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: 1820

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

Groups

Latest Activity

Safe-R Insulation commented on Chris Laumer-Giddens's blog post Rock Wool Insulation for Floor of High Performance Tiny House
"Thanks for sharing this much information about roof wall…"
10 hours ago
Lindsay Bachman's 4 events were featured
yesterday
Profile IconChris Hoskins and Ken Goodrich joined Home Energy Pros
yesterday
Diane Chojnowski commented on Diane Chojnowski's event Better Buildings Peer Exchange Call: Home Improvement Catalyst: Keeping the Ball Rolling with Homeowners by Delivering More Value
"Hi Victor, All the BBRN Peer Exchange Calls are archived so you can listen anytime. Check out over…"
yesterday
Victor Rols Lindsay commented on Diane Chojnowski's event Better Buildings Peer Exchange Call: Home Improvement Catalyst: Keeping the Ball Rolling with Homeowners by Delivering More Value
"Hi Diane, Unfortunately some of us are unable to partake in this webinar/ forum. Is there a…"
yesterday
Ken Summers replied to Gregory Cisco's discussion Abandoning under-slab HVAC ductwork which fills with groundwater seasonally.
"My largest concern is moisture. I have seen mold forming on interior walls in the heating season…"
yesterday
Seth Romme replied to Sonja Persram's discussion Energy Savings Guarantee for single family dwellings in cold climate??
"Hi Sonja We provide home energy optimization services and provide a 5-year heating and cooling…"
Thursday
Lindsay Bachman posted events
Thursday

Photos

Loading…
  • Add Photos
  • View All

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service