The project I'm working on currently is for a production plant and office zones all in one building. There is no cooling coils in all designed system with the exception of the Dx unit in the server room. All systems are Ventilation and heating. The question is related to the system in the Baseline model. There are allowed heating only systems when it is for stores, stairs, technical rooms, etc. In my case however the office zones are also designed as Heating only (ventilation and aux radiator heating). Should this be modeled in the Baseline also as the other heating only systems, regarding that it is for office areas. Thanks.

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Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4461 thumbs up

Sat, 10/04/2014 - 20:57

You can use the heating only systems for any space type.

Vassil Vassilev

Manager

Termoservice

LEEDuser Basic Member

13 thumbs up

Mon, 10/13/2014 - 13:16

Hi Marcus, Thanks a lot for your reply. There are however few more clearing questions to this issue, for which I'm not sure how to proceed. 1. Baseline system arrangement. In ASHRAE 90.1 2010 Manual (G-28) is written "For systems ...9 and 10, each floor is modeled with a separate HVAC system". My project has two floors (46 000 sqft), but has 8 different heating system servicing various zones, which are Radiation (heating only) and ventilation DOA (also heating only). Reading the manual, I'm considering that for Baseline I have to model 2 systems - Ventilation - heating only. Is this correct or I should model the systems as they are in the Proposed? 2. Number of Boilers, pumps. In app. G are written the conditions for these equipment, but applicable to systems 1, 5 and 7. My project has two gas fired boilers and the whole system is based on hot water circulated by pumps. Should I stick also to these systems (1,5,7) ? Your support will be highly appreciated. Thanks.

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4461 thumbs up

Mon, 10/13/2014 - 13:28

1. Baseline is one system per floor. Do not map the baseline systems to the proposed systems. 2. A system 9 uses a furnace, not a boiler. So the baseline would not have a boiler, pumps, etc.

Jean Marais

b.i.g. Bechtold DesignBuilder Expert

LEEDuser Basic Member

581 thumbs up

Tue, 10/14/2014 - 11:04

Marcus you are always(?!) right. However, I would like to ask you to perhaps bring this up with the TAG if you get the chance, i.e. to allow the baseline to map to the design case. It would make things a lot easier for the simulation program TrnSys (and most others as well) on large geometery projects and makes some sense on both accuracy (especially the routing and controls) and zoning practice. If you are of the other oppinion, I'd love to hear the reasoning from an expert such as yourself.

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4461 thumbs up

Tue, 10/14/2014 - 12:00

Jean I am frequently wrong, just ask my wife. I am no longer on the EA TAG and the issue is embedded in Appendix G so I don't think the TAG would opt to change it. You raise a good point. This makes sense in certain building type but does not make sense in others. 90.1-2013 has added building types and differentiates system type by climate zone instead of heating fuel. I think that as this continues to be refined hopefully they will do more differentiation by building type to address this issue. Your issue is with the Appendix G folks, not the LEED folks I think.

Manuel Romera Molina

Energy Efficiency Specialist

PGI Engineering

LEEDuser Basic Member

4 thumbs up

Wed, 04/29/2026 - 08:44

Hello everybody. I was reviewing this thread because we have a similar project, where the main use of the building is industrial process, with a small office area. The industrial process will be heated and ventilated only and we were wondering if, despite the actual design, we should model both the Baseline and Proposed cases as heated an cooled per G3.1.1.b. We understand that an industrial process building is not allowed to be classified as "Heated Only Storage" per G3.1.1A.
An older thread

https://leeduser.buildinggreen.com/forum/energy-modeling-unconditioned-human-occupied-spaces

suggested that all conditioned spaces shall follow the G3.1.1.b statement, even if they are not actually cooled.

Could someone please information to clarify this point? Thank you

Marcus Sheffer

LEED Fellow

7group / Energy Opportunities

LEEDuser Expert

4461 thumbs up

Thu, 04/30/2026 - 15:57

I would model the industrial process as heated only. Yes Appendix G technically requires that you model heating/cooling systems, but it does not regulate the temperature settings. So the work around would be to model the cooling system but have a cooling temperature set point so high that the system does not operate. This is allowed but knowing that why waste your time modeling the cooling system. Explain to the reviewer that you are aware of this work around and did not want to waste your time modeling a system that does not exist.

Manuel Romera Molina

Energy Efficiency Specialist

PGI Engineering

LEEDuser Basic Member

4 thumbs up

Mon, 05/04/2026 - 06:35

Thank you very much, Marcus. It makes sense.

My understanding is that the intent in Appendix G with this clause is to prevent design teams from gaining an artificial advantage by not modeling a system which is not present in the current design but could be installed in the future, perhaps ignoring the rules of the Standard. But perhaps some exception could be allowed for G3.1.1.b when the design intent and function are clear and justified enough.

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