[Bldg-sim] LEED baseline and swimming pools

[Ellen Franconi]

James,
I was involved in modeling an Aquatic Center recently. This was not a LEED
project but a utility DSM project but I think our approach would be
applicable. We assumed that the pool space was a process space. For this
case, the proposed design system and controls should be of the same type in
both the baseline and the proposed design. In our project, we took credit
for a controls innovation that modulated outside air based on indoor
humidity level instead of outside air (as is allowed through an exceptional
calculation method by LEED).

 I developed a spreadsheet to complete a mass and energy balance on the
space and figured out the outside air for each hour of the day throughout
the year based on the proposed control strategy. Then I developed an 8760
schedule for outside air and used it with the proposed model.

To figure out the latent losses from the pool to the space, we followed the
Shah Method (do a google search and  you'll find a spreadsheet of the
method). The results seemed to be more modest than those following the
ASHRAE method. However, both were high when compared to values used for
solar thermal system sizing (by the solar contractor). As I matter of fact,
I couldn't "turn down" the Shah model far enough to get close to those
values, which were about 1/2. In contrast, the mechanical engineers design
values were about double the Shah Method results. It was very frustrating to
go through such a detailed analysis only to be unsure of actual latent lose
values. In the end, I modified the Shah method results so they would be
consistent with the solar contractor's annual load estimate. The contractor
had done several local installations that delivered as expected.

Part of the analysis considered the impact of having the pool covered vs
having a solar thermal system that met 60% of the annual load. This is part
of the ASHRAE 90.1-2004, which the project needed to adhere to. This adds a
little extra through regarding scheduling the latent losses in doing the
modeling.

Good luck. This is one area of modeling that could surely use some help. But
based on my mixed results, I don't know if you want to follow the path I
did.
Ellen


On Mon, Mar 8, 2010 at 2:36 PM, James V Dirkes II, PE <jvd2pe at tds.net>wrote:

>  Dear Bldg-Sim community,
>
>
>
> I’m trying to plan a LEED energy model which has a *swimming pool* and am
> stuck thinking about how to model the baseline condition.
>
>
>
> A pool has such specialized needs that I have doubts whether one of the
> specified baseline systems in ASHRAE 90.1 can do an acceptable job of
> controlling temperature and humidity.
>
>
>
> At present, I am reasonably confident that I can schedule the pool
> occupancy properly, add  moisture in amounts that parallel the pool
> evaporation and specify the pool heater energy.
>
>
>
> My facility requires a “System 6” parallel fan powered VAV box HVAC system
> (95,000 sq.ft., single story, multi-purpose facility).  This is not a system
> type that makes sense for a pool, so I hesitate to use it at all.  If I have
> to, for purposes of following 90.1, I think it might meet temperature loads,
> but it certainly won’t meet humidity loads, at least not at the specified
> 20F airside delta T.  That, of course means that overall energy use will not
> even be close to what will actually be needed and the baseline will compare
> poorly with the actual (very efficient) HVAC system.
>
>
>
> I’ll appreciate any guidance from those among you who have done LEED
> projects with pools!
>
>
>
> Thanks in advance.
>
>
>
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>
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-- 
Ellen Franconi, PhD, LEED AP
Senior Consultant, Built Environment Team

Rocky Mountain Institute
1820 Folsom Street
Boulder, CO 80302
303.567.8609 (Desk)
303.245.7213 (Fax)

Rocky Mountain Institute drives the efficient and restorative use of
resources, creating a world thriving, verdant, and secure, for all, for
ever.

http://www.rmi.org
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