Environmental Conditions

Temperature and humidity targets are major drivers of cooling energy use - and cost. Yet most data centers are overcooled and missing the mark on humidity control. Once operators address air management, they should consider operating at recommended temperatures and humidity.


Identifying and establishing the optimal environmental conditions (in terms of temperature and humidity) can be tricky, but are crucial prerequisites for energy efficient and cost effective data center operation. Industry guidelines provide valuable guidance on allowable ranges. Operating data centers in a way that balances concerns of IT longevity and energy efficiency is attainable. While the importance of accurate measurements cannot be understated, there are cost effective ways to collect (and act on) this information. Additionally, data center owners and operators should be aware of opportunities to widen the environmental envelope – as relaxing conditions in accordance with industry guidance can result in significant energy savings without sacrificing performance.

High-Level Best Practices

Although most computer room air conditioners (CRACs) are controlled based on the return air temperature, air intake to IT equipment is the important specification to meet. 

  • At minimum, follow ASHRAE guidelines for data center temperature ranges recommended for reliable IT operations
  • Even better, operate at the maximum ASHRAE recommended temperature range (80.6°F)
  • Anticipate that servers will occasionally operate in a higher, but allowable, range (89.6°F)
  • Minimize or eliminate humidity control altogether

Many opportunities exist to reduce energy consumption of cooling equipment, including

  • Raising the chilled water temperature
  • Using air-, water- or refrigerant-based economizers
  • Installing variable-speed pumps and fans through the plant
  • Installing dry coolers
  • Installing rear door heat exchangers (RDHx) for high-density racks
  • Use a centralized cooling system instead of individual direct expansion (DX) systems

Featured Resources

Data Center Master List of Efficiency Actions 

This comprehensive list of recommended efficiency actions for data centers provides more information on the high-level operational best practices outlined above as well as a more detailed list of best practices related to cooling and air management. Access the Master List

Thermal Guidelines and Temperature Measurements in Data Centers

This guide initially develops a list of generalized thermal best practice recommendations as a first step towards temperature management and measurements in data centers, ultimately saving infrastructure energy as well as protecting electronic equipment. Access the guide.

Humidity Control in Data Centers

This report reviews the evolution of humidity control in data centers and makes recommendations on how to meet the current humidity control requirements in an energy-efficient manner. Guidance on the use of evaporative cooling is also provided. Access the report.

Webinar: Thermal Guidelines and Temperature Measurements in Data Centers

This webinar covers how to implement accurate and cost-effective temperature management in data centers, which is not only important for air management and overall energy efficiency but also for thermal management of the IT equipment. Access webinar.