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,
James Hansen, PE, LEED AP
**** - 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
