One team will be named the “winner” at the Solar Decathlon. The first two times, the University of Colorado team has claimed the honors. At the moment, this favorite is far behind and the odds aren’t looking so hot that they will get a hat trip. Yet … yet … this helps highlight how every single one of the 20 teams has winning concepts, winning innovations, and winning technologies in their entries.
The Colorado entry is named CORE, as the house designed is built around modular core elements (with heating, cooling, water, electrical systems) around which the rest of the house can be built. And, the Colorado team has done a magnificent job of incorporating the elements into the design, with radiant tubing providing a partial screening of the kitchen in a functional decorative element.
But, onto making ice from the sun. This is somewhat of a misnomer …. somewhat.
The Colorado solar system is 8.8 kilowatts of PV paneling with the solar hot water system underneath the PV paneling (which actually increases the PVs efficacy due to a cooling effect). During the day, the solar thermal water system will be used to heat water for building heating needs. Obviously, heating is most required at night. Thus, the system builds up a reservoir of heat in the tanks to be released to meet nighttime demands. (In essence, the house’s water tanks are used as the equivalent of the ground for geothermal heating systems.)
In summer, however, the CORE heat pump system will reverse the flow. Cooling is required during the day while the system operates more effectively at night. Thus, during summer nights, the solar thermal system on the roof will be utilized to throw off waste heat from the house. The high-efficiency heat pump will exploit this to make encapsulated ice, which will then carry the heating load during the hot daylight hours even though the tank has relatively limited volume.
The CORE’s “storage tanks storage tanks also allow optimization of the interaction between building loads and power sources, both from the sun and from the electric utility.”
Ice from the sky. Colorado’s Solar Decathlon approach to making hot summer days more toleable.