That is a good point about the exception size of 20,000 ft2 for baseline
systems, and I think the USGBC and/or GBCI would be justified in issuing a
general clarification about how to specifically approach fire stations as
many of them are LEED registered based on municipal requirements, and they
very frequently will have this mixture of usage types and small conditioned
areas. For fire stations, this isn't an exception, it is the rule!
My own LEED Gold fire station project was under v2.1, so I can?t help you
there.
The requirements for the Apparatus Bay spaces are so wildly different than
the residential areas that logically they should be separate systems,
regardless of the noted exceptions?these are clearly two different building
types, even if each is below the 20,000 ft2 individually. Or even sometimes
in total! And we haven?t even reached the ?office? spaces in the building
yet?
Also you may want to raise the issue on bldg-sim rather than equest-users,
as this could come up for users of all software packages?
*David S. Eldridge, Jr.**, P**.**E**.**, LEED AP BD+C, BEMP, HBDP*
I am doing EEM modeling, with both gas and electric effects on a multi family
unit in Los Angeles.
?
One EEM is a lighting reduction. Another is weather stripping, which reduces
infiltration.
?
I add up the EEMs individually and get a gas savings (negative from the lighting
reduction obviously). I add them together in a COMBO run (where they
interact)?and the gas savings goes UP !!
?
WHY !!!!
?
John R. Aulbach, PE, CEM
Because the air leaking in the windows in the base case was cold, presuming
you were using the gas for space heating, that is. It's just a guess....
Do you mean that the net gas savings got worse or better? (Compared to when you summed the gas savings individually)
Michael
I guess it is because the lighting generates internal loads which will
benefit heating in winter. The reduction of lighting will reduce the
internal loads which is more predominant than the savings from infiltration.
Then you got higher gas requirement in your model.
Cheney
If I understand you correctly, you ran both the lighting EEM and the weather stripping EEM separately. In the lighting EEM, the gas savings got worse. In the weather stripping EEM, the gas savings got better.
Then you manually added the two together, for a net gain of gas savings (the gas savings from the weather stripping more than compensated for the gas consumption increase from the lighting EEM).
But when you run the two simultaneously, you get a different savings number. One that is better, for increased gas savings. You're wondering why.
I'm pretty sure it's because when you improved the envelope, the gas increase from the lighting reduction is not as significant. In your first run (individually) the gas increase from the lighting reduction is occurring within a lousy envelope. In the simultaneous run, the gas increase from the lighting reduction is occurring within a good envelope building, so the increase is now not as drastic. Make sense?
Michael
My guess is that lighting reduction EEM works only during day time and has hardly any or no effect during when the occupants are sleeping (obviously depends on the lighting schedules).
Infiltration (again depending on the schedules) works all throughout the day. And specially results in gas savings during night time when the outside air is cold. However, it does have some effect during day time as well.
It seems that in the combo case during the day time, the reduced OA (due to infiltration) is offsetting the penalty in the space heating due to reduced LPD.
To explain it further:
In the reduced infiltration case the savings in heating energy during the day time do not show up because the excessive Lighting is taking care of it.
However, in the Combo case the reduced infiltration shows even more savings and surpasses the penalty in heating energy due to reduced lighting because the OA load during the day time is larger than the penalty. And when the OA is reduced during the day time as well as the night time, larger savings are seen. Does that make sense?
Gaurav Mehta, LEED? AP BD+C
i did post to bldg-sim as well. haven't heard back from that list yet.
also sent the usgbc a question thru their 'contact' us in the support
section. may or may not hear from there. this is relatively recent, i
think. my previous fire stations under leed 2.2 were certified a year
ago+ and this didn't come up.
if the argument for classifying them as residential is based solely on
the definition of residential in chapter 3 (it does list fire stations)
i would think that #4 below from the user's manual would still clarify
that the residential space classification does not apply.