How Energy Efficient are Bifold Doors

How Energy Efficient are Bifold Doors

How Energy Efficient are Bifold Doors

Energy efficiency grows more important by the day. As the climate crisis increases and green incentives and regulations strengthen, now is a great time to start improving your energy efficiency. Whether you care about the environment, or your bills, or both, energy efficiency is a great way to save expenses and save the planet at the same time. The first step to energy efficiency is understanding U-Values and finding out how to improve them. How energy efficient are bifold doors? That depends on their U-Value.

How Energy Efficient are Bifold Doors

What is a U-Value?

U-value is a measure of thermal transference, which tells you how effective a given product is at insulating or conducting heat. U-Values measure how much heat a product transfers depending on its thickness. Engineers and designers express U-Value as WM2K, or Watts per metres squared per Kelvin. The lower the U-Value, the more insulation a product offers. Energy-efficient homeowners aim for lower U-Values to keep their houses green and cosy.

Some manufacturers make their products seem more energy efficient by separating the overall U-Value of the product, and the U-Value of the material involved. To ensure your home stays energy efficient, aim for a low overall U-Value product. For glazed doors, like aluminium bifolds, Building Regulations state that their U-Value must not exceed 1.8WM2K. Anything under this mark, therefore shows a highly energy-efficient design.

How Energy Efficient are Bifold Doors?

With a structure of conductive metal and see-through glass, aluminium bifold doors may not seem very energy efficient. However, looks can be deceiving. Modern, well-designed bifolds offer a variety of thermal efficiency technologies that create a competitive energy efficiency rivalling any other product on the market.

Bifolds manufacturers choose aluminium for its strength and resilience, not its thermal efficiency. However, they balance this quality by introducing thermal breaks into the frames. These thermal breaks create a layer between the metal, usually composed of polyamide fabric, to prevent heat conduction and dramatically increase thermal efficiency.

Energy Efficient Glazing

Similarly, designs in the glass itself can radically increase thermal efficiency and decrease U-Value. U-Value depends on material thickness, and, of course, glass comes in different shapes and sizes. Alongside the thickness of the glass, bifolds and other glazed products create differing gaps between double-glazed panes. The gaps range from around 5 to 20 millimetres and disrupt convection currents in the surrounding air. The best aluminium bifold doors also come with sealed and treated panes to create thermally insulated glazing units. This strengthens the glass and adds water-tightness to prevent leaks.

Many double-glazing designs also fill the gap between panes with inert gasses, like argon on krypton. As a dense, unreactive gas, this forms a barrier, like the frame’s thermal break, that ramps up thermal efficiency. Ultimately, triple glazing increases all of these measures, with the added bonus of insulating against noise pollution. The fact that colder Nordic countries use triple glazing as a standard reveals its relevance in Britain’s growing thermal efficiency drive. 

How Do Other Materials Compare?

Timber Bifolds

Some designers point to timber as a natural, thermally efficient framework material. When treated with weather-proofing, many of the densest wood frames offer excellent thermal efficiency and a rustic look. However, as a material, timber’s thermal efficiency and overall quality varies. Under the wood and timber brackets, homeowners could get softwoods, hardwoods, solid wood, composite wood, or engineered wood. Between these styles, consumers often exchange thermal efficiency for budget and environmental impact, walking an eco-friendly balancing act. 

Overall, no matter how weather-treated timber becomes, it can still suffer more from weathering and warping than other material like uPVC and aluminium.

uPVC Bifolds

Offering the most budget-friendly material option, uPVC can seem counter-intuitive to homeowners trying to be more green. As a thick, moulded plastic material, uPVC creates an impressive insulating seal and high thermal efficiency. However, it also has a fairly high environmental impact, which deepens depending on resourcing and recycling. While energy-efficient as a material, uPVC can also suffer as a product. Sun-bleaching and weather-warping can affect uPVC designs, creating draughts and worsening a product’s U-Value over time.

How Energy Efficient are Bifold Doors Capable of Being?

Regardless of material thermal properties, aluminium bifold doors bring thermal efficiency through their impermeability and fortitude. Unlike timber or uPVC, they do not warp or wear. This ensures that they maintain thermal breaks and exclude draughts and leaks. The fact that they do not rust also helps: aluminium bifolds will not swell or let moisture in to form damp as other materials might. Of course, they are not a perfect thermal insulator. Like any other material, they can be improved by adding layers and panes. Consider reinforcing your bifold doors’ thermal efficiency with blinds or curtains.


The answer to the question ‘how energy efficient are bifold doors’ depends on the materials used and the design’s technology. However, the answer to the question ‘can bifold doors be energy efficient is an unequivocal yes.

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