Hello, I have taken a look at Appendix B which includes Title-24 guidance within the District Thermal Energy LEED Guidance document. However, we had received the following reviewer comment and I just wanted to make sure that it's outdated. It seems to say that you cannot take credit for DES when using Title-24. Maybe I just need help in understanding: can you take credit for DES when using Title-24?
"The project team has stated that they have followed the document Required Treatment of District Thermal Energy in LEED-NC version 2.2 and LEED for Schools, version 1.0; (DES v1) dated May 28, 2008. In accordance with USGBC guidance, this approach should not be used with Title-24 modeling.; Projects with district energy plants that are documented using Title-24 2005 in lieu of ASHRAE 90.1-2007 are NOT required to follow the energy modeling guidance provided in the document "Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 Design and Construction"; (DES v2) dated August 10, 2010 which can be accessed at: http://www.usgbc.org/ShowFile.aspx?DocumentID=7671.
However, Title-24 2005 does not allow credit for the efficiency of district energy systems. Therefore, if the project is taking credit for the efficiency of the district energy systems serving the project, then the DES v2 document referenced above must be followed in its entirety.
Please revise the model to follow the Option 2 requirements defined in the DES v2 document. Otherwise, confirm that the Proposed case plant inputs represent the default Title-24 inputs, and no central plant has been modeled for the Proposed case in the Energy Pro software. Update the form and Table 1.4.1 through 1.4.6. Attach Title-24 compliance forms (PERF-1, ECON-1, UTIL-1 and OLTG) as well as BEPS, BEPU and ES-D reports for the Baseline and Proposed cases to confirm correct modeling and reporting."
Tristan Roberts
RepresentativeVermont House of Representatives
LEEDuser Expert
11477 thumbs up
March 21, 2013 - 1:02 pm
Lauren, sorry, but I"m not sure of the answer to this one.
rodd borgogno
mechanical engineerstate of californiat
April 9, 2013 - 6:52 pm
I received the EXACT same comment on a recent project. Has anyone discovered where Title 24 excludes DES credits? In 2007 I submitted Title 24 calculations using a DES and its associated energy savings and it was approved. No comments were made about DES not being allowed in Title 24.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
April 19, 2013 - 9:38 am
The review comment says that DESv1 cannot be used with Title 24 but DESv2 can be used. So the most recent DES can be used for Title 24 projects, see Appendix B for further guidance.
rodd borgogno
mechanical engineerstate of californiat
April 19, 2013 - 11:08 am
Thanks Marcus.
I can't find any DES information in the Title 24 literature that states DES is not allowed to be used in a model. I would like to know where the reviewer found this information. If I am showing compliance with Title 24, and USGBC has approved Title 24 as an equal to ASHRAE 90.1, then I shouldn't need to recreate my model.
I realize the USGBC is giving me an option to model the DES, but the issue is that I don't have the time or money to create the 90.1 model in order to show the energy savings.
My question is probably better suited for a Title 24 forum instead of a LEED forum, but if anyone has any information on how to show Title 24 compliance for a building that is connected to a central plant I would love to hear about it.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
April 19, 2013 - 11:34 am
This issue is a LEED rule not a Title 24 rule. You don't have to do a 90.1 model, just follow the Title 24 guidance in the DESv2 as it relates to your already existing Title 24 model.
Eddy Santosa
Director of SustainabilityDBR Engineering Consultants
376 thumbs up
April 24, 2013 - 1:58 pm
Lauren, In my understanding, You can use option 2 if you want take advantage of the DES. You can see page 20 of the guideline. In order to follow the guideline, you may need to have 2 energypro files to address the issue.
rodd borgogno
mechanical engineerstate of californiat
April 24, 2013 - 3:18 pm
Based on the research I have done, Appendix B of the DESv2 (page 20 of the guideline) states that you can either change the proposed equipment to match the Baseline equipment (Option 1), or you can develop a "virtual DES-equivalent plant" (Option 2). To develop the virtual DES-equivalent plant you need to model per the guidelines given in the main body of the DESv2 text. These guidelines have you creating a 90.1 model, and following Appendix C of the DESv2 guidlines. Appendix C says you either need to use actual energy data from the central plant and the served buildings or you can model the central plant and all of the connected buildings. If you don't have the energy data, then you have to model the central plant, and you must do this based on 90.1 Appendix G.....and round and round you go...........bottom line, as far as I can tell you have to have an ASHRAE 90.1 model if you are going to try to take credit for a DES system.
If someone has a different (and easier?) understanding of what the USGBC is trying to make us Title 24 users do, it would be great to hear.
Thanks.
Eddy Santosa
Director of SustainabilityDBR Engineering Consultants
376 thumbs up
April 24, 2013 - 9:28 pm
Option 1 : basically you need to model per Title 24 ACM manual which excludes the existing DES.
Option 2 : your baseline is based on option 1 so you don't need to worry about making the baseline per ASHRAE 90.1. However, you need to make another model of your proposed case by inputting the central plant per the guideline.