LEED Prerequisite EA 2 Ashrae 90.1 2004

Questions, answers, and discussion specifically related to practical working issues with LEED and other robust green certification systems.

LEED Prerequisite EA 2 Ashrae 90.1 2004

Postby Misvit » Mon Jul 02, 2007 5:29 pm

Under LEED prereq EA 2 Minimum energy performance, a building must meet among other sections, 5.4 of ASHRAE 90.1 2004.

In ASHRAE 90.1 2004, section the fenestration area is required to be at a maximum of 50% of your gross vertical surface.

We at the firm are wondering if any provisions have been made in LEED for such surfaces that have been totally shaded using devices, overhangs, solar panels, etc. Our building is basically a glass box with a very large roof overhang and we have done rudimentary sun shading experiments to find that for instance, the south facade receives no direct solar daylight during any part of the year during business hours. Furthermore we have had mechanical get us a number $$ in savings for a similar building with 50% spandrel instead of what we have shown, which was $400 per year on the 100,000 sf office building.

Once again my boss questions the intent of this point and would like to argue that the minimum difference in cooling load and savings would denote that our overhang has met the requirements put forth in this prerequisite.

Sorry for asking what seems to be so cut and dry, but I don't know what else to do and once again, LEED refuses to answer when I call them until they see $$.
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Postby joelmckellar » Tue Jul 03, 2007 1:20 pm

Don't forget that you may comply with the second half of the requirements by running a performance calculation without complying with the prescriptive requirements. From the Credit:

"the prescriptive requirements (sections 5.5,6.5,7.5, and 9.5) or performance requirements (Section 11) of ASHRAE/IESNA Standard 90.1-2004 (without amendments)"

Basically what this means is that if you are running a performance calculation, LEED and ASHRAE allow you to throw out the prescriptive requirments set forth in those sections. You will still need to comply with the mandatory provisions (5.4, 6.4, 7.4, 8.4, 9.4, 10.4), but the section you mentioned ( is not in this requirement.

I say run the numbers (which you're likely doing for EAc1 anyway) and you should be fine.
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Postby gleearch » Tue Jul 03, 2007 2:33 pm

I agree with Joel. You have the option to run the computer simulation for EA credit 1. If your building complies, the pre req does mention that you can use the simulation. I just went over this with my mechanical engineer yesterday on an 40k sf office building.
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Postby svenglezz-ASMEIL » Fri Aug 22, 2008 10:41 am

Keep in mind on an apartment/condo you do not get the flexibility as say a commercial building with having a central HVAC system that can reclaim energy (HRV etc.) So the other method is not possible on an apartment/condo.

My personal experience is that an apartment or condo building will not pass the program if it is over 50% glass. And if you go over this 50% you will need first HEAVY tint in the glass and have triple or quad pane glass to pass the program.

Also the location of the glass is a big factor to (North, South, East, West).

Shading will have a factor but nothing like the ratio of glass to wall.

It's amazing to see how many building being built will not pass this program/code (even with shading devices etc.). Guess that's why it's becoming more of a standard in Europe to build with triple pane glass.

Kind regards,
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Postby amcink » Tue Jan 27, 2009 8:14 pm

Does the performance calculation - computer simulation be done with a MICROPAS software. or which software is the one usually used for this type of computer simulation?
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Postby svenglezz-ASMEIL » Sun Feb 01, 2009 9:25 am

You get the program from A.S.H.R.A.E. directly.

Cost bit over $100 and comes with the program book.

Good luck and happy savings,
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Postby chris@korbtredo.com » Mon Mar 23, 2009 7:08 pm

Can anyone inform me regarding the following:

EA Prerequisite 2 states that a LEED building must comply with AHRAE 90.1 and more specifically with Lighting Mandatory provisions. Automatic controls are mandatory for a building over 5000 square feet. We are trying to certify a dormitory and are wondering how to get around having to have automatic controls in the living units. My assumption is that the dormitory use would fit under an exception that is a 24 hour operation. Has anyone else dealt with this and can you tell me how? Thanks
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Postby svenglezz-ASMEIL » Thu Mar 26, 2009 10:58 am

Recommend purchasing the program at A.S.H.R.A.E. for the 90.1 code it also has the electrical side of things (program), to see if the project complies.
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