What Is the Cost of Replacing Windows? [Complete 2024 Guide]

Table Of Contents

Do you know that replacing your windows can save you up to 25–30% of your annual energy bills that result from heat loss? While this is a compelling reason to consider window replacements in your office building, it's also crucial to understand the costs involved.

Windows form an integral part of any building, offering light, ventilation, and aesthetics. However, over time, they can become less efficient, leading to increased energy bills and maintenance costs. At this point, hiring commercial window replacement services is the way to go!

In this comprehensive guide, we'll analyse the cost of replacing windows, particularly sash windows, in the UK and the benefits that come with it. Let’s begin by considering the options available.

Window Replacement Options and Cost

There are different options available for office building replacement windows, including:

1. uPVC Sash Windows

uPVC sash windows, also known as plastic sash windows, are a cost-effective and low-maintenance alternative to traditional wooden sash windows. They replicate the classic charm of wooden sash windows but offer improved thermal efficiency and security. If you are planning to replace your office windows, uPVC sash windows prices in the UK range between £1000 and £1500 per window.

uPVC Sash Windows Image

Tip: Given their high cost, it’s important to understand when you need to repair uPVC window or replace it.

2. Double Glazed Windows

Double-glazing sash windows provide a significant upgrade in terms of energy efficiency. A double-glazed window consists of two panes of glass with an insulating gas layer in between, reducing heat transfer and making your office more comfortable.

The cost of sash windows double glazed can be slightly higher than single-glazed ones due to the additional pane of glass and the insulating gas layer. However, the increased cost can be offset by the energy savings they provide. On average, double-glazing sash windows cost starts at £600 per window, and up to £1,125.

3. Bay Windows

Bay windows can add a unique architectural element to your building. They project outwards from the wall, creating a bay in the room. This not only provides additional space but also allows more natural light into the room. A uPVC sash bay window can be a cost-effective and attractive addition to your property.

Bay Windows

The cost of uPVC sash bay windows can vary depending on their size and design. However, they are generally more affordable than their wooden windows counterparts. To get a precise cost, it's recommended to use a uPVC sash window cost calculator, which can provide an estimate based on your specific requirements.

In case you’re wondering if there are any benefits to replacing windows, given the cost, there indeed are. We will discuss some of the advantages of replacing your building windows in the next section.

What Are the Benefits of Replacing Windows?

Window replacement provides several benefits that can’t be gotten from an older window, such as the following:

  • Enhanced Appearance: Replacing old and worn-out windows with new windows can enhance the aesthetic appeal of the office building, giving it a refreshed and updated look.
  • Energy Efficiency: New, thermally efficient windows contribute to a more energy-efficient environment, reducing heating and cooling costs and promoting sustainability.
  • Cost Savings: Replacing old, drafty windows with modern ones can significantly reduce energy costs, offering potential savings on heating and cooling expenses.
  • Improved Security: Modern windows offer improved security features, reducing the risk of break-ins and providing peace of mind for building occupants.

Having understood the perks that come with replacing your office building windows, let’s walk you through how to calculate the cost in the next section.

Calculating the Cost of Replacing Windows

It’s crucial to understand how much a window costs to make an informed decision when budgeting. For this, you will need a plastic sash windows cost or uPVC cost calculator. 

A uPVC sash window cost calculator can be an excellent tool for estimating the cost of your window replacement project. It considers factors like the size of the window, the type of glazing, and the style of the window. Simply search online for some handy options to make your decision.

Calculatinf Cost Replacing Windows

Alternatively, you may contact a professional glazier to evaluate your existing windows and get a quote on what a replacement will cost. Professionals can analyse the building based on verifiable factors and give you a more accurate estimate based on current market data.

Take note that cost is largely influenced by the window type and other factors. For example, the cost of replacing sash windows is typically higher than other types due to their complex design and installation process. On average, replacing a sash window with double glazing starts at £1,300 per window. However, this can vary depending on many other factors that we will discuss in the next section.

Factors That Influence the Cost of Replacing Windows

The cost of replacing windows can vary depending on several factors, including:

  • Window Material: The choice of material significantly influences the cost of new windows. Wood is generally the most expensive option, with uPVC being the cheapest. Aluminium offers a mid-range price point.
  • Window Size: Larger windows require more materials, hence increasing the cost.
  • Design Complexity: If you opt for a more intricate design, expect to pay more.
  • Glazing Type: Single, double, or triple glazing will affect the price. While single glazing is the most affordable, it offers fewer benefits than its counterparts. Check out our post on triple glazing vs. double glazing for more info.
  • Number of Windows: Generally, the more windows you need to replace, the higher the total cost.
  • Accessibility: Difficult-to-access windows will take longer to replace, hence increasing labour costs. You will typically need rope access glazing services for difficult-to-reach areas.
  • Location: The cost of labour and materials may vary depending on your location.

In summary, there is no one-size-fits-all method to determine the cost of a window replacement. If cost is a great consideration, we will recommend substituting sash windows with many other alternatives available. The next section covers some budget-friendly window replacement options.

