[Bldg-sim] Radiant Cooling and VRV systems giving Lower savings than anticipated in DesignBuilder

[Javed Iqbal via Bldg-sim]

Hi Kartikay,

I recommend you worth checking all the models thoroughly before arriving on
any conclusions. I quickly checked some of the critical parameters for
Radiant case and found some issues but not limited to as follows:

   - The Radiant chiller is set-point manager is at OA reset and operate at
   6 degC regime. In general, Radiant, TABS system works on raised chilled
   water supply temperatures (14-15 degC) compared to conventional system
   which is at 6-7 degC. Refer the EDR
   <https://energydesignresources.com/media/1783/EDR_DesignBriefs_radiantcooling.pdf?tracked=true>
   resources to know more on this.
   - The AHU (DOAS) has a coil size of 4.8 MWc and supply volume of 149
   m3/sec (400,000 CFM) which means AHU takes most of the cooling load
   compared to the radiant system. I believe, DOAS is in the design to meet
   ventilation loads ONLY. Additionally, if this is to meet ventilation loads
   and supplying air directly to the zones, the supply air set-point should be
   very close to the zone set point temperature~21-22 degC. You should also
   look into *equipment sequencing* in order to make sure each system is
   meeting the desired loads (Radiant meeting sensible loads and DOAS all the
   ventilation loads).
   - Most importantly, DesignBuilder/EnergyPlus has great flexibility in
   generating variables to do quality checks which is very useful and must
   have before arriving on any preliminary conclusions. Remember garbage in,
   garbage out...

Similarly, other model should be investigated accordingly.

Hope this helps!!
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