Latent cooling with no dehumidification
Hi!
I am using HVACTemplate:IdealLoadsAirSystem in EnergyPlus to estimate the heating and cooling loads to keep all zones within a building between 20 and 25 degrees Celsius.
For the time being, I have both the humidification and dehumidification control types set to None. However, looking at the output variables, I notice that DistrictHeating and DistrictCooling do not equal the Sensible Heating and Cooling being reported.
Sensible heating is reported at 973 kWh while DistrictHeating is at 977 kWh - this might seem negligible, but I am particularly concerned about sensible cooling being reported at 2745 kWh while DistrictCooling is at 3122 kWh - almost a 15% difference!
This leaves me with considerable amounts of Latent Cooling and some amounts of Latent Heating being reported - which in my understanding should not happen since humidification and dehumidification controls are both turned off.
Turning dehumidification ON does increase latent cooling loads considerably (sensible cooling loads remains exactly the same), but turning it off does not set latent cooling to zero.
So my question is, what are some possible sources (besides dehumidification) for the existence of latent cooling in the results?
Many thanks in advance.
Do you introduce outside air into the zones? What is your climate zone?
The values I referenced are for OutdoorAir set to None.
With OutdoorAir set to 0.00944 m3/s Flow per person, there's even more latent cooling and latent heating, again with humidification and dehumidification set to None.
The I/O reference document states that the IdealLoads unit will use Humidistat instead of the selected humidification control ("None", in my case) whenever the unit is in Deadband mode - could this be the source of the issue?
My climate zone is temperate, specifically Mediterranean.
@MiguelPereira How about infiltration?
@Avi I am not modelling infiltration, but I am modelling natural ventilation from open windows, which the Sensible Heat Gain Summary report seems to file under the Infiltration columns.
With (de)humidification set to None and ventilation turned on, 88% of district cooling is sensible cooling. Without ventilation, the number drops to 81% (these two should be 100%, I assume).
Using Humidistat with 30%-50% humidity setpoints, 76% of district cooling is sensible with ventilation, 73% without ventilation.
@MiguelPereira I might be wrong but I think that once you are cooling below dew point temperature you must have some latent heat removed as you condense water. Try graphing Outside Temperature against Dew point.