Dear eQuesters,
Sorry for the repost! I do need your help about this due to time limit. If any one can give a hint, I really appreciate that!
My client requires to do a thermal simulation for a two-story atrium/staircase to check if the cooling system is required for it. The atrium has a revolving door, which revolves once every 30 minutes, and the swing door opens for 30 minutes every 8 hours for shift change. My question is how to simulate the revolving door and swing door in eQuest? I noticed that ASHRAE 90.1-2010 mentioned the infiltration from these two types of doors is 1.0 cfm/ft2 tested at a pressure of at least 1.57 pounds per square foot (psf), but I do not quite understand what this means and how to use this number in my model. If any one has an idea, please give the comments. Thank you so much!Best regards,Zarah
Zarah,
If you break it down, here's what a door is:
- Thermal losses through the glass and frame: for that you define a Uvalue
for the door
- Infiltration when the door is closed
- Added Infiltration when the door is open
In your case, you could model added infiltration (schedule multiplier) for
the 30min shift change.
Best,
Julien
--
Julien Marrec, EBCP, BPI MFBA
Energy&Sustainability Engineer
T: +33 6 95 14 42 13
LinkedIn (en) : www.linkedin.com/in/julienmarrec
LinkedIn (fr) : www.linkedin.com/in/julienmarrec/fr
2016-02-24 5:17 GMT+01:00 zhouzarah:
Thanks a lot, Julien! Now it seems to be much simpler with the breakdown method. I appreciate your help!
Hi Zarah,
As per my understanding you need to know the cooling load requirement of
any space for any time.
For this one can do peak load calculations and try to find out the cooling
load requirement of any space at desired time.
I have also referred ASHARE 90.1 and have found that the swinging door has
1 cfm / sq. ft. and windows have 0.40 cfm / sq .ft as infiltration.
............................................................................................................
eQUEST have the option to input the required infiltration in Internal load
tab and input it in as cfm /sq. ft for the space.
The infiltration being input is the total infiltration in that space.
You need to have proper weather file as per location, have some cooling
system as per project and proper infiltration as input.
Then from the hourly report being derived from the File< Export File<
Hourly result (CSV) and have the finding in cooling end-use energy.
This will help you to find out whether that space at any desired time needs
the cooling or not. Additionally one needs to have proper schedules.
The better software to have these kind of analyses is IES-VE but eQUEST can
also help.
The design time is the cooling load having the most peak value of cooling
energy in Hourly report.If the Cooling requirement is less than 300 hours
over the year then may be you can ignore installing cooling system.
If it is for the major part of year then you can choose to have cooling
system. Also have a go on the cooling plant requirement size.
Hope this can be helpful.
Thanks,
Sharad. Kumar.
Green Horizon Consulting LLP.
Gurgaon.
2016-02-24 5:17 GMT+01:00 zhouzarah:
Dear eQuesters,
Sorry for the repost! I do need your help about this due to time limit. If
any one can give a hint, I really appreciate that!
My client requires to do a thermal simulation for a two-story
atrium/staircase to check if the cooling system is required for it. The
atrium has a revolving door, which revolves once every 30 minutes, and the
swing door opens for 30 minutes every 8 hours for shift change. My question
is how to simulate the revolving door and swing door in eQuest? I noticed
that ASHRAE 90.1-2010 mentioned the infiltration from these two types of
doors is 1.0 cfm/ft2 tested at a pressure of at least 1.57 pounds per
square foot (psf), but I do not quite understand what this means and how to
use this number in my model. If any one has an idea, please give the
comments. Thank you so much!
Best regards,
Zarah
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Apologies for not contributing sooner(I?ve been in a busy week myself), but I notice a few critical points may have been missed in the discussion so far:
? The numbers 90.1 cites for window (0.4 cfm/ft2 ) and door (1.0 cfm/ft2) leakage are at NFRC-400 testing conditions (75 pascals). These represent maximum permissible infiltration in a closed state with head-on windspeed equivalent to 75 Pa.
? Open windows & swinging doors will infiltrate much more than closed assemblies. The real-world problem of airflow through free openings is rather complicated depending upon many variables (including relative temperatures, windspeed direction vs. orientation, building pressurization, stack effects, whether and where other nearby openings are occurring?).
? Conservatively & for a back of envelope / sanity check with free openings, I might consider CFM = hourly windspeed(fpm) x free area(ft2) on an hourly basis.
? Revolving doors by design are never ?open? in the above sense ? see this image from Wikipedia if that isn?t immediately clear:
So the whole picture is perhaps a bit more complicated than you might have initially thought, but I believe you will find eQuest is generally well-equipped to tackle all of the above!
