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Misvit
Joined: 21 Jun 2007 Posts: 42
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Posted: Mon Jul 02, 2007 2:29 pm Post subject: LEED Prerequisite EA 2 Ashrae 90.1 2004 |
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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 5.5.4.2.1 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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joelmckellar
Joined: 31 May 2006 Posts: 86 Location: Charleston, SC
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Posted: Tue Jul 03, 2007 10:20 am Post subject: |
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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 (5.5.4.2.1) is not in this requirement.
I say run the numbers (which you're likely doing for EAc1 anyway) and you should be fine. _________________ Joel McKellar, LEED AP
http://www.reallifeleed.com/ |
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gleearch
Joined: 07 Jul 2005 Posts: 185 Location: Oakland, CA , USA
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Posted: Tue Jul 03, 2007 11:33 am Post subject: |
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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. _________________ Gerard Lee Architects
http://www.gleearchitects.com
San Francisco bay area, Oakland, CA based sustainable architecture & planning firm specializing in residential, education, commercial, community & civic projects. |
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Xenon
Joined: 05 Jun 2007 Posts: 13
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