Hi,
In a project to go for LEED, in winter, the heat source is steam purchased from public utility company with fixed rate, say, $5,000/month in spite of the real heating demand, how to simulate this in Equest? ASHRAE 90.1-2004 stated that "For systems using purchased hot water or steam, hot water or steam costs shall be based on actual utility rates, and on-site boilers shall not be modeled in the baseline building design." Is it feasible to choose "no heating" in the proposed case and do some simple calculation instead, say, $5,000/month*3 month=$15,000, to generate a result?
Any comments are welcome. Thanks.
Rick, PE, LEED AP
Rick,
I wouldn?t go with no heating; you can model this scenario directly in eQUEST:
? Make sure you have your steam loop created, then create a steam meter under ?Utility & Economics?
? Assign the meter to your steam loop when prompted
? Create a utility rate of type ?steam? and make sure it is set to serve your steam meter
? Set up block charges for different times of the year to create your steam rate. For the three months that have a fixed rate, you could create a block with $0/unit and define a minimum $5,000 charge (steam rate properties?Min/Max Charges tab?Fixed Chrgs ($/mon) column). Set the min to $0 or whatever it should be for the other 9 months. Note that for a steam meter, you can define the Btu/billing unit under the steam meter?s Properties/Basic Specifications tab.
Creating the rate schedule will be the hardest part, but it?s not that difficult. The process is also well-documented in Volume 2 of the supporting documentation. The way I would do it is:
? Create a block schedule of type ?flag? ? this will define when your various blocks are active/inactive
? Create your blocks as needed; you?ll only have two if the rest of the year follows a single rate schedule
? On each block?s Basic Specifications tab, apply the block schedule you created and give each block a flag value
? If necessary, adjust your block schedule to ensure it corresponds to the flag values you assigned to the blocks (you will probably have thought this out when creating the schedule, however)
To ensure you set it up correctly, you can use the ES-E and ES-F reports to inspect your steam rate?s monthly billing. Feel free to contact me directly if you have more questions about the above.
Thanks,
DAKOTA KELLEY
Depending on when you registered this LEED project, you may need to use the "Required Treatment of District Thermal Energy in LEED-NC version 2.2" from May 28, 2008. You can download this memo from the USGBC off of their website.
David Eldridge, PE
Hi Dakota,
Your information is complete and thorough. Thank you very much!
Best Regards,
Rick
Subject: RE: [Equest-users] Purchased Heat
Date: Fri, 14 Aug 2009 15:08:54 -0500
Seun,
Good question, and I?m copying the user list to complete my original response to Rick.
You do not need to have a boiler or chiller as long as you have the appropriate meters created and assigned to your loops. The meter, in effect, becomes the primary equipment for its loop.
However, you do have to have a pump created for each loop. If the proposed design does not include pumps downstream of the meter, you may want to put them on a separate electric meter so that you can back the energy out of the totals. Or, if they?re the only pumps in the project, you can simply neglect the ?pump/aux? end use from EM1?s results.
I have attached two screen shots from a sample project to demonstrate the above. ?Purchased 01? is the Water-Side tab with the appropriate meters and pumps assigned to each loop, and ?Purchased 02? shows the corresponding Utility & Economics tab. This is the bare minimum setup for the simulation to run without errors.
Thanks,
DAKOTA KELLEY