Does anyone have experience applying the “USGBC LEED 62MZCalc” spreadsheet for Indirect Evaporative Cooling (IDEC) systems? Or, is there an alternate compliance path elected due to the significant differences as compared to ordinary air handling systems that return a large percentage of return (re-circulated) air? We are challenged with how to correctly apply this spreadsheet for an IDEC system that runs, for most of the year, at 100% outside air. It would seem that there would be a special steps provided within this spreadsheet to consider IDEC systems since, looking from a broader perspective, it would seem intuitive that an IDEC system will much more than satisfy the ventilation requirements for 95% of the year.

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Ben Stanley

Senior Sustainability Manager

WSP - Built Ecology

LEEDuser Expert

188 thumbs up

Mon, 11/30/2015 - 23:06

Hi Dustin, How does the system run at the worst case condition or how is it running when it's not providing 100% outside air? In general, the calculations and measurement conditions should reflect that worst case condition (minimum outdoor air provided relative to required outdoor air) of the system. Check this newish calculator from USGBC to facilitate the calculations http://www.usgbc.org/resources/minimum-indoor-air-quality-performance-calculator.

Dylan Connelly

Mechanical Engineer

Integral Group

LEEDuser Expert

342 thumbs up

Wed, 12/09/2015 - 15:24

I second what Ben said regarding this being a worst case calculator. You take credit for the energy savings from the IDEC but this LEED doesn't credit you for better air quality for more of the year because you have 100% outside air more of the year.

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