Manual N Commercial Load Calculation

Manual NManual N® - Commercial Load Calculation

The New 5th Edition of Manual N greatly improves on the capabilities, sensitivities, and information provided in previous editions. The New 5th Edition also provides (N5ae), an abridged version that supports hand calculations for the N5 subset of applications and procedures.


Part 1 - Basic Manual N Procedures (N5ae)
Part 1 contains sections that provide training and calculation tools for the limited use of Manual N procedures.

  • Section 1 - Identifies and discusses the types of heating and cooling loads.
  • Section 2 - Specifies protocols for producing accurate load calculations.
  • Section 3 - Addresses issues and concepts related to diversity, sizing loads, comfort, default input, discretionary input, temperature differences, constructions, tables and procedures used by N5ae vs. the full version of Manual N.
  • Section 4 - Defines indoor-outdoor design conditions for heating and midsummer cooling.
  • Section 5 - Provides procedures for calculating midsummer fenestration loads.
  • Section 6 - Provides midsummer procedures for calculating opaque panel loads.
  • Section 7 - Provides the default procedure for calculating internal loads for midsummer.
  • Section 8 - Provides the default procedure for calculating infiltration loads for midsummer.
  • Section 9 - Provides the procedures for calculating duct loads.
  • Section 10 - Provides the procedure for calculating the heating, sensible cooling and latent cooling loads produced by the most common type of engineered ventilation system.
  • Section 11 - Provides the procedure for calculating blower heat for supply and return air fans.
  • Section 12 - Office building example: Heating and Cooling Loads for an office Area.
  • Section 13 - Office building example: Zone Loads for an Office Area.
  • Section 14 - Review of subsequent steps in the design procedure (what to do after heating and cooling loads are determined)

Part 2 - Advanced Manual N Procedures
Part 2 contains sections that provide all-year procedures, along with adding new capabilities 

  • Section 15 - Provides 12-month , 24-hour design conditions and optional use of ASHRAE monthly weather data on CD.
  • Section 16 - Provides 12-month, 24-hour procedure for fenestration loads.
  • Section 17 - Provides 12-month, 24-hour procedure for opaque surface loads and adds constructions not covered bu N5ae. 
  • Section 18 - Provides comprehensive guidance for all types of internal loads, evaluation of time of day load schedules and cooling loads factors for the thermal mass effect.
  • Section 19 - Provides 12-month, 24-hour procedure for infiltration loads and the option to use blower door data. 
  • Section 20 - Expands the capability and sensitivity of the duct load procedure.
  • Section 21 - Engineered ventilation loads for systems that use heat reclaim equipment, a ventilation dehumidifier, or other type of ancillary equipment.
  • Section 22 - Hydronic pump and piping loads, steam piping loads.
  • Section 23 - Moisture migration load.
  • Section 24 - Water humidification load.
  • Section 25 - Advanced example: Heating and Cooling Loads for a Multi-Use Building.
  • Section 26 - Advanced example: New HVAC Plan for a Multi-Use Building.

Part 3 - Tables 
Part 3 contains a wide variety of tables to give input to worksheets and equations involved in load calculations procedures. Specific tables include many aspects of load calculation, including but not limited to:

  • Table 1B - Micro Climate Conditions for Arizona, California, Hawaii, and Nevada.
  • Table 2B-2 - Heating HTM equations for windows and glass doors.
  • Table 2B-4 - Skylight curb size.
  • Table 3D-2-MS - Peak solar factors for fenestration for midsummer.
  • Table 3D-5 - Cooling HTM equations for glass and plastic block.
  • Table 4A - Full set of opaque panel U-values, Group Numbers and CLTD values.
  • Table 6A-1 through 6A-9 - Heat produced by lighting fixtures.
  • Table 7-AMB - Ambient Conditions for duct systems.
  • Table 8 - Default ventilation rate for load calculations.

Part 4 - Related Guidance and Information
Part 4 contains basic guidance and guidelines for relevant information regarding commercial load calculation. Appendices eleven through eighteen are for the full version of Manual N, featuring advanced topics for high-level practitioners, advanced-course instructors, and software programmers. Information included in Part 4 include but are not limited to:

  • Appendix 3 - How to make a field survey.
  • Appendix 5 - How to troubleshoot system design problems.
  • Appendix 14 - Component leakage areas for low-rise commercial buildings.
  • Appendix 16 - Part load analysis and load lines


Additional Manual N Resources

ACCA Speed-Sheets

ACCA Speed-Sheets are Excel spreadsheets available for purchase that can be used in conjunction with ACCA Technical Manuals, which assist in learning important system design concepts. Speed-Sheets are not a replacement for the full Technical Manual, and are not a replacement for ACCA-approved software.

Learn more about ACCA’s Speed-Sheets here.

Video Resources

Instructions for using an ACCA Manual N Speedsheet:

become an acca member

And Get Member Exclusives

learn more

PLUS It's Risk-Free!

Connect with ACCA

Corporate Partners