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.