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: 1646

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

Amber Vignieri posted a blog post
4 hours ago
Barbara Smith's video was featured

Weatherization: Crawl Spaces

Crawl Spaces - Training for Weatherization Installers. Re-posted from Seventhwave.org
5 hours ago
Kelly replied to Colin Genge's discussion What is the value of using a pressure pan to test outlets?
"Hi Colin, I like using the pressure pans at outlets to guide my inspections once I'm in the…"
22 hours ago
Leo Klisch commented on Home Energy Magazine's blog post Natural Gas is Becoming Less Attractive
"It seems a bit wasteful to use NG for such a low temperature application as space heat. If a heat…"
23 hours ago
HomeWiz posted photos
23 hours ago
Kobus Niemand commented on Jim Gunshinan's blog post A Healthy Home and a Healthy Bottom Line
"Thanks for the download! Great paper,  Homes receiving EE can experience increases in radon…"
yesterday
Jan Green replied to Rob Madden's discussion DOE Home Energy Score
"Agreed Sandy on all counts!   HES and HERS will be confusing to everyone that doesn't…"
yesterday
Steven Lefler replied to David Eakin's discussion A Growing American Problem In Search Of Valid Answers
"Modular Lifestyles has developed proven Net Zero factory built as a modular or his HUD code…"
yesterday

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service