Predicting internal temperature with or without HVAC

In summary, the conversation discusses predicting indoor temperature with or without HVAC. It is mentioned that the temperature without HVAC is roughly equal to the average outside air temperature, while the temperature with HVAC depends on the insulation value and heating/cooling capacity of the building. The purpose of the questions is to find an approximate formula for predicting indoor temperature for HVAC control. Two forms of prediction are mentioned, with an emphasis on approximation.
  • #1
Claude_mar
2
0
Hi,
how to predict indoor temperature with or without HVAC? I have the internal temperature's value, the external temperature's value and the temperature of HVAC's air output. I want two function, one with HVAC on and other with mode off.
Hp: start time 0,
end time Tend.
Tend has values from 0 to 12 hours.
The calculation is approximated. I do not need a detailed formula, but approximated. I apologize for my bad English.
 
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  • #2
Welcome to PF!

The temperature without HVAC is roughly equal to the average outside air temperature.

The temperature with HVAC is dependent on the total insulation value (in units such as watts per degree C) of the building and the heating or cooling capacity (in units of power, such as watts) of the hvac system.

Those are steady-state values. For time varying, you need to know the heat capacity of the building in watts per degree C...which is really difficult.

What is the purpose of your questions?
 
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Likes Claude_mar
  • #3
Thank you,
I want to realize a HVAC's control; I need an approximate formula to predict indoor temperature. For example, internal temperature is 24 degrees, the HVAC is OFF and the external temperature is 18 degrees. Which is temperature after 30 minutes? This is the first form of prediction. The correct prediction is made with another form. The approximation can be great. How can I do?
 

1. How accurate are predictions for internal temperature with or without HVAC?

The accuracy of predictions for internal temperature depends on various factors such as the type and efficiency of the HVAC system, insulation of the building, and external weather conditions. Generally, HVAC systems can maintain a temperature within a few degrees of the set point, but this can vary based on individual circumstances.

2. What methods are used to predict internal temperature without HVAC?

Predicting internal temperature without HVAC can be done through various methods such as energy modeling, weather data analysis, and building simulation software. These methods use mathematical equations and algorithms to estimate the internal temperature based on factors such as building materials, orientation, and occupancy.

3. Can internal temperature be accurately predicted with HVAC in extreme weather conditions?

In extreme weather conditions, HVAC systems may struggle to maintain a set temperature. However, advanced HVAC systems with features such as variable-speed compressors and multi-stage heating/cooling can better adapt to extreme weather conditions and provide more accurate predictions for internal temperature.

4. How does the age of the HVAC system affect internal temperature predictions?

The age of the HVAC system can significantly impact its ability to predict and maintain internal temperature. Older systems may not be as efficient and may struggle to reach and maintain the set temperature. Regular maintenance and upgrades can help improve the accuracy of temperature predictions.

5. Can building occupants impact the accuracy of internal temperature predictions?

Yes, building occupants can have a significant impact on the accuracy of internal temperature predictions. For example, if occupants frequently open windows or doors, it can affect the temperature inside the building and make it more challenging for the HVAC system to maintain a consistent temperature. Occupants can also affect temperature predictions by adjusting the thermostat frequently, which can cause the system to work harder and potentially impact its accuracy.

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