Technical and economic analysis of thermal modernisation process of a detached house

Abstract

The aim of this paper is to analyse the cost-effectiveness of thermal modernisation of a detached house, making use of different technologies. In order to reduce heat losses three thermo-modernisation options are considered. In the first option the exterior walls are insulated with 10 cm thick Styrofoam and the roof is insulated with 15 cm thick mineral wool. This produces the following heat transfer coefficients: for the exterior wall U = 0.213 W/(m2K) and for the roof U = 0.214 W/(m2K). In the second option, additionally to the wall and roof insulation, the windows whose heat transfer coefficient is U=0.9W/(m2K) are replaced. In the third option all the work as in the second option is done and a new, state-of-the-art boiler of the 93 % efficiency is installed. The heat calculations for the thermal modernization of the detached house are performed with the computer program PURMO OZC v 4.80b. To cost the thermomodernisation works the computer program Norma Pro v 4.03 – pricelist for the April-July quarter 2013 is used. The thermal modernization of the existing detached house encompassing insulating external barriers, replacing old windows with new tighter ones and installing a new more efficient boiler resulted in a considerable reduction of the heat demand coefficient (EA) and allowed classifying the house as energy-efficient. The scope of the thermo-modernisation in the three options increases as well as the costs incurred. The third option is twice as expensive as the first one, yet the payback period is similar - approximately nine years. The most profitable is the third option of thermo-modernisation because in a twenty-year period the owner can save about 41324 PLN as compared to the costs incurred currently.