Vanade puitakende energiatõhusesuse parandamine / The Energy Efficient Renovation of Old Wooden Windows

Replacing old wooden windows with new ones is a common way of improving the energy efficiency of the buildings, although there is no general agreement on whether changing windows is a rational step to take. The architectural and the cultural changes, as well as the building waste generated by the removed windows, have been seen as problematic. Nor has a consensus been reached on the amount and significance of the energy savings achieved by such changes.In this study, the thermal and physical properties of old windows and theeffect which different renovation methods have on them were investigated. The renovation methods used in this study were light, and therefore there was no need to work on the wooden parts or to take out the frames.The energy efficiency of a window consists of its airtightness, heat conductivity and radiance permeability. The large air leakages of the test window were fixable by stuffing and taping, but it was found that the result was unsatisfactory when rubber sealants were used. The U-value of the test window was improved by changing the selective glass in the inner frames. The energy efficiency of the test window improved significantly when the appropriate renovation and replacement work was done. On the other hand, even after the repairs, the energy consumption was still almost twice as high as that of modern windows. Both renovating and replacing the windows are reasonable attempts to decrease energy expenditure, but they are not cost-effective. Culturally and architecturally speaking, replacing windows is a destructive action.Arriving at an answer to the question of what to do with old wooden windowswill depend on one’s viewpoint, and we cannot promulgate a single, invariably correct, course of action. As a compromise, it can be recommended to always seal the windows carefully at the beginning of the heating season and to change the selective glass in the inner frames during the renovation