What is a heat separator? – Construction work in progress

Windows performs several functions, but there is no doubt that is one of the main functions thermally insulated in our homes. That is why glass manufacturers have been working tirelessly for years to improve the insulating properties of their products.

Composition of the multiple glazing of the PVC window

Multiple glazing is not just glass. In addition to the two or more windows with insulating glass, the following points are particularly important:

  • for sure separator (or spacer): a part that simultaneously separates and connects the two panes, with the perimeter surrounding the air chamber, like the heat separator proposed by Veneo.
  • for sure air or noble gas that fills the chamber,
  • for sure low radiation layer: A metal layer with a high percentage of silver and other metal oxides that covers the surface facing the interior of the chamber « reflects » some of the heat that tries to escape from the inside of the home into the room. An essential element is the fulfillment of the function of laminated glass, namely ensuring its thermal efficiency.

Traditional spacers

Traditionally, the spacers are from PVC windows are pieces of aluminum that are covered on the so-called Desiccant molecular sievethat is, a surface with micropores and filled with granules with high absorption efficiency. Its function is to absorb and store moisture caused by condensation in the chamber.

However, aluminum has a high thermal conductivity. When used as a non-stick material for windows, it creates a linear thermal bridge of considerable length and therefore the result is lost due to the use of low-emission layers. To avoid this, some manufacturers have chosen innovative proposals, such as: Stainless steel spacers. The Veneo brand, for example, uses them as a standard part of their products. Other options are polymer materials or silicone foam, all of which have lower thermal permeability.

Heat separator

These are the removed items that they have thermal efficiency Very high and, thanks to their composition, they minimize the thermal bridge (marked with the symbol ()) that arises between the glass and the wing profile. In order for a separator to be considered thermal, it must meet the following requirements:

e* λ ≤ 0.007 W./.K.


d – wall thickness of the separator (m)

λ – coefficient of thermal conductivity of the material from which it is made (W / m * K).

The thermal conductivity of the separator influences the height of the thermal bridge Ψ and this number directly influences the value of the total heat transfer of the window (Uw). Let’s look at the following formula:


UW – total coefficient of heat permeability of the window [W/(m2*K)]

Af – brand area (m2)

Uf – coefficient of thermal permeability of the frame [W/(m2*K)]

Ag – glazing area (m2)

Ug – coefficient of thermal permeability of many glasses [W/(m2*K)]

Ψ – linear coefficient of thermal permeability [W/(m2*K)]

Lg – circumference of the glazing edge (ml)

Analyze a PVC windows With the same dimensions (1.2 x 1.5 m), but with different separator types, the following values ​​for the linear heat permeability (Ψ) and the total heat transfer coefficient (Uw) are obtained

As can be seen, the value of the total permeability (Uw) decreases from 7.7 to 11% depending on the separating material. Therefore, when buying windows, it is advisable to ask the seller what kind of spacer his products have and whether he can offer us PVC windows s Heat separator. It should be noted that the brand vSneo offers such solutions, for example PVC windows IGLO ENERGY CLASSIC, manufactured by the world market leader Drutex.