How to Reduce Heat Loss Through Windows: 2024 Guide

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Did you know that 18% of heat loss in most offices and homes in the UK occurs through windows? A common culprit is single-glazed windows — reports have shown that they lose heat 2x as fast as the standard double-glazed windows, eating deep into energy bills.

In this blog, we'll explore how you can exploit GLRE’s glazing services to reduce heat loss through windows and save your business some money. Say goodbye to wasted energy and hello to a more comfortable, energy-efficient office building.

Understanding Heat Loss Through Windows

Before we can discuss how glazing replacement can combat heat loss, it's essential to understand how heat escapes through your windows.

Heat loss through windows refers to the transfer of heat from the interior of a building to the exterior through the windows. This can occur through conduction—where heat is transferred directly through the window materials—air leakage, and radiation.

Heat loss can affect the overall comfort of the workspace, potentially leading to decreased productivity among employees.

More importantly, heat loss through windows can significantly impact businesses in terms of increased energy costs. It can lead to higher heating expenses during the winter as the warmth generated inside the building escapes through the windows. Implementing measures to reduce heat loss through windows can help companies save on energy costs in the long run.

Reducing Heat Loss Through Windows

Given the high impact heat loss has on a business’s bottom line, it’s important to take drastic measures to combat this issue. One of the most recommended ways is replacing windows with double-glazed window insulation. This is quite different from single-glazed windows, and we’ll break down the differences in this section.

Single vs. Double-Glazed Windows

Single-glazed windows, common in older buildings, consist of a single pane of glass. While they may have been sufficient in the past, they’re far less effective at insulating your office than double-glazed windows.

The single pane of glass provides little resistance to heat transfer, making it easier for warmth to escape in the winter and heat to enter in the summer. Double-glazed windows, on the other hand, are energy-efficient windows that offer superior insulation, making them a popular choice for modern facilities and renovations. If you’re unsure about what windows are present in your office, contact us today for a free evaluation.

Single-Glazed Windows Insulation

If you use single glazing for your windows and aren’t ready to invest in full replacement windows, you can still take measures to improve their solar heat gain coefficient (SHGC). SHGC is a measure of a glass’s ability to absorb heat from the sun and transmit it into a building.

Adding secondary glazing or using heavy curtains can create an extra barrier against heat loss. Additionally, sealing gaps and cracks around the window frames can help reduce drafts and air leakage, improving the overall energy efficiency of your windows.

How Does Double Glazing Reduce Heat Loss?

Double glazing is a highly effective means of reducing heat loss through windows. Double-glazed windows consist of two panes of glass with a layer of insulating gas, such as argon, between them. The space between the panes and the insulating gas work together to create a barrier that reduces heat transfer.

How much energy does double glazing save? 

Double glazing saves heat energy that amounts to about £105 to £155 yearly in bills. This form of window retains the warmth inside your office during the colder months; also, the heat from outside is less likely to enter during the warmer months.

To take advantage of double-glazed insulation, you’ll need professional glazier replacement companies. GLRE is a prominent glazing replacement provider for office buildings in the UK. Contact us now for an evaluation and to discuss your project needs further.

Should Double-Glazed Windows Feel Cold on the Inside?

Double-glazed windows should feel cold on the inside when you touch them. They help reduce heat loss by trapping insulating air between two glass panes to protect warm air inside the house and prevent cold air from escaping the inner glass pane. This helps to maintain a comfortable indoor temperature; however, the trapped air will cause the windows to feel cold when touched.

Checking Heat Loss and Efficiency of Double Glazing

If you already have double-glazed windows or are considering investing in them, knowing how to check heat loss from windows is essential. So, what’s the procedure on how to check the efficiency of double glazing? You can do this by checking for signs of condensation between the glass panes and by using a thermal detector.

1. Checking for Condensation

Condensation between the glass panes of your double-glazed windows is a clear sign of a failed seal. This allows air to pass between the panes, reducing their insulating properties and leading to heat loss.

