Next to heating and cooling, hot water for bathing, dishwashing and appliances takes the most energy in a house-and running out in the middle of a shower is a common pet peeve.
When designing the lab home, we found that the heating and cooling system that made the most sense, a ground source heat pump, also made great sense for heating water, and by combining the systems, we could save even more energy and reduce equipment costs in the process.
You can read more about this system in Heating, Cooling, and Ventilation. But attached to the heat pump is a clever piece of equipment called a desuperheater, which uses the extra heat being vented by the pump to heat water.
During the summer, when the heat pump vents a lot of extra heat, the desuperheater will be able to supply all the hot water anyone will need, using no more energy than what was being used already to cool the home. In spring, fall and winter, the desuperheater will likely need some extra help from a standard electric water heater to meet the homeowner's needs.
We're going to be examining just how much energy the heat pump-desuperheater combination can save, and how to make them work more efficiently together. We're also looking at how their combined installation can be made more standard on a large scale for homebuilders.
Another existing source of heat we're experimenting with is the home's wastewater. We've installed a heat recovery system with devices at points along the drain system, so that the hot water swirling down the drain while bathing or doing a lot of dishes can help to heat the clean, hot water that's coming out of the faucet.
Who would have suspected you can recycle heat, too?
