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Forum discussion

CS-2009 EAp2:Minimum Energy Performance

LEED CS 2009 Existing Equipment

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Lorey Flick
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could you clarify something for me: Existing HVAC equipment: 1. If it's not touched it may be used identically in the baseline and proposed case. 2. If it is changed, the baseline HVAC becomes the the ASHRAE 90.1 2007 min requirements table xx. 3. What about if it is modified? For example, an air handler is given a new ECM fan motor or equipped with a VFD. Does the baseline now require to use the fan power calc in the model? 4. Similar to above: What if the existing boiler is to remain but is now equipped with a new control system to provide HW reset and OA reset? Does the baseline require 90.1 App G to be modeled even the though the efficiency of the boiler in the proposed is worse? Any input you have would be greatly appreciated!

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Wed, 02/15/2017 - 08:17

You have to model the baseline HVAC system according to G3.1.1, which reference Table G3.1.1A also for existing buildings. I.e., it doesn't matter if a HVAC system exists before the project.
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Marcus Sheffer
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Wed, 02/15/2017 - 14:36

In your email to me you had indicated that you noticed a shift in the responses on this subject. A few years ago GBCI reviewers were requiring the Baseline HVAC to always be according to Appendix G. That changed about 2012, which is why you may have noticed a shift in advice. 1. Existing HVAC is modeled identically.See Page G-21 in the 90.1-2007 User's Manual. 2. Correct. 3. This is a bit grey. What I would do is model the components that remain as existing identically and model the components that change according to Appendix G. 4. I would do the same as above here. Model the existing boiler efficiency identically since that did not change but model the controls as if they were new.
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Lorey Flick
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Flick Engineering Professionals
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Wed, 02/15/2017 - 14:51

R2M - Your reply is in conflict with what is stated in the 90.1 2007 User's Manual. The manual states "unchanged components are modeled at their existing levels of energy performance" under section G3.1. Furthermore, there is an exception if an HVAC system exists: "...the proposed building and baseline building models are the same and are based on the existing HVAC system" under section HVAC systems of the User's Manual. What is LEED's stance on the statements above? Can you please help to clarify?
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Marcus Sheffer
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Wed, 02/15/2017 - 15:14

I summarized the current stance of the LEED/GBCI reviewers above. We were probably typing at the same time perhaps.

Wed, 02/15/2017 - 16:01

I'm sorry, my interpretation was wrong (at least for the current situation). Regards

Tue, 05/09/2017 - 10:49

Is the principle "...the proposed building and baseline building models are the same and are based on the existing HVAC system" valid also for the renewable energy sources and for the ventilation air flow rates (i.e., is exception c. of G3.1.2.6 not valid?)? Cheers
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Marcus Sheffer
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Tue, 05/09/2017 - 13:09

I'm not sure that is a principle. For an existing renewable I would think you could still get credit for it. They align so well with the intent of LEED and are rare enough that they should count no matter what IMO. There is a difference between an energy consuming system and an energy producing system. 90.1 does really deal with energy producing systems so much. As for the ventilation it needs to be identical in both models for an existing system and it needs to comply with ASHRAE 62.1. My copy of 90.1 does not have an exception c for G3.1.2.6?

Tue, 05/09/2017 - 13:25

Sorry, my comment was relative to ASHRAE 90.1-2010. Shall I write the question in the forum relative to LEED v.4?
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Marcus Sheffer
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Tue, 05/09/2017 - 13:36

Yes please

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