Data Centers | Informative Delta T – The Air-Side Temperature Difference in Data Centers In the world of data centers, Delta T (ΔT) plays a vital role in evaluating cooling efficiency. It refers to the temperature difference between supply air (from CRAC/CRAH units) and the return air (after it passes through heated IT equipment). This difference is a key indicator of how effectively heat is being removed from your environment. Why Is Delta T Important? Optimized Cooling Efficiency A higher ΔT means that the cooling system is absorbing more heat per unit of air, indicating more effective use of cooling capacity. Energy Savings Maintaining an optimal Delta T reduces the need for overcooling, which lowers energy usage and operating costs. Supports Hot & Cold Aisle Design Implementing proper airflow separation using hot aisle/cold aisle layouts improves Delta T, ensuring targeted cooling and minimizing hotspots. Best Practices for Managing Delta T Monitor Airflow Use containment strategies (hot or cold aisle containment) to prevent air mixing, stabilizing the temperature difference. Strategic Equipment Layout Position IT racks to align with airflow direction and ensure uniform air intake and exhaust. Perform Regular Maintenance Dirty filters or blocked vents can restrict airflow and degrade ΔT performance—keep cooling units clean. Formula: How Delta T Relates to IT Load and Airflow To calculate Delta T in a data center environment: ΔT = (3160 × IT Load in kW) / CFM Where: ΔT = Temperature difference in °F Q (IT Load) = Power load in kilowatts CFM = Airflow in cubic feet per minute 3160 = Conversion factor from kW to BTU/min This formula helps determine whether your airflow volume is appropriate for the heat being generated. If ΔT is too low, it may mean excess airflow or inefficient heat absorption. A well-managed Delta T leads to energy savings, reduced operational costs, and improved cooling effectiveness, especially in high-density environments.