Re: [EnergyPlus_Support] Re: Mechanical Rooms

Hi JV;

Thanks for your thoughts. A few things:

Just for background: the CaGBC version of LEED is in my understanding pretty close to the USGBC version. One difference that is pertinent to this discussion is that the LEED Canada allows the use of either ASHRAE 90.1 or the Model National Energy Code for Buildings (a Canadian energy code based largely on ASHRAE 90.1 that was developed by the the Canadian government) for the evaluation of EA credits.

With respect to the mechanical room issue: so, were you me, would I be correct in understanding that because 90.1 requires the modeling of all spaces as heated cooled, you'd simply create a system, identical in both "proposed" and "baseline" cases, to condition the mechanical room space? Also, would I be correct in assuming that doing this renders the question of process heat gains from equipment in the mechanical room somewhat irrelevant?

Finally, with regard specifically to the process gains, the main thing I was concerned about was the boilers. In this particular building there are 3 of them, each with a seasonal efficiency of around 90%; it seems to me that the "other" 10% of the heat they generate would be discharged to the mechanical room, and would not be insignificant...

Josh

On Fri, Jul 18, 2008 at 12:00 PM, JV Dirkes II <jvd2pe@xxxxxxx> wrote:

Dear Josh,

For your consideration:
1) I'm not familiar with any variations of LEED that Canada may be using
2) LEED EA credits require compliance with ASHRAE 90.1, which in turn
requires modeling ALL spaces as heated and cooled (subject to some
anmormal exceptions noted in the Scope statement, par 2.2 and 2.3)
Also note Table G3.1, no. 4 regarding schedules.
3) I think that you can model the mechanical room "cooling" system
with a very high setpoint so that it never operates. Just use the
same setpoints in "Baseline" and "Proposed" systems.
4) You raise a good point regarding possible double counting of fan
and pump motor heat. Although they're small in the overall scheme, I
don't know where E+ puts that heat. For fans, at least, the motor is
often in the airstream and thus part of the cooling load. Not so with
pumps!

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "josh_miarch" <jeemang@...>
wrote:

>
> Howdy All;
>
> I'm preparing a model for a LEED Canada EAc1 submission third party
> review, and I'm curious as to how I should account for the building's
> two mechanical rooms (this is the first LEED submission I've done). In
> this building, they are both within the building envelope, and neither
> is directly conditioned.
>
> The literature says that if they're inside the main building envelope,
> they should be modeled, but doesn't provide much guidance beyond that.
> My thought, based on this, was that I should keep them uncontrolled
> and add some internal gains objects to account for the heat given off
> by the AHUs, pumps, boilers, etc, but I haven't the first clue about
> how I could accurately estimate the heat emitted by this equipment,
> particularly when it would be changing in response to the loads in
> other parts of the building and the ambient temperature in the room.
>
> Alternatively, it was suggested to me that I add a single-zone system
> of some sort (UNIT HEATER perhaps; the building isn't cooled) to
> control it to a relaxed setpoint (16-18 C), which makes some amount of
> sense to me, as it would avoid the problem of having to create a very
> elaborate internal gains schedule. However, the problem I see (and
> perhaps I'm misunderstanding something) is that this would
> effectively double count the inefficiencies of the equipment in the
> mechanical room.
>
> Any suggestions on either method (or another) would be greatly
> appreciated.
>
> Many thanks,
>
> Josh
>

--
Josh Kjenner, EIT, LEED AP
Manasc Isaac Architects Ltd.
10225 100 Avenue :: Edmonton, AB T5J 0A1
780.429.3977