Thermal insulation

With the help of modern technologies plain glass (pane) surface is covered with a layer of metal oxides, glass (pane) has much better thermal insulation and remains clear. Oxide covering reflect from 40% to 70% of heat, which conventional glass would conduct.

Heat transfer coefficient is expressed by heat transfer coefficient U - heat transfer through the surface of 1 m2 area of 1 degree Kelvin or Celsius temperature difference between the different sides of the surface (W/m2K). U - is the heat transfer coefficient which shows glass or a glass packet heat loss level. It is expressed by (W/m2K). The lower of U value of the glass or pane packet keeps the heat more efficiently.

Good thermal insulation properties of glass or glass packet are essential not only to preserve heat in the premises, but also for protection against heat. The total energy of sunlight falling through the glass or the pane packet to the premises is described by the factor (g).

The following table presents the individual and glass packet g and U values:

It is easy to note that pane packets heat transfer coefficient (U) is much lower than one glass. There are several reasons:
a) Dry isolated chamber in between the panes reduces heat transfer.
b) In chamber between the panes there is low conductivity inert gas (usually argon) that reduces heat transfer.
c) Heat transfer is reduced by radiation, using a special glass with a low permeability (EN) coating (Planitherm Futur (en = 0.033), Planibel Top N (en ≤ 0.04), Planitherm Ultra-N (en ≤ 0.05)).

¹ - Frame width (mm).
² - Filling the chamber between the panes with argon (85% -90%).
³ - Filling the chamber with air between the panes.

In most cases, when producing insulated glass units the conventional aluminium spacer is installed between the glass panes.

This is the glass packet of conventional design, in which glass panes are connected using an aluminium spacer and sealant. In these insulated glass units the space between panes might be filled with air or argon gas, in order to protect inside of the packet against fogging and the frame is filled with moisture absorbing material. After this pane packet is sealed.

Aluminium spacer is cheaper compared with others (Swisspacer, Termix), so it lets to save, the only drawback compared to the other frames (Swisspacer, Termix) is that it is more conductive to heat (cold).

This is a new generation of "warm frame" Swisspacer that is made from organic material, which was created for the space needs and reinforced with metal filaments to meet the high requirements for mechanical and thermal resistance. Impermeability to gas and vapour provides a thin metal film of the invisible side of the frame.

Advantages:
- The production of insulated glass units with Swisspacer frame, the cooling (heating) effect at the edges of the pane packet is lesser compared to conventional glass windows with aluminium spacers.
- The window heat transfer coefficient (U) can be reduced to ≤ 0.3 W / m² K.
- At the pane packet edges cold bridge effect is reduced. This ensures a higher temperature of its edges and gives better comfort.
- Reduces the risk of condensation at edges of glass packet.
- Heating costs can be reduced ≤ 5%.
- Less investment improves the heat transfer coefficient (U).
- Indoor humidity can maintain a higher level without fear of condensation.
- Four standard colours (titanium gray, black, white and brown), allows to adjust design.
- Strength provides the same mechanical properties as well as aluminium spacer.
- Frame Swisspacer 15.5 mm thermal conductivity (λ) W / mK) is 0.51. it is one of the best world achievements.

The following table presents teh impact of aluminium Swispacer frames to window’s linear heat transfer (ψ) :

Ψ - A linear heat transfer coefficient is expressed as (W / mK).