Time Setpoint not Met

laverne.certeza · Posts: 3

Hi all,

I would like to ask for guidelines or tips on how to reduce the "Time Setpoint not Met" in my simulation results. I already have an acceptable number of unmet hours (around 80 hours), yet, the time setpoint not met during occupied cooling is very high (approx. 6000 hours).

I believe the high incidence of time setpoint not met may be attributable to the very small tolerance for time cooling setpoint not met which is 0.2. Adjusting this tolerance would be of great help but I am still looking for other means to reduce the time setpoint not met.

Thanks in advance,

Bern

Andy Tindale · Posts: 2619 Location: Stroud

Hi Bern,

The latest beta allows you to adjust the tolerance for this value. You can do this under the Output header of model optiions or on the Output tab of the Simulation calculation options dialog.

www.designbuilder.co.uk/betas

Help text isn't yet uploaded but will read:

Time Setpoints not Met Tolerances

This section of input allows more control over the reporting of “Time setpoint not met” hours.

Tolerance for time heating setpoint not met
This data defines the maximum difference from the heating setpoint when reporting the time heating setpoints are not met. If the zone temperature is below the heating setpoint by more than this value, the following report variables will increment as appropriate:

•Time Heating Setpoint Not Met
•Time Heating Setpoint Not Met While Occupied

It also impacts table report "Annual Building Utility Performance Summary" sub-table "Comfort and Setpoint Not Met Summary".

Tolerance for time cooling setpoint not met
This data defines the maximum difference from the cooling setpoint when reporting the time cooling setpoints are not met. If the zone temperature is above the cooling setpoint by more than this value, the following report variables will increment as appropriate:

•Time Cooling Setpoint Not Met
•Time Cooling Setpoint Not Met While Occupied

It also impacts table report "Annual Building Utility Performance Summary" sub-table "Comfort and Setpoint Not Met Summary".

Andy

Sukreet · Guest

Hi Andy,

I am facing the same issue as Bern. I can change the tolerance value. But what are 'OTHER WAYS' to bring it under control.

If I am keeping it on Autosize, it should automatically size it to the best possible cfm isn't it??

Thanks in advance,

Sukreet

Andy Tindale · Posts: 2619 Location: Stroud

The first thing to do is to view hourly or even sub-hourly results for short periods to check when and why the system is not providing perfect comfort at certain times. This may indicate undersizing, poor control or other issues. Armed with this information you are in a position to decide how to proceed.

Andy

jlong · Posts: 25

sorry to thread hack..but does the new beta version include solar thermal modelling simulation in detailed HVAC?

Andy Tindale · Posts: 2619 Location: Stroud

James,

Yes, but some things to consider:

1) Please wait for v3.1.0.012 beta which has an important bug fix in solar loops related to tank "recovery time". It is expected to be released later today.

2) We are still concerned about some results where the solar loop connections seem to cause losses. We are talking to E+ support about this. So please treat results with caution.

3) There is a solar loop all set up in the HVAC templates to speed data set up.

4) No documentation is available yet on the solar loops.

Andy

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