In data center cooling, what does delta-T represent?

• A. Temperature difference between supply air and return air.
• B. Temperature of IT equipment.
• C. Humidity level.
• D. Airflow rate.

Answer: (A)

Delta-T in data center cooling is the temperature difference between the air being supplied to the space (supply air) and the air returning from the space after it has absorbed heat (return air). This difference shows how much heat the air has picked up as it passes through IT equipment and racks, which is a direct measure of cooling effectiveness. A design-consistent delta-T means the cooling system is removing heat as expected and air is flowing properly. If delta-T is too small, there may be insufficient cooling or excessive mixing of cold supply air with warm exhaust air; if it’s too large, it can indicate abnormal heat buildup or airflow issues that warrant investigation. This concept is distinct from the IT equipment temperature, humidity level, or airflow rate, which are separate measurements.