Effects of acoustic ceiling units on the cooling performance of thermally activated building systems (TABS)

Europe, with a building stock responsible for about 40% of the total energy use, needs to reduce the primary energy use in buildings in order to meet the 2020 energy targets of the European Union. High temperature cooling and low temperature heating systems, and as an example, Thermally Activated Building Systems (TABS), have proven to be an energy efficient solution to provide buildings with an optimal indoor thermal environment. This solution uses the structure of the building to store heat and decrease the primary energy use. TABS require the active (heated or cooled) surfaces to be as exposed as possible to the room, but exposing bare concrete surfaces will have a diminishing effect on the acoustic qualities of indoor spaces. Acoustic solutions capable of providing optimal acoustic comfort while allowing the heat exchange between the TABS and the room are desirable. This study quantifies the effects of two types of free hanging ceiling absorbers (horizontal and vertical) on the cooling performance of the TABS and the implications this has on the occupant thermal comfort. The measurements were carried out in a full-scale TABS test facility. The results show a reduction of 11% of the heat removed by the TABS when 43% of the ceiling area was covered with free hanging horizontal sound absorbers at 300 mm (0.98 ft) from the active surface. This reduction was 23% for a ceiling coverage ratio of 60%. The decrease in heat absorbed by the TABS is less pronounced in the case of vertical sound absorbers for equivalent levels of sound absorption. A reduction of 12% of the heat removed by the TABS has been measured for vertical sound absorbers (equivalent sound absorption levels to 60% coverage ratio with horizontal sound absorbers). This reduction was of 13% for vertical sound absorbers (equivalent sound absorption levels to 80% coverage ratio with horizontal sound absorbers).