As mentioned before, our energy needs can be broken down according to category. From our table of electrical usage for the Peak Oil Homestead, we can extract the following:
Heating
Furnace: 300W, 8 h/day --> 4 kWh/day
Water: 4500W, 6 h/day --> 27 kWh/day
Cooling
Air conditioner: 600W, 8 h/day --> 4.8 kWh/day
Deep freezer: 600W, 12 h/day --> 7.2 kWh/day
Refrigerator: 600W, 8 h/day --> 4.8 kWh/day
Cooking
Oven: 5000W, 3 h/week --> 2.1 kWh/day
Microwave: 1500W, 10 min/day --> 0.25 kWh/day
Stove (range): 2000W, 5 h/week --> 1.4 kWh/day
Slow cooker: 200W, 10 h/week --> 0.29 kWh/day
Electrical
All other appliances: 3.6 kW, 12.56 kWh/day
In analyzing these numbers again, it appears the values for heating the house are off by an order of magnitude for most climates and insulation. A true average number for cold climates is in the range of 14,000 – 15,000 kWh/year, or over 150 kWh/day during the cold season.
This higher number does not take into account the energy savings possible with good insulation, but can serve as a baseline for comparison as you do trade studies on passive solar heating, better insulation, and so forth.
Depending on its availability, one of the first things you might want to consider for your home heating design is heating with wood. A good hardwood can provide around 7000 kWh per cord if burned efficiently. Taking the value of 15,000 kWh/year for home heating therefore implies using just over 2 cords of hardwood per season for a wood stove.
A cord is a rough measure of wood defined as a stack of wood 4’ x 4’ x 8’ (128 ft^3). It is an inexact measure because the diameter of the cut logs can vary – that is, you can fit more small logs into a cord than big logs. Still, given all the uncertainties with wood heating, it’s about as accurate a measure as we need.
We’ll explore other home heating alternatives shortly.
Delicious
Digg
Reddit
Magnoliacom
Furl
Should Heating be Included in Electrical Requirements?
Goal one in the Homestead Project ORD is "The homestead shall have electricity." Home heating today however can be produced from different energy sources including natural gas, electricity, oil, LP, sun (active and passive solar) as well as the burning of wood. Additionally, heat can be produced from multiple energy sources simultaneously. So, should heating be included in the table of electrical usage? If not, would creating a separate goal dedicated to heating be appropriate?
Probably not
Once we decide for sure how to design the heating system (e.g. electric furnace, passive solar, wood, etc.) it will likely make sense to either put it under Goal 5 (providing shelter) or modify the electricity goal to be a little more broad.
Watts or BTUs?
With regards to heating requirements. Just curious.
You need both
power and energy numbers in your requirements in order to capture your needs. Just remember Watts, BTU/hour, or Horsepower for power; and Watt-hours (or kWh), Joules, or BTUs for energy.