Re: [EnergyPlus_Support] HVAC sizing

Julien

—�

Sent from a mobile device, please excuse the brevity.

Julien Marrec, EBCP, BPI MFBA
Owner

Direct: +33 6 95 14 42 13
Website: www.effibem.com

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Le 1 août 2018 à 10:21, Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> a écrit :

... and that is an excellent insight, Joe. Most systems ARE oversized ... a lot.

There are a lot of moving parts which need evaluation in order to minimize oversizing:
Client expectations
warmup time after a long period of setback temperatures
unknowns or less-knowns such as infiltration
construction flaws
... and others
There could be a substantial research project which evaluates the relative impact, pros and cons, for these factors! It's easier and "safer", however, for the designers to oversize. At one time, my design philosophy was something like "Make sure it's big enough for all situations, but assure good part load efficiency." That only gets part way toward an excellent holistic design, but it's pretty common.
On Tue, Jul 31, 2018 at 9:58 PM, Joe Huang YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
Although this has been the standard procedure for defining the heating design day, I question the underlying logic and think that will lead to oversizing. If the building is unoccupied, i.e., no occupants, no lights, no equipment, then why would it be heated to standard operating levels? I understand combining all the worst case conditions to get a design load, but not when those worst case conditions tend to exclude some others from ever occurring.

Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang@whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
On 7/31/2018 11:47 AM, Jim Dirkes jim@buildingperformanceteam.com [EnergyPlus_Support] wrote:
Whatever you specify as applicable on a Winter DesignDay is included.. Most designers calculate heating loads, however, with zero lights (or maybe 5% for security lights), zero equipment and zero people.

Most of the time, this makes sense, e.g., a long holiday such as Christmas or New Year, when everyone is gone and the building is quiet and dark. the Schedules might look something like:

SCHEDULE:COMPACT

Sched_PeopleAssembly

Fraction

Through: 12/31

For: Weekdays

Until: 8:00,0.00

Until: 11:00,0.20

Until: 18:00,0.80

Until: 22:00,0.20

Until: 23:00,0.10

Until: 24:00,0.00

For: Saturday

Until: 8:00,0.00

Until: 11:00,0.20

Until: 21:00,0.60

Until: 22:00,0.80

Until: 23:00,0.10

Until: 24:00,0.00

For: Sunday Holidays

Until: 8:00,0.00

Until: 13:00,0.10

Until: 22:00,0.70

Until: 23:00,0.20

Until: 24:00,0.00

For: SummerDesignDay

Until: 8:00,0.00

Until: 11:00,0.20

Until: 18:00,0.80

Until: 21:00,0.70

Until: 22:00,0.80

Until: 23:00,0.20

Until: 24:00,0.00

For: WinterDesignDay AllOtherDays

Until: 24:00,0.00

SCHEDULE:COMPACT

Sched_LtgAssembly

Fraction

Through: 12/31

For: Weekdays

Until: 6:00,0.05

Until: 9:00,0.40

Until: 22:00,0.75

Until: 23:00,0.25

Until: 24:00,0.05

For: Saturday

Until: 7:00,0.05

Until: 9:00,0.30

Until: 23:00,0.50

Until: 24:00,0.05

For: Sunday Holidays

Until: 7:00,0.05

Until: 12:00,0.30

Until: 22:00,0.65

Until: 24:00,0.05

For: SummerDesignDay

Until: 6:00,0.05

Until: 9:00,0.40

Until: 22:00,0.75

Until: 23:00,0.50

Until: 24:00,0.05

For: WinterDesignDay AllOtherDays

Until: 24:00,0.00

SCHEDULE:COMPACT

Sched_PlugsAssembly

Fraction

Through: 12/31

For: Weekdays

Until: 6:00,0.05

Until: 9:00,0.40

Until: 22:00,0.75

Until: 23:00,0.25

Until: 24:00,0.05

For: Saturday

Until: 7:00,0.05

Until: 9:00,0.30

Until: 23:00,0.50

Until: 24:00,0.05

For: Sunday Holidays

Until: 7:00,0.05

Until: 12:00,0.30

Until: 22:00,0.65

Until: 24:00,0.05

For: SummerDesignDay

Until: 6:00,0.05

Until: 9:00,0.40

Until: 22:00,0.75

Until: 23:00,0.50

Until: 24:00,0.05

For: WinterDesignDay AllOtherDays

Until: 24:00,0.00
On Tue, Jul 31, 2018 at 2:07 PM, my_sunny_night@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com> wrote:

Hello All,

Is the internal heat gain from occupants taken into account for heating equipment sizing?

Thanks

--

James V Dirkes II, CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504

(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@buildingperformanceteam.com

Website l LinkedIn

Coffee conversation:
A friend describes himself as “mediocre”. In my estimation, he’s clearly amazing and exceptional, so it irritates me to hear him say that. Upon some reflection, I realize that he may be right.
Only one person in the world is the (literal) world’s best. All of us can improve and should be actively improving. That means we’re all in the middle � a mediocrity of sortss... Maintaining a sense of our need to become better and appreciation of others’ greater talents is also a way to maintain healthy humility. I think I’m up for mediocrity � in a wonder-filled, amazing ssort of way.
--
James V Dirkes II, CEO / President
The Building Performance Team Inc.
1631 Acacia Dr, Grand Rapids, MI 49504
(alphabet soup of efforts for greater understanding: PE, BEMP, BCxP, LEED AP)

Direct / Mobile: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l LinkedIn
Coffee conversation:
A friend describes himself as “mediocre”. In my estimation, he’s clearly amazing and exceptional, so it irritates me to hear him say that. Upon some reflection, I realize that he may be right.
Only one person in the world is the (literal) world’s best. All of us can improve and should be actively improving. That means we’re all in the middle � a mediocriity of sorts. Maintaining a sense of our need to become better and appreciation of others’ greater talents is also a way to maintain healthy humility. I think I’m up for mediocrity � in a wonder-filled,, amazing sort of way.