Retrofitting Original Windows in Historic Buildings | Glaze & Save

Listed and historic buildings need some extra attention when it comes to adding energy efficient improvements to their windows, but we could all do with enhancing the efficiency of our homes. By adding improvements to the existing windows, you can save yourself money as well as saving the planet.

What is Retrofitting?

Retrofitting is the addition of improvements to a property to reduce energy consumption. Retrofitting energy efficient improvements to your original windows will extend the life of historic and traditional buildings while making them consume less energy, therefore being more environmentally friendly.

Why do we need to retrofit older buildings?

Scotland had many traditional buildings, with buildings built prior to 1919 making up roughly 19% of total building stock. As well as this, many inter war properties have solid walling, meaning that over half of all of Scotland’s houses are energy inefficient. Over 40% of our CO2 emissions comes from current building stock.

Listed and traditional buildings are generally deemed to be hard to treat, and planning controls associated with listed buildings generally create issues in obtaining funding for upgrading schemes. As such, it is important to look into retrofitting measures that work within the planning constraints of your building. Demountable or removable improvements such as Glaze & Save InvisiTherm™can often be more beneficial and easier to approve in these situations.

Windows often account for large areas of walling in traditional houses and tenement flats. It’s a feature that we love; however they can be massively inefficient. Despite this ineffiency, keeping your original windows in tact is almost always the best way to ensure the look, feel and character if your property, while reducing the construction waste associated with installing replacement windows. Original windows are almost always made of superior quality materials as well, ensuring that they will stand the test of time better than their modern equivalents.

We use U values to measure how effective a material is as an insulator: the lower the number, the better an insulator the material is. Single glazed windows are a very poor insulator with a U value 5.5. Adding heavy lined curtains to your windows can bring this down to 3.3. Shutters can bring this down to 2.2. (Insulated shutters 1.6)

Secondary Glazing

Secondary glazing sometimes has a bit of a bad reputation. Metal-framed glass windows, or musty acetate, affixed with ugly hinges do little to counter this. Glaze & Save InvisiTherm™ changes that by using innovative polycarbonate and a discrete, demountable magnetic strip to hang from. Because InvisiTherm™ is completely removable with no damage to your existing windows, in many cases you do not need to obtain planning permission to install it. Not only that but InvisiTherm™ can also be fitted to allow shutters to work and involves no loss of the original fabric of your windows. You can retain original your sash windows with historic glass, and avoid altering or removing them to receive double glazing.

Glaze & Save InvisiTherm™ is the most energy efficient secondary glazing on the market and can bring the U value to 1.7.

Draught-proofing

Original sash windows helped a home to breathe, but they were not meant to be draughty. As time passes the wood of the sash window becomes warped, leading to gaps of up to a combined ten inches squared! Draught-proofing is therefore one of the easiest and most efficient ways to increase the energy efficiency of your home by combatting uncontrolled air flow.

This can involve the use of brush strips fitted to parting beads, baton rods and meeting rails, and can also involve routering out new units or brand new beading. This can cause problems to your original windows, as such invasive procedures inevitably weaken the wood of the window and can lead to further warping, or dropped sashes. Glaze & Save InvisiSeal™ is another option: an innovative homogenous silicone that seals the draughty areas of your windows and doors before discretely drying like rubber. Best of all, InvisiSeal™ is completely non-invasive, meaning that your windows remain completely intact, all while being almost completely invisible.

Draught-proofing wont decrease the U value of your windows; however it will seal off some of the air flow in your home, allowing you to reduce your energy consumption and enjoy a less draughty house.

Window Films

One of the quickest ways to treat tricky original windows, or to add some extra privacy, glare reduction of cooling functions is by the addition of window films. Gone are the days a limited options and bubbly films. Glaze & Save InvisiFilm™ is professionally installed film with a range of different functions and aesthetic appeal. In conjunction with draught proofing measures such as InvisiSeal, this is a great option for fragile older frames that may not cope with the added weight of secondary glazing, or for those who would simply like a privacy solution that doesn’t include net curtains (which is particularly beneficial if you want to use your working shutters for example).

So there you have a few ways in which you can go about retrofitting the original windows of your historic buildings. Remember: retrofitting original windows is almost always more cost effective and generates better payback times than installing replacement windows. So preserve these integral parts of your building’s history and character, while saving yourself some money at the same time.

You can find details of all of Glaze & Save’s retrofitting solutions on our website.