It seems paradoxical that solar energy can be used to cool buildings, but a showcase project has been set up at a Pretoria hospital to demonstrate the efficiency and economic viability of a solar driven air-conditioning system at commercial scale.
The system, using absorption chiller technology and installed by Voltas Technologies, is currently fully operational and data is being collected and monitored for analysis. The aim is to define a new method for cooling buildings in Southern Africa.
Voltas Technologies is the South African importer and distributor of absorption water chillers produced by Japanese multinational, Yazaki, which is recognised as a world leader in the industry. The Johannesburg-based company specialises in solar technology solutions and offers a range of renewable energy products through its network of dealers and installers across Southern Africa.
Christian Cernat, CEO of Voltas Technologies, suggests that solar thermal energy has perhaps the greatest potential of all solutions to transform global energy issues. It is a highly efficient renewable energy source for heating and cooling and is being used increasingly around the world.
A mechanical engineer with 20 years’ experience in heating, ventilation and air conditioning design, installation and system integration, Cernat selected Yazaki products based on the company’s outstanding international reputation for high quality absorption chiller products, its advanced technology and research and its ISO 9001 and ISO 14001 certification. The distribution agreement between the Yazaki Corporation and Voltas Technologies was concluded in 2008.
“Today, almost 150 years from its inception (Carre 1858), absorption cooling technology has reached an acceptable level of process stability,” says Cernat. “Newly developed chillers are suitable for use with low (less than 90ºC) hot water temperatures. This characteristic makes them applicable for systems based on recovered waste heat or solar heating systems. In South Africa, few absorption systems have been implemented and, as far as we know, none has been solar power driven.”
With the technology newly available in South Africa, Cernat says, “We needed a showcase installation which could prove to the market that absorption technology is a reliable, efficient and cost-effective solution for the South African air conditioning market.
“Thanks to an agreement with Netcare Hospitals and support from their technical management, Voltas Technologies was able to install and operate the system in parallel with the existing air conditioning plant at Moot Hospital, one of Netcare’s facilities in Pretoria.”
The solar chiller plant, which is known as the ‘Solar Thermal Driven Chilled Water System’ (STDCHW), is a first in Southern Africa.
Cernat says, “The installation produces chilled water, the cooling agent used in the building’s air conditioning system, by employing a thermally driven absorption cycle based chiller unit in place of an electrically driven compression chiller. Thus, solar thermal energy can be used to cool efficiently in the summer, and heat domestic hot water and buildings in the winter.”
“With the data collected we will be able to establish a real baseline for consumption so that eventual savings can be presented in perspective,” says Cernat. He is confident that the results of the project will demonstrate absorption technology as an optimal air conditioning solution for South African conditions.