According to Ademe, in old houses, up to 15% of heat loss comes from poorly insulated windows1. Good insulation guarantees both thermal comfort and a reduction in energy bills. It is therefore essential to choose the windows carefully when renovating or new construction of a home. Several solutions exist, discover the best ones to create a pleasant and energy-efficient home.
The key role of insulated windows in energy comfort
Windows make up around a third of the facade of a house. Their waterproofing helps to improve environmental and energy performance. In fact, thethermal insulation helps minimize heat loss in winter. These heat losses result in low thermal comfort and a significant increase in energy consumption. It is therefore essential to remove all thermal bridges which compromise the energy efficiency of your heating system.
Good window insulation is also an excellent way to avoid high heat in summer. This significantly reduces cooling requirements.
In all cases, the quality of windows impacts living comfort, but also the energy costs (gas or electricity) of owners. To save on costs and have optimal comfort, windows with adequate insulation should be installed. It is a sustainable investment that provides savings over several years.
Window choices for better energy efficiency
Windows come in several types: casement, sliding, fixed, tilt-and-turn, etc. The types of glazing differ depending on their thermal characteristic. The joinery materials can also vary: PVC, aluminum, wood, or mixed. Find out more on the possible choice of materials for your new or renovated windows.
As a result, there is a wide choice of windows, but to gain in thermal comfort, only energy-efficient models should be preferred. The glazing and the frame material are the two elements to consider in terms of thermal comfort and energy efficiency.
The glazing
Adapted to all types of climate and different house architectures, double glazing is the most common type of glazing. It effectively limits heat loss. This consists of two panes of glass trapping between them a blade filled with gas or air. It should be noted that compared to air, gases such as krypton and argon provide better thermal insulation efficiency.
Double glazing with reinforced insulation (or VIR) provides slightly greater insulation than standard double glazing. It has low emissivity thanks to a layer of silver placed on one of its two glasses.
Double glazing with reinforced thermal insulation (or ITR) is more efficient than the two previous glazings. It is reinforced with a treated interior window.
Triple glazing offers superior energy performance to double glazing. It contains three glasses and two gas blades, and is therefore heavier. However, it requires specific carpentry.
The 3 main materials for insulating windows
The frame materials can also impact the thermal insulation of a house. Wood, PVC, and aluminum each have advantages in terms of energy efficiency.
The wooden window
Wood, as a natural insulator, is a recyclable material. It offers excellent thermal comfort when combined with double glazing. It has the advantage of not rusting and gives an aesthetic and warm appearance to a house, with the possibility of customizing the finish. To ensure its durability, it is recommended to use certified class 3 or 4 wood. However, wood can be expensive and requires regular maintenance, including the application of stain, to protect it from bad weather.
The PVC window
PVC is a material recognized for its excellent thermal and acoustic insulation properties. This plastic is widely used in carpentry due to its versatility, strength and durability. Equipped with air inlet grilles, PVC reduces the effects of condensation. Plus, it's easy to maintain, and it offers customization options to fit the aesthetic of your home. PVC is also an economical choice with good value for money.
The aluminum window with thermal break
When equipped with a thermal break system, aluminum offers thermal performance equivalent to PVC. It is popular for its lightness and ease of maintenance. Thanks to the thinness of the amounts, aluminum windows allow you to gain more light in a room. It is also a rot-proof and very robust material that adapts perfectly to large windows (bay windows). It resists solar radiation and violent winds. On the aesthetic side, aluminum offers a contemporary appearance with a wide choice of colors.
The HPC window
Hybrid Premium Composite (HPC) is a mixed material containing glass fibers, which gives it high strength, great finesse and remarkable rigidity. It makes it possible to create windows offering excellent thermal insulation, thus contributing to the reduction of energy bills. In addition, HPC also provides good sound insulation.
How to know the thermal performance of a window?
The heat loss coefficient U windows (Uw) is expressed in W/m² K. This indicator makes it possible to quantify the thermal performance of a window (glazing and frame). The closer the value is to zero, the more effective the insulation. It is recommended to opt for a coefficient less than or equal to 1,3 W/m². A low index can qualify you for ecological financial aid.
Financial aid for installing windows
The energy renovation of windows entitles you to certain bonuses or financial aid, subject to specific conditions:
- MaPrimeRénov': up to €100 per window, to replace old joinery, subject to resource conditions;
- the energy bonus (CEE): bonus offered by energy suppliers;
- Zero-rate eco-loan: amount of up to €30, depending on the extent of the work carried out;
- reduced VAT: reduction of 5,5% or 10% depending on the thermal performance of the windows;
- aid granted by local authorities.
To make your home energy efficient, consider optimizing the thermal insulation of your windows using high energy performance models. The glazing and frame material are the most important things to consider when making your choice.