[Bldg-sim] Energyplus Schedules and Daylight Saving Time

Ryan Tanner ryanatanner at gmail.com
Tue Oct 15 11:24:13 PDT 2013


Greetings,

Can someone explain to me why energyplus behaves the way that it does when
daylight saving time is used?

Specifically, scheduled values are shifted in the following way:
In a simulation, during DST, (summer), a schedule with 24 unique values for
a single day will have values [2:24] used during hours 1:23, and value [1]
used during hour 24. The first part seems reasonable, shift scheduled
values back by one hour, but the last part seems wrong, shifting a
scheduled value from hour 1 to hour 24 of the same day.

Since I'm doing controls studies, and I use schedules to define when some
systems are on or off, this issue is particularly troubling. When I intend
for a system to be ON during hour 1 and OFF during hour 2, the schedule is
adjusted by energyplus so that during the simulation the system is OFF
during hour 1, and ON during hour 24...not exactly what I intended.

Have any other users experienced this? Any suggestions for a workaround? I
would like to have DST in effect, so that occupancy, lighting schedules,
equipment schedules, etc. are correct relative to the sun's position and
the local weather conditions - and I would ALSO like for my controls
schedules to be used as intended, not shifted forward or backward, so that
when I schedule a system to be ON during hour 1, it is ON during hour 1,
whether it's winter or summer in simulation.

An example file and complete results are attached; file description and
results sample are included below.

Cheers,
Ryan

----
I've attached an example IDF that demonstrates the issue, as well as the
CSV output, my file is adapted from the example
file: 1ZoneUncontrolledResLayers.idf; I made the following changes:
1. added a RUNPERIODCONTROL:DAYLIGHTSAVINGTIME object that applies DST from
March 5 to November 5
2. added a schedule:compact object called DST_test_schedule
**this schedule has the following format, each hour for each day has a
unique value which should match that day and time; so the value for March
2, hour 5 is 3.0205, the value for March 4, hour 7 is 3.0407, etc.
3. added an output for the above schedule, removed all other outputs
4. removed annual runperiod, added two shorter runperiods that encompass
the DST start and end dates.

In the InputOutputReference, the following note is provided:
----
Note: For EnergyPlus Output:Variable and Output:Meter reporting, the time
stamps are always in standard time. When daylight saving time is active,
scheduled loads and controls will shift one hour relative to standard time.
----
**this is not accurate, since MOST values are shifted (backward) by 1 hour,
but values scheduled during hour 1 are shifted (forward) by 23 hours.

--excerpt from results CSV--
Date/Time, DST_TEST_SCHEDULE:Schedule Value [](Hourly)
...
...
...
 03/03  22:00:00, 3.0322
 03/03  23:00:00, 3.0323
 03/03  24:00:00, 3.0324
 03/04  01:00:00, 3.0401
 03/04  02:00:00, 3.0402
 03/04  03:00:00, 3.0403
 03/04  04:00:00, 3.0404
 03/04  05:00:00, 3.0405
 03/04  06:00:00, 3.0406
 03/04  07:00:00, 3.0407
 03/04  08:00:00, 3.0408
 03/04  09:00:00, 3.0409
 03/04  10:00:00, 3.041
 03/04  11:00:00, 3.0411
 03/04  12:00:00, 3.0412
 03/04  13:00:00, 3.0413
 03/04  14:00:00, 3.0414
 03/04  15:00:00, 3.0415
 03/04  16:00:00, 3.0416
 03/04  17:00:00, 3.0417
 03/04  18:00:00, 3.0418
 03/04  19:00:00, 3.0419
 03/04  20:00:00, 3.042
 03/04  21:00:00, 3.0421
 03/04  22:00:00, 3.0422
 03/04  23:00:00, 3.0423
 03/04  24:00:00, 3.0424
 03/05  01:00:00, 3.0502
 03/05  02:00:00, 3.0503
 03/05  03:00:00, 3.0504
 03/05  04:00:00, 3.0505
 03/05  05:00:00, 3.0506
 03/05  06:00:00, 3.0507
 03/05  07:00:00, 3.0508
 03/05  08:00:00, 3.0509
 03/05  09:00:00, 3.051
 03/05  10:00:00, 3.0511
 03/05  11:00:00, 3.0512
 03/05  12:00:00, 3.0513
 03/05  13:00:00, 3.0514
 03/05  14:00:00, 3.0515
 03/05  15:00:00, 3.0516
 03/05  16:00:00, 3.0517
 03/05  17:00:00, 3.0518
 03/05  18:00:00, 3.0519
 03/05  19:00:00, 3.052
 03/05  20:00:00, 3.0521
 03/05  21:00:00, 3.0522
 03/05  22:00:00, 3.0523
 03/05  23:00:00, 3.0524
 03/05  24:00:00, 3.0501
 03/06  01:00:00, 3.0602
 03/06  02:00:00, 3.0603
 03/06  03:00:00, 3.0604
...
...
...
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