Under G3.1.13 "Modeling Limitations to the Simulation Program", it says to substitute a thermodynamically similar component model when the software can't explicitly model a component. And it says the Baseline component shall be the same as the Proposed component.
This makes sense to me for the case where I am trying to simulate a utility room with an exhaust fan for ambient cooling and a unit heater for minimal heating. Whatever I come up with, I'll just copy the exact same system or process energy load to the baseline building. However, what about in the case of a vestibule that only has cabinet heaters?
In HAP, there is no cabinet heater system so you model a packaged RTU with the heating coil removed and add a zone heating fan coil unit. Now for the baseline building, would I do exactly the same or would I model a packaged RTU with gas heat? In my case the primary baseline system type is packaged VAV with hot water reheat, so any exceptions are supposed to be modeled as single zone packaged units with fossil fuel heat. Does my cabinet heater "simulation" fall under G3.1.13?
Thanks.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
September 18, 2013 - 12:16 pm
Table G3.1-13 Proposed means that if the software you are using cannot model something directly that you need to use a work around that will produce similar results relative to what would be expected if it modeled it directly.
Table G3.1-13 Baseline means that if you have a similar situation in the Baseline model you would do the same thing. This does not mean that the Baseline and Proposed must be identical on a component level.
In your example the work around for the vestibule in the proposed Case should be identified and justified in a narrative for the reviewer to evaluate. In the Baseline it is modeled according to the Appendix G requirements. If it meets an exception to G3.1.1 then you could model a system 3 instead of the system 5. It should not be identical to the proposed.
Matt Scott
EngineerN.E. Fisher & Associates, Inc.
18 thumbs up
September 18, 2013 - 2:24 pm
OK, thanks!