Are French Doors Energy Efficient? Let's Break it Down

French doors have been a popular door type in homes since the Renaissance period, allowing ample light to flood rooms. These elegant doors are available in different materials like wood and uPVC to complement different home designs. But what about this door’s efficiency in today’s energy-conscious times, where retaining as much heat inside your home is a priority?

We’re here to answer: are French doors energy efficient, while addressing some of the main concerns homeowners face when installing new French doors or maintaining existing ones.

What Are French Doors?

Stylish, traditional and user-friendly, French doors were popularised, you guessed it, in France during the Renaissance period. To this day, their design still prioritises large, often multiple glass panels and a swing functionality.

How Energy Efficiency Is Measured in Doors

French doors have had to adapt over the years to be more energy efficient, and this is measured in U-value – the ability of a door to conduct heat – as well as components like glazing and seals affecting energy efficiency.

U-Values and Why They Matter

U-values are taken from the glass in French doors. The lower the U-value, the better the feature performs as an insulator. These depend on the glass type and thickness of the unit. An example of a standard 1.2 U-value would be:

• 28mm clear, toughened, low e, argon gas filled

While no door or other material will have a U-value of zero, you should look for this target when choosing new French doors.

U-value is measured in watts per square metre per Kelvin (W/m²K), and a good U-value for French doors would be around 1.5-1.8 W/m²K. It’s important to look at the U-value of not just the entire door but also each component, including the glazing, frame, and the type of material the doors are made of. This will help you make an informed decision on the best and most energy-efficient French doors on the market.

The Role of Glazing and Seals

Double or triple glazing French doors improve energy efficiency and will be given a rating ranging from A++ to E from the British Fenestration Rating Council (BFRC). Argon, an inert gas, is also commonly trapped between the double- or triple-glazed glass panes to further improve energy efficiency, keeping more heat within the home.

Gaps in French doors should be filled with weather seals and thresholds to prevent draughts, especially between the door and the frame. This helps to maintain consistent temperatures and reduce heat loss.

Are French Doors Energy Efficient?

Common Energy Efficiency Concerns

Maybe you’ve decided on the ideal French doors for your home and found a perfect material, colour and style. However, you might still be concerned about which glazing to get or other features that can enhance keeping heat within your home during colder seasons.

Traditionally, French doors featured single-glazing and minimal sealing and their double door design also created more gaps compared to single-panel alternatives.

Modern Improvements in French Door Design

Fortunately, French doors today are built with multiple energy efficient components and features. From double and triple-glazing, with argon filled in between, quality frames made from materials like uPVC and aluminium to advanced weather seals and multipoint locking systems join together to provide a low U-value, tighter seals and reduce heat transfer.

Comparing French Doors to Sliding or Bi-Fold Doors

French doors are found in homes across the country and are more popular as patio doors or to separate interior and exterior spaces. Other door alternatives are available, including sliding doors and bi-fold doors. But which door type is the most efficient?

When comparing sliding doors with French doors, one door type can be more energy efficient than the other and vice versa, and this is because it is case-specific. Door materials, size of glass, and depth of glass all contribute to a door’s energy efficiency.

Ultimately, all three door types can be energy efficient as long as they are fitted correctly, made from high-quality materials and have modern features to seal gaps and trap heat.

Tips for Improving the Energy Efficiency of French Doors

Choosing the Right Materials

There are several modern and traditional materials to choose when it comes to French doors, each offering its own stylistic benefits but also individual levels of energy efficiency.

Wooden French doors:

For a classical look, wood is a robust and customisable material and acts as a strong insulator. However, wooden French doors will need to be maintained frequently, with regular coats of paint and treatment to maintain aesthetics and energy efficiency.

Aluminium French doors:

Aluminium is excellent at keeping heat in and unwanted sounds out. Aluminium can also be powder coated or painted to mimic other materials like wood but will require some maintenance like an annual clean to keep it looking pristine.

uPVC French doors

This is a particularly popular material for French doors thanks to its extremely low maintenance and good insulation. It’s cheaper than most other materials but won’t be as robust as aluminium, wood or steel, and offers less thermal insulation but will suit modern homes easily.

Steel French doors:

Steel French doors are ideal for older, heritage homes and are one of the strongest materials on the market. However, the steel will need regular treatment and painting to prevent rust and is prone to scratches and dents. While they have thinner frames and slim sight lines, they’re still energy efficient.

At Green Doors, we offer Crittall Doors, a brand of steel doors that can last hundreds of years. We also offer full refurbishment on this type of product to bring these doors back to their full glory. Speak to one of our experts if you are interested in these doors or services.

Decide on the best material for French doors based on your budget, preferred style and how energy efficient you want them to be.

Double or Triple Glazing

Are French doors more energy efficient with double or triple glazing? Well, you can’t simply opt for triple glazing in any door, and this is true for French doors, as it depends on the door’s rebate.

You can enhance the glass by opting for toughened, laminated, or thicker glass. Standard double glazing comes with 2-4mm thick glass, but you could choose to have 6mm or 8mm, which will enhance energy efficiency, security, and soundproofing.

These additional features help keep heat inside during the winter and outside during the summer. If it’s possible to install triple glazing for your French doors, it will be a more expensive choice, but you’ll benefit from further enhanced thermal and acoustic insulation.

Professional Installation and Maintenance

Even if the U-value is close to zero, you’ve got a frame and a pair of French doors made from the best materials with all the added features, energy efficiency will be thrown out the window if everything isn’t installed by a professional. Installation by door experts ensures a tight, level fit and properly sealed joints.

As the owner, performing checks and maintenance, from inspecting seals and hinges to assessing locks for wear and tear, replacing faulty components or adjusting the door alignment can prevent draughts and keep energy efficiency at a high. If you are ever unsure how to properly maintain French doors, it’s best to seek professional assistance.

Explore Our Range of French Doors Today

Are French doors energy efficient? Yes they are, and at Green Doors, we provide a range of affordable new and second-hand French doors, made from energy-efficient materials, including wood, aluminium, composite and steel. We rescue doors and windows to give them a new lease of life, passing the savings onto our customers.

Shop our range of doors and windows to find your new energy efficient home feature. You can also get in touch with us for any enquiries or help, with our expert team happy to explain any details on our range of French doors and services.

Are French Doors Energy Efficient? FAQs