As a generation, we are becoming more and more aware of our impact on the environment. From the foods that we consume to the paint we use inside our house, there is a constant need to reduce our carbon footprint. For those renovating their homes or looking to invest in quality updates, your windows are an ideal place to consider environmentally-friendly practices. Is there such a thing as an environmentally-friendly window? And, if so, what styles should you be choosing and why? In today’s article, we’ll look into all of this and more.

What Is an Environmentally-Friendly Window?

When we talk about windows or objects that are environmentally friendly, what we’re referring to is their impact on the planet. This includes all aspects of their creation and uses, from manufacturing materials through to how effectively they reduce heat loss. With windows, it refers to the entire window unit including frame, glass and fixings of any sort. How well do all of these components work together to help minimise the damage and impact they have on our surrounding environment.
When we consider it in this way, it becomes easier to understand which options are ‘best’. Let’s break windows down into their individual components and lay out what you need to look for.

Window Frames

In general, you’ll find that window frames are manufactured from 4 main materials:
  • Wood.

  • UPVC.
  • Fibreglass.
  • Metal.

When considering the most eco-friendly option, you’ll want one that has a low thermal transmittance (U-value), a low energy-intensity rate during manufacture and, ideally, one that can be recycled after use.


Being a natural material, wooden frames are some of the most eco-friendly options available. This is particularly true if the wood used has been harvested from sustainable sources. For some manufacturers, they also opt for recycled and reused wood during their manufacture. Wooden window frames also tend to have a U-value of around 1.2 W/m2, making them an ideal choice for helping to minimise heat loss.


It may surprise you to know that UPVC windows are actually one of the most environmentally friendly choices you can make. Modern design and manufacture allow most options on the market to achieve energy efficiency ratings of A with tailored channels and designs that minimise draughts. UPVC is also a recyclable material that can be melted down after use and re-used. All of this can happen without the material losing any of its original strength or insulating properties. With triple glazing, UPVC windows can have a U-Value of as low as 1.1 W/m2, which only increases to 1.6 W/m2 with standard glass.


While fibreglass cannot be easily recycled, it has still become a popular alternative to vinyl windows. This material has exceptional strength and provides good insulation, allowing homeowners to better manage the temperature in their homes. The actual construction of fibreglass windows is less environmentally impactful than some other processes. And, they have longevity which makes them more eco-friendly too.


While it may seem like an unusual option, some metal frames can be less harmful to the environment than you think. Aluminium, for example, is 100% recyclable. This process saves up to 95% of the energy used to create it from the raw material. However, overall, metal frames don’t provide as much insulation as other options. The consideration here will also be between choosing an environmentally clean material or saving money – as metal frames, particularly those made of vinyl, will often have a cheaper prices tag.

Glass Glazing

The term ‘window glazing’ refers to the glass that sits within a window. On the market, you’ll find:
  • Single glazing – Single pane.

  • Double glazing – Double pane.
  • Triple glazing – Triple pane.

In short, the more ‘panes’ you have within your window, the better insulated it will be. In turn, the more panes you have, the less heat you will lose and the easier you’ll find it to manage the temperature within your home.

Single Glazing Windows

Single pane windows have been around for many many years – since windows were first used back in 100AD. At this time, we knew very little about the need to thermally protect our homes. Windows were there to allow light in and create a view out of a building. Today, you tend to find them in older buildings or in homes where the main concern is cost.


  • Low-cost.

  • Can help maintain a traditional look.


  • Low security / Increased risk of break-ins or theft.

  • Low energy efficiency (up to 20% less than an insulated wall / 80& less than double-glazing).
  • Poor noise reduction.
  • Result in higher energy bills.

Double Glazing Windows

In the 1970s, double-glazing was introduced along with aluminium frames. In 2002, a Building Regulation came into place that any new homes must have windows that provide adequate thermal, ventilation and safety standards. While this doesn’t specifically mention the need for double-glazing, these double-pane designs offer all of these to the required standard. Estimates reckon that you could save as much as £150+ on your energy bills per year by changing single glazed windows to double-glazes. And, that this change will reduce window-related heat loss by 74%.


  • Significantly reduce heat loss.

  • Reduce the amount of cold air that passes into your home.
  • Better noise reduction.
  • Offers a U-value no higher than 1.6.


  • More expensive investment.

  • More possibilities for damage and problems.

Triple Glazing Windows

In recent years, triple glazed windows have entered the scene. As the name suggests, they consist of three panes of glass within a sealed frame. In between each glass, there is a pocket of air or argon gas which provides insulation against both heat and noise. Because there are two pockets of air in these designs, they are said to further improve the performance by approximately 50%. With these, some manufacturers claim that their triple glazed windows have a U-value of as low as 0.5. However, there is an argument out there on whether homes in the UK climate need this level of insulation, specifically with prices reaching as much as 20% more than standard double-glazed.


  • Further improved noise reduction.

  • Significantly warmer home during winter.
  • Even more energy efficiency.
  • Additional strength to reduce break-ins.
  • Can potentially add value to your house.


  • Due to thickness, you’ll have to replace frames too.

  • Increased cost.
  • Less solar-generated heat internally.

From the points above, the most environmentally-friendly option for your windows is either double or triple-glazing, depending on your available budget.

Here at Castle Home Improvements, we work hard to support each and every one of our customers. This means pairing you with the right windows, whether you’re focused on reducing your carbon footprint or sticking to a strict budget. If you would like to speak to a member of our team, please do get in contact here today.