Energy investigation of a semi-detached residence in middle Sweden: a study on household ventilation, energy balance and potential energy efficiency measures

Abstract

Nordic houses have extended heating demand periods due to their climatology,in addition to some of the highest electricity consumptions in Europe. In Sweden, the residential sector accounts for 40% of the energy end use, and as such, it is imperative to evaluate plausible energy efficiency measures both in old and new buildings should the latest European Union regulations be met.Particularly, energy auditing practices are a step towards proposing robust changes. This work conducts an energy investigation over a semi-detached light-concrete house built in 2007, located in the municipality of Gävle in Middle Sweden. The study consists of several visits to conduct experimental measures in the ventilation system and indoor thermal conditions to map out the energy inflows and outflows of the dwelling. Results are contrasted with a simulated model using IDA-ICE software and the proposed energy efficiency measures are backed up with existing literature. The results indicate that the house is proficiently insulated with transmission losses in the order of 12 000 kWh/year and its mechanical exhaust ventilation system regulated well enough to comply with indoor air quality standards above 0.35 L/(s·m2), yet the overall energy demand remains above policy targeted levels. Measures like indoor temperature control and the implementation of heat recovery in the ventilation system are analyzed. In addition, a 5 kWp PV system is designed to help alleviate electricity needs from the grid. Some alternatives, however, proved to be insufficiently appealing from an investment standpoint as in the case of thermal collectors. The measures report potential energy savings of 26% over the base model, with financial benefits of over 7 800 SEK/year, though with hefty investments with payback periods close to a decade. This thesis ultimately aims to improve upon the energetic balance of its study dwelling, and it intends to contribute to the domestic energy auditing practices in a broader scope. Future work remains to be performed in the form of the development of more accurate auditing techniques for the removal of complex to meter variables that tend to fall under simplified assumptions.