Rehau played a part in the construction of South Africa’s first building to achieve a 6-star Green Star SA rating from the GBCSA – the Vodafone Site Solution Innovation Centre in Midrand.
Designed by GLH Architects, the building makes use of Rehau’s thermally activated building systems (TABS) to provide for energy savings on heating and cooling. This is just one of the technological innovations that have been brought together in the design of the Vodafone Innovation Centre to distinguish it as a 6-star Green Star SA building.
In this installation the TABS use heated water, or cool water, circulating through specialised piping, to precondition the temperature of the concrete structure and minimise the need for conventional HVAC equipment to maintain comfortable indoor temperatures in the building.
According to Rehau, TABS provide for a significant reduction in energy consumption in new buildings. Although well recognised in Europe, the USA and China, they are just beginning to make an impact in South Africa and are set to become an integral part of green building technology. As well as the energy savings they afford, TABS offer the further advantages of low investment costs, high levels of comfort and performance and draught-free ‘soft’ cooling.
TABS rely on the high thermal capacity of thick concrete slabs to deliver efficient heating or cooling, according to the seasons. Cold or hot water, as required, is circulated through the pipes which are embedded in the concrete floor/ceiling slab during construction. This converts the concrete mass of the slab into a giant thermal accumulator which extracts excessive heat or cold from the space and carries it away through the circulating water – effectively cooling or heating the building.
The new SANS 10400-XA regulations set challenging energy consumption levels for offices, at between 185kWh/m² and 210kWh/m² over the year. Rehau recommends the use of TABS in new-build projects as an innovative and energy-efficient solution – for both heating and cooling – to help achieve these targets.
TABS is more energy-efficient than conventional air-conditioning because the chilled water in the pipe circuits operates at a moderate temperature of 15 to 18°C, improving the efficiency of the water chiller and lowering energy costs significantly over the long term.
Integrated into new buildings during construction, TABS make it possible to install a much smaller than usual air-conditioning system – to remove peak heat loads, dehumidify the air and supply fresh air. The main cooling load is handled by the concrete core. By moderating the internal temperatures, this allows for reduced air exchange rates and fewer air handling units, ducts or fans.
Less space is required for ducting, so room heights can be reduced. And by reducing the energy usage required by the building’s HVAC system, CO2 emissions are also reduced.
