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Re: [EnergyPlus_Support] Excessively High Window Heat Removal



Hi, Poh Khai,

I guess you need to check your air-con equipment scheduling. If the air-con system runs only 10 hours a day, a large amount of the internal heat generated in the other 14 hours tends to exit through windows, since they may have the smallest u-value on building envelope.

You also need to check the thermal mass of the zone. For zones with low thermal mass, zone dry bulb temperature could be higher than outdoor temperature. For zones with high thermal mass, heat can be stored in the zone and window heat removal is less.

Lastly, you need to check outdoor environmental temperature. Sometimes, outdoor air temperature is high, but environmental temperature is low.

Regards,

Chen Fangzhi

On Fri, Aug 31, 2012 at 12:03 AM, Ng Poh Khai <ng_khai@xxxxxxxxxxx> wrote:
 

 
Dear All,
 
I have a problem that as I have a relatively high heat loss from window as shown in the table extracted from the html file.  The window heat gain removal is around half of the window heat gain addition.  The location is Singapore where it is hot and humid.  I have also checked that the time that the outdoor air temperature is lower than the setpoint is less than 2 hours for the entire year.  May I know what can cause the Window Heat Removal? This is probably causing me to obtain results that show that having a 50% window to wall ratio will have a cooling load lower than having no windows at all.
 
Thanks for any inputs.
 
  HVAC Input Sensible Air Heating [GJ] HVAC Input Sensible Air Cooling [GJ] HVAC Input Heated Surface Heating [GJ] HVAC Input Cooled Surface Cooling [GJ] People Sensible Heat Addition [GJ] Lights Sensible Heat Addition [GJ] Equipment Sensible Heat Addition [GJ] Window Heat Addition [GJ] Interzone Air Transfer Heat Addition [GJ] Infiltration Heat Addition [GJ] Opaque Surface Conduction and Other Heat Addition [GJ] Equipment Sensible Heat Removal [GJ] Window Heat Removal [GJ] Interzone Air Transfer Heat Removal [GJ] Infiltration Heat Removal [GJ] Opaque Surface Conduction and Other Heat Removal [GJ]
50% WWR SOUTH ZONE 0 -106.201 0 0 23.95 27.69 38.768 10.723 0 12.492 0.192 0 -6.206 0 -1.408 -0.002
WEST ZONE 0 -108.368 0 0 23.85 27.093 38.768 13.568 0 12.485 0.617 0 -6.514 0 -1.499 -0.005
EAST ZONE 0 -108.466 0 0 23.866 26.598 38.768 13.786 0 12.486 0.754 0 -6.303 0 -1.49 -0.001
NORTH ZONE 0 -105.651 0 0 23.978 27.747 38.768 10.659 0 12.492 0 0 -6.131 0 -1.379 -0.482
Total Facility 0 -428.687 0 0 95.644 109.128 155.071 48.737 0 49.956 1.564 0 -25.154 0 -5.776 -0.489
0% WWR SOUTH ZONE 0 -108.747 0 0 23.783 31.743 38.768 0 0 12.496 3.504 0 0 0 -1.547 -0.008
WEST ZONE 0 -109.619 0 0 23.735 31.743 38.768 0 0 12.492 4.466 0 0 0 -1.585 -0.003
EAST ZONE 0 -109.86 0 0 23.727 31.743 38.768 0 0 12.491 4.725 0 0 0 -1.595 -0.001
NORTH ZONE 0 -107.59 0 0 23.839 31.743 38.768 0 0 12.497 2.234 0 0 0 -1.491 -0.007
Total Facility 0 -435.816 0 0 95.085 126.973 155.071 0 0 49.976 14.929 0 0 0 -6.218 -0.019




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