Future energy effective multi-dwelling buildings

The housing sector of today represents for almost 40% of the energy consumption, an energy consumption of which the major part consists of non-renewable energy sources. This is not sustainable and utilization of new energy-efficient technologies in buildings can be a step in the right direction, towards a sustainable energy society. This report has been made on behalf of and in cooperation with Älvstranden Utveckling AB in Gothenburg to examine how future energy-efficient technologies can affect the energy demand in energy-efficient multi-dwelling buildings. The report is based on Älvstrandens passive house, Hamnhuset, a house whose energy consumption is far below the BBR's requirements. The report looks at the opportunities for improvement within windows, insulation, solar energy technologies, as well as white goods. Computer simulations are then made to apply the selected technologies into a reference building. Technologies are selected from an energy efficient perspective and no account has been taken of other aspects such as the economy. They must also be available on the market within a ten-year period. Information has been gathered through interviews and contacts with experts in their respective fields, as well as representatives of the various technologies. By using high-efficient insulation and smart windows, heat transmission losses and thus the heat demand can be reduced. Increased solar irradiation through the windows during the winter months also contributes to a reduction in need of purchased energy during the coldest part of the year, when the supply of renewable energy is minimal. A large part of the needed electricity may be covered by electricity from solar cells mounted on the roof, balcony fronts and facades. A reduction of purchased electricity has a major impact on the building's stress on the environment and carbon dioxide emissions from a life cycle perspective. That is also why electricity heated white goods are exchanged into appliances on district heating. By installing a larger amount of and more efficient solar collectors which also has a smoother heat production over the year, the need for heating domestic hot water is reduced. The calculations are made in two stages, the first sets out the various technologies effectiveness and potential individually; several simulations have been made for one and the same technology to provide different variations depending on the situation it is used. For example, several combinations of windows are tested in different orientations. In step two, the techniques with the greatest energy saving potential are selected in order to jointly result in a final house. To see how a future streamlining of household technology and lighting affects the energy balance of a building, a simulation is also made where household electricity is reduced by 40%. The result of selected energy efficiency measures shows a reduction of the specific energy demand by 70 % compared to the BBR's requirements and 50 % compared to the reference house. In addition the environmental impact of the building reduces from a CO2 perspective with 85 % compared to the reference house. However, there is an uncertainty of the results as they are based on speculations in the technologies future capacity. Results should therefore be seen as an inspiration for how high the objectives can be set in the construction of energy-efficient buildings. Still, in the light of this report, there are great opportunities to within a ten-year period build multi-dwelling buildings that are way more energy efficient than today