Laren, I agree that seasonal storage is impractical. The Sola Roof approach is a diurnal storage of thermal energy:
With bubbles to reduce the heating and cooling loads, and a set of efficient mechanisms for capture and release of heat from our Liquid Thermal Mass system (that includes the Soap Solution) allows the thermal storage to be effective, relatively cool and not too huge. Duing the sunny mid-days of summer the Liquid Film operates over the inner cover and flows under the bubble filled cavity. Thermal gain is rejected by reflection and diverted by absorption from reaching the Controlled Environment growing space. The majority of the thermal energy is absorbed by concurrently operating the two systems, while 50% approximately of the PAR will reach the leaf canopy. The Inner Cover shows a cool skin temperature to the greenhouse - a temperature that will track the temperature of the Liquid Thermal Mass. Overnight, no bubbles are used and Liquid Film process operates in the roof Cavity Space for purpose of cooling and chilling the water based thermal mass back to the start temperature for the next day's cooling needs. Therefore, diurnal cooling with a temperature swing can be designed into the Sola Roof projects.
The system specs for cooling will easily serve for the solar, dynamic "heating" during the winter where the system easily captures and retains daytime solar thermal gain and uses the bubble system to deploy that solar energy into the building envelope during a cold night. No need to build mechanical heat exchangers when we have the entire surface area of the Inner Cover? to act on the greenhouse environment. These cooling/heating mechanisms are powerful and effective and cost nearly nothing.
With conventional cooling the problem is that Just as outside air temperatures are peaking a conventional greenhouse has its highest demand for cooling by ventilation. Sola Roof is a liquid based system and while it can operate very effectively with the simple mechanical systems described, it is also quite easy to integrate a liquid-to-liquid heat pump that can extract thermal energy from the Liquid Thermal Mass and supply it to your home or to make fine adjustments to the temperature and humidity within the Sola Roof greenhouse. By such adjustment the supply temperature of the Soap Solution (as the primary working fluid) can be warmer or cooler using a flow through exchanger to alter the temperature of the liquid before it reaches the Cavity Space.
Mechanical systems can also backup the control of the Liquid Thermal Mass system, preventing it from going below a minimum set point in winter or above a maximum in the summer. These interventions are possible and provide backup to peak conditions - but for the most part Sola Roof can use natural, ambient solar thermal gain and ambient radiant cooling and chilling in diurnal cycles, with the thermal flywheel of the a liquid thermal mass to absorb and release the energy. The "parasitic load" is very small compared to the total cooling/heating loads that are handled. In the Hot Roof Problem I propose that the Sola Roof system COP could be about 50. This merits serious research. In the past, most of the people in institutions (like the response of the Florida organization) objected to the Sola Roof method out of hand and often the biggest objection is that the system cost is next to nothing. So they say its impossible.
I challenge this DIY community to do the so-called impossible. Lets have 10 DIY projects (most of them will be a Back Yard Project) completed this summer. Who is in?
Posted to the Yahoo Sola Roof Forum today