Energy Demand

There are various options for upgrading windows and doors, depending on the type of windows and doors you have and their condition.

The thermal performance of different types of windows varies dramatically, for example the thermal performance of some triple glazing is about 7 x better than some single glazing.

Below are some tips for upgrading or replacing windows and doors to improve the performance of the thermal envelope of your building.

• If you have single glazing, or windows and doors that are in poor condition consider replacing it with double or triple glazing.
• If you have double glazing that is old or the seals have failed but the window frames are in good condition you can replace the double-glazed units with modern units to improve the performance without having to replace the whole window.
• If you have single glazing and live in a listed building then you may not be able to replace historic glazing with modern windows. In this case secondary glazing might be a good option. In secondary glazing systems, a separate, double-glazed unit is fitted inside the window reveal to provide the performance of double glazing but without affecting the external appearance of the building. Secondary glazing is generally cheaper than replacing windows so it is also a good option for those with a lower budget who are looking to improve the thermal performance of their windows.
• It is also important to think about the window/door reveal – this can be insulated to minimise cold bridges around the window/door.

4. Are older properties more difficult to make energy efficient due to their construction? 100 years plus...

It is completely possible to improve the energy efficiency of older houses, including those with solid walls or timber frames. In fact, older buildings are often the worst performing so there is the most opportunity to improve. Work to historic buildings may require consent, so make sure you get all the permissions required before doing any work to a historic building. At Keystone, we have experience of upgrading the thermal performance of historic buildings, and working with listed and heritage buildings generally and can assist you in gaining any necessary consents.

The construction of old buildings is often breathable – which means that the building fabric allows moisture to move through it which prevents damp from occurring. Changing the construction can affect the way the building works and trap moisture which can cause damp and damage the structure. Therefore it is important to think carefully about the existing building and how it works and choose an appropriate solution. This will often involve specifying breathable insulation and finishes.

Replacing the windows and doors in heritage properties can make a big difference to their environmental performance. If you live in a conservation area or a listed building there are sensitive options for replacement doors and glazing that provide modern levels of performance with a traditional aesthetic. If replacing doors or windows is not permitted due to their heritage value you can install secondary glazing to improve the performance of windows and doors without removing historic fabric.

Historic buildings are often very leaky – this means that they can lose lots of heat in the winter through uncontrolled air infiltration. If this uncontrolled ventilation is reduced through added insulation and improved fittings then to prevent the build- up of moisture, pollutants and toxins it may be necessary to add other forms of controlled background ventilation to provide an adequate supply of fresh air to the building.