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, with the temperature at nearly 70° F (21° C) here in the Atlanta area. In terms of heating degree days (HDD), we’ve gone from about 12 HDD/day at the beginning of the month to 24 HDD/day in the past week. With only four days to go in the month, we’re at 515 HDD and probably won’t hit our average of 684 HDD for January so it may be another down year for heating degree days here.

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Still, with temperatures dropping into the low 20s Fahrenheit for the next couple of nights, we’ll have lots of demand for heating in the ATL. And nearly all of that heating will 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.


But capturing solar radiation for heat turned out to be mostly a deadend. As Martin Holladay has shown, superinsulation won the battle between more windows or more insulation (pdf). Now we know it’s better to use that solar radiation to make electricity.

In the end, if you’re wondering where the heat in your home comes from, it’s almost certainly one of the three main sources: combustion, electric resistance, or the outdoor air, ground, or water.

See more: 2002 Chevy Silverado Radio Wiring Diagram, 2002 Chevrolet Silverado 1500

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