hello folks,
I just received the comments from the reviewer and have some questions about them. The reviewer questioned a lot about the fan power simulation.
Q1. AppendixG assumes each floor served by an individual AHU in baseline case. However my system is quite complex: image a vertical section view of the building, then different systems serve various vertical areas. In the proposed design case, I modeled as design; in baseline case I left eQuest autosizing these AHU's flowrate. Here comes the quesiton: in Table 6.5.3.1.1B, pressure drop adjustment of AHUs need input of heat recovery device in the baseline. The table says "Pressure drop of device at fan system design condition" for the heat recovery device. How can I find it? The system layouts are totally different between design case and baseline case, so I think I can't use the info from the design case.
Q2. My AHU is 100% of outdoor air supply with heat recovery, however, even though I forced eQuest's minimum outside air ratio to be 1.0, the SV-A still reported the OUTSIDE AIR RATIO is 0.267 and various AHUs had similar values. Is that the right way to model this system? I input 90% of supply air flowrate into the RETURN FLOW in eQuest . I hope eQuest had not regarded it as the recirculation air.
Plus, in this 100% of outdoor air system, is the fan supply volume supposed to be always the same as the ventilation rate?
Q3. Some underground areas are served by PTAC according to G3.1.1 exceptions. But in the design case these areas are conditoned by AHU with heat recovery. Do I need to model heat recovery for the PTAC systems?
Your quick reply is highly appreciated.
Michael Tillou
Director of Energy ServicesCannon Design
52 thumbs up
September 27, 2010 - 8:56 pm
Q1:That's a tough one. The first thing you should check is whether the baseline systems even require heat recovery. When you reconfigure the systems so you have one per floor it helps to have the volume of outside air fixed at the zone level. This way when you reconfigure the zones onto the new air handlers you can be assured that the ventilation volume is the same in both the baseline and proposed design models. Do your baseline AHU sizing runs and then check the ventilation air volume against the supply air volume to see if ventilation is greater than 70% of the total airflow. If it's less than you don't need heat recovery on the baseline system. If you still need heat recovery in a baseline system use the proposed design pressure drop or if you think the number is too high than use a more appropriate value and just document your assumption with your LEED submission. I do this on ocassion when I come across loopholes in Appendix G, the worst thing that could happen is the LEED reviewer will make you use a higher pressure drop increasing your energy savings (trust me its happened).
Q2: Your problem here is that keywords have a hierarchy within eQUEST. Minimum outside air is one of those keywords. If outside air is specified at the zone level than this takes priority over what you enter at the system level. You will need to reset the outside air keywords in each zone to the default so that the OUTSIDE AIR RATIO keyword at the system level will take priority.
Q3: You only need to model heat recovery in the baseline if the conditions requireing heat recovery are met. CFM>5,000 and MIN OA > 70%. This would apply to your other baseline systems as well (see Q1 answer)
Florian Schmidtchen
EGS-plan International GmbH95 thumbs up
September 27, 2010 - 10:44 pm
Thank you for the quick reply, Mike.
My proposed design case includes fancoil system plus 100% of outdoor air system(DOAS), so the autosized supply air volume of system-7 in the baseline is much larger than the counterpart in the design case.
Let me confirm my understandings: Since I need to ensure that ventilation volume is the same in both the baseline and proposed design models, I have to stick to the zone level outside air settings. Then, the SV-A reports that in my baseline model all the AHUs’ OUTSIDE AIR RATIO are smaller than 70%(only 0.15~0.32), so I should NOT model the heat recovery in the baseline. Is that understanding correct?
My project is LEED-CS certification. One additional question is about underground garage lighting. The reviewer requires that the parking garage lighting is entered as a separate energy end use with separate consumption and demand figures in template section1.8. The garage should be a part of core areas. So in the baseline, I will use values from Table 9.6.1 in the 90.1-2007, and in the design case I will just use the design documented values, and finally separate report it in the section1.8. Is that alright?
I am looking forward to your prompt reply and thank you in advance.
Michael Tillou
Director of Energy ServicesCannon Design
52 thumbs up
September 27, 2010 - 10:56 pm
Yes that's right. You need to double check that the total building ventilation CFM is the same in both models unless you are modeling Demand Control ventilation or other ventilation exception.
Regarding the PG lighting you are correct. I think the reason they want to see the garage lighting seperate is because the baseline LPD for parking garages is ~0.3 W/sq.ft. (going off the top of my head so double check) and they want to confirm that you use the correct baseline LPD and the same schedules in both models. The reviewers check run hours by dividing kWh by kW to determine approximate run hours.
Florian Schmidtchen
EGS-plan International GmbH95 thumbs up
September 29, 2010 - 11:43 pm
Thank you again Mike.
We are now filing an appeal review. All the comments in preliminary and final review have been addressed. Since the Appeal Review will be assigned to another person, I am little worried that the new reviewer will start to search new issues, which the former reveiwer did not pointed out. Is that normal pratice for the new reviwer, or does he only check the final review is adequately adressed?
Do I need also include the eQuest model files into the supporting documentation for the appeal review?
Because it is EAp2, do I need to appeal the EAp2 only(1 credit) , or along with EAc1 together(2 credits)?Currently EAp2 was marked a X and EAc1 was denied.
Your quick answer would be appreciated. Thanks.
Michael Tillou
Director of Energy ServicesCannon Design
52 thumbs up
September 30, 2010 - 10:12 am
I haven't had any problems with Appeal Reviews in the past. My understanding is that they start the reveiw process over so I guess there is a chance they can ask about something else but I haven't had them bring up new issues. My only advice would be to really make sure you understand your model and provide a detailed narrative explaining anything that seems out of the ordinary.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
September 30, 2010 - 10:57 am
Appeal reviewers are not allowed to bring up new issues that were missed by the original reviewer (even if it it a major error). If something was missed the reviewer may point it out in the appeal comments for future reference but cannot deny the appeal based on something that was missed in an earlier review. So typically the appeal reviewer is only looking to see that the final review comments have been addressed by the appeal.
To properly conduct an appeal review the reviewer looks at all previous submission documentation and review comments. Since LEED Online does not necessarily save older versions of the form it is always a good idea to keep a copy yourself. Older supporting documents provided for the preliminary and final reviews documents should never be deleted from LEED Online. When submitting the appeal you should provide both the preliminary and final versions of the form and any supporting documents you may have deleted from either review phase.
The supporting documents should include the requested DOE2 reports for all models including the ones submitted for the preliminary and fianl reviews.
You should only need to appeal EAp2 assuming that EAc1 is pending the resolution of EAp2.
Mike is absolutly right about providing narrative explanations for anything that looks out of the ordinary or is unexpected. They can be extremely valuable for the reviewer in answering questions that come to mind during the review process.
Christopher Schaffner
CEO & FounderThe Green Engineer
LEEDuser Expert
963 thumbs up
October 16, 2010 - 1:58 pm
I have had an appeal denied by the reviewer based on new info. They told us we had satisfied the concerns raised in the review, but that another issue, previously unmentioned in the reviews was "unresolved".
So it has happened. Hopefully this is a thing of the past.