagnetic waves. These waves can travel through empty space, so they can even transfer heat through a vacuum.

Windows are made of materials that conduct heat, letting heat in and out of your home. The amount of heat that is transferred through a window depends on the following factors:

  • The type of glass used. Energy-efficient windows typically use low-emissivity (low-E) glass, which has a thin, transparent coating to reflect heat out of the home during the summer and back into the room during cold weather.
  • The number of panes of glass. Double-pane and triple-pane windows are more energy efficient than single-pane windows because they are separated by an insulating gas, such as argon or krypton, which have higher insulating properties than air. The additional layers also help to reduce heat transfer and improve insulation.
  • The frame material. Energy-efficient windows typically have insulating frames made from materials such as hardwood to minimize heat transfer and reduce thermal conductivity.
  • The installation. Energy-efficient windows must be installed properly to be effective. Proper installation includes sealing gaps and using insulation around the window frame to prevent air leaks.

6 benefits of having energy-efficient windows

The advantages of installing energy-efficient windows extend beyond cost savings; they offer increased indoor comfort for the whole family, noise reduction, UV protection, enhanced resale value, and environmental sustainability.

1. Reduced energy bills

Energy-efficient windows are designed to keep your home cooler in summer and warmer in winter by reducing the heat that enters and leaves through your windows. By improving insulation and reducing air leakage, energy-efficient windows help to maintain a more consistent indoor temperature, keeping your home cool in hot weather, negating the need for air conditioning, and leading to significant energy savings, which translate into lower utility bills over time.

2. Increased comfort

Energy-efficient windows effectively insulate against external heat or cold, helping to maintain a more comfortable and consistent temperature throughout your home. This improved thermal performance creates a pleasant living environment by minimizing hot spots, cold spots, and uncomfortable drafts near windows.

3. Improved noise reduction

If you live in a noisy or busy neighborhood, energy-efficient windows, especially those with multiple glass panes and insulating gas fills, provide better sound insulation, reducing external noise infiltration compared to traditional single-pane windows.

4. Enhanced UV protection

Windows with low-emissivity (low-E) coatings help block harmful ultraviolet (UV) rays from entering your home. As well as reflecting heat away from your home, these coatings can help prevent fading and damage to furniture, carpets, artwork, and other interior surfaces that may be sensitive to sun exposure.

5. Increased resale value

Energy efficiency is an increasingly important factor for homebuyers. Having energy-efficient windows installed can boost the resale value of your property as potential buyers will recognize the long-term cost savings and comfort benefits associated with them, making your home more appealing and desirable on the property market.

6. Environmental sustainability

As well as helping you save money, energy-efficient windows help save the planet by reducing energy consumption and greenhouse gas emissions. How? Installing these functional windows means you rely less on heating your home in winter or air conditioner systems for cool air on unbearably hot days.

Different types of energy-efficient windows

Energy-efficient windows don’t come in a one size fits all solution. There are multiple different types of high-performance windows to choose from. The most common ones available include double-pane windows, triple-pane windows, Low-E windows, and casement windows.

Double-pane windows

Double-pane windows consist of two layers of glass with a sealed gap in between, typically about 16mm, which is filled with air or an inert gas, such as argon, xenon, or krypton. These windows provide better insulation than single-pane windows because they reduce instances of heat transfer and minimize air leakage. However, they can still let in (and out) a significant amount of heat.

Triple-pane windows

Triple-pane windows take double pane one step further by featuring three layers of glass with two sealed insulating gaps, again filled with air or insulating gases. These types of windows can offer even higher thermal efficiency compared to double-pane windows by providing an additional layer of insulation. These are particularly beneficial in extreme climates where temperature variations are significant.

Low-emissivity (low-E) windows

Low-E windows have a thin, transparent coating of metal oxide applied to one of the internal glass surfaces. The low-E coating reflects heat into the room while allowing natural light to pass through. This helps to reduce heat gain in warmer months and heat loss in colder months, making the windows more energy-efficient. Low-E windows are available for both single-pane and multiple-pane configurations.

