[bldg-sim] Modeling UFAD

[Jeff Haberl]

Varkie. 

This issue was discussed at length at the Fri meeting of the 90.1 ECB subcommittee in Quebec City. You can find a write-up on the ECB website. 

Long story short, a method has been proposed with EQUEST that is being tested by LBL. When/if they finish the report, then I think you'll be able to use this for a UFAD, with limitations, of course. 

Jeff
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Jeff S. Haberl, Ph.D., P.E.............................jhaberl at esl.tamu.edu

Professor......................................................Office Ph: 979-845-6507

Department of Architecture.......................Lab Ph: 979-845-6065 

Energy Systems Laboratory.......................FAX: 979-862-2457 

Texas A&M University..............................77843-3581

College Station, Texas, USA.......................URL: www-esl.tamu.edu

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-----Original Message-----
From: bldg-sim at gard.com
To: bldg-sim at gard.com
Sent: Sat Dec 09 14:22:43 2006
Subject: [bldg-sim] Modeling UFAD

Are there any examples of modeling UFAD with DOE2.1E (or EQUEST).

This is a commercial project with electric heating in climate zone 3A.  The baseline System No. is 8 - VAV w/PFP Boxes).  The proposed is also PIU (DOE2).  The perimeter zones up to 3 ft are served from the ceiling.  

The remaining interior zones have UFAD.  The CHW coil leaving temp of the primary air is 48F.  The UFAD supply temp is 65 F.  The ceiling return air temp is 78.  The System MIN-SUPPLY-T = 65 and COOL-SET-T = 48.  ZONE-FAN-RATIO = 1.74 ??    80% glass.

The Baseline primary air is 53F and ceiling supply is 55F.  The ceiling return air temp is 76.  System MIN-SUPPLY-T = 55 and COOL-SET-T = 53.  ZONE-FAN-RATIO = 1.1.  40% glass.

Is all this correct?  Increasing the ZFR increases the Fan energy.  Increasing the MIN-SUPPLY-T from 55F to 65F increased the System Supply Air and Fan energy considerably.

For UFAD is it acceptable to assume the following space volume temps?

$ Baseline Summer & Winter Space Volume Temp = 75 $

 

$ UFAD: 75F from 0' to 7' 85F from 7.1' to 10' Avg Summer Space Temp = 78F $

$ UFAD:  75F from 0' to 7' 65F from 7.1' to 10' Avg Winter Space Temp = 72F $

STD62.1-2004 Table 6-2 ‘Zone Air Distribution Effectiveness (Ez)’ shows

Ez = 1.0 for Ceiling Supply of Cool Air

Ez = 1.2 for Floor Supply of Cool Air and Ceiling Return.

How would you apply this in DOE2.1E for Under-floor Air Distribution?

How is occupancy based lighting modeled?  Based on 10CFR435 Table 401.3.3.  Lighting Schedule = Max Design Lighting * Base Lighting Schedule * 0.7 ?

How is occupancy based ventilation modeled? Percent Outdoor Air for Hour = Maximum Design Percent Outdoor Air * Occupancy Schedule Fraction.  Apply this schedule in MIN-AIR-SCH ?

V.C. Thomas



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