The importance of ASHRAE TC 9.9

🔹 Understanding ASHRAE TC 9.9: A Guide for Construction Project Management

ASHRAE TC 9.9: Mission Critical Facilities, Data Centers, Technology Spaces, and Electronic Equipment is a technical committee within ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). This committee unites experts from various fields, including:

• IT hardware manufacturers (e.g., Dell, HP, IBM, Cisco)

• Facility and mechanical engineers

• Operators of hyperscale and colocation data centers

• Researchers and energy-efficiency organizations

  
  

The Mission of ASHRAE TC 9.9

The primary goal of ASHRAE TC 9.9 is to develop thermal guidelines and best practices. These guidelines aim to balance equipment reliability, energy efficiency, and sustainability in mission-critical environments.

🧠 Key Publications by ASHRAE TC 9.9

Title	Focus
Thermal Guidelines for Data Processing Environments	Defines allowable & recommended temperature/humidity ranges for IT equipment (foundation document).
Liquid Cooling Guidelines for Datacom Equipment Centers	Covers direct-to-chip, immersion, and hybrid liquid cooling systems.
Best Practices for Datacom Facility Energy Efficiency	Guides on optimizing power and cooling efficiency (including PUE and WUE).
High Density Data Center Design	Addresses air and liquid cooling for >20 kW/rack environments.
IT Equipment Power Trends and Cooling Applications	Predicts thermal and power evolution for next-gen servers (useful for AI and HPC).
Datacom Equipment Power Trends and Cooling Applications (6th Edition)	Latest version reflecting GPU and AI-era thermal requirements (2022–2023).

🌡️ Environmental Classes: Thermal & Humidity

The “Thermal Guidelines for Data Processing Environments” (currently 5th Edition) defines four key Environmental Classes (A1–A4) for air-cooled equipment and H1–H3 for liquid-cooled systems.

Air-Cooled Classes (Typical Ranges)

Class

Recommended Temp (°C)

Recommended RH (%)

Allowable Temp (°C)

Typical Use

Liquid-Cooled Classes

Class

Coolant Inlet Temp (°C)

Typical Use

Note: Modern HPC and AI racks (e.g., NVIDIA H100) often operate under H2/H3 conditions with liquid inlet temperatures around 30–40 °C to enable free cooling (chillerless operation).

⚙️ Importance for Data Center Design

ASHRAE TC 9.9 provides industry-accepted design envelopes for:

• Temperature and humidity control

• Airflow and containment design

• Liquid loop management

• Instrumentation and monitoring

• Reliability vs. energy trade-offs

  
  

These guidelines help define:

• Setpoints for CRAH/CRAC or CDU systems.

• Free cooling strategies based on local climate.

• Equipment selection (servers, chillers, heat exchangers).

• Service Level Agreements (SLA) for uptime and hardware reliability.

  
  

🔄 Integration with Liquid Cooling

In recent years, TC 9.9 has expanded its focus to include:

• Direct-to-chip cold plate design (ΔT limits, leak containment, dielectric fluids)

• Coolant quality standards (conductivity, corrosion inhibitors)

• Facility and IT loop isolation

• ASHRAE H1–H3 classification (as above)

• Energy recovery and water-side economization

  
  

It acknowledges that air cooling alone is no longer sufficient beyond approximately 20–25 kW/rack in modern compute environments.

📊 Relationship to Other Standards

Standard	Connection
ISO/IEC 30134	Energy metrics (PUE, WUE, REF).
ANSI/TIA 942	Data center topology and Tier classification — ASHRAE TC 9.9 defines environmental parameters used within it.
IEC 62368 / UL	Safety and material compatibility for cooling fluids.
ASHRAE 90.4	Data center energy efficiency code; TC 9.9 data underpins compliance.

Conclusion

Understanding ASHRAE TC 9.9 is crucial for effective construction project management in data centers and industrial plants. By adhering to its guidelines, we can ensure that our projects meet industry standards for reliability, efficiency, and sustainability. For more information, please refer to the ASHRAE TC 9.9 website.