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FAQs about EAp2 :

Are there any exceptions to the daylight control requirement of ASHRAE 90.1–2010?

Our proposed design has insulation R-values that are below those prescribed by ASHRAE 90.1-2010. Can we still meet the prerequisite?

Do the required savings for this prerequisite (and credit) need to come only from building energy, or also process loads?

Our project doesn't have enough energy savings to earn the prerequisite. Can we get there by incorporating onsite renewables?

Does the base building information need to be included in the minimum energy performance calculator, or is it sufficient to just include the tenant space?

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CI-v4 EAp2:Minimum energy performance

LEED CI V4 Energy Model, 2 Floors

Hi, I am doing the energy simulation for LEED CI v4 Rating. There are 5 buildings named as Block 1,2,3,4&5 in the site and all buildings are conditioned by the centralized air cooled chiller plant which is also located inside the site. Tenant spaces /project spaces are located in the 2nd floor and 3rd floor of block 4. 2nd floor and 3rd floor are conditioned by AHU 2A and AHU 3A respectively. 18% of 2nd floor and 40% of 3rd floor is coming under project space. My questions are Proposed case: 1. U values of wall, roof, floor and glazing, shgc are considered as built. Is this correct? 2. AHU's are located at roof and connected with fan powered vav. Fan is available in AHU and also in fan powered vav. Which fan power has to be included in model? AHU fan or vav' fan or both. 3. Whether whole floor has to be modeled? Since the AHU serving the whole floor. 4.how the capacity of chiller , pump power to be considered with respect to project space. Basecase: 1.U value of wall, roof, floor and glazing are considered as per ashrae standard rather than existing u values. Is this correct? 2. LPD of interior lighting has considered as per ashrae LPD. Is this correct. 3. Cooling and heating capacities are autosized as 1.15 & 1.25 respectively. Is this correct? 4. Base case fan power has considered as per ashrae standard. Is this correct? 5. System 6 has considered baseline HVAC system. Since the no of floor is less than 5 and total conditioned area is less than 1.5 lakhs sq.ft. is this correct. I am waiting for your reply Please.
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Fri, 09/15/2017 - 14:35

Please support me on the questions asked.
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Fri, 09/15/2017 - 15:05

You will need the guidance in the Reference Guide to complete these models. Proposed 1. yes 2. Both. The Reference Guide explains how the AHUs should be modeled in your situation. 3. Usually not. 4. Proportionally. Baseline is according the Appendix G 1. Yes 2. Yes 3. Yes 4. Yes 5. The Baseline system is based on the total building area and number of floors, not the project area/floors.

Fri, 09/15/2017 - 16:26

Whether baseline HVAC will change since the proposed system is district cooling (centralized air cooled chiller plant serving all the five buildings)
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Fri, 09/15/2017 - 16:35

The district guidance is also in the Reference Guide. I would think that the baseline system would not change.

Sun, 09/17/2017 - 14:00

As I mentioned above, Baseline System 6 Packaged VAV has considered in the base-case Model. Since the no of floors is less than 5 and the total conditioned area is less than 1.5 lakhs sq.ft. Whether system 8 has to be considered instead of system 6, as per Appendix G 3.1.1.3.2. Because the proposed system is district cooling (centralized air-cooled chiller plant serving all the five buildings). Please advise me. Thanks
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Mon, 09/18/2017 - 13:39

You clearly need the Reference Guide. There are a few options you have and the baseline depends on the option you choose. Typically they are according to Appendix G. The new DES guidance does not change the baseline system like the previous one did.

