What is a neutral pressure plane and why is it important in room-by-room balancing?

What is a neutral pressure plane and why is it important in room-by-room balancing?

• A. A reference pressure where supply and return pressures are held at the same value as outdoor atmospheric pressure
• B. A pressure level used to monitor humidity
• C. A pressure point used to calibrate door position sensors
• D. A reference pressure where supply and return/adjacent pressures balance to limit unintended air leakage, helping maintain stable zone airflow

Answer: (D)