How can I create an ideal radiant heating and/or cooling system ?

asked 2023-02-13 04:26:48 -0600

updated 2023-02-13 08:40:59 -0600

14145 ●83 ●24 http://bigladdersoftware.com/

Hello, I would like to create an ideal system working like the existing "ideal air load system" but with no new air poored into the zone. The objective would be to do thermal comfort simulation with an ideal system equivalent to a "radiant system" which would not affect the humidity by pooring new air. The humidity would affected only by the air coming from ventilation, permeability and internal latent gains.

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answered 2023-02-13 09:37:01 -0600

Aaron Boranian

14145 ●83 ●24 http://bigladdersoftware.com/

Unfortunately, it doesn't appear that there is a single object to assign to a zone for ideal hydronic heating/cooling. As you mentioned, the zone HVAC ideal loads air system is for fully-convective forced air heating/cooling.

As a work-around, you can define the demand side of the radiant heating/cooling system as normal (surfaces with internal source constructions, radiant panels assigned to those surfaces, etc.). For the supply side of this system, you can define a district heating and district cooling object with appropriate setpoint managers. When post-processing results, you would focus on the District Heating & District Cooling meters, just like for the ideal loads air system.

If you believe that this should be a new feature of EnergyPlus, you can add a new issue to their GitHub repository.

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Thank you!

My goal is to do a simulation for thermal comfort with an ideal system that would not affect humidity by providing outside air with a different humidity than the area it is heating/cooling. That's why I first thought of an ideal radiant system. But I found that the HVACTemplate:Zone:IdealLoadsAirSystem has a field called "Outdoor Air Method" that can be set to "None" to provide no outdoor air. With this configuration combined with the dehumidification and humidification fields set to none for the ideal load system, will this do the trick?

Robin.hayGR ( 2023-02-13 10:39:26 -0600 )edit

@GraitecRH ah, thanks for clarifying. In that case, yes you can leave the outdoor air & de/humidification fields to None to achieve this end. Note that the heating/cooling will now be fully convective and applied to the zone air node instead of fully radiant applied to the surfaces of the zone.

One more thing to clarify: outdoor air is usually required for health concerns and called "ventilation". In your original question, when you say "ventilation" do you mean "infiltration" -- outdoor air leaking into the zone through cracks and other means?

Aaron Boranian ( 2023-02-13 11:08:46 -0600 )edit

Yes, I think this what I want.

I do have outdoor air for coming from both ventilation (through ZoneVentilation:DesignFlowRate object), which will cover the air renewal necessary for health reasons, and infiltration (ZoneInfiltration:EffectiveLeakageArea). What I didn't want was for my ideal heating/cooling system to participate in this air renewal and affect the humidity of the zone.

Thank you very much for your help !

Robin.hayGR ( 2023-02-14 02:39:01 -0600 )edit

@GraitecRH Just to clarify, the ZoneVentilation object will affect the humidity of the zone because it introduces outdoor air as operable windows, ventilation fans, or other air renewal strategies (unless you have it set up as an exhaust fan). ZoneInfiltration does also, but it represents the leakage to/from outdoors that you can't control. So, whether you bring in air renewal via ZoneVentilation or IdealAirLoadsSystem objects, it won't matter -- the change in zone humidity will be the same if they each bring in the same amount of outdoor air.

Aaron Boranian ( 2023-02-14 17:16:43 -0600 )edit

Yes it is clear, that i will have humidity influenced by ventilation and leakage and that is what i want. I didn't want only the ideal load air system to do so.

Robin.hayGR ( 2023-02-15 02:05:00 -0600 )edit

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answered 2023-07-26 10:39:08 -0600

Liebwin
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Another easy way, if you are only interested in a radiant heating system, is to use the ZoneHVAC:Baseboard:RadiantConvective:Electric object. This requires no further design objects or node definitions, however you need to specify how much radiation will reach which surface (up to 20 are possible). It will not introduce new air, but note that it will influence the humidity due to heating up the air. You can set the radiant fraction as desired (0-1). If set to 0 it acts like an IdealAirLoadsSystem without, outdoor air method and humidity control.

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Hello, Thanks for your answer. I though about ZoneHVAC:Baseboard:RadiantConvective:Electric , but there is no equivalent to cover for the cooling loads... Maybe combining ZoneHVAC:Baseboard:RadiantConvective:Electric for heating and HVACTemplate:Zone:IdealLoadsAirSystem for cooling could do the trick.

Robin.hayGR ( 2023-07-26 11:05:46 -0600 )edit

Yes, that is exactly what I used before - but it is not a radiant cooling system.

Liebwin ( 2023-07-28 07:41:42 -0600 )edit

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