Although geothermal heat exchange system installations have become common in other parts of the world, this technology is still fairly new in South Africa.
US Environmental Protection Agency figures indicate that geothermal exchange systems (or geoexchange systems for short), represent a cost effective, energy-efficient, and environmentally friendly way of heating and cooling buildings. They save homeowners between 30% and 70% in heating costs, and 20-50% in cooling costs compared to conventional systems. Even in the temperate South African climate, this indicates a potential for major savings, while also having important environmental and sustainability advantages.
A geoexchange system normally includes one or more ground source heat pumps to take heat from one location to another, a ground heat exchanger and a distribution subsystem. Most geoexchange systems use air ducting for the distribution system, and high density polyethylene pipes underground for the heat exchanger.
“When the building needs heating, the system extracts energy from the ground and pumps it into the building where it is concentrated by a heat pump. Conversely, when the building needs cooling, the heat from the building is concentrated by the heat pumps and the system pumps it back into the ground,” explains Bert Dennison-Farrar of Geothermal Energy Systems.
“In some instances geoexchange systems can be installed for the same cost as conventional systems, but generally the added investment of installing the ground heat exchanger can cause the initial cost of a geoexchange system to be higher. The lower energy and operating costs over the life of the system, however, often offset the added initial investment.”
A successful local example is the My Pond Hotel in Port Alfred where the architect had to be concerned about the height of the building, since local municipal regulations prohibited a tall structure. “The geoexchange system eliminated the need for rooftop and external condensing units,” Dennison-Farrar explains. The owners were also anxious about energy bills, and required a system with a quiet operation for the sake of their hotel guests.
The slow adoption of geoexchange systems in South Africa is mainly due to a lack of awareness, and also because there are still too few examples of successful large local case studies, says Dennison-Farrar. He believes there are major opportunities for cost-effective geothermal installations in the agriculture industry, for fish farms and in many other industries with major cooling or heating requirements.
Gerhard van der Merwe, urban designer and a director of dhk Urban Concepts, agrees that it is not yet easy to convince South African clients to choose geothermal exchange systems.
Architect Alan Walt adds geothermal technology “is simple and it works and saves huge amounts of energy and money during the building’s lifetime…I became involved in the geothermal option when reading an article by chance, and so we have followed the process and are 95% complete with the installation on a boutique wine farm and hotel on a lake in the Grabouw valley. The cost and installation of this system has worked out far more economical than a comparable non-sustainable system would have, and its real benefits are still to come when it’s up and running.”
The Geothermal Energy Association of Southern Africa is being established to promote the technology locally and to become a platform for engagement between stakeholders.
The original article appeared in the August-September 2011 on p34.