HVAC Load Profiles is different to the sum of Zone Air System Sensible Cooling Rate

asked 7 years ago

gonchotorena
181 ●5

updated 7 years ago

Julien Marrec

30056 ●105 ●79 http://www.effibem.com/

I´m learning Openstudio step and step, finally I reach the simulation results about "HVAC loads", unfortunately a question appeared, and I wondered if someone could solve.

The Sum of monthly HVAC load profiles is different to the sum of zone Zone Air System Sensible Cooling Rate. I thought it would be the same.

I´m using a Cooling district in order to discover the cooling demand. Maybe the different is the latent load, if it is true, which value should I reach, because I have used "Zone Total Internal Latent Gain Rate" and all values are 0.

answered 7 years ago

Julien Marrec

30056 ●105 ●79 http://www.effibem.com/

updated 7 years ago

The difference is because you're not using the right reporting variable^[1]. But yes, simply put the biggest difference is likely the latent load (but it could also be zone multipliers, etc).

You can get the total cooling rate from the HVAC system rather than the zone. What's the HVAC system you're using?

For example, if your district cooling serves terminal equipment that includes a Coil:Cooling:Water, you would use the Cooling Coil Total Cooling Rate (W).

If you use a ZoneHVAC:IdealLoadsAirSystem system, you would likely use Zone Ideal Loads Supply Air Total Cooling Rate [W].

^[1] I also suggest you read in detail the section that explains what the Zone Air System Sensible Heating/Cooling Energy/Rate actually reports. It'll help you understand why this is not the variable to use if you want to sum them to match the DistrictCooling's cooling rate.