The renovation of old buildings is essential for the efficient useof energy. Improvement in the thermal characteristics of thebuilding envelope makes a significant effect on energy savings.For assessing the real impact on buildings, energy efficiencyof various measures applied in renovation is one of the mostimportant problems. Actual energy savings significantly differfrom those calculated according to the methodology described intechnical documents. The article analyses 8 renovated buildings.Three main external elements, including walls, windows androofs, in all buildings were retrofitted. Using theoretical energysavings through each element and knowing the actual savingsof the building, actual energy savings through each element arefound. Theoretical energy savings for heating after renovation,in every case, are bigger than actual energy consumption forheating before renovation. There is a big difference betweentheoretical and actual savings after renovation, sometimes up to2 times. The paper describes dependency between the envelopearea of buildings and the mismatch factor of theoretical andactual consumption. The payback period of renovated buildingsis calculated using theoretical and actual data. The theoreticalpayback period of renovation is up to 2 times shorter than theactual one. The calculation method for the estimation of the actualpayback period using the mismatch factor has been proposed,and the model of the building has been made to calculate itsprobable payback period.

Article in: Lithuanian

Article published: 2013-12-19