Energy calculation for HVAC systems

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SUMMARY

The discussion focuses on estimating heating and cooling costs for a commercial office space controlled by eight Lennox rooftop units, ranging from 3 to 7 tons. The user, Mac, seeks a method to approximate energy costs without installing temporary gauges due to budget constraints. Recommendations include utilizing ASHRAE handbooks for standard heating and cooling procedures and employing computer modeling programs for accurate estimates. A suggested resource is Trane's modeling software, which offers a free 30-day trial for users to explore.

PREREQUISITES
  • Understanding of HVAC systems, specifically rooftop units
  • Familiarity with ASHRAE standards for heating and cooling
  • Basic knowledge of energy calculation methods
  • Experience with computer modeling software for HVAC
NEXT STEPS
  • Research ASHRAE handbooks for heating and cooling energy balances
  • Explore Trane's HVAC modeling software and its features
  • Investigate other HVAC modeling programs available for trial
  • Learn about energy calculation methodologies used in commercial buildings
USEFUL FOR

HVAC engineers, energy consultants, and facility managers involved in estimating heating and cooling costs for commercial properties.

MacLaddy
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I've been asked to approximate a dollar amount for heating and cooling an occupied tenant space in a commercial office building.

We've looked into installing a temporary gauge on each unit to give us a good approximation, but the cost to gauge up all the electrical and gas was beyond the scope of what I'm allowed. I even looked at just gauging up a few and approximating the rest, but that wasn't feasible either.

The only variables I can provide are square footage, head count, and a possible computer count.

Any ideas on how I can come up with a reasonable number? Any help is appreciated.

Mac

Additional Info - This space is controlled by 8 package rooftop Lennox units, varying between 3 and 7 tons.
 
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ASHRAE provides standard heating and cooling procedures for estimating heating and cooling energy balances. See if you can access any of their handbooks or technical standards at your school or company library.
www.ASHRAE.orgor get an estimate from a heating and air conditioning contractor or your local utility.
 
The only way to get a realistic estimate is to use a computer modeling program.
 
NUCENG said:
ASHRAE provides standard heating and cooling procedures for estimating heating and cooling energy balances. See if you can access any of their handbooks or technical standards at your school or company library.
www.ASHRAE.org

Thanks for the link. I'll look through it.

russ_watters said:
The only way to get a realistic estimate is to use a computer modeling program.

That's what I was afraid of. There are just too many variables to take into account.
Just curious, what kind of program could model this? I haven't delved into anything like that yet.

Mac
 
Thanks Russ! I'll give it a shot. (although I doubt I'll be able to accomplish much without training)
 

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