The six-story Prometheus Pyrphoros building in Paleo Faliro, Athens, Greece has a total of 6,500 square feet (600 square meters). Sol Energy Hellas has used DuCool's chiller-free, desiccant-based dehumidification and cooling technology in the Prometheus Pyrphoros building to save 90% on energy costs.
The 6,500 square foot (600 square meters) building is now cooled with only 6 kW of electricity to save $22,000 (€16,854) in energy costs per year. The energy savings amount to $3.38 per square foot (€28.09 per square meter). DuCool's technology uses geothermal water and hot water from a solar thermal system to provide cooling and dehumidification.
"DuCool's unit helped us reach comfort zone conditions while reducing energy consumption by 90%," said Nikos Manioudakis, Senior Research Engineer for Sol Energy Hellas, which designed and operates and maintains the Prometheus Pyrphoros building. "These savings provide less than a three-year return on investment without even taking any possible tax savings into account."
Sol Energy considered a conventional solution of using a 40 ton refrigeration (TR) capacity cooling tower and chiller and 3400 cubic feet per minute (5,800 cubic meters per hour) air handling unit. This approach would have cost approximately $47,000 (€36,000) and consumed 59 kilowatts of electricity during 2650 annual hours of operation for an annual energy cost of $24,700 (€18,762).
Instead, Sol Energy utilized a much more energy- and cost-efficient approach based on DuCool's desiccant-based dehumidification and cooling technology. The DuCool DH-3400 unit treats the outside air to comfort conditions using only solar-heated water at a temperature of approximately 149°F (65°C) and geothermal well water at approximately 66.2°F (19°C).
In the process section of the DH-3400, outdoor air is forced upward through the unit while the cold desiccant solution flows downward through honeycomb media and absorbs the humidity in the air due to the differences in vapor pressure between the cold solution and warmer air. In the regeneration section, return air is forced upward through honeycomb media while moisture-laden desiccant solution flows downward. The return air extracts the moisture from the desiccant solution and then exhausts the moisture from the building. After it has released the moisture, the desiccant solution moves to the process section to collect additional humidity.
The DH-3400 provides 100% fresh air to the building, providing a substantial improvement in indoor air quality. The use of concentrated natural salt as the air treating media not only dehumidifies and cools the air to very comfortable levels but also eliminates approximately 91% of microorganisms from the air and approximately 80% of airborne particles larger than 5 microns, providing additional improvements in indoor air quality.
The total investment in the new approach including the solar panels, geothermal well and DuCool DH-3400 unit is approximately $105,000 (€80,000). The energy consumption is only 6 kW which amounts to a cost of only $2512 (€1908) per year, a savings of $22,180 (€16,854) per year. These energy savings pay back the $58,000 (€44,000) additional investment in the DuCool unit in only 2.61 years.