For 90.1 modeling, as you said earlier baseline supply air flow rates shall be based on supply air to room air temp difference of 20 F i.e. 11.1 C. In Sizing:system, 'Central Heating Design Supply Air Temperature' is the design supply air temperature at heating coil outlet i.e. AHU outlet. So this has to be thermostat heating setpoint + 11.1 to meet 90.1 modeling requirement. Heating coils will be sized using this information and will have to be oversized by 15% to meet G3.1.2.2 requirements. This is my understanding.p.s. One quick comment regarding max PIU secondary flow rate to be 50% of primary air flow rate. EMS may be able to provide some help but I couldn't explore it well. If I find some solution for that, will share it here.On Fri, Apr 29, 2016 at 12:09 PM, telemar87@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:--ÂThanks Chandan for your adices,
there is just one thing I don't agree with. Why should I size the cental heating air flow with a 31°C (20°C heating zone SP +11.1°C) temperature when, during the simulation I'll have a central heating temperatureof max 17.78°C due to the setpoint manager?
In my opinion, using a 17.78°c as central heating temperature seems to be sufficient. In this way, the central AHU works just in a cool or preheat mode, while the 100% heating is reached by the PIU units. Â
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