[Bldg-sim] ASHRAE 90.1 Baseline building question

[Chris Jones]

The project has 4 rooftop units, and one ERV that provides OA to the 
four roof top units.  Except the ERV only provides 50% of the minimum 
OA for each of the four rooftop systems.  DOE2.2 and DOE2.1e do not 
seem to handle heat recovery in a make-up air system using the 
OA-FROM-SYSTEM command.  The way I typically handle this arrangement 
is to prorate the heat recovery effectiveness and the ERV fan power 
to each of the 4 roof top systems.  The 4 rooftop systems have 
typical OA % for an office building - less than 50%.  My 
interpretation of 90.1-1999 Section 6.3.6.1 is that the ERV has more 
than 5000 cfm and more than 70% OA (the ERV is 100% OA), therefore 
the Budget building ERV requires heat recovery at 50%.  To model 
this, the Budget building will have prorated heat recovery at the 4 
roof top units - again because one can't properly model a make-up air 
system with heat recovery using equest (DOE2.2) or DOE2.1e.

Does this make sense?

And thanks for all the help provided by this group!




Chris Jones
14 Oneida Avenue
Toronto, ON M5J 2E3.
Tel.  416-203-7465
Fax. 416-946-1005