Pre-renovation considerations for a Swedish single-family house : Analysis of energy saving potential

Abstract: According to United Nations 7th sustainable development goal, increased use of fossil fuels in energy accounts for around 60 percent of total global greenhouse gas emissions and in order to debacle this crisis of global warming, the European Union aimed to reduce energy use by 32.5 % within 2030 by improving energy efficiency. Whereas, the Swedish energy goals include reducing energy use by 50% in 2030 compared to 2005 and at producing 100% electricity from renewable sources by the year 2040. In the year 2018, the housing and service sector contributed to 40 per cent of the total final energy use in Sweden according to energimyndigheten. For this reason, energy conservation in the residential sector is given a priority. Furthermore, the emissions from old houses are much higher compared to that of newly built homes, which demonstrates higher scope of introducing energy efficient renovation measures in Swedish buildings. During the year 1965 to 1976, there was an enormous construction work to build up single family housing areas in Sweden under the million homes program which are now in need of renovation. Therefore, an old single-family villa from million homes program was selected for the purpose of energy efficient renovation.There are different environmental certification systems to assess energy performance of a building which are commonly expressed in terms of kWh/m2 and year. Among them, the seven energy classes from A to G was chosen for building rating in this project. The aim was to improve the current energy rating of the house from D without compromising the indoor air quality and cost effectiveness. At the same time, objective was also set to increase the amount of green energy as fuel for electricity production in the building. At first, a literature review was performed to observe the renovation strategies previously applied in similar projects. A study of the construction used for the million homes villas was also conducted to assess the original construction of the reference villa in Valbo. The research was conducted with the help of energy simulation software IDA ICE and LCC software BELOK Totaltool. The theory behind the application of these software in this project was analyzed in the beginning. Then, the building model was created with the help of building floor plan. The input parameters were set according to the standards of FEBY and Boverket regulations. After forming a base model for the existing construction of the building, different sensitivity analyses were performed with various renovation measures for one month or for one year. The results obtained from the sensitivity analysis helped in choosing the most energy efficient measures for renovation. Then the economic analysis of the model was conducted to investigate the most cost-effective measures. Later on, these expensive measures were omitted from the renovation plan to yield both energy efficient and cost-effective renovation of the villa. Next, the indoor air quality and green footprint in the building were compared before and after renovations. The results indicated that, it was possible to maintain good indoor air quality and increase green energy footprint in the building when the building rating was changed from D to B. In the end, the simulation results were compared with that of the literature review. It was found that both the qualitative and quantitative results have common realizations. Overall, it was possible to reduce the energy consumption in the house by 46.82%.