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Tips to keep windows energy efficient

4 Jan 2019
EEBAK partners share good practice knowledge in building energy efficiency.
Finnish windows.jpg
Finnish windows.jpg
Our partners from EEBAK project are finishing pilot case studies in previously chosen buildings in the Arctic regions in Finland, Sweden and Norway. These studies are producing good practice knowledge in building energy efficiency and our partners have now shared very valuable information and tips. 

Did you know that new windows can also give 5-10% saving? According to our EEBAK partners, it needs to be remembered when structural renovations are done that ventilation and heating systems should be adjusted properly to answer the new situation. 

They also mention that t
oday’s typical window’s thermal insulation is about three times better than the 1970’s window. The U-value of the current basic window is 1,0 W/m2K, which is also the requirement for building construction in the collection of the National Building code of Finland. Nevertheless, the durability of the window will depend essentially on their structure, materials used, the quality of maintenance and damage (because of outdoor exposure, poor handling or air pollution, for example).

Repair options
Usually, a fitness assessment reveals which repair options are to come and where corrective measures should be taken. However, typical repair options for window structures are window upgrades. Regular and systematic maintenance of the windows is usually more advantageous than the fact that the windows had to be replaced prematurely due to damage due to maintenance failure.

Experts advice that to renew windows, attention must be paid to:
  • Additional thermal insulation (U) value of the windows
  • The total permeation of the solar radiation of the windows, the so-called g-value
  • The purchase of potential blinds
  • Airtightness of the windows sound insulation and
  • Operation of the ventilation after window shutter.

"The new windows must have a U-value of not more than 1,0 W/m2K, and attention should be paid to g-values as it affects the living comfort of the summertime. The old windows have a g-value of about 0,75, which means that 75% of the solar radiation that is affected by the windows comes into the room. There is a difference between the passing values of today’s windows: typically, 45-55% penetration, but there are also effective sunscreens that pass through solar radiation by only 23-30%", explain our partners through their pilot case studies.

About ventilation
"If the room replacement air has previously been obtained from leakage from old windows, it reduces the number of windows exchanging air volume into the room. In this case, the ventilation becomes insufficient. When replacing the windows, the installation of replacement air valves and the basic regulation of the ventilation system should be ensured. At the design stage of the renovation, it is important to consider what kind of compensation solutions will ensure the best result. For example, incorrectly selected replacement air valves can significantly reduce the sound reinforcement on new windows or cause unnecessary drawbacks in winter".

Our partners highlight that improved air-tightness and thermal insulation of refurbished windows generally reduces the need for heating rooms. Furthermore, temperature increases in the room can be avoided by re-setting the heating curve or by basing the radiator network.