Optimize Energy Performance -HVAC-

January 26, 2015

Gustav Alfaro

Mechanical Engineer

LEEDuser Basic Member

16 thumbs up

January 26, 2015

Hi, I have a couple of questions regarding EAc1.3

1. Our HVAC design includes VRF systems that are compliant with sections 1.4 and 2.9 of the Core Performance Guide, but those systems don't have variable control of air (required by section 3.10) However, the standard has an exception if the fans motor horsepower are smaller than 5hp which is our case. Is that an allowable exception to be used for submittal review purposes?

2.We are trying to pursue the zoning and controls strategy; is it correct if we use occupancy sensors for independent offices, conference rooms, etc. that turn on and off the units based on occupancy but with no setback and with no demand-controlled ventilation strategies?

Thank you in advance

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Michael Smithing

Director - Green Building Advisory
Colliers International Ltd.

LEEDuser Basic Member

304 thumbs up

January 26, 2015 - 8:26 pm

I can only comment on the second question. There are two LEED Interpretations on this topic (#10242 and #10263). The second requires demand controlled ventilation in conference rooms, but not individual offices. We've successfully appealed this on CI a project with a base building CAV system by pointing out this approach would increase rather than decrease energy, but this only works because the building has not installed variable frequency controls on the AHU drives.

Gustav Alfaro

Mechanical Engineer

LEEDuser Basic Member

16 thumbs up

January 26, 2015 - 9:01 pm

Thank you Michael for your answer, I will check the leed interpretations immediately.

Id really appreciate if anyone can help me with the first question, is it necessary to have variable control of air in a VRF system if the fans motor horsepower are smaller than 5hp? Is that exception a valid path for submittal review purposes?