Energy audit of a century-old single-family house in Sweden

Abstract

The Swedish residential sector uses 140 TWh of energy, making the residential sector the largest energy user. The Swedish single-family houses (SFHs) are responsible for 12 % of the final energy use. From those dwellings, there are 417 909 single-family houses built before 1930.On the basis of the above information, the Swedish residential building stock is considered to be of relatively high age. Due to this situation, there is a great potential for the implementation of energy saving measures. This work consists in a study case of a single-family house (SFH) built in Stråtjära which uses electricity and wood as energy carrier, the aim in this dwelling is to propose measures to reduce energy expenditure proposing cost- effective measures and reaching a minimum label of bronze category in the Miljöbyggnad energy use indicators. At first, a literature review was performed to observe the renovation strategies previously applied in similar studies. A quantitative and empirical approach was completed, where energy data from the bills of 2023-2024 together with on-site data collection were combined as a way to determine the energy entering and leaving the dwelling. The research was conducted with the help of the IDA ICE energy simulation program, to monitor the energy and ventilation performance of the dwelling. The results obtained from the simulation and hand calculations indicated that there was room to improve the property. Namely, the calculations concluded that the ventilation and the primary energy number need to be improved to meet the Swedish building regulations. Furthermore, the installation of photovoltaic (PV) modules to meet part of the electricity demand could helped to improve the energy situation. Finally, the reduction of electricity use was focused on the efficient use of electricity, avoiding the electricity consumption in unused rooms, such as the guest room, and the reduction of heat/thermal losses through the insulation of the envelop. The methodology used consisted of two different scenarios, one that meets the objectives of monetary savings and economic viability and the other that seeks to comply with the requirements imposed by the Swedish authorities in terms of energy efficiency.

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