Draught proof your home with secondary glazing

Glaze & Save are magnetic secondary glazing and draught proofing specialists – “Our award-winning flagship bespoke magnetic secondary glazing InvisiTherm® is an innovative polycarbonate secondary glazing that turns single glazing into double glazing, eliminating the need to replace windows.”

On 15th November, Dr Tanya Ewing, inventor and businesswoman, came to talk about her company’s secondary glazing product InvisiTherm. Hosted by Eco Savvy, a number of interested Arran locals attended and were treated to a practical, informative and optimistic hour with Tanya. She then visited attendees at home to give further advice on energy saving changes we can make.

While her talk focused on this innovative product, Tanya was overflowing with helpful advice, information, and enthusiasm on ways more generally to help keep our houses warm and increase energy efficiency. In the traditional built houses on the west coast of Scotland this can seem a tricky matter, and her aim she said, is as much to demystify the seemingly huge task of energy saving as it is to sell her product. Faced as we are now with the changing climate and increased moisture levels in the air, keeping our homes warm and dry is getting harder and more expensive. Heating cold damp air is very hard to do and while new builds are not immune to these problems, many of the traditional built houses are now experiencing such problems as reverse condensation. Tanya’s over-riding message however, is that ‘All is definitely not lost’, and there are many small and large things we can do help, not only for our homes, our warmth and lower bills, but also in reducing our carbon emissions.

Tanya explaining the movement of water through old stone walls

Increasing energy efficiency

She said there are four things we can do to help cut energy costs and mitigate the effects of the changing climate. Her talk focused on the first two:
1 – simple behavioural changes
2 – low cost easy install solutions
3 – pay back solutions
4 – high cost solutions.

Tanya’s view is that we can lead with the first, making a few small, practical and free changes in our behaviour. Even implementing a few of the following will make a significant difference to our energy efficiency. These include turning down heating by one degree to save up to 10% on your annual heating bill; getting to know your heating controls and how best to use them can save an average of 15% without compromising on warmth; closing your curtains one hour before it gets dark keeps your home an average of 2 degrees warmer; and insulating gaps or holes around pipes to eliminate draughts in your bathroom and kitchen. This can increase temperatures by up to 5 degrees.

Tanya also suggested using a plug-in energy usage display to understand how much it costs to run household appliances. We can save over £200 per year by turning off just four items at the socket. Buy insulating underlay to go underneath rugs, a chimney pillow to stop heat disappearing up the chimney, and heat reflectors for radiators. Radiators that are placed on external walls lose around 35% of their heat. Radiator foils reflect the heat back into your room and get 25% more efficiency.

For slightly bigger alterations insulate floors, walls, ceilings and lofts, using breathable materials such as rock wool. If you have a room that is difficult to insulate, use thermal (and breathable) insulating wall paper or insulating paint inside, and which can be used outside as well. The insulating wall paper can give up to 5 degrees more warmth in a room, and so it is great for the external walls in the house which suck out the warmth and retain the moisture. The secondary glazing option for windows is another relatively low cost easy install solution, as it avoids the need of replacing windows, and this is what Tanya talked about next.

Wood windows – friend or foe?

Tanya explained that draughty windows may not need to be replaced or even restored. Original wooden window frames, made with very good hardwood can last over 100 years. Problems come with newer fast growing hardwood that is used in wooden replacement windows today and can last under 20 years. Furthermore much of the modern draught proofing methods that window restorers use actually damages the frames and increases problems. The way brushes are inserted into the frame means the windows are not water tight leaving the window exposed to rain and will quite quickly start to rot.

However she said even if the windows have been replaced since 1960s and beyond, it is still possible to get life out of them. The thing is not to assume they must necessarily be got rid of, but learn how they can be improved. We need to ask ourselves – do I need to do anything with this window? She said that 80-90% of windows do not need replacing. If you do need a replacement however and are looking for a wooden window, the best hardwood to get is Accoya. It is organic and long lasting.


Many people have double glazed windows, and have replaced single glazed in traditional built houses too. If you do still have single glazed windows however it does mean a lot of heat is leaving through them. Single glazed windows can be replaced with double glazed glass but Tanya explained that a lot of the double glazing glass that is used in Scotland is ‘slim profile’ double glazing which does not actually meet building standards and is not as effective as thicker glaze. Or as Tanya was here to tell us, not as effective as secondary glazing.

Windows fitted with InvisiTherm glazing

Understanding these problems, and a gap in the glazing market, Tanya’s company developed a special glass called InvisiTherm, which fits magnetically onto your existing windows. It provides instant secondary glazing, and reduces heat loss by as much as 63%. It is very good at thermal efficiency, retaining the heat and bouncing it back again, and can keep rooms warmer by up to 5 degrees.Their company works mostly with heritage buildings, but they have also secondary glazed inefficient double glazed windows too!

Keen to do something about their cold and inefficient houses, the attendees at Eco Savvy were certainly convinced, and I think a couple of people have put in orders already with Glaze and Save to have their windows fitted.

For more information see the Glaze and Save website or contact Charlotte at Eco Savvy

Tanya’s final (and perhaps most important) tip, as the moisture levels rise in the air, is to invest in a dehumidifier! Some of these are low on energy consumption apparently, and inspired to help my dripping house, I will certainly look into getting one for Christmas. Before I start on insulating and in my case, window replacing, in 2020!