Future buildings should be planned to use or suited to use sustainable energy sources for heating and cooling. If reasonable efficient systems are desired, the development of low temperature heating and high temperature cooling systems is necessary precondition for the usage of alternative energy sources. This low exergy systems are defined as heating and cooling systems that allow the use of low valued energy source. In practice, this means that provide heating and cooling energy at a temperature close to room temperature. The purpose of this study was to analyze the performance of a novel radiant heating & cooling system using simulation (CFD) of convection and radiation. Unlike an all-air heating & cooling system, the radiant systems could remove the heating and cooling load by convection and radiation. To evaluate the performance of the proposed system, the thermal environment of the model space, which is heated and cooled by system composed of radiant wall, floor and ceiling was analyzed using CFD. Computational fluid dynamics (CFD) simulations were also used to investigate possible cold draught problems, differences in vertical temperature gradients, air speed levels and energy consumption. The general conclusions from this study were that low temperature heating systems may improve indoor climate, giving lower air speeds and lower temperature differences in the room than a conventional high temperature radiator system.