Numerical analysis of the potential of using light radiant ceilings in combination with diffuse ventilation to achieve thermal comfort in NZEB buildings

Renewable energy resources for heating and cooling of buildings have temperatures close to room temperature and therefore a limited convertibility potential, i.e. they are of low value. To exploit low-valued energy sources Low Temperature Heating and High Temperature Cooling (LTH-HTC) systems must be developed.

Hydronic radiant ceiling systems with large surfaces for heat transfer are well suited for the usage of LTH-HTC. In this paper, the aim is to create a system that can be flexible and include ventilation. The system analysed are a suspended capillary tube ceiling placed on top of perforated gypsum ceiling panels.

These panels make it possible to combine the heating/cooling ceiling with the diffuse ventilation method. The diffuse ventilation method or leak ventilation use larger surfaces to provide air into the room instead of diffusers. An office building is investigated an analysed on an annual basis in the dynamic building simulation tool IDA Indoor Climate and Energy (IDA ICE).

The office building contains both offices and meeting rooms. Worst-case scenarios are investigated in the office building considering heat gains, solar gains and the temperature offset between supply water temperature and room air temperature. The studies a carried out to identify the potential of reducing the temperature offset in near-zero energy buildings (NZEB) to the level where temperatures between ±2-4 °C becomes possible.

The reduction should not compromise on the thermal comfort of the building occupants and comprise energy savings. The investigations showed that with a NZEB building it was possible to create an adequate thermal comfort with a minimum use of energy. The studies showed that an energy saving of 36-41 % from a fan coil system running with the same temperatures was possible.