I'm having issues with the validation of my model through comparison of operative temperature between VE results and the field reading (measured by a black-bulb sensor per each room). It seems like the operative temperature is 0.8 - 2.2 degree higher than the air temperature in reality whilst in my model, they are really close values within 0.1 difference.
It is important to note that the building test is unoccupied so the model ran in passive mode and I have the air temperature validated. The building is very airtight and all windows are close during the test period so air exchange is only assigned with air infiltration value. Should I assign another air exchange value or emissivity of internal surface (which I already assigned with CIBSE value for the material in use)? I cannot think of any thing else.
I'm looking forward to your replies.
Many thanks
Dry resultant temperature
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rais_du_soleil
- VE Newbie
- Posts: 4
- Joined: Fri May 08, 2009 3:20 pm
Re: Dry resultant temperature
Thanks for your reply.
The black sensor in use is TT 915 (http://www.sontay.com/Datasheets/TT/TT-915.pdf) so it does include radiant temperature. I don't know if the comparison would be not valid due to the equipment (I'm trying to contact the supplier for information but haven't reached yet) or I just miscount the radiation part in my simulation. It burdens me that the difference is significant, varying within 0.6 - 2.5 deg C between the reading and simulation when daylight is available.
As I stated, the test building was unoccupied so no heating system is active (radiant fraction is down 0 so I don't think it's an issur). I think I get the solar factor (g-value) of the glass and emissivity of building fabric right (from CIBSE table in correspondant with datasheet from suppliers). It's also complicated that the weather station (inc the pyranometer) doesn't locate onsite (even 2 miles far away but the micro climate is slightly different). I'm using an equation in CIBSE guide J (appendix 2) to split the global irradiation values to diffuse and beam normal ones and inputthose in weather file.
And Happy New Year
The black sensor in use is TT 915 (http://www.sontay.com/Datasheets/TT/TT-915.pdf) so it does include radiant temperature. I don't know if the comparison would be not valid due to the equipment (I'm trying to contact the supplier for information but haven't reached yet) or I just miscount the radiation part in my simulation. It burdens me that the difference is significant, varying within 0.6 - 2.5 deg C between the reading and simulation when daylight is available.
As I stated, the test building was unoccupied so no heating system is active (radiant fraction is down 0 so I don't think it's an issur). I think I get the solar factor (g-value) of the glass and emissivity of building fabric right (from CIBSE table in correspondant with datasheet from suppliers). It's also complicated that the weather station (inc the pyranometer) doesn't locate onsite (even 2 miles far away but the micro climate is slightly different). I'm using an equation in CIBSE guide J (appendix 2) to split the global irradiation values to diffuse and beam normal ones and inputthose in weather file.
And Happy New Year