When modeling district cooling and heating systems using Option 1, Path 1: ASHRAE 90.1-2010 Appendix G, the LEED Reference Guide instructs the following:
"If tariffs or rates are not available from the district plant serving the project, such as for campus or military plants, calculate the rates based on the virtual electric and fossil fuel rates from the model."
The Reference Guide does not elaborate as to how this is done.
Without actual utility rates, we reference EIA for our virtual electric and natural gas rates, which we plug in to the model economics to show energy cost.
Back in LEED 2009, the District Energy Systems Guidance document provided formulas to calculate the virtual rate of district chilled water, steam, and hot water based on the virtual electricity and/or gas rates.
Are these formulas still applicable for LEED v4 projects?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
June 23, 2017 - 1:09 pm
Those formulas and complete instructions on how to calculate the rate is in the online version of the Reference Guide. Do you have a paper copy? If it is not there then maybe in an addenda?
Todd Tewksbury
Mechanical EngineerBala Consulting Engineers, Inc
4 thumbs up
June 26, 2017 - 9:58 am
Thank you for the tip, Marcus. The formulas were added to the addendum document about two months ago.
Craig Flandermeyer
10 thumbs up
January 28, 2020 - 5:52 pm
Where do you get the addendum documents for LEED NC V4?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
January 29, 2020 - 9:31 am
The DES is not a stand alone document in v4. It is embedded within the LEED Reference Guide. If you subscribe to the online version of the Reference Guide it is automatically updated so you don't have to worry about any addenda to it. You can find the addenda here -https://www.usgbc.org/leed-interpretations
Michael Brown
Energy Analyst & Energy Systems Design EngineerHKS
LEEDuser Expert
9 thumbs up
January 29, 2020 - 12:39 pm
Additionally, in some jurisdictions if your building will be tied into the central district utility plant (like the City of Austin) they may also provide a detailed utility rate structure for assessing chilled water/hot water district energy rates.
Jamy Bacchus
Associate PrincipalME Engineers
20 thumbs up
January 29, 2020 - 7:46 pm
I don't recall seeing the v3 DES formulas in the v4 Ref Guide. But the online version appears to be down/going thru updates as it's partially blank at the moment, so I can't pull it up. Looking in the v4 MEPC, and selecting DES Path 1, I'm not seeing it embedded in the table's virtual rate cells; you manually energy the baseline energy costs for each rotation (cells G155:J155) and then it creates a virtual rate to apply to the proposed.
Pulling up the static pdf v4 Ref Guide, I don't see the formulae, just these notes:
Energy rates
All virtual DES energy rates must be identical in the baseline and proposed cases. If tariffs or rates are not
available from the district plant serving the project, such as for campus or military plants, calculate the rates
based on the virtual electric and fossil fuel rates from the model.
Anyone else want to solve the great mystery of the day?
1 thumbs up
January 6, 2023 - 10:23 am
100002152 | U.S. Green Building Council (usgbc.org)