How Can I Optimise the Energy Efficiency of My Windows?

We all want our carbon footprint and energy costs to be decreased this winter but did you know that overhauling, updating, or replacing your windows to make them more energy efficient could help reduce both?

In this article, we will outline the many window upgrades you can make, energy-efficient window options available, and the best strategies to reduce these escalating costs in your home. There are several solutions available for upgrading your window system, regardless of whether you are a leaseholder or freeholder, live in a new-build home, or you are considering renovating a traditional period property.

Ways to improve window performance

  • Draught-proofing. Finding and correcting draughts will increase the comfort and energy efficiency of your house. Draughts and ventilation both allow for the entry of cold air into your home. Ventilation can inadvertently let heat escape although it reduces the chance of internal condensation and dampness in the winter months.
  • Thermally efficient single or double glazing within existing frames. Installing a “secondary” window, a totally independent interior window, on the room side of your current primary window is known as secondary glazing. Secondary glazing can offer a practical and affordable method to increase the security, soundproofing, and heat retention of your windows. 
    Although it’s worth bearing in mind that this cost would go a long way towards investment of full replacement windows.
  • Window replacement. Window replacement may not be a viable option for every household, but it does allow you to pick the best and latest in energy-efficient technology to help properly insulate your home in winter. 

Understanding the energy performance of windows 

Windows are proven to help with energy efficiency and a reputable window manufacturer should be able to tell you what ratings their windows can deliver. All windows and doors in the Genesis Collection have been designed to deliver excellent energy performance characteristics.


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Both UPVC and aluminium windows & doors can make a huge difference to energy costs in everything from period homes to newbuilds – the key is to ask and understand what performance they offer. 

Understanding and getting the best WER (window energy rating) windows and doors is a great place to start. Sometimes WER can be measured by the U-Value and this can typically range between 1.8 and 0.8W/m2k, the lower this number, the more energy efficient your windows will be. 

All Genesis Collection windows and doors hold an excellent energy efficiency rating. Simply scroll down on all our products to see each rating.

Windows that are best for New-Builds 

Part L building regulations, require all new-builds to achieve a good standard of energy saving for the potential homeowner and at this present time it is a 31% improvement on the preceding legislation. 

You may already be aware and familiar with A, B, and C energy-rated windows but it’s also worth understanding U-Values and the lower the number the better. As mentioned previously, these typically range between 1.8W/m2k and as low as 0.8 W/m2k. 

If you are looking to add new windows into a new build property, we recommend any of the following options which adhere to government guidelines. 

  1. Double glazing with argon-filled glass units and warm edge spacer bars is available on all products.  Check out all of our Double Glazing options here.  
  2. Triple Glazing with argon-filled glass units and warm edge spacer bars are available on all products except sliding sash windows. Which includes:

  • Flush casement windows
  • Casement windows
  • PVC bifold doors
  • PVC Sliding patio doors
  • French doors
  • Flush French doors
  • Aluminium windows
  • Aluminium bifold doors
  • Aluminium Sliding patio doors

Windows that are best for renovations

When you are looking to upgrade your home in the form of renovations, there can be a number of regulations you have to follow. Whilst part L doesn’t apply to renovations, homeowners today are instead motivated by environmental concerns and the rising cost of energy. Having energy-efficient windows and doors makes a huge difference to both of the above. 

If you are looking to implement windows into your renovation we recommend any of the following options: 

  • Energy-efficient sliding sash windows
  • Energy-efficient aluminium windows
  • Energy-efficient aluminium bifold doors
  • Energy-efficient flush casement windows
  • Energy-efficient flush casements
  • Energy-efficient French doors
  • Energy-efficient sliding patio doors