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: 1282

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

tedkidd liked Luis Hernandez's discussion Airsealing an old basement ceiling
5 hours ago
Ryan T De La Rosa posted a blog post

The Clean Power Plan and What You Can Do

Last month, Jessica Hardcastle at Environment Leader described an especially non-polarizing…See More
6 hours ago
Ed Minch replied to Luis Hernandez's discussion Airsealing an old basement ceiling
"Luis Think of it as a part of the house that is not being used, but part of the house none the…"
11 hours ago
Luis Hernandez replied to Luis Hernandez's discussion Searching for a multifamily study book in the group Energy Auditing Equipment for Sale, Trade or to Purchase
"Hey Craig!  Well, let's get serious and keep asking all our friends in the Home…"
12 hours ago
Luis Hernandez replied to Luis Hernandez's discussion Airsealing an old basement ceiling
"Hey there Ed,      I appreciate you comments... this is an interesting case because…"
12 hours ago
tedkidd replied to Luis Hernandez's discussion Airsealing an old basement ceiling
"bit.ly/ESHPhabitat1 our habitat project -mostly dirt floor..."
13 hours ago
Bryan Gabriel replied to Luis Hernandez's discussion Airsealing an old basement ceiling
"Luis, thanks for being open to sharing your experiences and photos of your project. What is the…"
14 hours ago
Craig McManus replied to Craig McManus's discussion Inventions that save energy, licensing to a US manufacturer?
"Yes happily."
15 hours ago

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service