Efficient Furnaces, Boilers & Air Conditioners

Almost all of us grew up with either a boiler or a furnace that heated our home. What's the difference? A boiler makes hot water that heats the home, whereas a furnace makes hot air that heats the home. Because we as humans experience heat radiantly, hot water heat tends to feel a little nicer than blowing warm air, so that's why so many houses have baseboard heating in America. 

Furnaces and boilers do share one trait though - both burn fossil fuels to create heat. It's easy to see why; fossil fuels pack a punch when they are burned. Although it is inefficient and dirty as a fuel source (even today), it's hard to compete with the raw volume of thermal energy that can be produced on demand with fossil fuels. Although other better alternatives (heat pumps!) exist, our entire housing infrastructure is centered around burning carbon to heat our homes. 

Back when most of us were growing up, furnaces and boilers were much more dirty and inefficient than they are now. These days, with high-efficiency equipment, furnaces and boilers are approaching 100% efficiency, meaning nearly all the energy is wrung out of the natural gas or propane that is consumed. These appliances are also much cleaner, with sealed combustion chambers that don't leak to the inside of the home. 

By the same measurement standard, heat pumps are more like 200-400% efficient, so considerably more than even a high-efficiency furnace. There is a lot to like about heat pumps, but it's not the right solution for everyone. Dollar for dollar, high-efficiency furnaces are  cheaper to install and operate, and maybe even a bit more reliable with high-end equipment. That is because natural gas is cheap and millions of these types of units are sold every year.

Long term, however, heat pumps are the obvious answer, so it's smart to make sure your home can be retrofit in the future when they become the dominant technology, even if you opt to go for a fossil fuel system now. In Europe and Asia, heat pumps are already the dominant technology, and the future looks promising. 

Ironically, most Americans have been familiar with heat pumps for a long time. Your air conditioning system is a heat pump, utilizing the hot humid outdoor air to create cool, dry indoor air through the magic of refrigerant gases, compressors and expansion valves and coils. Likewise, your refrigerator is also a heat pump, moving energy from one vessel to another. 

And like with furnaces, we can select high-efficiency A/C systems. I would argue that in our mostly-heating climate in Southeast Michigan, it's probably less important than choosing the right heating appliance, but the industry has made great strides in improving this type of equipment as well. 

Heating and cooling is a big topic for any building project and should be given the priority it deserves. We also don't want to forget about ventilation, the V in HVAC. This topic has everything to do with the quality of the homes exterior envelope as well - a tight and well-insulated home with a thermal break will perform at least twice as well as a standard code-built home. That can mean smaller, better equipment that is tuned to the needs of the room you're in no matter what is happening outside.