March 20th, 2009

Ann Vole

To have and to hold

The four most powerful alternatives to conventional power are often overlooked because they are not an actual source of energy. These four are efficiency, "cogeneration", storage, and loss reduction. Efficiency has lots of tools to find the most efficient appliances and equipment so I will not talk about that here. "cogeneration" specifically deals with making electricity with an engine and using the resulting heat. I don't know of a better term but there are other similar shared uses of heat and cool that I think could be explored such as using a heat pump to make both hot and cold tanks of liquid which could be used for both hot water and refrigeration or air conditioning. Skating arenas have used this to great effect with well designed heat pump systems that both cooled the ice and heated the air for the audience. This is also not what this post is about but rather the last two listed, storage and loss reduction.

If you are dealing with heating and cooling for the same space, storage of the heat and cool can eliminate all the heating or all the cooling needs and only the other one needs to be dealt with. For daily movement of temperatures, storage of heat and cool can be placed in the area to be controlled for direct use. A more efficient way would be to design the input of the temperature (cold or heat) to be on one side of the storage mass and the room that is controlled on the other side and the storage designed to delay the transmission of the heat or cool to be about 12 hours so day heating would heat the room at night and night cooling would cool the room 12 hours later in the day. If you are working with a cycle of heat and cool that is seasonal, you need to store summer heat for winter use and winter cool for summer use. This requires a slightly more complex system of storing heat for 6 month intervals in the ground under the building. The size of the storage (both daily and seasonal) is determined by how much loss of heat or cool the building has (or other heat storage situations like storing hot water from solar for morning shower use). This loss can be reduced to zero if enough insulation and prevention of fluid movement in and out of the space (both liquid and air) is installed. This involves insulation, barriers to air and vapor and liquid, and heat exchangers for any fluids moving in and out of the space (like fresh air exchange for houses to control vapor, smells, and CO2 levels). The details of making things air-tight or water-tight, controlling heat exchanger use, and maximizing R-value of insulation by reducing "bridging" are all rather involved and would fill many books but the basic idea I think is simple enough for a child... more insulation the better, more air-tight or water-tight the better, and only use heat exchangers as needed (must keep the humidity down to prevent building damage and people need more fresh air when there are lots of people).

Some buildings in Norway and Sweden were in the far north where fuel, electricity, and wood were not available and where solar and wind were not alternate energy options (deep forest or being on the north side of mountains) so they created and tested buildings successfully that are heated with body heat of the occupants simply by using a combination of heat storage and heat loss prevention. Many houses in cities have limited solar input and wind power is not an option so I think these highly insulated high-thermal-mass buildings are the way to go to eliminate the need for any energy (alternative or traditional)