? Your weather file has windspeed data that can be used each hour for calculations
? Looking to your SPACE inputs for infiltration, you can read up on the variety of options for how sophisticated you want to make your simulation. Most options do account for hourly windspeed. In all cases, you can define an INF-SCHEDULE to account for behavior like swinging doors & windows opening.
? If this is all flying a little too high in complexity for your purposes/timeframe, I suggest leveraging the wizards to observe what infiltration schedules and inputs are generated using a few dummy ?shell? models. Note ?perimeter? vs. ?core? infiltration schedules are commonly generated side by side and will be named accordingly.
? I?d personally prefer leveraging a custom hourly report for this sort of assessment. Starting variables to spot check my expectations would include
o SPACE infiltration (cfm) as calculated,
o local windspeed
o ZONE temperature
o ZONE tstat setpoint
Other thoughts:
? Ultimately you are going to be making a ?Yes/No? decision based on how the temperatures in this space float. Step back before getting too far into the study and make some decisions regarding what would be subjectively ?acceptable? comfort criteria considering anticipated atrium/staircase usage, occupancy profile, & expectations specific to your regional climate/locale.
? High-level assessment idea, if you don?t want to assess this ?manually? via hourly outputs: You could perhaps most simply create a pair of zone temp schedules reflective of maximum comfort thresholds, then leverage simulation unmet hours inform how often & when you cross those lines.
? At only 2 stories effects probably won?t be extreme, but keep in the back of your mind that eQuest/doe2 assumes ?perfect thermal mixing? within a zone hour by hour. If your space does not have fans or other means of consistent circulation, there?s potential for buoyancy/stack effects in the real world to result in different conditions on the 1st vs. 2nd level.
Probably more than you?re looking for? sorry for the wall of text!
~Nick
---------------------------------------------------------------------------------------------------------------------------------------------
Nick Caton, P.E.
Senior Energy Engineer
Energy and Sustainability Services
North America Operations
Schneider Electric
D 913.564.6361
M 785.410.3317
E nicholas.caton at schneider-electric.com
F 913.564.6380
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
*Please consider the environment before printing this e-mail
To estimate airflow through an opening due to wind, see the 2013 ASHRAE Handbook ? Fundamentals, page 16.13, equation 37. For stack effect use equation 38. For no wind and no stack effect see 2014 ASHRAE Handbook ? Refrigeration, page 24.5. The wind and stack effect equations are in cfm while the one from the refrigeration handbook is heat load, but it might still be helpful for you.
Remember that the wind is not always blowing directly toward the door?unless the building swings on a big weather vane so that the door always points into the wind! The weather file has wind direction in addition to the speed.
Keith Swartz, PE | Senior Energy Engineer
Seventhwave
608.210.7123 seventhwave.org
Good call ? my back-of-envelope for wind driven infiltration would have been high for sure.
Incidentally, the hourly variables* for equation (37) and (38) are simple enough to include in a custom hourly report, though you?ll need to establish the orientation of your opening(s) to crunch the ?opening effectiveness? relative to the wind direction.
The calculated hourly cfm total could then be lined up against eQUEST?s hourly infiltration output using no INF-SCHEDULE (or else 1.0?s each hour), to determine an hourly ?correction? multiplier. EMIT could crunch that column of 8760 multipliers into an importable INF-SCHEDULE in a matter of seconds. Fun!
* The full list for rolling your own hourly stack+wind calculations would then include ZONE: Indoor temperature + GLOBAL: Outdoor Temperature, Wind Direction in radians, Wind Speed (knots).
~Nick
---------------------------------------------------------------------------------------------------------------------------------------------
Nick Caton, P.E.
Senior Energy Engineer
Energy and Sustainability Services
North America Operations
Schneider Electric
D 913.564.6361
M 785.410.3317
E nicholas.caton at schneider-electric.com
F 913.564.6380
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
*Please consider the environment before printing this e-mail
It seems to me there are two distinctly different sources of "infiltration" through a
revolving door -
(1) leakage through the cracks and imperfect seals
(2) bulk air exchange when the door is used and acts like a piston bringing in
Pi*(r2/4)*ht volume of outdoor air and exhausting the same of indoor air.
The relative importance of the 2 depends entirely on how much the revolving door is being
used.
It might be interesting to do some back-of-the-envelope calculations to see.
Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
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Thank you so much, Joe, Nick, Keith, Sharad and Julien!Previously, I modeled this as increased infiltration. But your suggestions give me more hint, I need to modify the model for accuracy.
Best regards,
Zarah
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