Space Heating Systems
Heating systems were evaluated based on efficiency, fuel source, and cost. The heat delivery system was a major consideration, whether forced air or radiant, which would have implications for the rest of the system. The simple debate over gas vs electric has become more complex in recent years, especially considering technologies like heat pumps, alternative fuels, and passive and active solar heating. Montana has had warmer summer temperatures in recent years as well, so cooling can not be discounted.
Forced Air VS Radiant:
While evaluating heating systems, efficiency was the major deciding factors. In researching the differences between forced air and radiant, very few comparisons provided conclusive efficiency comparisons. This article , however, finally shed some light on the major differences. Radiant heating provides an increase in comfort due to the way it heats, which is often translated to mean greater efficiency due to a lowered thermostat setting. The other half of the picture, however, is demand placed on the boiler providing heat, and how that boiler handles the demand. Ultimately, in a tightly sealed house a radiant heat system proves to be no more efficient than a forced air system.
Fuel source:
In Montana, natural gas is still the most cost effective fuel source. It is, however, a nonrenewable fossil fuel, the cost of which will continue to climb. While geothermal heat pump systems are quickly becoming more popular, they were still too expensive for this application. Two other alternatives were evaluated for this project: wood burning appliances and air exchange heat pumps. The air exchange heat pump, which operates like an air conditioner in reverse, is a very efficient system. A heat pump will run 200% to 300% efficient, but only down to an air temperature in the mid 30's. When the temperature drops too much farther, the system must switch to another fuel source, in this case falling back on the furnace. Wood, on the other hand, is a readily available resource (especially in Montana), completely renewable, and carbon neutral as a fuel source . In a newer, energy efficient fireplace or stove, this makes a great heat source that burns very clean. In this project, an EPA Certified fireplace was placed in the living room, while the main return air duct for the furnace was placed in the same room on the opposite wall. This way, the fan on the furnace can be run (with out the heat) and circulate the heat from the fireplace to the rest of the house.
Electrical Energy
Here again, conservation on the front end goes a long way toward reducing demand and cost over the life of the building. Taking another look at the Montana DEQ energy use pie chart reveals that the second biggest portion of energy costs are in lighting and appliances at 23%. Another 5% accounts for the refrigerator alone. More information coming soon.
Photovoltaic (PV) Power:
Coming soon
Water Heating
Water heating comprises the third largest portion of a typical home's energy usage. More info is coming soon.