To check for condensation, carefully inspect the gap between the panes, especially along the edges and corners. If you notice any moisture or fogging, the seal has likely failed, and the windows need to be replaced or repaired. To understand how to get rid of condensation between double-glazed windows, check out this guide.

2. Using a Thermal Leak Detector

A thermal leak detector is a handy tool for identifying areas where heat is escaping from your windows. These devices detect temperature differences and can pinpoint drafts and leaks around the frame and sashes.

To use a thermal leak detector, simply scan the window perimeter, paying close attention to areas where the frame meets the glass and the sashes meet each other. If the detector indicates cold spots, it suggests that heat is escaping through those areas. Offices with high-rise windows should contact GLRE for a professional evaluation.


In addition to opting for double glazing or improving the insulation of single-glazed windows, there are other steps you can take to reduce heat loss through your windows.

Simple actions that can help minimise heat loss and make your office more comfortable include:

  • Using draught excluders
  • Applying window film
  • Properly sealing your windows
  • Facing windows to the west in your office buildings: West-facing windows and doors usually experience more energy gain during the day.

Heat Reflecting Glass for Reducing Heat Loss

In addition to traditional double glazing, heat-reflecting glass is another option for more solar gain. This type of glazing minimises heat transfer, keeping your offices cooler in the summer and warmer in the winter.

Heat-reflecting glass works by reflecting a higher percentage of solar heat compared to traditional glazing. Thus, it can significantly contribute to the overall energy efficiency of your office, making it an attractive choice for organisations looking to maximise comfort and savings.

5 Signs It’s Time for Glazing Replacement

Knowing when it's time to replace your windows is crucial for maintaining your office's energy efficiency and comfort.

Signs that indicate the need for glazing replacement include:

  • Visible damage to the window frames
  • Persistent drafts
  • Condensation between the glass panes
  • A noticeable increase in energy bills
  • A noticeable decrease in the office temperature

If you observe any of these windows heating signs, contact us immediately for an evaluation and to learn more about the benefits of upgrading to more efficient glazing.

Reduce Heat Loss Through Window With GLRE

GLRE (Glazing Refurbishment) specialises in providing commercial glazing refurbishment and window replacement services. We offer solutions to help companies reduce heat lost through windows by upgrading their building’s glazing systems. At GLRE, we can help your businesses improve energy efficiency by replacing outdated single-pane windows with energy-efficient double and triple-glazing units.

We also offer low-emissivity (Low-E) glass solutions to help minimise heat transfer and slash energy consumption. Additionally, we offer services such as installing low-E exterior or interior storm windows and tightly installed cellular shades to prevent further heat loss.

Our team of experts in glazing refurbishment and replacement are super qualified to enhance your office building’s thermal performance with double or triple-glazing units.

Frequently Asked Questions

Are windows a big source of heat loss?

Yes, windows are a big source of heat loss in buildings. A typical office or home loses 18% of its heat through the windows, majorly contributing to increased energy bills and reduced office comfort. Windows typically occupy up to 40% of the surface area of the walls in offices. As a result, poorly insulated windows can lead to substantial heat loss, impacting heating and cooling costs.

How much heat is lost through a window?

A typical building loses 18% of its heat through the windows, making it a significant source of energy loss. Single-glazed windows lose heat 2x as fast as double-glazed windows. This loss occurs due to radiation, convection, conduction, and air leakage.

How much heat is lost through double-glazed windows?

Double-glazed windows don’t cause heat loss but minimise heat loss by up to 30% compared to single-glazed windows. This helps save up to £155 in yearly energy bills.

How do you prevent heat loss through windows?

To prevent heat loss through windows, you should increase the number of panes or glazings in the window unit of your office buildings. This is because singled-paned untreated windows are highly energy-inefficient. Low E-glass, custom-crafted windows, and insulating drapes can also help minimise heat loss and keep your office cool in warm climates.


Reducing heat loss through windows via glazing replacement is a valuable investment that can enhance your office’s comfort, energy efficiency, and sustainability. For real-life examples of how GLRE has transformed company buildings, check out these case studies.

Contact us today to learn more about how we can help you reduce heat loss and improve the energy efficiency of your office buildings.

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