Vulindlela Academy, Development Bank of South Africa, South Africa. Holms and Friends: Domestic warm water and under floor heating system with 28,3 m2 vacuum tube collectors.
SHORT DESCRIPTION OF THE UNDER FLOOR HEATING SYSTEM
Holms and Friends completed a solar water heating (SWH) project for the Development Bank of South Africa, located in Midrand, in 2010. The company specializes in integrated energy strategies and EPC for large scale, commercial solar water heating and photovoltaic systems. They are known for the training they offer in the renewable energy and energy efficiency sector as well as education for sustainable development. The system provides hot water for the gym, the office toilet facilities and a prep kitchen.
CHARACTERISTICS OF THE UNDER FLOOR HEATING SYSTEM
The low temperature (30° C) required for the under floor heating (UFH) system creates the opportunity for very high solar water heating (SWH) system efficiency. Both the collector and domestic water system are direct and connected to the fresh water. This in itself leads to high energy transfer efficiencies. The UFH system (500m2) has a heat exchanger of 15kWth. A peak demand of 30Watt/m2 floor area is only required in extreme cold weather, as the building as excellent solar passive performance. The building is also ventilated by a pre-heated earth tube system. As the UFH system warms the well-insulated structure (which has a high energy capacity), the continuous opening and closing of doors has very little effect on the thermal comfort.
The water heated by the solar panels is stored in the 2 500 litre high pressure steel vessel with enamel coating. Backup heating is supplied through 2 x 9kW resistive elements. The domestic hot water system is circulated through a well-insulated circulation pipe loop, which avails hot water instantaneously when the water efficient taps are opened.