Long Beach's Rancho Los Alamitos historic park, a 7.5-acre site that preserves both an early Californian land grant ranch and the Tongva village Povuu'ngna, has just built a new interpretive center with a state-of-the-art climate control system that doesn't compromise the park's historic integrity with noisy boilers, condensers, or generators. Instead, the park's new earth-friendly heating and cooling infrastructure takes advantage of the very earth the Tongva walked.
Instead of a typical HVAC system with its high power demand and visually prominent infrastructure, the new Rancho Center has its temperature maintained at a comfortable level year-round with the help of a ground source heat pump, sometimes called a geothermal heat pump.
Built with the assistance of Guttman & Blaevoet Consulting Mechanical Engineers, the new 13,000-square-foot Rancho Center's climate control system consists of a series of 30 loops of 2-inch polyethylene pipes running 350 feet into the ground in bore holes drilled into the Rancho's grounds. Water is pumped in closed loops between the boreholes and heat exchangers in the building. Below about 20 feet from the surface, the earth's temperature averages 68°F: maintaining the Rancho Center's interior at this temperature provides welcome relief from summer heat and a bit of warmth on the occasional cold winter day.
Unlike the energy source usually referred to as geothermal energy, ground source heat pumps don't rely on heat from volcanic processes in the earth's interior, but more from the phenomenon of "thermal mass," in which substances such as rock and soil tend to retain a lot of heat. This means that cold water circulated through ground source heat pump pipes buried in soil at 68° can extract a significant amount of warmth from that soil without lowering the soil's temperature significantly. The reverse is true for hot water flowing through the pipes: it can lose its heat to the surrounding soil without warming it much.
As the majority of the Rancho Center's climate control infrastructure is underground, the system has only minor impact on the historic appearance of the Rancho. Despite its low-key profile, the Rancho expects the system will save it 20-50% on cooling costs and 30-70% on heating costs.
"We searched for a system that would be in line with our conservationist ethos," said Rancho Los Alamitos Foundation Director Pamela Seager. "Geothermal pumps were the most fitting option for us, particularly since they have proven to be successful components in the restoration of historically significant structures and sites."