What does it cost to run that exhaust fan?
I wondered how many BTU it took to heat my exhaust fan induced infiltration. Using this paper for infiltration rates I have tried to work it out.
https://aceee.org/files/proceedings/1996/data/papers/SS96_Panel1_Paper11.pdf
I will use the Site 10 “Jenn-Air” Fan @ 0.486ACH, The home is 2324sq ft, 16951 cubic foot.
0.486ACH*16951 ft^3 = 8238 ft^3 per hour or 137CFM
So if outside its 23f and 70 inside delta t = 47.
I have read that 1.08 *delta t * CFM = BTU
This is my source for the 1.08. I dont understand it well.
https://www.ruppair.com/documents/white-papers/Actual%20Air%20Density%20BTU%20Calculation.pdf
47 delta T * 137CFM * 1.08 = 6954 BTU
6954 BTU = 2kWh
6954 BTU, is a lot of energy. Please tell me where I have messed this up.
Thank you
*Edit. I think heating/cooling degree days might be applied to calculate total energy/year but I cant do it. Sorry I did not mention the my purpose for all this is to try to come up with the return on investment for an HRV on an exhaust fan.
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I'd do the calculations with the required amount of ventilation (much less than 137 CFM).
I have not looked into required ventilation. I thought my 1970 house might ventilate itself enough. I am trying to figure out what is the energy cost of running a exhaust fan such as a bathroom or kitchen fan.
Then it looks good at 23F outside. Perhaps $.30/hour when operating. I think you can use HDD as long as you multiply by the fraction of an hour per day that you run the fan. So for me, at 7000 HDD and .25 hours/day of fan use:
7000 * 137CFM * 1.08 * .25 = 258930 Btu = 76 Kwh
So about $12/heating season. Plus a few dollars for summer AC loss.
Don't use it...BTU loss goes to zero.