Low-energy houses are a good concept for reducing energy use during the building's use. Especially when studies have shown economic profitability in buildings that meet the requirements for the definition of low-energy houses - that the energy performance is at least 25% better than the building standard from the Swedish National Board of Housing, Building and Planning. The investment cost of houses with low energy performance is higher, but the economic profitability is achieved under the reduced operating costs. However, it can be difficult to ensure the quality of all new construction techniques and installations, which can lead to worse energy performance than projected values ​​show. To maintain economic profitability, buildings must be maintained throughout their lifetime without unexpected costs to a greater extent. Moisture damage, which can seriously damage the construction and add odors that lead to a bad indoor climate, has over time caused great costs in our buildings. Poor indoor climate can have consequences that create or strengthen mental and physical symptoms. This is something we want to counteract with knowledge of how the indoor climate is in use. In Sweden, most evaluations of low-energy houses have treated houses in the southern parts of the country. There are large climate differences across the country. Construction techniques that are proven to work in the south, do not always perform as well in the north. In the northernmost parts, there is a subarctic climate - where the average temperature exceeds  for a maximum of three months a year. The purpose of this study is to evaluate a low-energy house in a subarctic climate and make a contribution to increased knowledge regarding the type of building in this climate. To achieve the project's goal, to map the house's performance in terms of energy use, indoor climate and moisture migration, literature and case studies have been carried out. These studies are aimed at one of four apartment buildings that are located in the northernmost parts of Sweden and have been built according to a concept with environmental thinking in focus. The evaluation is based on previously performed field measurements during 2016/2017 as well as a survey of residents in the case study building and its three adjacent almost identical houses. The energy performance in operation turns out to exceed the projected value. The house is designed with very small margins for the construction year's low-energy house requirements. Requirements from the Swedish National Board of Housing, Building and Planning are achieved, but the specific energy use of buildings exceeds the low-energy house requirement and achieves energy class C according to the Lågans definition. If the house's energy performance is set against today's stricter requirements and with the new calculation method with primary energy, it will not be able to achieve class C. Possible causes can be heat losses related to the house's supply air system and storage of domestic hot water. To evaluate the indoor climate, the thermal climate, humidity and carbon dioxide content of the house are studied. This is weighed together with the survey about the living experience of residents. The case study building is considered to perform well regarding the indoor climate, as no critical values ​​have been identified according to the field measurement and very little dissatisfaction from the survey study. The moisture content of the house's wall construction exceeds the critical moisture condition several times in all facades during parts of the year. There is no risk of microbial growth as this is during very short periods or periods where the corresponding temperature in the wall is too low. However, inactive measurement periods during the holiday season in the summer creates uncertainties. There may be value in continued control that runs continuously over the warmer period of the year. The general conclusion from the evaluation of the low-energy house is positive. A good concept with the environment in focus that has also tested modern technical solutions in the northern parts of the country.