When it comes to saving energy within our homes, windows and doors are proven to be one of the biggest contributing factors to success. According to The Energy Saving Trust, windows and doors could be responsible for as much as 20% of a property’s heat loss. This not only ramps up a household’s energy bills, but it will increase its carbon footprint too. Wasting energy is far too costly in today’s world and, therefore, if homeowners can improve the thermal efficiency of their property, we recommend they do so with gusto.

With regards to windows, thermal efficiency is independently verified by the British Fenestration Rating Council (BFRC), the UK’s most trusted ratings council with the most widely used rating system for energy performance in windows and doors. This rating system is like those used on domestic appliances like washing machines and fridges. BFRC rated products are assigned an energy rating to indicate their energy performance with A++ being the highest and E being the lowest. The bandings on the BFRC energy label are calculated by taking into account a standard size of window, standard building occupancy, and average climate conditions.

In short, windows and doors with an energy rating of 0 or higher (Ratings A to A++) are considered to be energy positive.

What is A Rated double glazing?

A Rated, A+ Rated, and A++ Rated windows are the highest performing windows available in terms of energy efficiency and overall performance. Installing A Rated windows will help reduce the amount you pay each month on energy bills and can also help reduce the amount of heat loss in your home. The higher a window’s rating, the more it will cost. However, it is important to remember that, over the lifetime of a window, the initial outlay should be more than recouped in reduced energy bills. Plus, your home will be warmer, cosier, and more comfortable too.


What is the U-value of an A Rated window?

A U-value measures how effective an insulator a material is and, therefore, how successful it is at reducing heat loss. It is calculated by dividing the rate at which heat is transferred through a structure by the difference in temperature throughout the structure. Basically, the lower the U-value measurements are in your home, the more energy efficient it is.

  • An A Rated window can provide a U-value of around 1.4 W/m2.K
  • A+ Rated windows can achieve U-values of 1.2 W/m2.K
  • A++ Rated windows can reach U-values as low as 0.8 W/m2.K


Are sash windows energy efficient?

Many older period properties built in the Victorian and Georgian eras still boast their original sash windows. Although unquestionably beautiful, they are renowned for being energy-inefficient and draughty thanks to single-glazing, failing frames, and the general wear and tear that you would expect from windows that are more than a century old! However, that doesn’t have to be the case.

Many owners of period properties are unaware that it is possible to double glaze sash windows.  Modern timber sash windows are certainly able to accommodate thicker double-glazing. In fact, double glazed sashes will add value to your property too. It is possible to fit new double-glazed sashes into your existing frames (sash repair), but if your original box frames are beyond repair, it will be necessary to remove the whole window (sash replacement), including the box frame, and fit a completely new one complete with double-glazing, architraves, window boards, and everything else.

If you own a listed property, you may be concerned that replacing sash windows completely will require planning permission or remove too much of the originality and aesthetics of your home’s tradition roots. This no longer needs to be the case. At Parsons Joinery, we can improve the energy efficiency within listed properties because we are one of a few approved installers of Fineo vacuum-insulated glass windows. Fineo is the perfect solution for retrofitting into the original, smaller sash frames found in listed properties. The super thin vacuum glass can be fitted into the original sash window frames that listed properties are keen (and required) to preserve.

Despite being the width of single glazing, the glass is more thermally efficient than a traditional triple glazed unit. In fact, Fineo vacuum-insulated glass boasts a U-value of just 0.7 (A++ standard). On top of being super energy efficient, Fineo vacuum insulated glass provides a 34% reduction in perceived traffic noise compared with single glazing, better light transmission, and better solar gain.

If you already have double glazed sashes, regular maintenance and repair is key to ensure the existing sashes and frames not only look like new but are as efficient as they can be. A regular overhaul of your sashes will highlight any damage, broken locks, rotten timbers, or poor insulation, so you are able to get these issues resolved quickly and retain the quality and energy efficiency of your windows.

If you would like to discuss new sash window glazing options, sash window repairs, or draught sealing services, the team at Parsons Joinery would welcome your call or website enquiry.