Ashrae’s New Thermal Guideline Update: A New High Density Trend

By | 2023-10-19T08:35:37+00:00 October 19th, 2023|Data Center, Precision Cooling|0 Comments

The most recent version of the ASHRAE Thermal Guidelines includes a new class of IT equipment called the H1 envelope.

The H1 envelope is a new class of IT equipment that was introduced in the 2021 ASHRAE Thermal Guidelines. H1 systems are high-density systems that tightly integrate a number of high-powered components, such as server processors, accelerators, memory chips, and networking controllers. These systems require more narrow air temperature bands than other types of IT equipment, and the ASHRAE Thermal Guidelines provide recommendations for the design and operation of cooling systems for H1 systems.

Ashrae H1 Envelope

The H1 envelope is defined by the following temperature and humidity ranges:

  • Air temperature: 18°C to 22°C (64.4°F to 71.6°F)
  • Dew point temperature: 3°C to 18°C (37.4°F to 64.4°F)

This ASHRAE Thermal Guidelines recommend that the air temperature in the H1 envelope be maintained within the recommended range to ensure that the equipment operates reliably and efficiently. However, the allowable envelope is slightly wider, with upper limits of 25°C (77°F) for air temperature.

The ASHRAE Thermal Guidelines also provide recommendations for the design and operation of cooling systems for H1 systems. These recommendations include:

  • Using a closed-loop cooling system to prevent contamination of the IT equipment.
  • Using a redundant cooling system to ensure that the equipment is always cooled, even if one component of the cooling system fails.
  • Using a monitoring system to track the temperature and humidity in the H1 envelope and to alert operators if any problems are detected.

The ASHRAE Thermal Guidelines with new H1 envelope are a valuable resource for anyone involved in the design, operation, or maintenance of data centers that contain H1 systems. By following the guidelines, data center operators can ensure that their H1 systems operate reliably and efficiently.

New Trend of Moving Towards High-Density Applications

The industry is moving towards high-density applications because they offer a number of advantages, including:

  • Increased performance: High-density applications can deliver more performance per square foot of data center space.
  • Reduced energy consumption: High-density applications can consume less energy than traditional data center applications.
  • Reduced costs: High-density applications can reduce the cost of building and operating a data center.

The move towards high-density applications is being driven by a number of factors, including the increasing use of GPT, cloud computing, the growth of big data, and the development of new technologies such as artificial intelligence and machine learning.

Power Recommendations for H1 Equipment

H1 equipment can consume a significant amount of power. The power consumption of H1 equipment will vary depending on the specific equipment and its configuration. However, it is important to design your data center to provide adequate power for your H1 equipment.

A good rule of thumb is to provide at least 1 kW of power per rack of H1 equipment. However, it is important to consult with the manufacturer of your H1 equipment to get specific power consumption requirements.


The new ASHRAE Thermal Guidelines update 2021 version includes a new class of IT equipment called the H1 envelope. The H1 envelope is a new trend in the data center industry and shows how the industry is moving towards high-density computing and energy efficient data centers.

By following the recommendations in this blog post, you can ensure that your data center is properly designed and operated to support H1 equipment.


The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is the world’s leading professional association for heating, ventilation, air conditioning, and refrigeration (HVAC&R). ASHRAE publishes standards and guidelines that are widely used by the HVAC&R industry. The ASHRAE Thermal Guidelines are the industry authority on data center cooling, provide recommendations for the design and operation of cooling systems for data centers.

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