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: 286

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

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Richard Beyer posted discussions
21 minutes ago
Brandon Walton replied to Brandon Walton's discussion EFAZ and APS Hosting Huge Welcome Party!!
34 minutes ago
Brandon Walton shared their discussion on Facebook
34 minutes ago
Brandon Walton posted a discussion

EFAZ and APS Hosting Huge Welcome Party!!

If your in Arizona on August 20th, stop on by and check it out!APS Home Performance Program Q&A…See More
35 minutes ago
Brandon Walton posted an event

Efficiency First AZ is Hosting Huge Meeting August 20th! at Rennick's Restaurant in the Hilton Phoenix Airport Hotel

August 20, 2014 from 5:30pm to 7pm
APS Home Performance Program Q&A w/new leader Maggie Gibbs!Join Efficiency First Arizona (EFAZ)…See More
40 minutes ago
Dennis Heidner replied to Jamie Kaye's discussion Flickering LED lights
""CFLs produce light by using electricity to instigate a chemical recation between mercury…"
1 hour ago
Richard Beyer joined Michael Stuart's group
Thumbnail

INFRARED THERMOGRAPHY USERS

This group is dedicated to knowledge sharing and discussion of infrared thermography for building…See More
1 hour ago
Profile IconRichard Beyer and Diane Chojnowski joined Hal Skinner's group
Thumbnail

Radiant Control Coatings

A group where people who work with radiant barrier coatings can let others know all of their uses.See More
1 hour ago
Profile IconTomás León, Tauran Ivall, Alex Burnham and 1 more joined Home Energy Pros
2 hours ago
Home Energy Magazine posted a discussion

Let's Talk Gender

It’s no secret that home performance is a male-dominated industry. Attend any industry conference…See More
5 hours ago
Mark Rogers added a discussion to the group Energy Auditing Equipment for Sale, Trade or to Purchase
Thumbnail

Retrotec Blower Door Kit $1800

Retrotec Blower Door Kit complete with:DM2 Mark II digital manometer & automated fan…See More
5 hours ago
Maria Lacey replied to Jamie Kaye's discussion Flickering LED lights
"I think the tendency is to look at lamps (light bulbs) as though they're the same if they all…"
5 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service