In the proposed building that I’m modeling there is a CAV system without cooling system (in the AHU a water coil is heated by hot water). How shall I model the cooling system? I know that “Where no cooling system exists or no cooling system has been specified, the cooling system shall be identical to the system modeled in the baseline building design” (Table G3.1 item 10.c.). In the baseline model I have to create a System 5 – Packaged VAV with Reheat. Shall the reheat coil of the proposed model be heated by the boiler of the actual system or shall it be heated by a virtual boiler having the same efficiency of the boiler of the baseline model? More generally speaking, in the proposed model shall the cooling system be completely independent from the heating system?
How shall I determine the set-points for the cooling system? If I impose a high temperature as set-point (e.g. 35°C) the cooling system will never work. In that case, why modeling a cooling system?
With Regards
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
September 5, 2012 - 10:19 am
I think the reviewers in general are pretty flexible on this issue. They are (or should be) fully aware of the high temperature set point work around for this issue so that it does not affect the energy use. As such requiring the modeling of a cooling system for this space is just a waste of time. If you explained it and mentioned the work around the reviewer should let it go.
Francesco Passerini
engineer90 thumbs up
September 5, 2012 - 11:34 am
Thank you, Marcus. In your opinion, if I decided to model the cooling system, in the proposed model the reheat coils should be heated by a boiler corresponding to the actual boiler (proposed design boiler) or by a virtual boiler having the same efficiency of the baseline boiler?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
September 5, 2012 - 12:19 pm
The proposed model should reflect the actual boiler design. The baseline model should follow Appendix G related to the boiler in a system #5. If you need to add the cooling system model the baseline according to Appendix G and if necessary model the identical system in the proposed. If you need to model a separate system to make it work then do that.