Hydraulics, performance and comfort of ground coupled heating-cooling systems

The energy demand for heating is decreasing significantly in modern highly-insulated dwellings. Due to larger glass areas and well insulated buildings overheating becomes a problem. In a research project several hydraulic schemes with ground-coupled heat pumps and passive cooling with borehole heat exchanger have been evaluated. A parametric study with MATLAB/Simulink simulations using a residential low-energy building with floor heating system has been carried out. Simultaneous simulation of building and mechanical system showed dynamic interaction of floor and ground heat exchanger. Main objective is to estimate energy demand for heating and cooling, thermal comfort and economical feasibility of the overall system. A big challenge is appropriate control providing an optimal thermal comfort with a minimum of additional energy compared to heating only systems. Especially the meteorological conditions in spring and autumn cause intermittent heating and cooling which increases heating energy demand, since the concrete structure is alternately heated and cooled.