Mon, 09/25/2017 - 13:11

Dear Marcus, For the above-said project, System 6 has considered baseline HVAC system. Since the whole building's no of the floors is less than 5 and the total conditioned area is less than 1.5 lakhs sq.ft. I would like to consider the Baseline HVAC System 6 - Packaged VAV with PFP Boxes in Baseline Energy Model & Virtual on-site DC with default COP of 4.4 in Proposed Energy Model. I have reviewed the reference guide and ASHRAE 90.1.2010. However, I am not able to select the correct path (Path 1, ASHRAE 90.1–2010, Appendix G; Path 2, Full DES or central plant performance accounting; or Path 3, Streamlined DES modeling). Could u guide me / tell me the path which is suitable for my case? Please....
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Mon, 09/25/2017 - 15:01

Sounds like you want Path 2. Path 1 and 3 treat the DES as purchased energy. The only difference in Path 3 is you account for an average plant efficiency in the rates.
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Omar Elrawy
Green Building Consultant | Researcher
GreenA Consultants
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Thu, 04/30/2020 - 16:20

Dear Marcus, I've noticed you mention " The new DES guidance does not change the baseline system like the previous one did." Need to know which version is the "new", as the latest I find is entitled "v2.2 and v2009 (guidance v2.0)" , and need to know if there's a more recent one please...
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Thu, 04/30/2020 - 17:42

The v4 version is included within the Reference Guide.
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Omar Elrawy
Green Building Consultant | Researcher
GreenA Consultants
LEEDuser Basic Member
38 thumbs up

Tue, 06/02/2020 - 15:43

Another related question, 
When AHU is serving the whole floor, and my tenant area is only 15% of the whole floor area, reference guide asks to adjust both AHU flow rate and fan power (to account for relative contribution), so I multiplied both by 0.15.

Actually doing this yielded very low efficient fan, that's because because fans always have curves (nothing is linear), but applying the reference guide linearized fan performance, giving very low fan efficiency in proposed case.

My question is, can I leave fan power and efficiency autosized, and just model actual contribution of the flow rate in the proposed case?
otherwise I'm not making any savings, especially my space is already small (300 m2)...

Thanks a lot
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Jonathan Weiss
Jacobs Buildings & Infrastructure
LEEDuser Premium Member
140 thumbs up

Thu, 06/18/2020 - 22:09

New question - the reference guide has two conflicting pieces of information (to my reading).  What am I missing? Reference guide says, "exception - base building must use ASHRAE 90.1 sections a-e, and not Section f" But in the reference guide table under "common issues with energy models" there is a first line that says the same, and the second line that refers to "existing building envelope" differently, that says that we can / should use the base building existing condition if it was conditioned pre-construction.  Does that mean that we CAN use the preconstruction condition (this is a 40 year old building with a poor envelope, we are adding insulation to the envelope as part of our interior fitout of the floors we're renovating).   Thx  
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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Fri, 06/19/2020 - 13:37

The exclusion of "f" is right in the credit language so this would superseed anything else in the Reference Guide. So you model the ASHRAE 90.1 insulation values from Table 5.5x in the baseline no matter what the existing or pre-existing conditions are. Personally I don't think this is how it should be. In your case if you are bringing the envelop up to better than code conditions you should get credit for it. The logic behind it, I suppose, is that if you are touching the envelop you would technically be required to bring it up to the code minimum anyway so that should be the comparative.
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Jonathan Weiss
Jacobs Buildings & Infrastructure
LEEDuser Premium Member
140 thumbs up

Wed, 06/24/2020 - 13:26

Thanks, Marcus! I guess we should hope that the reference guide is changed - if that specific line in the reference guide table does not apply, it should be removed.  What purpose could it serve other than to confuse people - and in fact in this case it even confused the LEED reviewers, who later sent a clarifying email saying, 'pay no attention to the comment about the envelope.'  So at least we're in good company with our confusion! I would agree with you - upgrading the envelope is something we recommend but there is an incentive (first cost) to leave it alone.  In my mind there should be an extra incentive to upgrade an older and poorer performing envelope - so using the existing condition as a baseline would reward people for taking on the envelopes most at need for upgrade.  Of course the owner has the operational incentive to upgrade regardless of LEED, but it should be in sync, if you ask me.  And of course I would not mind getting credit for more savings. Thanks again for the comment.

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