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EEBAK completes a literature study of energy efficiency for buildings

28 Mar 2019
Don't miss tips on structural renovations, windows maintenance, saving in electrical cost and reducing heat energy and water consumption.
EEBAK project started in the beginning of 2017 and has progressed beyond the midway point. As 2019 approaches, the project aims to finish pilot case studies during the upcoming winter months. These pilot case studies are done in previously chosen buildings in the arctic regions in Finland, Sweden and Norway. The studies are expected to produce good practice knowledge in building energy efficiency. EEBAK Project has planned to hold seminars in all three countries to disseminate the results during spring-autumn of 2019. The results will be disseminated mainly to the municipalities in the Interreg Nord area.

As a part of the studies in EEBAK, a literature study of previously completed energy efficiency studies and projects has been done. Here are a few highlight samples of good energy efficiency practices lifted from those studies:

Structural renovations
Additional insulation of external walls can provide 10% savings. It is typically economically feasible if done when other repairing is done for external walls. Typically, additional insulation during structural renovation raises investment cost only 5-15%, so the payback period stays short. (Niemikorpi 2017).

Additional insulation of attic floors is economically feasible in detached houses if it is technically possible to do. Possible energy savings can be 5 to 12%. Heat losses through attic floor is relatively small in Apartment buildings but in detached houses heat losses are much higher. Additional insulation for attic floors should be considered, especially when there is enough space between attic floor and roof. Additional insulation could be done with blow wool on the top of old insulation. (Virta & Pylsy 2011)

New windows can also give 5-10% saving. It needs to be remembered, when structural renovations are done that ventilation and heating systems should be adjusted properly to answer new situation. (Niemikorpi 2017) Today’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. The best U-values for insulating windows vary between 0,6 W/m2K and 0,8 W/m2K (Virta & Pylsy) .
The durability of the window depends essentially on their structure, materials used, and the quality of maintenance. Correspondingly, the necessary maintenance and their practical implementation depend on both the material of the window fittings and the window types. (Virta & Pylsy 2001).

Damage to the windows is due to among other things. Outdoor exposure. The worst are the sloping slope, solar radiation (especially dark windows) and air pollution. Most suffer from weathering the south and west side of the upper floors and windows. Window damage is also caused by the use of windows and poor handling. The general cause of the damage is the failure to observe the regular care of the paintwork and paint surfaces. (Virta & Pylsy 2001).

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. (Virta & Pylsy 2001).

The cost of window repairs is 60-90 € per living area, when the window price is 450€/m2. Energy saving estimates are based on the assumption that the window area is 15% of the residential area. The larger the window area relative to the residential areas, the higher the investment cost and the energy savings. If windows are combined with blinds, the additional cost is 30-50 €/window area. For example, in a 80 m2 apartment, the installation of a Venetian blinds at the window can cost about 500€. (Virta & Pylsy 2001). Replacing windows will also improve living comfort. The better the window isolates the heat, the higher the temperature inside the window’s inner glass in the winter. 

Saving in electrical cost
Basic maintenance of ventilation system can provide 10% savings. Old fashioned lightning bulbs can be replaced with more energy efficient ones and get 5-10% savings. The new building automation system can create 5-10% savings. In addition, basic maintenance of elevators can also save some electricity in apartment houses. (Niemikorpi 2017) In addition, energy efficient household appliances can reduce electricity usage. 

Reducing heat energy and water consumption
In many cases heat energy is wasted due the radiators do not work as they should. Radiators might be too small, which is compensated by raising temperature of circulating water. Thermostatic valves might not work properly or customer does not know how they are used. Balancing heat loads and repairing heat distribution systems can together provide about 15% savings. (Niemikorpi 2017)

Water could be saved 10% with nozzles and valves, which controls water flow and pressure. If every apartment doesn’t have own water meter, it can provide massive savings, due the end user can follow their water consumption. When larger renovation is done for the pipelines, it is usually feasible to install new water fittings same time. New taps and toilets can save 10-25% water compared as old ones. (Niemikorpi 2017) 

Investing in an air-heat pump is a good way to reduce electricity or oil usage for heating. Heat pumps can be also used for cooling in summer time, however active or unnecessary cooling might cancel the savings. If heat pumps are used to support direct electricity heating, the savings in electricity usage are 8-26%. 

Niemikorpi, A. 2017. Energiansäästö kerros- ja rivitalojen korjauksissa. Referred 2.8.2018
Virta, J. & Pylsy, P. 2011. Taloyhtiön energiakirja. Referred 25.9.2018