Robby - the fans must cycle with occupancy, and then when the space is not
occupied the must cycle with load. They can not cycle with load only. For
Mike Kennedy's system he would need to model the baseline with VAV heating
and cooling. And also model the same system in the proposed, however you
could set the heating coil capacities to zero, not create a heating plant,
or not assign any systems to the heating plant for the VAV system. (This is
if you are using Trace 700).
Good luck.
-Shariq Ali
I'm not sure I follow you. By cycling with occupancy do you mean that the
system must provide ventilation air while occupied? If that's the case
then the fans would never turn off during occupied hours and then would
cycle with the load during unoccupied hours.
Why would you not model a heating system in the proposed building? The
scenario is for a warehouse that has heating but no cooling. I don't see
a requirement anywhere in Appendix G for the baseline and proposed to have
the same fan system, so I believe when it states that the same cooling
system is to be modeled in the baseline and proposed they mean just the
cooling coil and heat rejection device.
Robby Oylear, LEEDR AP
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Mike,
You would keep your CUH's for heating, and you would only zero-out your
heating coils, not cooling coils (in your design case only). You would keep
both coils operating in your baseline case. Thinking about it further I
would not create a VAV heating plant for your design (I'm not sure if Trace
automatically creates one or if your require to create it in Trace). I
would just assign the heating systems to the CUH heating plant. In Trace,
your fans will cycle when occupancy is at 5% or above, realistically, if
your occupancy is never at 5% your fans will not turn on due to occupancy.
However they will cycle with load - which is how you want the system to
operate anyway. And for a warehouse I'm guessing there isn't much going on
in most of the place anyway, so setup your thermal zones / rooms so you
have your storage area separate from the loading dock and offices and you
should set yourself up pretty well.
Be sure to use good insulation on the walls and roof, 90.1 calls out for
continuous insulation, for a warehouse I'm assuming your going to be using
steel stud construction, I'd double check the arch's U, and SC values
against what the minimum are in the arch section of 90.1. Another thing -
if your lights are all on a time clock or occupancy sensors, you can take a
10% credit in lighting power (I've found this little credit is something
that is often overlooked, it's the last table in the standard).
Good luck.
-Shariq
Mike Kennedy
To
Shariq_Ali at URSCorp.com,
06/23/2009 06:22 PM bldg-sim at lists.onebuilding.or
g
cc
Subject
Re: [Bldg-sim] Bldg-sim
Digest, Vol 19, Issue 20
Shariq Ali,
Can you really say you are modeling cooling in the base and proposed cases
if you set the cooling capacity to zero?
Mike
Robby - the fans must cycle with occupancy, and then when the space
is not occupied the must cycle with load. They can not cycle with
load only. For Mike Kennedy's system he would need to model the
baseline with VAV heating and cooling. And also model the same system
in the proposed, however you could set the heating coil capacities to
zero, not create a heating plant, or not assign any systems to the
heating plant for the VAV system. (This is if you are using Trace
700).
Good luck.
-Shariq Ali