Thermal transmittance of fixtures –

What is the thermal transmittance of windows and doors and how is it calculated

The thermal transmittance of fixtures it is the quantity of heat that can pass through an element, in this case the window, and is calculated in W/m²K (Watts per square meter Kelvin) and for fixtures it is given by the average calculated between the transmittance of the glass, indicated as Ug, and that of the frame, indicated as Uf.
The transmittance of the entire window is indicated with Uw and the lower this value, the better the window.

Factors to consider regarding the thermal insulation of windows and doors

Among the factors to consider for thermal insulation, before choosing your window, there are certainly:

• An hermetic closing system
• A double glazing filled with high performance gas
• Quality materials
• Correct interaction between glass, frame and glass spacers
• Structural stability
• Better thermal insulation.

The importance of this value lies in the fact that the capacity of a window and door depends on it isolate the house from heat and cold.

Too often, however, we focus solely and exclusively on this parameter, neglecting other factors that could affect the performance of the window.

Living room with Radia PVC French windows by WnD

In fact, even if a frame has good transmittance values, its performance may still not be optimal due to incorrect installation or other neglected quality parameters.

What is the best material for frames for good thermal transmittance

Among the best window and door materials, in terms of thermal transmittance, we find the PVC.
However, this does not exclude that a frame can be created using several materialsmore or less performing:

• Wood
• Aluminum
• PVC
• Steel
• Mixed

Approximately the norm UNI EN ISO 10077-1 provides a formula with which it is possible to calculate the transmittance of fixtures.
For the most used frames, the thermal transmittance values ​​are:

• Legno: 1,5-1,8 W/m²K
• Aluminum with thermal break: 2.4-3.9 W/m²K
• PVC con 2-3 camere: 2-2,2 W/m²K

Performance of PVC windows

The fixtures in PVCThanks to new technologies, they are among the most resistant on the market, they resist both the patina of time and atmospheric agents, in fact windows and doors made with PVC are waterproof, self-extinguishing and require very little, if any, particular maintenance.

Konfortline PVC window by WnD

Another line of fixtures proposed by WnD is comfortlineit is a PVC window, with a thin profile and larger double glazing to have maximum brightness in the home environments.

Its structure with a reduced central node and a lowered frame allows for the installation of larger double glazing compared to a standard window of the same size, thus favoring the entry of natural light, but at the same time guaranteeing excellent thermal insulation performance and perfect resistance to agents atmospheric.

What is the best thermal transmittance of windows and doors?

A good thermal transmittance of fixtures is around 1,3 W/m²K but it can reach excellent values ​​such as 0,8 W/m²Keven if the question to ask is not how much the window transmittance should be, because there is a risk of neglecting other important factors when choosing the right window.

An example is the Ravia EVO windowWnD PVC frame, designed to guarantee maximum energy efficiency, is also capable of guaranteeing excellent performance in terms of thermal and acoustic insulation. Characteristics of this frame are the six chambers of the structure, the triple rebate seal and the possibility of supporting quadruple glass, all elements that reduce energy dispersion to a minimum, allowing exceptional levels of insulation to be achieved.
Another element to consider is that the legislation imposes specific transmittance values ​​for each climate zone in which theAENEAS divided our country.

In particular, if you want to access the Fixtures Bonus 2024 it is necessary to respect the following transmittances:

There are six zones, from A which is the warmest to F which mainly concerns high mountain areas.
For example, if you are in Milan, you are in zone E and you will have to respect a thermal transmittance of the windows equal to 1.3 W/m²K.

PVC window frames by WnD Finestre

Among the best PVC windows, we find those offered by WnDcapable of offering very high performance, thanks to the quality of the materials and attention to every factor involved, such as excellent resistance and good thermal transmittance.

WnD production hub

L’WnD window company And leader in the PVC window and door sector energy saving and with very low thermal transmittance values.

Ravia PVC window by WnD

The excellent results are obtained thanks to the combination of the PVC frame with low-emissivity double glazing filled with Argon gas. This union allows you to have a Ug equal to 1,1 W/m²K and even a Ug equal to 0,8 W/m²K if you use a 36 mm triple glass and 6 chambers filled with Argon gas with 3 gaskets, an example of this is Ravia PVC window.

The benefits of WnD windows with very low thermal transmittance

I WnD windows with a very low thermal transmittance determine a series of tangible benefits, including:

1. First, one reduction in consumptionwith a saving on the bill that already affects our wallets and is easily noticeable.
2. What also improves is the comfort at home. Bearing in mind that in this case we are not just talking about thermal comfort, as has been said, because good transmittance can also guarantee good Rw, i.e. a soundproofing power capable of protecting us even from annoying external noises.
3. Finally, an excellent PVC window and door, built with the best materials and the right systems and with attention to the smallest details, also helps to prevent annoying condensation and mould.

All these factors guarantee the healthiness of individual environments, but also of the entire building, protecting us from the so-called “Sick Building Syndrome”.

End of article