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Description 2021 ASHRAE Handbook—Fundamentals

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Table of Contents—2021 ASHRAE Handbook—Fundamentals

The 2021 ASHRAE Handbook—Fundamentals covers basic principles and data used in the HVAC&R industry. The ASHRAE Technical Committees that prepare these chapters provide new information, clarify existing content, delete obsolete materials, and reorganize chapters to make the Handbook more understandable and easier to use.

This edition includes a new chapter on global climate change. Individual Handbook chapters have long addressed sustainability, global warming potential, greenhouse gases, recycling, and reclamation as they apply to those chapters’ specific topics, but ASHRAE is pleased to present an entirely new chapter dedicated entirely to designing and operating in a changing world environment.

Other highlights of the updates include the following:

  • Chapter 1, Psychrometrics: updates to properties tables and expanded discussion of transport properties of moist air
  • Chapter 2, Thermodynamics: expanded discussions of reverse Brayton and reverse Stirling cycles
  • Chapter 5, Two-Phase Flow: corrected I-P value for liquid-phase mass transfer coefficient
  • Chapter 6, Mass Transfer: corrected equations for Sherwood number for laminar and turbulent flow
  • Chapter 13, Indoor Environmental Modeling: updates to text throughout
  • Chapter 14, Climatic Design Information: example city calculations updated throughout the chapter
  • Chapter 16, Ventilation and Infiltration: expanded discussion of residential ventilation and infiltration
  • Chapter 17, Residential Cooling and Heating Load Calculations: editorial tweaks to text for clarity
  • Chapter 18, Nonresidential Cooling and Heating Load Calculations: updates to heat and moisture emittance rates for humans, lighting densities, efficiencies for motors, and cooking appliances
  • Chapter 19, Energy Estimating and Modeling: new discussions on occupant modeling and passive heating and cooling.
  • Chapter 20, Space Air Diffusion: terminology updates
  • Chapter 23, Insulation for Mechanical Systems: new discussion of insulation system moisture resistance
  • Chapter 24, Airflow Around Buildings: new equation for wind-induced pressure difference between indoor and outdoor environments
  • Chapter 31, Physical Properties of Secondary Coolants (Brines): expanded discussion on service considerations
  • Chapter 34, Energy Resources: updated figures and discussion of energy resources to reflect recent consumption figures
  • Chapter 35, Sustainability: new discussion of commissioning
  • Chapter 38, Measurement and Instruments: new coverage of resistance sensors and vortex shedding in airflow measurement

Members who receive the Handbook PDF can download a special revision supplement containing just these updated chapters from, along with PDFs of the entire I-P and SI volumes and individual chapters.

Future corrections for this volume will be listed in subsequent volumes and on the ASHRAE website. Any extensive out-of-sequence updates in future will be posted to ASHRAE Handbook Online as a supplemental feature.

This volume is published, as a bound print volume and in electronic format as PDF and online, in two editions: one using inch- pound (I-P) units of measurement, the other using the International System of Units (SI).

Corrections to the 2018, 2019, and 2020 Handbook volumes can be found on the ASHRAE website at and in the Additions and Corrections section of this volume. Corrections for this volume will be listed in subsequent volumes and on the ASHRAE website.

Reader comments are welcomed. To suggest improvements for a chapter, please comment using the form on the ASHRAE website or write to Handbook Editor, ASHRAE, 180 Technology Parkway, Peachtree Corners, GA 30092, fax 678-539-2168, or e-mail

Heather E. Kennedy