In the middle of planning your home renovation, extension or self-build and thinking about your patio doors? One of the main considerations you’ll most likely be thinking about is the energy efficiency of your glazing, especially with the rising costs of gas and electricity. If you’ve already decided on the style, say external French doors, and you are looking for some reassurance they’ll not add to those rising costs, then you’re in the right place! Let’s take a look at our external French door options and how energy efficient they are.

How is energy efficiency measured?

Before we take a look at our external French doors in more detail and their energy efficiency, you’re going to need to know how the energy efficiency of glazing is measured in the doors and windows industry. For your new windows and doors to comply with building regulations, they must meet a certain U-value – the industry-standard metric used to measure the heat transfer through the frames and glass of windows and doors. In general, the lower the U-value is the more energy-efficient the glass and frames are. Read our ‘What is a U-value?’ FAQ to find out more.

Kloeber’s external French doors

Now that you know how we measure energy efficiency, let’s look at our different external French door options. We have 4 different types available due to our different materials…

Our timber French doors

modern french doors

Bringing an added warmth to both contemporary and traditional homes.

Our aluminium French doors

Adding a contemporary touch suitable for both modern and classic homes.

Our aluminium Heritage French doors

Providing a classic industrial style through the addition of glazing bars.

Our alu-clad composite French doors

The best of both worlds, with timber on the inside to add warmth and aluminium on the outside for a low maintenance modern exterior.

Which is more energy efficient; timber, aluminium or alu-clad?

Timber is a naturally insulating material and because of this, it has been previously deemed more energy efficient than aluminium. As ours is engineered it is also stronger and more stable than normal timber, meaning it won’t warp or become less energy efficient in the future.

Don’t let the past cloud your judgement though as new technologies have increased the thermal performance of aluminium making it as energy efficient as timber. Our aluminium is also thermally broken – something which is needed to pass building regulations – and durable meaning it won’t peel, rust or discolour.

Why pick one or the other, with alu-clad composite you gain the benefits of both timber and aluminium meaning it is also a super energy-efficient material.

Still not sure? Read our timber vs aluminium, timber vs alu-clad and our aluminium vs alu-clad blogs where we have put each material in a head-to-head battle.

Can Kloeber’s French doors be more energy efficient?

As mentioned above, although your frame material is important as you can lose heat through your windows and doors frames, it is more likely that you will lose the heat through the glass making this a very important factor in energy efficiency and a very important decision.

Luckily, all of our windows and doors are fitted with double glazing as standard and this is super energy efficient on its own. Why? The air pocket between the two panes of glass (hence the term double glazing) creates a seal against the outdoors and reduces the transfer of heat. However, if you did want your windows and doors to be even more energy-efficient, we do have other glass options for you to choose from which will help with this including triple, Low-E coatings, solar control glass and more.

Find out more about our glass options.

So, are Kloeber’s bifold doors energy efficient?

What do you think? We hope by reading all the above you can easily see all of our external French doors are energy efficient. In fact, if you’re still not convinced, let us brag a little more. Remember the U-value metric we discussed? To meet the level needed for a new build your doors must achieve a U-value of 2.0W/m2K and 1.8W/m2k for an extension or renovation. Some of our French doors measure as low as 0.7W/m2K!

It is not all about energy efficiency when it comes to picking your patio doors. We have some other French door blogs including;

  • A complete guide to French doors
  • French door design ideas and inspiration
  • French door colour options

Why not take a look before you commit!

Or if you have further questions regarding any of our glazing products our team will be more than happy to answer them. You can contact them by calling 01487 740044 or emailing us at

Posted: April 6, 2022

Category: Energy Efficiency, French Doors