Retrofitting double glazing to wooden windows can improve energy efficiency, increase comfort and reduce energy bills.
Absolutely, original sash windows in historic properties can now be refurbished, draught-proofed and upgraded with slim-profile vacuum double-glazing units.
This ensures that such unique windows keep their charm while providing the convenience of energy efficiency.
The reglazing of the original windows can improve their energy efficiency to match the performance of modern A-rated windows.
These photos show a sash window before and after renovation. The second image displays the same window after being refurbished and double glazed.
1. Remove existing single glazing
2. Retrofit new slim-profile vacuum glazing into existing sashes
3. Change cords and add additional weights to counterbalance the additional weight of the new heavier glass. Service pulleys and add new cords.
4. Draft proof the existing sashes
In most period properties, original sash windows still have single-pane glazing installed. Single-glazed windows are not energy efficient; as a consequence, homeowners pay higher energy bills and have condensation on their window panes during colder winter months. Single glazing also has low acoustic insulation properties.
Retrofitting double glazing to wooden windows is done by removing existing single panes of glass and installing new slim-profile heritage double glazing.
We use slim profile, vacuum-sealed units with exceptional thermal insulation properties, equivalent to triple glazing. Our double-glazing installation methods ensure that important original characteristics of the historic property are preserved, living conditions are enhanced, and the extended service life is guaranteed.
Thermal camera testing of our recent double glazing retrofitting projects.
When compared to the thermal performance of single glass pane windows, double-glazed units reduce heat loss and improve the energy efficiency of original sash windows by up to x8.
Vacuum slim-profile double glazing (only 8-10mm) with Low-E glass has the same thermal and insulation properties as 36 mm triple glazing.
It also beats by energy performance the standard heritage double glazing with laminated glass and insulated with inner gasses such as Krypton and Argon.
Different glazing options for sash windows are compared by thermal efficiency, thickness and stability to fit existing original sashes.
By retrofitting double glazing to wooden windows, the noise pollution from outside your house will be reduced.
For example, the Fineo glass has an acoustic performance that reduces perceived noise by over one-third compared to single glazing.
If you live on a busy road, this reduction in external noise will help you sleep longer in the morning instead of waking up with the first commuters.
Double-glazed units are harder to break, so they increase the house’s safety.
Where required by building regulations, the units can be made using toughened glass (laminated glass or tempered), which is even more secure.
The market value of your property will also increase after retrofitting.
The market value of your property can significantly increase after retrofitting, with studies showing an average boost of 10-12% to property values.
This increase can be even more substantial for specific energy-efficient improvements: Installing double-glazed windows could add up to 12% to your property’s value.
With our advanced vacuum-sealed glazing units, you can expect even higher returns on your investment, as they provide superior thermal performance comparable to triple glazing while maintaining the authentic appearance of your period windows.
On the 10-sash windows project, our team will usually spend around 5-7 working days. The work will include wooden frame refurbishment, retrofitting and painting.
The most likely answer is yes!
There is a wide range of challenges involved in retrofitting double glazing to wooden windows. It all depends on the condition of the wooden frames, access to the window and the size required.
Slim-profile double-glazing units are evaluable in special shapes: curved, full-curved, trapezoidal or oval shapes.
Maximum: 1.50 m x 2.50 m or 1.60 m x 2.40 m
Minimum: 0.20 m x 0.20 m
Vacuum-sealed double-glazing units are not visible when fitted into the sashes.
The traditional sash windows with this new generation of double glazing look no different to how they looked with single glazing.
New double-glazed sash windows with standard double-glazed units and E-coating are 120-270% less efficient than the original sashes that our specialists retrofit with vacuum glass.
The sash window secondary glazing, on the other hand, does change the appearance of the original windows. It is bulky from the inside, takes up much of the interior window sill space, and is noticeable outside.
The photos below show the window our team double glazed and a traditional sash window with secondary glazing:
When installing double glazing in period windows, we face and overcome several key challenges:
Yes! We mostly work with Grade 2 listed buildings.
For listed buildings, installing modern vacuum-sealed double glazing is often the best solution, both technically and from a conservation perspective.
Thanks to recent technological advances, we can now offer glazing options that weren’t available when your original timber windows were made. Our vacuum-sealed double glazing units are:
What does this mean for your listed property? We can upgrade your windows while preserving their historic character because:
We are able to provide a wide variety of glazing options to suit all different needs and window styles.
We expertly select and install the best double-glazing for sash windows to maximise benefits, comfort, and security. Here are some of the glazing options you could choose from:
Additional glass panes also mean the addition of weight.
Thankfully, this does not impact the smooth operation, strength or safety of your windows. Correct adjustments of weight and pulley system will leave your sashes running even smoother, stronger and safer than before.
We replace and upgrade sash cords and re-balance your sash windows using additional weights.
When we remove sashes to fit in new glazing, we also check pulleys and replace them if required. We also straighten sash joints while doing other restoration work on wooden frames and sashes.
To properly prepare wooden windows for safely accommodating the additional weight of your glazing upgrade, we provide all the services you need, including sash windows refurbishment.
When we fit new vacuum glazing we repair box sash window frames and sashes because rot is a very common issue in historic windows.
Over time, original timbers succumb to the elements and need professional restorations to return them to full health.
We repair all rotten timbers and frames, as well as any structural damage, leaving them ready for secure new glazing installation.
Our team can reinforce weak frames and original joinery without impacting its aesthetic. We carefully assess each window to guarantee the best fit and provide a safe, smooth-functioning experience.
It is common practice for us to install draught-proof systems alongside fitting double-glazing. This further enhances the thermal, acoustic, and functional benefits.
Combining services such as double-glazing, woodwork repairs, decorations and draught-proofing as part of the same project is a great way to really optimise your living conditions, property value and all-around quality.
These services all go hand-in-hand and provide an effective, efficient way to complete comprehensive restoration work.
The two panes of glass trap air in the small gap between them. This layer of trapped air insulates against heat transfer from the outside to the inside of a property and vice versus. The air between the panes is also a barrier to noise and condensation. So double glazing is basically a clear layer of insulation for your home.
Most double-glazed units use gas as insulation.
This gas is argon. Over time, this gas will dissipate and disappear. This typically happens in around five years. We use vacuum double-glazing technology at Chameleon, though.
Vacuum double glazing does the same job as gas-filled double glazing but lasts for much longer. Vacuum double glazing comes with a 15-year guarantee and improved noise reduction, and a great deal more.
It is why we choose vacuum insulated glazing for all of our window restoration projects. It offers the same heat, noise and condensation protection as triple-glazed windows but in the form factor of double-glazing. It is highly energy-efficient and will insulate your home much longer than traditional double glazing.
No, we complete all work on-site.
If you have an older property with single-glazed windows, they can cost you a lot of money because of how inefficient they are at keeping the heat inside your home.
Double glazing is a great option for you. However, many restrictions exist for double-glazing units in older homes.
For example, listed buildings cannot have double glazing installed, which changes the character of the property.
Chameleon installs ultra-thin vacuum double glazing into existing old sash window frames that keep the character of a property intact.
Double-glazing is better than single glazing at stopping heat transfer because of the layers of glass.
Double glazing is a great way to keep your home’s temperature stable.
It acts as a barrier between the inside and outside, preventing cold or hot air from mixing with the air in your home.
Additionally, double glazed windows help block noise and condensation, keeping you comfortable all year round.
