[Equest-users] SS-J Peak loads vs Design Day loads?

James Hansen JHANSEN at ghtltd.com
Tue Dec 16 17:00:34 PST 2008


I'm trying to figure out an interesting result for heating energy for a
building I'm modeling.

 

5-story, 400,000 sq ft office, shutoff VAV boxes fed from chilled water
AHUs and a hot water loop fed from gas-fired boilers.

 

Here is a copy of the SS-J report for one of the (5) AHUs serving the
space.  What I don't understand is why there is a HUGE delta in the
hourly heating load after-hours.  All of the "even" hours from midnight
until about noon have high heating loads, and all the "odd" hours have
low heating loads (I've highlighted these below).

 

What's going on?  I know there is a "demand window" for a utility rate,
but this seems to be a different issue.

 

OK - I think I found out why this is happening.  Under the "Simulation
Options" in the PROJECT & SITE tab, there are options for the hourly
reports.  

However, it seems like none of the loads, system, plant or economics
reports can be processed at a frequency exceeding hourly.

But what this means is that I can't pull an accurate peak building load
if it keeps bouncing between too high and too low of a reported load.

 

Is there any way around this?  I looked into creating design day
schedules, and that seems to have worked, but it doesn't change anything
under the SS-D report (Significantly). 

 

Where do you review the Building HVAC Load Summary for the design days?
Is there a separate report that I just can't find?

 

Also, regardless of what shows up for the design day, doesn't this large
fluctuation in the hourly heating values negatively impact the accuracy
of the model?

 

Thanks in advance,

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

 


**** - Proposed
DOE-2.2-44d5  12/16/2008    18:25:54  BDL RUN  3

 


REPORT- SS-J Peak Heating and Cooling for   EL1 Sys1 (VAVS) (G)
WEATHER FILE- WASHINGTON, DC      

------------------------------------------------------------------------
---------------------------------------------------------

 

 

 

          - - - - - C O O L I N G - - - - -       - - - H E A T I N G -
- -       D A Y   C O O L I N G   P E A K

 

                        AUG 16                              JAN 15
JUL  9

 

 

          HOURLY                                    HOURLY
HOURLY

         COOLING    SENSIBLE    DRY-   WET-        HEATING    DRY-
WET-        COOLING    SENSIBLE    DRY-   WET-

            LOAD        HEAT    BULB   BULB           LOAD    BULB
BULB           LOAD        HEAT    BULB   BULB

HOUR      (KBTU)       RATIO    TEMP   TEMP         (KBTU)    TEMP
TEMP         (KBTU)       RATIO    TEMP   TEMP

 

 

 

   1     290.433       0.446    74.F   70.F       -632.664    10.F
9.F        224.550       0.407    74.F   72.F

   2     262.461       0.454    73.F   69.F      -2019.841     9.F
8.F        204.537       0.412    73.F   71.F

   3     254.020       0.454    73.F   69.F       -725.447     8.F
7.F        193.290       0.399    72.F   71.F

   4     254.247       0.461    72.F   68.F      -2035.241     7.F
6.F        198.909       0.402    71.F   70.F

   5     526.613       0.454    73.F   69.F       -805.752     7.F
7.F        506.639       0.394    73.F   72.F

   6    1954.301       0.777    73.F   69.F      -4975.409     7.F
7.F       2092.500       0.711    74.F   73.F

   7    2528.958       0.741    74.F   70.F       -927.359     7.F
6.F       2711.656       0.698    76.F   74.F

   8    2542.338       0.740    76.F   71.F      -4975.296     9.F
8.F       2748.939       0.704    80.F   75.F

   9    2644.668       0.744    79.F   72.F       -738.268    11.F
10.F       2841.915       0.707    83.F   76.F

  10    2792.738       0.726    81.F   74.F      -4927.778    13.F
12.F       2925.798       0.711    87.F   77.F

  11    2793.809       0.754    86.F   74.F       -486.871    16.F
14.F       2913.226       0.717    88.F   77.F

  12    2856.012       0.770    92.F   75.F      -1161.596    19.F
17.F       2923.506       0.728    90.F   77.F

  13    2869.460       0.797    97.F   75.F       -402.573    22.F
19.F       2936.946       0.733    91.F   77.F

  14    2940.005       0.785    97.F   76.F       -692.877    22.F
19.F       2876.902       0.751    91.F   76.F

  15    2972.225       0.782    96.F   76.F       -797.705    22.F
19.F       2890.462       0.753    91.F   76.F

  16    3047.949       0.767    96.F   77.F       -816.324    22.F
19.F       2912.354       0.751    91.F   76.F

  17    2971.663       0.765    93.F   76.F       -995.525    21.F
19.F       2927.038       0.747    90.F   76.F

  18    2190.738       0.677    89.F   77.F       -731.953    20.F
18.F       2144.074       0.688    88.F   76.F

  19      72.359       0.473    86.F   76.F      -1410.968    19.F
17.F         72.887       0.483    87.F   76.F

  20     445.845       0.470    84.F   75.F       -625.920    18.F
16.F        387.226       0.459    83.F   75.F

  21     558.937       0.455    81.F   74.F      -1929.490    17.F
15.F        489.783       0.431    79.F   74.F

  22     446.512       0.451    79.F   73.F       -642.555    16.F
14.F        352.304       0.419    75.F   72.F

  23     401.832       0.439    78.F   73.F      -2073.865    17.F
15.F        312.851       0.407    74.F   72.F

  24     362.264       0.446    77.F   72.F       -653.700    17.F
15.F        285.874       0.426    74.F   71.F

        --------                                  --------
---------

SUM
39074.168

MAX     3047.949                                 -4975.409

 

 

              SYSTEM-TYPE         VAVS                     SQFT/TON
698.0

              COOLING PEAK          17.19 (BTU/HR- SQFT)   HEATING PEAK
-28.06 (BTU/HR- SQFT)

              SUPPLY AIR PEAK FLOW   0.46 (CFM/SQFT)       MIN-OA/PERSON
20.00 (CFM )

              OA FRAC AT CLG PEAK   0.191                  OA FRAC AT
HTG PEAK   0.997

 

              * ASTERISKS INDICATE HOURS LOADS NOT MET


 

 

 


The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com, and destroy this communication and all copies thereof, including all attachments.  Thank you.



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