We are modeling a large data center for LEED V4 using the ASHRAE 2010 appendix G as the baseline. The selection of baseline system is not completely clear to me and I was hoping for some guidance. By number of floors (1) and area (very large) alone the building would be system type 8.
The building can further be broken down into an admin portion (typical space types of an office/PDR building) and data center portions, each of which is over 150,000 ft2, though the data center dominates in area by far.
How should exceptions a and b to G3.1.1 be applied in this case?
We are currently applying system 8 to the data center portions and system 4 for all other zones. In my mind it would be more appropriate to essentially treat the admin and data center spaces as if they were on different floors (i.e. give each a system 8 and remove individual zones form those systems based on load/schedule diversion).
It seems like this has been cleared up in 2013 with an additional exception, but I would love to hear from anyone who has had success submitting whole building energy models of large data centers for LEED v4.
Two somewhat related questions:
1) Table G3.1.1B gives systems 1 - 4 as CV, should this have an note saying something like "unless system meets requirements of 6.4.3.10 a or b," in which case it would have a variable or 2 speed fan?
2) When removing systems that differ in the average load according to exception b to G3.1.1, does the average need to be recalculated every time after a zone has been removed? e.g. zone loads (Btu/h ft2) = 100, 40, 10, 10, 10, average load = 34, so remove zone with 100. Now if average of all zones remaining on the system is calculated, ave = 17.5, so zone with 40 should also be removed?
Thanks.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
June 15, 2018 - 2:23 pm
Exception a does not apply.
It looks like the office area should follow exception b since it is the smaller of the two areas. Even in 90.1-2013 the office would follow exception 2.
1) You model the system 4 as CV.
2) The average for the data center area should be compared to the average for the office area. If the difference is greater than 10 BTU/hr-ft2 the the exception applies. So yes remove the 100 and the 40 in your example.
Tien Duong
LEED AP BD+C, PM / Energy Modeler1 thumbs up
September 22, 2018 - 4:28 am
Hi All,
I am doing the data center project, too. So, Should I assume the IT Equipment is the process load and model identical for both Proposed and Baseline. Baseline will model with system 8 and proposed will model with design (CRAH Units), is that OK?
The cooling load for IT Equipment too large (about 2000 W/sqm), 01 system 08 is not enough for one floor, Can I using more system 08 when them enough for serve cooling load.
Thanks
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
September 24, 2018 - 11:55 am
Yes the IT is process and your baseline systems sound right.
Is it a software limitation for coil capacity or airflow? If something like this it would be acceptable to model a second system for that floor.
Tien Duong
LEED AP BD+C, PM / Energy Modeler1 thumbs up
September 24, 2018 - 9:48 pm
Thanks Sir. Marcus,
This is a very big help to me. One more thing, I found this calculator (https://www.usgbc.org/resources/minimum-energy-performance-data-center-c...) according to this files I found 2 options in Instructions Sheet for compliance with LEED:
The results from this calculator may be used in one of two ways:
1. The calculated energy savings from the IT and Electrical Systems will be calculated in kWh and can be directly claimed without needing to run another energy model. This approach is simpler, in that no additional energy models are required, but it will likely lead to a conservative estimate of savings since it does not show the HVAC savings associated with lower IT and electrical loads.
2. The calculated electrical load for the Baseline IT and Electrical Systems can be used as inputs to an exceptional calculation method, where the Baseline Case model is revised to show the Baseline IT and electrical loads from this calculator. This approach requires additional energy modeling, and additional efforts to report the outputs in the LEED calculator/forms, but will lead to a more accurate estimate of savings, since it will calculate the HVAC savings associated with the lower IT and electrical loads.
So, in options 1, we just need complete this form and submit for LEED, no need any simulation more, this is right ?
And for options 2, we will use this form for defining the IT equipment of baseline for input in simulation and Proposed case will following design. Then submits the results within ECM, is that right?
Conclusion, we will have 3 ways for compliance this Prerequisite:
1. Doing the simulation with IT is process for 03 model 1, 2 and 3.
2. Using the calculator provided by LEED, and no more model simulation.
3. Using ECM.
Thanks
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
September 25, 2018 - 11:16 am
Your conclusion in not correct.
You must do the three models. This is in the credit language.
If you are claiming energy savings for the IT load then you would select one of the two options for doing so within the calculator.
So these are not 3 different ways for compliance. The claiming of savings for the IT load is a subset of the required modeling.
Tien Duong
LEED AP BD+C, PM / Energy Modeler1 thumbs up
September 26, 2018 - 12:23 am
Dear Sir Marcus,
Thanks for your quick reply. I understand what you mention. But just a little confused about words in Calculator of LEED: 'The calculated energy savings from the IT and Electrical Systems will be calculated in kWh and can be directly claimed without needing to run another energy model. This approach is simpler, in that no additional energy models are required....', Can you enlighten me.
According to your advice, I have to do 3 model simulations, and if I want to claim IT equipment saving, I should select one of two options:
If I select the options one. I will have the result from simulation software with IT equipment is process and the calculator with IT equipment saving. Then how can I claim the total energy simulation compliance with LEED ? Please help me
And If I select the option two, I should use the information of IT Equipment Baseline for input to Simulations. and run the simulation. Am I right?
Thanks so much!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
October 1, 2018 - 2:15 pm
What that means is that if you wish to claim energy savings for the IT system you can use the calculator to do so and then just plug the results from the calculator into your modeling results. This is option 1. Under option 2 you model the different values and run the simulation to allow you to account for the impact of the load reduction on the other building systems.