Energy demand and indoor climate in a low energy building—changed control strategies and boundary conditions

Energy demand in the built environment is an important issue. In Sweden, 39% of energy use originates from the building sector, and this figure is increasing. Several attempts have been made to improve the energy use, for example low-energy houses, which are built with the aim of decreasing the use of energy, but still providing a good environment for the occupants. An energy simulation program, ESP-r, was used for simulation of the energy requirement and indoor climate in a well-insulated terraced house in Sweden. The building model was compared to measured values from the real object. A computational fluid dynamics (CFD)-model for one room was used to simulate and visualize the airflow and temperature pattern. Increased set-point temperature increases the power demand by about 200 kWh/°C. Thinner insulation increases the heat demand but decreases the demand for passive cooling by airing and deteriorates the indoor climate. Different types of windows affect both the energy demand and the indoor climate significantly. Load management was simulated by restriction on the heating possibilities and an economical comparison was made to investigate the advantage of such an operation. The extra insulation has a payoff time of about 38 years at common Swedish energy prices.