One of the more novel approaches we using in the building is the process of heating and cooling the space with radiant mats in the ceiling. The mats have a more narrow diameter than the typical radiant tubing used in radiant floors (as seen below), but they work just the same. In the floor, the tubing is encased in finished concrete.
In the ceiling the tubing will be encased in plaster. Both will create a ‘thermal mass’ and radiate heating and cooling up and down into the space. The system works with a closed loop process, and hot water is pumped through the tubing in the winter and cold water is pumped through during the summer.
Heating water (to run through the tubing) is more efficient than heating air, so the system will use less energy to provide the same amount of heat. It will also be an even heat (making it more comfortable). And because it is not a forced air system it will reduce the amount of contaminants and allergens blown around the space.
Because the overall system is solar-based, the majority of heating will be free heat from the sun. The set-up of the solar system is also novel in that it maximizes efficiency in a way that most solar systems do not. The concept was initially implemented and shared with me by another green builder – Timothy Heppner.
Below are two typical solar set-ups:
The downside of the above set-ups is inefficiency. In the first example, the requirement is that the 100 gallon tank always maintain a certain temperature (ie 120 degrees). So if the sun is not shining then either a gas or electric element heats the tank water- Even if there is no demand for hot water. In the second example, there is no continual heating of the tank water (which helps efficiency), but if the tank water is not hot enough to supply heat to the forced air furnace, then the gas burner kicks on in the furnace and doesn’t use any of the solar heated water.
In the system we’ve installed – the “Tim Heppner model”, the system is efficient because if there is no demand for hot water no fossil fuels are used. If there is a demand, and solar production is sufficient then no fossil fuels are used either. And finally, if there is demand and solar production is existent but insufficient, fossil fuels are used only to make up the difference between what is needed and what the solar panels can produce.
Above, Wally Shah from Radiant Cooling explains the system.