Is there a reason why the equipment on the proposed can not be autosized? if you are inputting the fan consumption as "kw" and not based on cfm, what is the effect of exactly matching the capacities and airflow of the equipment to the schedules, since load calculations defer from energy calcs, one accounting for the highest peak possible and the other one for the lowest energy consumpting version. Load calculations possibly depicting the initial highest possible number of occupants and conservative envelope values, while energy model the highest efficiency.
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Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
October 16, 2014 - 12:55 am
1) yes. the leed process requires the proposed model to match the design documentation of the project. For initial testing of your model, or at early stages before the design documentation is finished, you could start with autosized values, but these are not for submission.
2) i use energyplus. in energyplus, you define a seperate set of schedules that are used for the load calculations when running the sizing simulations. sometimes these schedules are the same as used for the annual simulation, but for some items like occupation, they are not...they are also different for the heating load simulation and the cooling load simulation.
3) if your innitial question is about fan power consumption at different flow rates, then the answere is beyond the scope of this forum (hint: the flow impacts on the hydronic pressure that the fan must overcome in the system and directly impacts the power...check out your software's user forum).
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
October 20, 2014 - 7:13 am
Appendix G requires that you model the building as designed. It the capacities and airflows are autosized and only slightly differ it is usually not an issue. It is when they differ by a wide margin that it can affect energy use.
Most modeling software is not used to size equipment.