Can anyone suggest a calculator that will calc energy loss per hour for a 12 hour period?
 
My electric company is requiring I submit this info to qualify for off-peak rates. They would like to know if the outside temp is zero degrees, the inside is 70 degrees, what is the inside temps for each hour for 12 hours to make sure that the inside temp does not go below 65 degrees.

My installer has provided me with energy loss for structure of around 55,000 btu/hr. I have an 8 ton ground source heat pump, closed horizontal loop not in ground water.


Any ideas,

Rick

Rick

 

This is a very tricky question.  It depends in large part on the size and the mass of the building

I think you could get a very rough idea by multiplying the square ft of the house by 40 lbs/ft^2 to get a crude building mass estimate ie a 3000 ft^2 house *40 = 120,000 lbs   this is the mass of the house

Definition of a  BTU= energy required to raise the temp of 1 lb water 1 deg F

I would assume  that everything in the house  is part of the mass and disregard the air in the house from the calculations.

Now to raise the house 1 degree in temp, requires 1 btu/lb of house or 120,000 btus If the heat loss of the building is 55000 btu/hour the house will loose ~55000/120000 deg/hour or 0.45 deg/hour  so in 12 hours 5.5 deg temp drop.

Now this estimate would  be a crude ballpark  for an average  wood framed house if the basement was not part of the thermal envelope. It could easily be off 3 fold.

In reality to do a detailed calculation would require a lot of info on the construction type, location of the insulation relative to the mass, etc.  Not trivial and would probably involve a site visit by some way more qualified then me.
eric

This is a decent link to several calculators: http://www.builditsolar.com/References/energysimsrs.htm