Since the building sector is responsible for 40% of the energy consumption and 36% of CO2 emissions in the EU, the reduction of energy use has become a priority in this sector. The EU has adopted several policies to improve energy efficiency. One of these policies aims to achieve energy efficient renovations in at least 3% of buildings owned and occupied by governments annually. In Sweden, a large part of existing buildings was built between 1965 and 1974, a period commonly referred to as ‘miljonprogrammet’. Stora Tunabyggen AB, the public housing company in Borlänge municipality, begun a renovation project in the Tjärna Ängar neighborhood within the municipality with the greatest share of its buildings stock from this period. The pilot project started in 2015. The aim of this project was to renovate three buildings with similar measures, that is, by adding 150 mm attic insulation, replacing windows with higher performing ones (U-value 1 W/m ²K), by adding 50 mm of insulation to the infill walls and by the installation of flowreducing taps. The essential difference between the three renovation packages is the HVAC systems. The selected HVAC systems are (1) exhaust air heat pump, (2) mechanical ventilation with heat recovery and (3) exhaust ventilation. Life cycle cost analysis was conducted for the three building and sensitivity analysis for different values of discount rate and energy price escalation was performed. The study found that the house with exhaust ventilation has the lowest life cycle cost and the highest energy cost. The house with exhaust air heat pump has 3% higher life cycle cost and 18% lower energy use at 3% discount rate and 3% energy price escalation. The study found that mechanical ventilation with heat recovery is not profitable, although it saves energy. The sensitivity analysis has shown that the possible increment of price energy and lower discount rate give higher value for the future costs in life cycle cost analysis. This lead to the main finding of this thesis, which is that exhaust air heat pump is the best choice for the owner according to the available data and the assessed parameters.

The aim of this master project is to design a nearly zero-energy building of a guesthouse with a restaurant in the village Vrbice u Velkých Pavlovic. The project contains architectural-construction part and concept of building services. As the third part there is a design and concept of a wastewater treatment wetland system. The building has two floors. On the ground floor there is a restaurant, kitchen, reception and technical facilities, the premises of the 2 nd floor contain guest rooms. The structural system is designed from ceramic blocks with thermal insulation from mineral wool. Horizontal load-bearing structures and stair construction are designed from cast-in-place reinforced concrete. The building has a warm flat roof. The building has a mechanical heat recovery ventilation. For heating and water heating there is a heat pump and a condensing boiler, for cooling there is a multi-split and VRV system. The building also includes a storage reservoir for collecting rainwater and photovoltaic panels on the roof. The building site contains also an outdoor park, storage with carport and a garden with wastewater treatment wetland technologies and biotope lake. The project was carried out by the ArchiCad and Autocad programme.