Re: [EnergyPlus_Support] Re: Calculated Design Load = 0 ?

["Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

Are the setpoints for heating and cooling the same? or different?

E+ assumes that the zone temp may drift downward to the heating setpoint when a reheat system is in use. 

To confirm the setpoint which is in use, I normally report "System Node Setpoint Temperature" for the zone node. e.g., 

Output:Variable,  

â??

00:SpogliatoioMaschile 

â??

Zone Air Node, System Node Setpoint Temperature, Timestep;

 You might try that to confirm which setpoint is in use by E+ for your DesignDay

On Thu, May 11, 2017 at 7:52 AM, fpasserini.tn@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

It is a locker room. 

During the designday the setpoint temperature is met during the unoccupied hours (20°C) while it is not met during the occupied hours (the setpoint temperature is 24°C). If the setpoint temperature is not met, doesn't it mean that heat is needed, i.e. heating load > 0 ?

Best Regards

---In EnergyPlus_Support@yahoogroups.com, <jim@...> wrote :

6W/m2 of internal load may result in zero heating load if the envelope is well insulated or there is very little envelope load.

p.s., It would be unusual to have people and no other internal loads than lighting. There are always computers, coffee pots, copy machines, etc. That usually amounts to an extra 6W/m2

On Thu, May 11, 2017 at 6:54 AM, fpasserini.tn@... [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com> wrote:

 

Hello, Jim

I'm considering only heating load. The cooling load should be equal to 0 because the cooling setpoint temperature is very high (it is baseline model and in the design model there is no cooling system).

The floor surface of that zone is 150m2.

The outdoor temperature at peak load is -12.4°C.

The heating setpoint temperature is between 20°C and 24°C. 24°C during the occupied hours (20 people).

The internal lighting power density is 6W/m2. 

There are no other internal loads.

The floor is in contact with the ground and a wall is exposed to the outdoors.

I have tried to impose a nominal power for the reheat coil and in that case it works and the setpoint temperature is met. But in a baseline system for LEED the power should be autosized...

Cheers

--

James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct / Mobile: 616.450.8653
jim@...

Website l  LinkedIn

Coffee cup conversation:
Ideas have consequences. Bad ideas have victims. 


.

--

James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct / Mobile: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l  LinkedIn

Coffee cup conversation:
? the minute one is labeled mean-spirited simply for raising an opposing view, debate is silenced. If we disqualify legitimate discussion, we compromise our ability to know the truth. We need to cultivate the ability to disagree civilly and not take opposition personally. We must also have the grace to allow our own views to be challenged with evidence and reasoning? 




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Posted by: Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>

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