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

Temperature dependent window control using EMS

asked 2020-02-14 01:36:32 -0600

GARIMA.RKE gravatar image

updated 2020-11-20 10:14:09 -0600

I am working on a model with unitary air to air heat pump and AFN (without distribution). Natural ventilation setpoint 22 and cooling setpoint 24. What I want is system should first check if the outdoor temp is between 18-35 and the indoor temp is above 22- Natural ventilation should be working and only if these conditions are not satisfied only then HVAC should be running. First, I tried only hybrid ventilation but natural ventilation is running fine when the indoor temperature is between 22-24 and as the temp goes above 24 cooling loads are coming. I even tried doing it with EMS (i referred that relative humidity based temperature control) but still as the indoor temp goes above 24 cooling loads are coming.

image description image description image description

so can anyone help me with the same, please?

edit retag flag offensive close merge delete


@GARIMA.RKE are you able to resolve this issue? I am also working on similar lines for my thesis and I am stuck on this.

shubham gravatar imageshubham ( 2020-02-29 01:43:26 -0600 )edit

hey shubham, i find a diferent approach for this. @shubham

GARIMA.RKE gravatar imageGARIMA.RKE ( 2020-11-20 04:19:07 -0600 )edit

2 Answers

Sort by » oldest newest most voted

answered 2020-02-14 05:09:18 -0600

rafael.alonso gravatar image

Hi Garima,

I´m not sure how you are trying to use the EMS, but I´ve done this is the past and it is certainly possible. In my case I wanted to opent the windows of a Living room both when the internal temperature was above 24ºC, and when its internal temperature and that of an adjacent zone were above 20.5ºC (my heating setpoint was at 20ºC). I´m copying below some screen captures that could help you:

EMS Sensor

image description

EMS Actuator

image description

Program calling manager

image description


image description

Maybe you could check the AFN Surface Venting Window or Door Opening Factor to make sure that your windows are opening when you need them to.


edit flag offensive delete link more

answered 2020-02-15 01:46:37 -0600

GARIMA.RKE gravatar image

updated 2020-11-20 04:23:34 -0600

hey, @rafael.alonso Thank you for your prompt response. actually the problem was that as the ventilation setpoint temp (22) is lesser than cooling set point (24) so whenever the indoor temperature crosses 24 degrees, cooling system starts running. what i want is that the ventilation should run if following conditions are satisfied - (model should give priority to ventilation)

A - outdoor temp. between 18-35

B - indoor temp. above 22

C - outdoor temp. < indoor temp.

if the following conditions are not satisfied only then cooling system should run.

i updated the EMS program accordingly (plz refer the screenshot) also checked AFN Surface Venting Window or Door Opening Factor.. results are coming fine only but still there are few instances where the outdoor temp is high and indoor temperature is low still ventilation is running though as per my program windows should be shut in this condition (plz refer the output file screenshot). so still there is some problem.

EMS PROGRAM image description image description image description EMS PROGRAM

edit flag offensive delete link more


I see that you´re also using the AvailabilityManager:HybridVentilation to control your Cooling/Natural vent. I´ve never used that in the past so I can´t really help much with it.

However, I´m not sure you need the availability manager (or the EMS control), since I asume both are trying to do the same thing: control the on/off of the AFN and cooling system. I don´t know who gets priority though, if the EMS script or the Av. manager.

Have you tried using only the EMS? I believe this option is more flexible in terms of the variables you can use to control your openings.

rafael.alonso gravatar imagerafael.alonso ( 2020-02-17 09:34:59 -0600 )edit

i am using both AvailabilityManager: HybridVentilation and EMS because my main concern is giving priority to natural ventilation above cooling. Hybrid availability manager is only checking that both ventilation/cooling system doesn't work together, ifcooling system is running ventilation shut off and viceversa. But through EMS i want my model to first check the conditions for natural ventilation if these conditions are not satisfied only then cooling system should work. But it seems that as soon as the indoor temperature goes up to cooling setpoint, cooling system start working.

GARIMA.RKE gravatar imageGARIMA.RKE ( 2020-02-20 00:14:03 -0600 )edit

so when the indoor temperature is between the cooling setpoint and ventilation setpoint only then my model is running fine. @rafael.alonso

GARIMA.RKE gravatar imageGARIMA.RKE ( 2020-02-20 00:15:04 -0600 )edit


If I understand the issue correctly, all your conditions are working fine except C (C - outdoor temp. < indoor temp.). Can you post a screen capture of your EMS program? I see the rest of the inputs there, but can't see the program itself. If my intuition is not wrong, you might be forgetting to set openfactorbed and openfactorbed1 as NULL when conditions A and B are not met - so that the EMS doesn't not actuate and allows the opening to be governed by the AvailabilityManager:HybridVentilation (this is has happened to me before a few times).

rafael.alonso gravatar imagerafael.alonso ( 2020-03-07 10:24:47 -0600 )edit

@rafael.alonso Firstly, Sorry for the late reply. I hope you are safe, healthy, and doing as well as you possibly can in the face of this global pandemic. Please find the attached screenshot of my EMS program.

GARIMA.RKE gravatar imageGARIMA.RKE ( 2020-11-20 04:17:55 -0600 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer


Question Tools

1 follower


Asked: 2020-02-14 01:36:32 -0600

Seen: 119 times

Last updated: Nov 20