Gas-filled windows

As mentioned above, windows with multiple glazing panes typically have insulating gases between the panes. Argon and krypton gases are the most common gases used as they’re non-toxic, odorless, and non-reactive, and because they have better-insulating properties than just air, they help reduce heat transfer through the windows.

Gas-filled windows combined with multiple panes and low-E coatings provide the highest levels of thermal insulation, giving you the most energy savings.

How to choose the right energy-efficient windows for your home

Choosing energy-efficient windows for your home is a smart decision that can significantly improve your comfort, reduce energy consumption (saving money on your bills), and enhance sustainability. With a wide range of options available, you’ll want to consider several factors to help you select the right windows for your specific needs:

Look for windows with an energy efficiency rating

As mentioned above, the energy efficiency rating of windows is typically indicated by their U-factor and solar heat gain coefficient (SHGC).

  • The U-factor measures how well a window insulates, with lower U-values indicating better insulation.
  • The SHGC measures the amount of solar heat that enters through the window, with lower SHGC values indicating better solar heat control.

Look for windows with low U-factor and SHGC ratings to maximize energy efficiency.

Consider the climate in your area.

The climate plays a significant role in determining the type of energy-efficient windows that will best suit your home. If you live in a hot climate with hot air, windows with low solar heat gain coefficient (SHGC) will minimize heat gain from sunlight and keep your house cool. In contrast, if you live in a colder climate, windows with a lower U-factor are crucial for reducing heat loss and improving insulation.

Ask about the warranty on the windows.

A reliable warranty is an important consideration when choosing energy-efficient windows. It assures that the windows will perform as expected and protects you in case of any defects or failures. Pay attention to the duration and coverage of the warranty, including issues related to energy efficiency, glass breakage, and manufacturing defects.

Consider the style of your home.

Energy-efficient windows are available in various styles and designs. Consider the architectural style of your home and choose windows that complement its aesthetics. Whether you prefer casement, double-hung, picture, or sliding sash windows, ensure the energy-efficient options are available in the desired style.

Get multiple quotes from different companies.

It’s wise to gather quotes from multiple window companies to compare prices, product options, and services offered. Request detailed quotes that include the cost of the windows, installation, warranties, and any additional features or upgrades. By comparing multiple quotes, you can make an informed decision and find the best deal that meets your budget and requirements.

Have the windows installed by a qualified contractor

Proper installation is essential for the optimal performance of your energy-efficient windows. Hire a reputable and experienced contractor who specializes in window installation. They will ensure the windows are correctly fitted, properly sealed, and aligned to maximize energy-saving benefits. Ask them also to provide guidance on best practices for the maintenance and care of your new windows to prolong their life and energy-efficient performance.

How much money could energy-efficient windows save you?

The amount of money these windows could potentially save you depends on various factors, such as the local climate, energy prices, the size of the windows, and the energy efficiency of the entire building.

In general, though, because the windows minimize heat transfer and improve insulation, you’ll need to rely less on heating and cooling systems. As such, you could potentially save between 10% and 25% on your heating and cooling costs by upgrading to energy-efficient windows.

According to the Energy Saving Trust, by installing A-rated double glazing to windows in an entirely single-glazed semi-detached gas-heated property, you could save £195 a year and 330 kg of carbon dioxide.

Save money as the heat rises

In conclusion, energy-efficient windows are vital in keeping your house cooler during extreme summers. By incorporating advanced technologies such as multiple glass panes, low-emissivity coatings, insulating gas fills, and effective sealing, these windows effectively reduce heat transfer into your living spaces.

So, with the added benefits of increased comfort, potential cost savings, and environmental sustainability, energy-efficient windows are a wholly recommended investment for creating a cooler and more energy-efficient home environment, even during scorching summer months.