What is the difference between an (open interval) and a [closed interval]?

What is the difference between an open loop system and a closed loop system regarding a building's HVAC?

• I understand the fundamentals of it based off of thermodynamics classes but am new to building systems and want to know exactly what an open loop system is and what a closed loop system is in a large office building or other similar buildings. Thanks

• Answer:

  The distinction is that the closed-loop system has a feedback loop to the controller from sensors monitoring the environment being climate controlled. A household thermostat is a simple feedback device most people are familiar with. In large buildings, it's also possible to have an open-loop system which is basically programmed to deliver X amount of heat or A/C based on the temperature outside. When the space is large enough and conditions are relatively constant so that little things like a window open here or there, or how many people are in the building are insignificant, it's possible to control climate predictably without the feedback loop.