GLOBALLY INCREASING ENERGY PRICES DRIVE TOWARDS ENERGY SAVING AND EFFICIENCY. GLAZING INDUSTRY IS NO EXCEPTION.

Europa shopping centre, glass-aluminium roof

15 Jun GLOBALLY INCREASING ENERGY PRICES DRIVE TOWARDS ENERGY SAVING AND EFFICIENCY. GLAZING INDUSTRY IS NO EXCEPTION.

There is no other component in the building sector that has had rapid development in quality than in the field of windows. Since 1970 the window industry has undergone significant changes in terms of energy saving and efficiency. Today the energy efficiency has became a global phenomenon in all spheres of human activity and life. Although the development from recent years is characterised by huge improvements of the energetic quality, windows still have the lowest level of insulation of all the external components in a building. Due to the ever-increasing demand on low energy consumption, more and more attention is being paid to enhance the thermal insulation of the windows which are considered the risk areas of buildings.

Megrame Export reflects on the latest products and technologies which prevailed at the latest International Self Build Exhibition 2010 in Belfast, Ireland. “The exhibition mainly focused on the excessive use of energy and showed development for minimising heat loss and maximising heat gain in the construction sector. Passive house windows and low energy windows will all play very important roles within the construction industry in the immediate future. Self Builders, Residential and Commercial Builders and Architects all showed immense interest in the various displays of low energy windows that will have a huge impact on achieving increased thermal characteristics of buildings”

During the early 1970s most windows in Europe had single glazing; the Uw-value was around 5.5 W/ (m²K). Such windows caused expenses of 48 €/m2for heating each year. The windows had very poor insulation, as external cold could go through the window to the inside surface, causing frost on the interior surface creating huge energy loss.

In 1975 a new technology of double glazing was introduced. The distinctive feature being the type of window had an air gap enclosed between two panes. The heat loss coefficient was reduced to almost 2.8 W/ (m²K). The double-glazing panel saved half of the annual expenditure compared to single glazing.

1995 saw the introduction of razor-thin metal coatings inside the interpane space layer for low thermal emissions. This technology allowed significant reduction to the U value to 1.3 and 1.7 W/ (m²K) (Standard timber or plastic windows). Moreover, the gas in the gap changed from air to noble gasses (Krypton or Argon), which had a much lower heat conductivity. The “low -e-glazing” became standard in Europe especially in Germany. The quality increased significantly without affecting the price too much.

The reduction of the thermal transfer of windows has been reached, especially the thermal properties of the glazings, which has the highest impact on heat loss, were improved.

The breakthrough for energy efficient construction was the introduction of triple-pane low-e glazing, which had a U value of 0.5-0.8 W/ (m²K). This signified a completely new approach towards construction, the window being considered as an integral part of the entire construction. The energy saving efficiency is achieved via a synergy of all constituent parts (not only the glazing, but the whole window should have quality which includes an insulating window frame and insulating spacers.)  This kind of window helps to save 80 % of the energy costs per year.

 Type  Single  Double Double, low e, Ar  Triple, low e, Ar
 U value W/(m²K)  5.60  2.80  1.20  0.65
Surface temperature
-10 °C out/20 °C
 -1.8 °C  9.1 °C  15.3 °C  17.5 °C
 Solar transmittance  0.92  0.80  0.62  0.48

 

Basic parameters of different types of timber windows in Europe

Today high quality windows fall into the following categories (Types):

  • Triple-pane, double-low-e glazing
  • Insulated wooden frames
  • Insulated plastic frames
  • Insulated glass facade constructions
  • Insulating spacers
  • Components for thermal-bridge free and air tight windows.