by Bryan A. Thompson
Last Updated 2/12/2003
This information will help you determine energy requirements for your house.
How much energy is required to heat or cool your house?
Changes with outside temperature will change this amount. If it's 75F outside, this amount should be zero. When the temperature goes up or down, the energy required to maintain climate control inside goes up. Survey during cold weather, normal and hot weather times, and be sure to record the peak energy consumption. Since no one knows what the weather will be like for the emergency period, this is really just a guess.
If using Propane or Natural Gas:
Look at the gas or propane bill for the month under consideration, then for a month where you probably didn't need the AC or furnace. The difference is the amount used by everything other than the furnace. Subtract that amount from the peak fuel consumption. This is the amount of energy used by your furnace or AC.
Find out how much BTU your furnace or AC is rated for. This is the output energy. Find out how efficient your furnace is (or estimate it). Divide the Energy Output by the Efficiency. This is the Energy Input.
If using Electricity to heat and cool:
Measure energy input while it's on. Turn off everything electric except the furnace or AC, then count the revolutions on the electric meter. Measure the time it's on each hour. This should give enough information to calculate the amount of energy used by the AC or furnace.
How much energy is required to heat water?
1 BTU is the amount of energy required to raise the temperature of 1 pound (one pint) of water 1 degree Fahrenheit.
This means it takes 8 BTU/gallon/degree. You can assume the water is between 32F and 212F. The maximum amount of heat required to heat water is when the extreme case of heating ice until it boils.
Energy Required to Boil Ice = 8 * (212-32) = 1440BTU (422.04 Watt Hours) per gallon.
Hot tap water is usually 130F. Heating Ice to this temperature would require 784 BTU (229.77 Watt Hours) of heat energy per gallon of water.
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