Heat consumption for single family houses decreases each year with compacter and better building envelope construction. At a lower heat consumption there is the issue of the traditional methods of heating and ventilation is a good option for maintaining a good indoor climate or can new efficient methods obtain a similar indoor climate with less investment cost.This thesis study the indoor climate by computational flow simulations. In this study a model for a simple way to use CFD simulations (computer fluid dynamics) to investigate the indoor climate. The simulation model was built up in three steps to obtain stable results for a low-energy house produced by Glommershus according to convergence criteria and turbulence model.Studies on different solutions for distribution of heat have been analysed for different cases. One case with radiators, one with floor heating and a case with a heat pump for three different outdoor temperatures for each case. The results are considered in relation to the Boverkets rules for new construction of single family homes.The result showed that the building model in three steps is preferred for CFD simulations for low-energy buildings when a series of time-saving features are made. The CFD simulation tools can be used to evaluate different solutions for heating and ventilation in a conveniently way.For radiators and floor heating results show that temperature gradients horizontally varies very little. For radiators the vertical temperature gradient in the occupied zone increasing from the floor. For floor heating obtained a uniform temperature profile. For the heat pump it is obtained a poorer indoor climate with large temperature gradients but still within reasonable levels according of Boverkets rules.