How to Build a Green Extension for Your Home

Author Profile
Alexandra works in the marketing department, and in 2014, bought her first house, which turned out to be somewhat of a ‘project’.
Since then, the whole house has needed renovating, which has helped her gain a knowledge of basic DIY, decorating and making the best of a small space.

By Alexandra Giles

How reclaimed materials can make your extension ultra eco-friendly
The best choices in sustainable insulation
How underfloor heating and wood burning stoves can maximise the heat in your extension
Energy efficient doors and windows designed to limit heat transfer

Moving house is notoriously stressful, so it’s no wonder that many people choose to extend their current property rather than looking for a new home. Building an extension is also the ideal opportunity to increase your property’s green credentials by ensuring that your extension is as eco-friendly as possible.

Source the right materials

The material you choose to build your extension from will largely depend on the type of house you have, as most people look for materials which will complement their existing property. However, from an eco-friendly point of view, it’s good to consider all of your options.

Wood sourced from sustainably managed forests is an environmentally friendly choice, and because of its versatility, it can blend well with many different house styles.

If you would prefer a more traditional bricks and mortar style, then try to source previously used bricks as not only will these look fantastic as they blend into your home more naturally, but it is also a great way of recycling building materials.=

Reclaimed building materials

Reclaiming building materials is one of the most eco-friendly options for a new build. 19% of the UK’s total greenhouse gas emissions come from construction materials and transporting these materials accounts for 30% of all UK road freight. There is a myriad of reclaimed materials available including:

Reused timber floorboards and beams
Cleaned bricks
Glass panels and windows
Refabricated steel

Reclaimed material can be sourced from the following places:

Direct from an existing project – contact local demolition companies to enquire what projects they have coming up and if there is an opportunity to reclaim materials straight after the demolition.
Salvage yards and reclamation centres.
Specialist listings websites such as enviromate, PlanetReuse and Salvo.

Maximise insulation

As extensions tend to be only connected to the house by one wall, they can be prone to being chilly as they don’t absorb any heat from surrounding rooms, so insulation is a must when building an extension.

Ensuring that there is a continuous layer of insulation across the walls, floor and roof will mean that you can keep draughts out and save money on heating the area. There are plenty of options available for eco insulation, including sheep’s wool and loose-fill cellulose which is made from 85% recycled newspapers and 15% fire resistant material. Loose-fill cellulose has the highest level of recycled content of any insulation product available.

Another option for sustainable insulation is recycled denim jeans. It may sound strange but recycled denim is an excellent insulator which avoids many of the pitfalls of working with traditional insulation, such as glass or mineral fibre as it is not an irritant and is very easy to install. The downside of this material is that you will probably have to buy it from a specialist supplier and it’s much more expensive than glass or mineral fibre insulation.

If you have water running into your extension, don’t forget to insulate the pipework as this will ensure your water stays hotter for longer. According to the Energy Saving Trust, insulating pipework can save around £10 a year and is a simple job to do.

Maximise heat

Underfloor heating heats a room slowly from the ground upwards, rather than a radiator which heats pockets of air in a room rather than the overall space, making underfloor heating an efficient choice for heating a new extension. Underfloor heating works at a low temperature too which means it can potentially save money when compared to heating a room with a radiator. It’s very difficult and costly to retrofit a room with underfloor heating, so it’s worth considering at the planning stage of your extension.

Wood burning stoves have been a design feature in homes for a few years now and they remain a popular addition to living and dining rooms. The main benefit of a wood burning stove is that they are much cheaper to run than an electric fire. According to the Stove Industry Alliance, a stove is 77% cheaper per kWh to run than an electric fire and 53% of 277 Which? members surveyed agreed that installing a stove saved them money.

Fit a skylight

Skylights allow natural light to flood into the home, which can save on lighting bills, and they also provide a source of passive solar heating, although it’s important to remember that this is not necessarily a good thing in summer. So, if you are installing a skylight, don’t forget to include blinds to regulate the temperature and stop heat building up in summer and stop it escaping in winter, for all year efficiency.

Origin offer a range of stylish made-to-measure Electric Roller Blinds which can be installed in skylights. In cold weather, a skylight can lose up to 45% more heat compared to a window on a wall, as warm air rises. According to the Consumer Energy Center, the best position for a skylight, in order to get the right `balance with heat, is “to position your skylight with a slope equal to your geographical latitude plus 5 to 15 degrees”. If you’ve gone to the effort of insulating your extension, then it makes sense to ensure your skylight is equally energy efficient. Triple glazing can bring your skylight up to the same thermal value as your insulation, and therefore, your extension can avoid cold patches gathering around the glazing and drawing heat from the room which can cause condensation.

Fit Bi-fold Doors and windows with low U-Values

Lighting can account for 8% of the average household’s energy bills, so cutting down on this can prove to be very beneficial. One way of doing this is through introducing more natural light in your extension. An opportune way of doing this is through the installation of bi-fold doors.

Certain bi-fold doors can also provide energy saving benefits through their thermal efficiency. The best indicators of thermal efficiency are U-Values. U-Values show the amount of heat lost in watts (W) per square metre of material, so, the lower the number, the better the thermal efficiency. As of 2022, the U-Values for bi-fold doors within the UK must be:

Replacements: 1.4W/(m²K)
New Builds & Extensions: 1.6 W/(m²K)

Therefore, from a green perspective and to save on heating, it is advisable to install doors with certified low U-Values.

Having a door with a low U-Value means that the doors limit the heat transfer and subsequent loss from the internal to external environment, so that means that a room won’t lose its heat in the winter, and will keep it cool in the summer, therefore reducing heating bills and making the room usable all year round.

The Origin Bi-fold Door has a certified U-Value of 1.1, which exceeds the British Building Regulation requirements for optimum thermal efficiency. They are designed to handle the demands of UK weather as it is fitted with a thermal break as standard. A thermal break is a piece of low thermal conductive polyamide, separating the door interior and exterior profile.

The Origin Window is one of the best options available when it comes to well thermally efficient windows, especially because the window can be upgraded to include the revolutionary space age technology, Aerogel - the world’s best insulating material. When insulated with Aerogel, the Origin Window can achieve an A++ energy rating, and have a U-Value of 0.8. Installing the Origin Window into your new extension will therefore ensure your windows are as energy efficient as possible with limited heat loss.

Combining Origin’s high performance windows and doors with our thermally efficient blinds will ensure your extension is as energy efficient as possible. Origin Blinds prevent heat from building up in the home as the exterior of the blinds have a reflective covering. When it’s cold outside, Origin Blinds prevent heat from escaping and therefore will boost the thermal efficiency of your extension.

Install LEDs

Light-emitting diodes (or LEDs) are an eco-friendly lighting alternative. Incandescent and CFL bulbs contain environmentally hazardous mercury, and often waste up to 90% of the energy they consume on heat. In comparison to this, LEDs use small, powerful sources of light that only shine in one direction, which produces a fraction of the heat and allows them to last longer. They may have a higher up-front cost, but in the long run, LED bulbs can cut your lighting costs by up to 90%. LED bulbs are the only true environmentally friendly lighting option on the market.