[Bldg-sim] Unconditioned Zones

[Caroline Fluhrer]

Hi there,

I am responding to some LEED review comments regarding a small
building in Hawaii that only has 2 thermal zones. In reality one of
these zones is conditioned (small split system cooling only) and one
zone is unconditioned (naturally ventilated, no heating or cooling).
The LEED reviewer writes:

"ASHRAE 90.1-2004 Table G3.1.1(b) in the proposed building column
requires that all spaces that are conditioned and occupied in the
proposed design should be simulated as being both heated and cooled
even if no cooling or heating systems are to be installed per Table
G3.1.1(b) in the proposed building column." - this comment makes sense
per G3.1.1b.

The comment continues "Based on the building area, number of floors,
and principal heating source, system type 4: packaged rooftop heat
pump should be modeled for the unconditioned spaces and heating
component of system type 4: packaged rooftop heat pump should be
modeled for the conditioned office spaces unit. Please revise the
proposed and baseline models by modeling the same system type in both
cases in the unconditioned spaces and include heating equipment for
the conditioned office spaces." This second comments seems to say that
I need to put System Type 4 in the unconditioned space in both the
baseline and the proposed model ... does this seem to correct to
others?

If so, it seems to imply that you can never truly have an
unconditioned space in a LEED model? As a workaround, I plan to then
put the setpoints for cooling and heating such that those installed
systems will never turn on (which makes me wonder why a system should
be installed). If I don't do wide setpoints, my proposed model will
not be representative of the actual energy use of the design building.

Any thoughts on this topic would be much appreciated.

Caroline



--
Caroline E. Fluhrer
Built Environment Team
Rocky Mountain Institute

1820 Folsom St.
Boulder, CO 80302 USA
Main: 303.449.5226
Direct: 303.567.8631
Fax: 303.567.8626
Email: cfluhrer at rmi.org