Convert BTU/hr in a Manual J to actual fuel usages

I cannot find any conversion table that translates the BTU/hr heat loss in a Manual J report to the amount of fuel required to heat the building to the design temperature.  In this case I'm using propane and I have calculated the 92,000 BTU/gal using the actual BTU/Hr X Degree Days and end up requiring over 30K gallons of propane for a heating system.  This cannot be correct.  Any guidance would be greatly appreciated.

Views: 1521

Reply to This

Replies to This Discussion

Morgan,
From the perspective of the energy auditor, I don’t agree with that statement.
“Actual fuel and electrical usage" is anecdotal at best”
Unless you change something, the best predictor of future energy usage is past energy usage. Now if you are going to use fuel and electrical usage, you have to have a minimum of one years data, you need to know the heating degree days and cooling degree days over that exact period, (Or binned temp data) And you need to measure the combustion efficiency of the heat source.
I will try to dig up a paper I have on the subject- the punch line was that identically built and situated houses had a 2 fold difference in energy usage based on occupant behavior. Both have identical manual J heat loss, but use very different amounts of energy. If you are trying to make rational choices based on payback, you have to know the actual usage- which is related to occupant behavior.
An example- If you are going to recommend a solar pool heater to save money- you better make sure they are actually using their existing electric resistance pool heater. Likewise recommending a high efficiency AC replacement makes no sense if the homeowner hates AC. A customer who keeps his house at 80°F all winter, uses a lot more energy than someone who keeps the thermostat at 55. Some efficiency measures that have a reasonable payback in one situation will not in the other.
The customer generally does not care about manual J- design temps, etc. They want to know what it is going to cost to heat and cool their house, and what is the best way to do it. Manual J is one tool in the box to help do this.
Cheers,
Eric

RSS

Videos

  • Add Videos
  • View All

Twitter

Latest Activity

Glen Davison is now a member of Home Energy Pros
5 minutes ago
Rosie Smith replied to edward knight's discussion Minneapolis duct blaster for sale in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Hi Edward...is this equipment still available?? Thanks, Rosie Smith Fresno,…"
yesterday
Rosie Smith joined allen p tanner's group
Thumbnail

Energy Auditing Equipment for Sale, Trade or to Purchase

Discuss the pros and cons of the equipment you are interested in prior to purchase. Post equipment…See More
yesterday
Jim Gunshinan liked Tom White's discussion Home Energy Reader Survey
yesterday
Tom White posted a discussion

Home Energy Reader Survey

Home Energy wants to serve you better.  Please …See More
Monday
George Matthews's event was featured

Proof is Possible Tour by the Home Performance Workshop at Truitt and White Lumber Conference Room

October 7, 2016 from 9am to 1pm
Building Energy Performance Testing is sponsoring the Proof is Possible Tour to come to the San…See More
Monday
Profile IconAshley Noreuil, Fred Smith and Peter Moncada joined Home Energy Pros
Monday
George Matthews commented on George Matthews's event Proof is Possible Tour by the Home Performance Workshop
"Here is the flyer for the Advanced Techniques and Tools in Home Performance Friday October 7th at…"
Sunday

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service