Numerical simulation of the effects of hanging sound absorbers on TABS cooling performance

Recently there has been a considerable increase in the use of Thermally-Active Building Systems (TABS) in Europe as an energy-efficient and economical cooling and heating solution for buildings. However, this widespread solution requires large uncovered hard surfaces indoors, which can lead to a degradation of the room acoustic comfort.

Therefore, challenges arise when this system has to be combined with acoustic requirements. Soffit-hanging sound absorbers embody a promising solution. This study focuses on quantifying their impact on the cooling performance of TABS, assessed by means of the cooling capacity coefficient of the ceiling deck.

The influence of different ceiling coverage ratios (0-30-45-60 and 80%) as well as the influence of the distance at which the absorbers are placed is studied by numerical simulations using a new, specially-developed TRNSYS Type. Tests were performed in a test room simulating a two-person office of 20 m2, with a typical cooling load of 42 W/m2.

The results show that covering 60% of the ceiling surface with sound absorbers hanging at 300 mm from the ceiling active deck is expected to reduce the cooling capacity coefficient of TABS by 15.8%. This drops to 25.4% with a coverage of 80%. The presence of acoustic panels also affects the thermal comfort: the operative temperature in the room increases by 0.9°C in the former case and up to 1.6°C in the latter.

Results also show that comfort ventilation supplied to the enclosure has a considerable influence on the thermal conditions in the room; if the ventilation is removed, then the operative temperature increases by 1.8°C for a 60%-covered ceiling.