Mixed Mode schedule for HVAC With Natural ventilation

Hello Everyone. In the process of making a fully detailed model of a working mixed mode residence, i am bit confused in final few steps to completely set this to run. I am trying to generate mixed mode zones (bedrooms). I want to understand how can i set windows to be closed automatically when Air conditioning is turned on and Windows open when Air conditioning is turned off.

I am attaching the 3D and gh file. Any help is much appreciated.
D_Base_model1.3dm (1.0 MB) Complete_Mixedmode_EnergyBalc.gh (1.1 MB)

You can do the following;

  1. Find a list of hours of the year when you want to naturally ventilate
  2. Create a schedule based on those hours and use openingAreaFranctionSchedule input on Honeybee_Set Ep air flow component. So for these hours you want to keep the fraction as 1 to keep the window open.
  3. Create a schedule to show the remaining hours on and assign it to the cooling details component.

@devang thanks for the quick response. These steps seems to be quite meaningful. This has brought me to two doubts in the input parameters -
1- When we set the use openingAreaFranctionSchedule, does it override the opening principle already set (as i have set in image below) like opening as per max or min indoor air temperature.

2- I am not able to get through the principle of these two components. How different are they in setting the schedule for cooling or heating (Both are applied as schedules)

@chris Can you please help me out a bit.

What you referred to as the opening principle assumes that the window remains open. This opening is equal to the hight of the window the half of the width considering a sliding window. Now if you need to close this window at certain times of the year or reduce the opening then you’d use the opening area fractional schedule.

The coolingavailabiltySchedule takes binary values. Meaning it is a schedule that says whether HVAC system should be on or off.
The coolingSetPoint schedule is a schedule of actual values in temperature. This level of customization is usefule to adjust to different seasons in a climate.
The way I see it, you should be able to control your HVAC system from either of those. In any case, make sure to plot the schedule and see if they are not overriding.

@devang Thanks for all your quick assistance. I am working on the workflow described by you and will get back with the results.

Hello @devang @chris
As per suggestions and above discussion i modelled the mixed mode schedule for windows and Ac. To check the whole workflow i visualised the natural ventilation energy output and cooling load profile output on 3d chart. It seemed fine. But when i checked the unmet hours values it seems crazy. Can you please have a look on the attached modified file. Just to make clear what i wanted to achieve is that to switch on ac for a specified set of month (mid March to mid June with windows closed) and naturally ventilate for rest of the year (Typical type of usage schedule for ac in this composite climate). I have reattached the file.

Any update @devang @chris

@MingboPeng can you please give a hand on this issue. Unmet hours seems crazy.

Just a quick thought on this. Could it be that your zone is not meeting the Cooling Setpoint (24 C) during the months you are doing the natural ventilation (22 to 32 C)?

Probably it helps to see the distribution of those unmet hours over time, but I’m not sure which E+ output can give you that.

@RafaelA Thanks for the quick note. I have scheduled the glazing opening ratio as per cooling set point schedules. So I am guessing , if at all the windows should be opened as per temperature logic given, the opening glazing ratio schedule will keep the windows closed for ventilation.

I succeeded reducing the unmet hours between 60hrs-80hrs by removing cooling setpoint threshold and only depending on setpoint schedule temperature.

I tried to visualize the unmet hours on 3d chart but still not able to solve the problem.

Any help to understand this is much appreciated.

@Asisnath as @RafaelA pointed out, it is expected to have high unmet hour when NV is not coupled with setpoint.

Not sure what you are using to draw hourly chart. But to check hourly unmet hour, it is basically indoor temperature vs setpoint temperature. You can visualize two charts, or do math based on T(indoor) - T(setpoint), any hour >0 is unmet hour, then you can visualize it in this hourly chart.

@MingboPeng Thanks for the explanation. Just to be sure I connected the read ep HVAC result unmet hours cooling to 3d chart

@Asisnath This is total hours for each zone, not the hourly value (Yes/No).

@chris would you please have a look at the script for validation. I will be greatful. Thank you