Geothermal and solar thermal cooling are being used to supply cooling to the six-story Prometheus Pyrphoros building in Paleo Faliro, Athens, Greece.

Sol Energy Hellas used DuCool’s chiller-free, desiccant-based dehumidification and cooling technology in the development to cool the 600 square meters building.

Now cooled with only 6 kW of electricity, one tenth of its previous consumption, the installation saves $22,000 in energy costs per year. DuCool’s technology uses geothermal water and hot water from a solar thermal system to provide cooling and dehumidification.

DuCool’s desiccant-based dehumidification and cooling unit treats the outside air to comfort conditions using only solar-heated water at a temperature of approximately 65°C and geothermal well water at approximately 19°C.

Sol Energy had considered a conventional solution, using a 40 tonne refrigeration (TR) capacity cooling tower and chiller and a 5800 cubic metre per hour air handling unit. This approach would have cost approximately $47,000 and consumed 59 kW of electricity during 2650 annual hours of operation for an annual energy cost of $24,700, the company says.
The total investment in the renewable approach including the solar panels, geothermal well and chiller unit is approximately $105,000. The energy consumption is only 6 kW which amounts to a cost of only $2512 per year, a savings of $22,180 per year. These energy savings pay back the $58,000 additional investment in the DuCool unit in just over 2.6 years.

Nikos Manioudakis, senior research engineer for Sol Energy Hellas, which designed and operates and maintains the Prometheus Pyrphoros building said: ‘These savings provide less than a three-year return on investment without even taking any possible tax savings into account.’