As HVAC system for baseline I have to model System 5 - Packaged rooftop VAV with Reheat. I wonder what efficiencies I have to consider for the different components.
For the fan motor efficiency I have to use Table 10.8 of ASHRAE 90.1. In the calculation of the brake horsepower for the baseline fan system of Example G-J’ of the “User’s Manual” parameter A is supposed equal to 0, probably because pressure drops are considered equal to 0 (see tables 6.5.3.1.1A and 6.5.3.1.1B). Can I consider for the baseline model A equal to 0 or shall I make some further consideration?
For the cooling system (direct expansion) I would use Table 6.8.1A. Which “Equipment Type” and “Subcategory or Rating Condition” shall I consider?
For the heating system (hot-water fossil fuel boiler) I would use Table 6.8.1F “Boilers, hot water” -> “gas-fired” (the boiler of the actual building is fueled by natural gas).
Any corrections or suggestions, please?
Best Regards
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
August 3, 2012 - 8:46 am
If you have no pressure drop adjustments then A = 0.
For the cooling equipment you use Air Conditioners, Air Cooled. The Subcategory does not make any difference since the efficiency is the same within each size and heating type.
That is correct for the heating system.
Francesco Passerini
engineer90 thumbs up
August 8, 2012 - 6:46 am
Shall I model "fully ducted return and/or exhaust air systems" only for the WCs? In that case, shall I consider a pressure drop adjustment equal to
125 Pa (0.5 in IP units)
for every WC (see table 6.5.3.1.1B)?
If on one floor there are three WCs having exhaust air systems shall I consider a total pressure drop adjustment equal to 375 Pa (= 3 x 125 Pa)?
Thank you for your help.
Best Regards
ESD Singapore
1 thumbs up
December 3, 2012 - 3:02 am
as indicated on page 183. For system 1 and 2, there is no pressure adjustment; for system 3 to system 8, fan power can be adjusted basing on proposed design.