guide

Energy efficient doors: a complete guide

04 November 2021 | Celia Topping

An average home loses 15%1 of its heat through its doors. So when you’re trying to cosy up and make your home more energy-efficient, doors should be one of the first things to tackle. Luckily, stopping door draughts can be fairly cheap and easy, and often gives immediate results.

In this guide, we aim to answer all your main questions about energy-efficient doors and draught-proofing advice. 

What causes doors to be less energy-efficient? 

If your home’s exterior doors are old, uninsulated, unsealed or not properly installed, they can leak a lot of air through the gaps. Plus, heat can also escape through the door itself, via a process called conduction. 

Even the keyhole and letterbox are likely culprits for those pesky draughts if not draught-proofed effectively. 

How to choose Energy efficient doors

Since October 2010, all new doors have to have a U Value rating of 1.8W/m2K or less. The U Value is an energy-efficiency assessment. The lower the U value, the more energy-efficient the door is.

The British Fenestration Rating Council (BFRC) also rates energy-efficiency using the rainbow A++-G rating system you’re probably already familiar with.  A++ is the most energy efficient, and G is the least. 

Which doors are the most energy-efficient?

When you’re shopping for a new door, take a look at the technical specifications, including the U value as described above, and also the glazing. A double-glazed door means double the protection. It makes your home extra warm by reducing draughts and cold spots, and has the added bonus of being more secure!

Are wooden doors energy-efficient?

Timber is a natural insulator, which means it holds on to heat. Solid wood doors have one of the highest levels of energy-efficiency compared to other door types. 

Both soft- and hardwood doors are great materials, but hardwood is more dense and hard-wearing. But bear in mind: it can be more expensive and less sustainable than softwood.

Things to consider if you want to install eco-friendly energy-efficient doors 

cleaning door window

Not all energy-efficient doors are truly “green”. Look out for the presence of lead and CFCs. The most sustainable doors are CFC-free and made with calcium zinc-based compounds. These are less damaging to the environment, but still hard-wearing enough to mean that the door will last for years.

If, like us, you care about sustainability, it’s also worth looking at the carbon footprint created through the manufacturing and shipping of the door. If “going green” is important to you, look for a certified energy-efficient door made in one location, and then delivered directly to you.

This reduces the “product miles” as much as possible, cutting down on all that fuel use and time on the road. That saves you money and protects the environment at the same time. Result!

How can I reduce the heat lost through the external doors in my home?

When it comes to heat loss, doors are usually far worse than windows. If your home has an ill-fitting, unsealed external door, you might as well knock a 6-inch hole in the wall and let the warm air blow out through that!

The best way to prevent heat loss through doors is to create a double-door airlock. This is done by building a porch or conservatory outside, or adding a second door a few feet inside the original one. This works particularly well if you live in a Victorian terraced home where the front door opens onto a passage that’s the same width as the door.

With a double-door airlock, as long as everyone remembers not to open the second door until the first one is closed, you’ll lose a lot less hot air each time someone goes in or out.

How to draught-proof a door

Draught-proofing your windows and doors can save you around £202on your heating bills each year. Plus, without those draughts, you might be able to lower the setting on your thermostat too, which could save you even more. 

If you’d rather improve your old door than buy a new one, there are several products to help you do the job well. They can have different names, depending on the manufacturer, so it’s best to chat to a sales assistant to make sure you’re getting what you want.

  • Draught excluders (also known as door seals or weather strips) are metal or plastic strips that have brushes or wipers attached. The brush compresses slightly when the door or window is closed, creating a seal. These come in various sizes and work well on the bottom of doors, or anywhere there’s an uneven gap or a warped surface.
  • Compression strips, draught excluder strips, or tapes are self-adhesive foam strips that have some “give”. These are used to fill gaps between your door or window and its frame. It’s important to choose the right size strip. If it’s too large, it can actually stop the door closing properly – the opposite of what you want!

There are also products for specific parts of your door:

  • Flaps and brushes for letterboxes – measure your letterbox first to make sure you get the right size.

  • A metal disc on the front of the keyhole, which falls back over the gap when you remove the key.

  • Hinged flaps to fill the gap between the bottom of the door and the floor.

    How to adjust uPVC doors to stop draughts

    If your uPVC door is rattling, that means it’s not closing tightly and it’ll be causing draughts. Thankfully, it’s an easy fix:

    1. Open the door and you’ll see the latch on the door frame has 2 screws, above and below. Chances are, the latch has been fitted too far out, which is causing the gap, and the rattle. 
    2. All you have to do is unscrew the screws (not all the way, just so the latch can be moved) and move the latch across a little. 
    3. Then tighten the screws back up.  
    4. When you close the door again, the rattle and the draught should be gone.
    5. If not, repeat the process, moving the latch a little further over. 

    How to draught-proof a sliding door

    Insulation is also possible on sliding doors. Here are 3 ways to draught-proof them:

    • Weather strips can be used in much the same way as for normal doors. Apply them to the inside and outside of the door, where the door slides to latch. 
    • Foam insulation can be applied into the upper frame of the sliding door, and anywhere else you can put it without damaging the door or walls. Use a sealant or caulking gun for a neat job.
    • Door socks are long rolls fills with padding. They can be used along the bottom of the door, and are efficient against draughts.

    Make your own draught excluder

    Finally, here’s our handy guide to creating your very own sausage dog draught excluder!

    Plus: don't forget your light bulbs! Switching out old incandescents for energy-saving bulbs can really make a difference. Find out more in our complete guide to energy-saving light bulbs. 

    More smart ideas to help insulate your home

    There are all kinds of ways you can improve your home’s insulation levels when it comes to your roof, loft, walls, windows, and doors. Browse our handy user guides to learn more:

Sources and references:

1https://www.thisismoney.co.uk/money/experts/article-2156438/How-I-house-warm-costs-down.html

2https://www.which.co.uk/reviews/insulation/article/draught-proofing-aLi4N0F4P7VH

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