It’s wintertime in the Northern hemisphere, and that means we’re heating our homes. The new year started off a bit on the warm side here in the Atlanta area, with the temperature at nearly 70°F (21°C). In terms of heating degree days (HDD), we began with a mere 2.5 HDD on New Year’s Day and hit 30+ HDD/day only twice in January. Our total for the month was 616 HDD, below our average of 692 HDD for the previous 11 Januarys, so it’s another down year for heating degree days here, despite the Polar Vortex.
Still, with temperatures here dropping into the low 20s Fahrenheit some nights, we’ve had plenty of demand for heating in the Atlanta area. And nearly all of that heating has come from one of these three sources.
This one’s common in many places that do significant heating. It’s the furnace that extracts the heat from burning natural gas or propane, the boiler burning natural gas or fuel oil, and woodstoves burning wood. Fuels like natural gas (which is mostly methane), propane, fuel oil, and wood contain chemical energy. The process of combustion releases that energy in the form of heat. Then the heat is distributed through the living space with air ducts and hydronic tubes.
Burning a fuel and using the heat in your home will be less than 100% efficient. Furnaces, boilers, and woodstoves send exhaust gases up the flue and some of heat of combustion goes right out of the house along with the exhaust.
If you’re a clever person, though, you may be thinking to yourself, “Hold on a minute, Allison. What about…