Question-and-Answer Resource for the Building Energy Modeling Community
Get s tarted with the Help page
Ask Your Question

Revision history [back]

click to hide/show revision 1
initial version

how to autosize for dehumidification load in EnergyPlus

I have a built up PSZ air handler (I'm not using a Unitary system; I have a standard built up air handler with a chilled water coil, a max humidity setpoint manager on the cooling coil air outlet node, a humidistat in the zone, and the controller water coil is configured to meet both sensible and latent load) configured to provide max humidity control. In a proposed case model where the cooling coil is hardsized everything works fine. When I autosize for a baseline case, the cooling coil can't keep up with the dehumidification load. I tried to change the type of load field in Sizing:System to Latent or Total (instead of Sensible) but that didn't have any effect. Is there any way to get the autosizing routine to size the system to meet both the sensible and latent load?

how to autosize for dehumidification load in EnergyPlus

I have a built up PSZ air handler (I'm not using a Unitary system; I have a standard built up air handler with a chilled water coil, a max humidity setpoint manager on the cooling coil air outlet node, a humidistat in the zone, and the controller water coil is configured to meet both sensible and latent load) configured to provide max humidity control. In a proposed case model where the cooling coil is hardsized everything works fine. When I autosize for a baseline case, the cooling coil can't keep up with the dehumidification load. I tried to change the type of load field in Sizing:System to Latent or Total (instead of Sensible) but that didn't have any effect. Is there any way to get the autosizing routine to size the system to meet both the sensible and latent load?

UPDATE: After doing a bit more digging, it looks like the limiting factor is the fan flow rate, not (necessarily, at least; could be both...) the cooling coil. When I hard sized the cooling coil, the system performance didn't change. So I'm currently thinking that the issue has to do with Sizing:Zone, which I'm guessing does not account for the humidistat in the space when calculating cooling design flow. This is by no means a solution, just some extra info to consider.

how to autosize for dehumidification load in EnergyPlus

I have a built up PSZ air handler (I'm not using a Unitary system; I have a standard built up air handler with a chilled water coil, a max humidity setpoint manager on the cooling coil air outlet node, a humidistat in the zone, and the controller water coil is configured to meet both sensible and latent load) configured to provide max humidity control. In a proposed case model where the cooling coil is hardsized everything works fine. When I autosize for a baseline case, the cooling coil can't keep up with the dehumidification load. I tried to change the type of load field in Sizing:System to Latent or Total (instead of Sensible) but that didn't have any effect. Is there any way to get the autosizing routine to size the system to meet both the sensible and latent load?

UPDATE: After doing a bit more digging, it looks like the limiting factor is the fan flow rate, not (necessarily, at least; could be both...) the cooling coil. When I hard sized the cooling coil, the system performance didn't change. So I'm currently thinking that the issue has to do with Sizing:Zone, which I'm guessing does not account for the humidistat in the space when calculating cooling design flow. This is by no means a solution, just some extra info to consider.

how to autosize for dehumidification load in EnergyPlus

I have a built up PSZ air handler (I'm not using a Unitary system; I have a standard built up air handler with a chilled water coil, a max humidity setpoint manager on the cooling coil air outlet node, a humidistat in the zone, and the controller water coil is configured to meet both sensible and latent load) configured to provide max humidity control. In a proposed case model where the cooling coil is hardsized everything works fine. When I autosize for a baseline case, the cooling coil can't keep up with the dehumidification load. I tried to change the type of load field in Sizing:System to Latent or Total (instead of Sensible) but that didn't have any effect. Is there any way to get the autosizing routine to size the system to meet both the sensible and latent load?

UPDATE: After doing a bit more digging, it looks like the limiting factor is the fan flow rate, not (necessarily, at least; could be both...) the cooling coil. When I hard sized the cooling coil, the system performance didn't change. So I'm currently thinking that the issue has to do with Sizing:Zone, which I'm guessing does not account for the humidistat in the space when calculating cooling design flow. This is by no means a solution, just some extra info to consider.

how to autosize for dehumidification load in EnergyPlus

I have a built up PSZ air handler (I'm not using a Unitary system; I have a standard built up air handler with a chilled water coil, a max humidity setpoint manager on the cooling coil air outlet node, a humidistat in the zone, and the controller water coil is configured to meet both sensible and latent load) configured to provide max humidity control. In a proposed case model where the cooling coil is hardsized everything works fine. When I autosize for a baseline case, the cooling coil can't keep up with the dehumidification load. I tried to change the type of load field in Sizing:System to Latent or Total (instead of Sensible) but that didn't have any effect. Is there any way to get the autosizing routine to size the system to meet both the sensible and latent load?

UPDATE: After doing a bit more digging, it looks like the limiting factor is the fan flow rate, not (necessarily, at least; could be both...) the cooling coil. When I hard sized the cooling coil, the system performance didn't change. So I'm currently thinking that the issue has to do with Sizing:Zone, which I'm guessing does not account for the humidistat in the space when calculating cooling design flow. This is by no means a solution, just some extra info to consider.

how to autosize for dehumidification load in EnergyPlus

I have a built up PSZ air handler (I'm not using a Unitary system; I have a standard built up air handler with a chilled water coil, a max humidity setpoint manager on the cooling coil air outlet node, a humidistat in the zone, and the controller water coil is configured to meet both sensible and latent load) configured to provide max humidity control. In a proposed case model where the cooling coil is hardsized everything works fine. When I autosize for a baseline case, the cooling coil can't keep up with the dehumidification load. I tried to change the type of load field in Sizing:System to Latent or Total (instead of Sensible) but that didn't have any effect. Is there any way to get the autosizing routine to size the system to meet both the sensible and latent load?

UPDATE: After doing a bit more digging, it looks like the limiting factor is the fan flow rate, not (necessarily, at least; could be both...) the cooling coil. When I hard sized the cooling coil, the system performance didn't change. So I'm currently thinking that the issue has to do with Sizing:Zone, which I'm guessing does not account for the humidistat in the space when calculating cooling design flow. This is by no means a solution, just some extra info to consider.