It is an interesting paradox of South Africa's sunny climate that the very source of heat, which necessitates cooling in buildings, can in turn be utilized to cool these very same buildings.  An exciting showcase project to prove the efficacy, efficiency and economic viability of commercial solar driven air-conditioning system has been implemented in Pretoria.

The system has been installed by Voltas Technologies and utilizes absorption chiller technology, aiming to define a new method of cooling buildings in Southern Africa.

Solar thermal energy has perhaps the greatest potential of all solutions to transform global energy issues, as it is a highly efficient renewable energy source for heating and cooling.  During 2008, according to the European Solar Thermal Industry Federation (ESTIF), despite the economic downturn, solar thermal heating and cooling solutions gained significant market share in an increasing number of countries around the world.

Cristian Cernat, CEO of Voltas Technologies explained that trying to find a host for the showcase plant was challenging due to structural limitations of existing buildings and the need to prove that absorption chiller technology was ideal in the South African context.

Cernat approached a long-time client, Netcare Hospitals Pty Ltd.  "Thanks to the commitment of Peter Schilder, Group Technical Manager and Eddie Herrmann, Regional Technical Manager, Netcare Hospitals agreed to provide Voltas Technologies with sufficient roof space and the opportunity to install and operate the system in parallel with the existing air conditioning plant at Moot Hospital, one of their facilities in Pretoria," explains Cernat.

"In order to demonstrate the economics and the operating characteristics of absorption cooling systems in South African conditions, Voltas Technologies, in partnership with several reputable solar installers, installed the solar chiller plant.  The plant, known as the 'First Solar Thermal Driven Chilled Water System' (STDCHW) is a first in Southern Africa.  The STDCHW is a showcase project, with a 35 kW cooling capacity, based on the Yazaki WFC 10 chiller and a number of solar collectors for a heat source on the roof of the Netcare facility.  The installation will produce chilled water, the cooling agent utilized in the building's air conditioning system, by deploying a thermally driven absorption cycle based chiller unit in lieu of an electrically driven compression chiller.  Thus, solar thermal energy can be used to efficiently cool in the summer, and heat domestic hot water and buildings in the winter."

The aim of the two-phase project is (a) to prove the technology to the local market; (b) to establish the relationship between the kW cooling and the area of the solar collector field required in South African conditions to power the chiller; and (c) to optimise the heat storage solution in order to ensure a consistent and constant hot water temperature supply to the chiller.

Cernat says that the installation will be completed in two different phases: Phase One - the installation of an absorption based system, 35 kW nominal cooling capacity complete with a dual storage system and full monitoring with web access, and Phase Two – the upgrading of the system to 200 kW nominal cooling capacity.  Phase One is now complete, the system is up and running and online.  Once conclusive data is collected and the heat source/cooling ratio is confirmed, the project will move forward to Phase Two.
"The project will enable Voltas Technologies to establish a real baseline for consumption so that eventual savings can be presented in perspective," concludes Cernat.  "The project's results will be available shortly and the absorption technology will be proven as the optimal air conditioning solution for South African conditions" says Cernat.

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