Daylight Saving Time setting based on ASHRAE 90.1 Appendix G

asked 2021-06-16 23:13:20 -0600

Keigo
4111 ●1 ●48 ●21 https://www.linkedin.c...

updated 2021-06-16 23:16:31 -0600

Actually, this is not a technical question, just a question about interpreting ASHRAE 90.1 Appendix G.

I'm referring to 90.1 Prototype Building Models. By default setting for EnergyPlus, Use Weather File Daylight Saving Period is "Yes". However, it is deliberately changed to "No" in the Prototype Building Models.

!-   ===========  ALL OBJECTS IN CLASS: RUNPERIOD ===========

RunPeriod,
,                        !- Name
1,                       !- Begin Month
1,                       !- Begin Day of Month
,                        !- Begin Year
12,                      !- End Month
31,                      !- End Day of Month
,                        !- End Year
Sunday,                  !- Day of Week for Start Day
No,                      !- Use Weather File Holidays and Special Days
No,                      !- Use Weather File Daylight Saving Period
No,                      !- Apply Weekend Holiday Rule
Yes,                     !- Use Weather File Rain Indicators
Yes;                     !- Use Weather File Snow Indicators

Does this mean that "No" is the correct setting based on ASHRAE 90.1 Appendix G? Or is there no problem with either of these settings (Yes or No)? I couldn't find any mention of Daylight Saving Time in 90.1 and its User Manual.

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answered 2021-06-17 00:22:55 -0600

Keigo
4111 ●1 ●48 ●21 https://www.linkedin.c...

Sorry, I overlooked the other class: RunPeriodControl:DaylightSavingTime.

!-   ===========  ALL OBJECTS IN CLASS: RUNPERIODCONTROL:DAYLIGHTSAVINGTIME ===========

! Daylight Saving Period in US

RunPeriodControl:DaylightSavingTime,
2nd Sunday in March,     !- Start Date
1st Sunday in November;  !- End Date

And I/O Reference says that this input always overrides any daylight saving period specifed in a weather file.

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Then I guess that we should consider DST for energy models If the site location is in a country that uses DST.

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answered 2021-06-18 07:52:11 -0600

lklawrie
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Note that standard weather files do not have DST settings. It gets too confusing when various countries change the DST times/dates.

It is usually less confusing if DST is not used in simulations

Linda

FIBPSA, FASHRAE http://climate.onebuilding.org - free repository of climate data for building simulation Climate.onebuilding is a FREE service not supported by any outside organization or government agency.

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Oh, I thought people in countries with DST usually consider DST in their energy simulations. Otherwise, the operation schedule would be different from the actual schedule. I'm in a country without DST and I'm just curious.