Adding double glazing to a historic building is a sensitive and tricky business. You can greatly improve the energy efficiency of a period building by adding additional glazing to the windows, but the original design of the property should never go unchanged. This means uPVC units are out of the question, and most conservation areas will never agree to replace original sash windows with modern uPVC units anyway.
This can leave period property owners a bit stumped on what to do. Perhaps secondary glazing is the way forward. After all, this adds an additional pane of glass to the windows and can help with energy bills a bit.
However, adding secondary glazing to a glazed sash window means that the interior of your home will be changed. You’ll no longer have access to your window sill, for example. Plus, secondary glazing is not that energy efficient when compared with more modern window technology.
Can you add double glazing to existing sash windows?
You can additional panes of glass to your original windows by retrofitting another pane of glass into the existing window frame. This is what we specialise in. We can transform single glazing into double glazing without changing the look of your property at all.
While this sounds like window magic, the principles are very sound. We add an additional pane of glass to your glazed units, with a very small gap in between them. We then create a vacuum in this gap. The vacuum prevents heat transfer from the two panes of glass. So, in the winter, the internal pane is nice and warm from your heating, but the outside is cold from the winter weather. The vacuum doesn’t allow for any heat transfer, so vacuum-sealed double glazing is highly effective. So much so that this glazing technique is 3-4 times thinner than modern gas-filled double glazing, yet just as effective as triple glazing.
By adding vacuum-sealed glazing technology to your period windows, you are massively improving the energy efficiency of your home. Your glazed windows, which were once sucking the energy out of your home, are now helping keep the energy inside your home better than almost anything else.
Why do people retrofit double glazing into sash windows?
There are several reasons why people choose to add this new window technology to their homes, but the main one is to reduce their energy bills and improve the home’s energy efficiency. Investing in new window technology while on a Pennywise Power plan can ultimately lead to cost savings, increased comfort, and a more sustainable home. Glazed units in any building are responsible for a lot of the heat transfer of a home. So by improving the windows, you can greatly reduce how much heat is being transferred.
Another big reason for retrofitting this glass technology into windows is noise. If someone lives in a high-traffic or particularly noisy area, this technology can really help reduce the amount of noise entering their home. The acoustic performance of this FINEO glass (the glass we use in all of our window restorations) is exceptional. FINEO does make acoustic glass, but the standard units work so well that it is only ever needed in very extreme cases.
So, acoustic and thermal performance are the biggest reasons why most people choose to retrofit their single-glazed windows with this incredible window product. This doesn’t change the look of your original box frames at all, your sash windows will still look absolutely beautiful, but the thermal efficiency of your home will dramatically improve.
How to add double glazing to a period building?
Our wooden window restoration services begin by removing the windows and treating any rotten timbers. Rot is a big problem with wooden windows, particularly if the windows haven’t been cared for or maintained. We will go through all of the windows with a fine toothcomb and treat any rot we find. In some cases, this involves removing sections of the wood and splicing in fresh timber. We will do this with the window frame, the glazing bars, the sills and every other component to ensure that all of the timber is healthy and ready for the next steps.
After this, we will remove the glazing bars and clean up any old putty from the glass. We will clean or replace the glass where needed, and then reinstall the glazing bars, and add in the new pane of glass to create the double glazing. We then add new putty and create a vacuum, sealing the unit to create double glazing that is just as effective as triple glazing.
We can then turn our attention to the sills and the internal components of the window mechanism. If the sash cords, weights or pulleys need restoring or replacing, we will do this to ensure the windows work perfectly.
Once we have the windows working just as they did when they were first put in, we will mask off the glass, give everything a good sanding, prime and paint. We only ever use high-quality exterior-grade paint. This ensures that the work we do lasts for as long as possible and that your windows look excellent for years to come.
Will the energy efficiency of my home improve with double-glazing?
Compared with the single glazing that you have now, your windows will be a vast improvement. The EPC rating of your home will improve, and so will the noise levels from external noise. The sash window double glazing that we use has a U-value of 0.7. The single-glazed windows you have now will have a U-value of somewhere around 5. However, this number could be higher depending on the condition of the timber and glass.
To put that into context, regular uPVC double glazing has a U-value of 2.8, and modern triple glazing has a U-value of 0.7. This means that your existing windows can be brought to the same level as triple glazing without changing the look of your home at all. In short, double glazing can massively improve the energy efficiency of a period property.
Will the look of my sash windows change?
What’s more, your original timber sash windows will look completely unchanged. This is the biggest difference between retrofitting double glazing into traditional sash windows and replacing them with uPVC sash windows. If your windows are replaced with uPVC, the charm and look of your property will be changed forever. This is why retrofitting sash windows with double glazing is the best way to bring your home’s energy consumption into the 21st century.
The noise pollution will be reduced, your energy bills will go down, but the look of your property will be as beautiful as it always has been. The windows will look brand new, just as they did the day the window fitters installed them hundreds of years ago.
How our wooden sash window restoration services can help
If all this sounds a bit too good to be true, we urge you to explore our window restoration services more and take a look at the FINEO glass we use in each of our installations. It is a fantastic glass technology that has allowed us to restore timber sash windows to the highest level for years.
We are sash window experts, and we’re here to help you. While sash window restoration may seem like the expensive option, the money you save on energy bills compared to secondary glazing or refurbishing your current windows but leaving the glass untouched is unparalleled. It is the perfect way of investing in your home’s future. And with the proper maintenance schedule in place, your windows will continue to look great for decades.
We can restore all types of window in period homes, including sash and casement windows. We can also double glaze your French doors and restore all exterior wood. By choosing to retrofit double glazing into your windows, you are bringing your home into the 21 century while keeping the iconic and beautiful windows alive. In our opinion (biased as it is), this type of restoration is the best and only way of modernising your windows, improving the energy consumption of your home and preserving the history of your home.
For more information about our window restoration services, please explore our website further. We have all the info you need or feel free to call us. We can have a chat about your windows and offer advice on the best services to use. We are here to help you restore your home with the latest window technology. We’ll bring your timber windows back to life and ensure your home has never looked so good!