[Bldg-sim] Conservative design cooling load calculations vs baseline sizing

[Michael tillou]

Hi Patrick,

I just wanted to clarify for you that Appendix G (G3.1.2.2.1) requires the simulation of sizing runs for equipment selection based on either the peak from the weather file or ASHRAE 99.6% heating and 1% cooling design temperatures.  As far as I know this is not something USGBC or GBCI has written a clarifying rule on for LEED.

As far as being frustrated over engineers doing overly conservative load calculations, welcome to life as an energy analyst.  The best you can hope for is to use simulation to show them and the building owner that they are over engineering the system and try to get some concession.  Ultimately at the end of the day it's the engineer who is stamping the work and taking on the liability that has the final say.

Mike.  

Sent from my iPad

On Dec 4, 2013, at 11:17 PM, Patrick Bivona <patrick.bivona at gmail.com> wrote:

> Hi,
> 
> When sizing cooling equipment for apartments, the design team on my project used a worst case scenario approach of maxing out all internal loads. For instance, lighting would be on during the day, with full occupancy and all plug equipment running, while the sun is hitting the windows. Adjacent rooms would be considered without cooling.
> For LEED, the sizing for the baseline is based on schedules representing typical operations for occupancy, lighting, plug, etc. That leads the baseline to size equipment that has smaller capacity than what considered for the proposed design.
> There's an extra dimension, in the fact the design team sized equipment for each individual room, reaching their peak load at different times of the day. So the total cooling capacity is the sum of the worst possible scenarios. The model currently uses a single zone per apartment, with a not so worst case scenario.
> How do I solve this conundrum? Am I missing something?
> Thanks,Patrick
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