6 Budget-Friendly Alternatives to Sash Windows

While sash windows offer numerous benefits, they might not suit everyone's needs or budget.

In such instances, it's worth exploring alternatives such as the following:

1. Sliding Windows 

Sliding Windows

Sliding windows have the following features:

  • Horizontal sliding design.
  • Ideal for spaces with limited exterior space.
  • Offers unobstructed views and good natural light.

2. Dormer Windows

Dormer windows provides your office with the following features and advantages:

  • Vertical windows set into a sloping roof.
  • Adds architectural interest and aesthetic appeal.
  • Creates additional headroom and usable space in lofts.

3. Bi-Fold Windows

These types of windows have the following perks:

  • Multiple panels that fold back to create a wide opening.
  • Seamlessly connects indoor and outdoor spaces.
  • Enhances natural ventilation and modern aesthetics.

4. Tilt-and-Turn Windows

Tilt and Turn Windows

These windows are suitable for office spaces and have the following advantages:

  • Open inwards for ventilation or tilt for secure ventilation.
  • Easy to clean from the inside.
  • Offers enhanced security and energy efficiency.

5. Casement Windows

Casement windows offer the following benefits:

  • Hinged on the side and open outwards.
  • Provides good ventilation and unobstructed views.
  • Flexible design options to suit various aesthetics.

6. Aluminium Windows

Aluminium windows have the following features and advantages:

  • Durable, resistant to corrosion, and require minimal maintenance, making them ideal for office buildings.
  • Modern with sleek designs.
  • Affordable window prices.
  • Energy efficient.
  • Provide robust security features, contributing to the safety of the building premises.
  • Offer a range of design options, allowing for customisation to suit the specific architectural requirements of office buildings.

Any of the above will be a great alternative to sash windows if you’re looking to cut down on the cost of replacing windows. To get the best out of your new window unit, we recommend hiring glazing professionals, as they have the required expertise — more on this below!

Hire a Professional for Window Replacement

Window replacement is an often-complicated task that’s best left to professionals with “experience.” Glazing companies like GLRE offer commercial window replacement services for UK businesses. We have the equipment and expertise to handle complex and challenging projects, ensuring your window replacement is carried out safely and efficiently.

As the leading glazing services provider for UK office buildings, we also specialise in high-level glass replacements, leak resolution, glazing inspections, rope access, and more. Contact us today to discuss your window replacement needs and get a personalised quote.

Frequently Asked Questions

What is the average cost of replacing windows in the UK?

The average cost of replacing windows in the UK is based on several factors. A single window replacement costs between £160 to £2,000. However, for a typical 3-room building with 8–10 windows, opting for double-glazed uPVC windows could result in a total cost of approximately £1,200 to £12,400.

The final cost depends on various considerations, such as the size of the windows, the type of window frame, and any additional features like enhanced security or energy efficiency. Therefore, it's essential to obtain quotes from professional glaziers based on your requirements.

Is it cheaper to replace all windows at once?

Yes, replacing all windows at once can be cheaper in the long run. When addressing age and deterioration, replacing all office windows at once can result in substantial new windows cost savings. This approach may save thousands in future repair or replacement expenses, as windows tend to wear down over time.

By replacing them all at once, you can avoid the potentially escalating costs of individual replacements and ensure a consistent level of quality and energy efficiency across all windows. Additionally, bulk replacement often allows for better deals on materials and labour, further contributing to cost-effectiveness.

Should I replace 20-year-old windows in the UK?

Yes, it’s advisable to replace 20-year-old windows in the UK, given that’s just about how long windows last. Windows of this age are likely to be significantly less energy-efficient compared to modern alternatives. Their inefficiency can result in increased energy bills, as older windows may allow heat to escape during the winter and heat to penetrate during the summer, causing heating and cooling systems to work harder to maintain a comfortable indoor temperature.

By replacing these windows with newer, more energy-efficient models, you can save on energy costs and create a more comfortable and sustainable office environment.

Can I replace windows myself?

It’s generally recommended to hire a professional for window replacement. If anything goes wrong when fitting your own windows, the damage may not be covered by insurance. Additionally, installing windows yourself could void the manufacturer's warranty, so it's crucial to be certain about your ability to properly install the windows.

Moreover, not every window has the same installation process, making it a complex task that requires specific skills and experience. Hiring a licensed, reputable window installation company like GLRE ensures that the job is done correctly, protecting your investment and ensuring the warranty remains valid.


Replacing windows, particularly sash windows, can bring about a remarkable transformation to your office building. Not only does it enhance the aesthetic appeal, but it also contributes to energy efficiency and improved security. By understanding the cost of replacing windows, you can opt for traditional sash windows with timber frames, cost-effective uPVC alternatives, or explore unique options like bay windows, with substantial benefits.

For professional and reliable window replacement services tailored to your specific needs, contact GLRE, the leading commercial glazing services provider in the UK. Take the first step towards a more impressive and energy-efficient workplace.

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