Unusual Model

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Dear eQuesters:

I have an unusual building to model and request feedback on the most accurate
way to accomplish this task.

An 8,500 office area/research lab area, about 1/2 of the first floor, of a 5
story building is being renovated.

A MAU with a steam preheat, DX and a steam reheat coil that supplies minimum air
to all the areas and also conditions the main corridor area of 1,700 sq.ft. is
being specified. This is a 100% outside air unit. The exhaust air is vented by
a separate common building exhaust fan. The MAU design CFM is 7,500.

The labs require 8 ACH occupied and 4 ACH unoccupied, about 1200 CFM total.
Each lab has one fume hood with an exhaust of 600 CFM when the sashes are open
and 300 CFM when the sashes are closed. There will be air valves to modulate
the volume of makeup air to each lab area depending on occupancy.

All the areas, with the exception of the main corridor area are conditioned by
VRV heat pump cassette units with one main condensing unit. The system chosen,
a Mitsubishi Y-Series does not appear capable of transferring heat from one area
to another. The engineering manual states that the R-2-Series can provide this

One sticking point in my model is the exhaust air. I have added an exhaust fan
in each lab with a fractional schedule. How do I go about exhausting the rest
of the air from each lab, about 600 CFM occupied, and the exhaust air from the
office areas through the common building exhaust fan?

Any suggestions would be greatly appreciated,

Paul Diglio

Paul Diglio's picture
Joined: 2011-09-30
Reputation: 400