[Bldg-sim] HVAC Equipment Sizing

Sandeep Kachhawa sandeep.kachhawa at gmail.com
Wed Feb 16 07:01:20 PST 2011


yes the thermal mass of the building may lead to this sort of behavior, but
is it a general phenomenon? Further to my previous mail, there is no night
setback in my model and I am taking the same building for both the cases by
just changing the schedules accordingly

Regards
Sandeep Kachhawa
On Wed, Feb 16, 2011 at 8:13 PM, Michael A. Eustice
<MAEustice at htlyons.com>wrote:

>  My best guess would be the pull-down cooling load.  If you’re modeling
> the 12-hr building as 12 hours occupied and 12 hours unoccupied.  The
> software may let the building temperature float way up outside of setpoint
> during the unoccupied hours.  Then, when your occupied hours start, the
> equipment needs extra capacity to pull down the thermal lag of the building
> to meet setpoint in a reasonable timeframe.  Make sense?  Are you modeling
> it that way?
>
>
>
> Michael
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [mailto:
> bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Sandeep Kachhawa
> *Sent:* Wednesday, February 16, 2011 9:33 AM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] HVAC Equipment Sizing
>
>
>
> Dear all
>
>
>
> I am comparing the epuipment sizing of a day time and a 24 hr office
> building on EnergyPlus. When I simulate the two while autosizing the hvac
> equipment, the Nominal Cooling Capacity (W) of the 24 hr building comes less
> than the day time building. Though the total energy consumption, as
> expected, of the 24 hr building is more than the 12 hr building, why
> the cooling capacity (equipment size) of the 24 hr building is lower than
> the 12 hr building. In my particular case, for a conditioned area of around
> 1600 m2, the cooling capacity for day time and 24 hr building is coming
> around 146 kW and 128 kW, respectively.
>
> What could be the possible reasons for such behaviour?
>
>
>
> Thanks
>
> Sandeep Kachhawa
>
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