Manual J Residential Load Calculation

Manual JManual J Residential Load Calculation (8th Edition - Full) [ANSI/ACCA 2 Manual J - 2016]

Manual J 8th Edition is the national ANSI-recognized standard for producing HVAC equipment sizing loads for single-family detached homes, small multi-unit structures, condominiums, townhouses, and manufactured homes. A proper load calculation, performed in accordance with the Manual J 8th Edition procedure, is required by national building codes and most state and local jurisdictions.

Manual J 8th Edition produces equipment sizing loads for single-family-detached homes, small multi-unit structures, condominiums, townhouses, and manufactured homes.

Manual J 8th Edition provides detailed requirements for producing a residential load calculation per the CLF / CLTD method. The provision of the standard applies to any dwelling unit that has its own heating-cooling-ventilating system and equipment and its own exhaust air system(s). This includes:

  • Single family detached structures, duplex structures, and triplex structures;
  • Single family attached structures (row house or town house);
  • Dwelling units in multi-family attached structures (condo and apartment units); and
  • Energy efficient homes.


Below is a detailed overview of changes in the updated 2016 version vs. the 2011 release of Manual J (version 2.11) is as follows:

  • New Section N - This nine page section provides the normative requirements for undertaking a load calculation per the CLF/CLTD method contained in Manual J, 8th Edition. It is intended to help with code enforcement. A new requirement in the documentation output is to indicate whether or not AED exists.
  • Design Conditions - Reference to the design conditions clarifies that the designer may use either the Manual J Table 1A/1B outdoor design conditions or weather data from ASHRAE, but that they cannot be mixed per Section 18-7. Guidance is also given for calculating the Grains Difference values from ASHRAE data.
  • Adjustable Defaults - Figure 3-1 (Adjustable Defaults for Local Conditions and Practices) has been expanded to include more information on rules for default use or default values. New topics addressed are: windows and skylight glazing assemblies; vertical glass – insect screen; vertical glass – sun screen; foreground reflectiveness; skylight tilt angle, exposure direction, and assembly U-value (Ueff); opaque panels; garage partition wall; encapsulated attics; infiltration; duct load factors and latent load factors; duct wall insulation R-value and duct leakage; duct wall surface area; AED excursion value; moisture migration.
  • Interpolation Rules for Software - Per Section 3, page 30: "Interpolation is required when rounding down, or up, from the actual variable value, or set of variable values, produces more than five percent (5.0%) difference between the rounded value and the fully interpolated value."

  • Additional Section 3 Guidance - More detailed guidance has been added to Section 3 (Important Issues and Concepts) that covers: engineered ventilation as a system load; engineered ventilation as a space load; kitchen range hoods; fireplaces and space heating stoves.

  • Tables Deletions - The following tables from the 2011 Manual J have been deleted (See the Table Deletion Notice on page 256 for an explanation of why each table was deleted):
    • 3A-2 (Heat absorbing glass – windows)
    • 3A-3 (Reflective glass – windows)
    • 3C-2 (Flat heat absorbing glass – skylights)
    • 3C-3 (Flat reflective glass – skylights)
    • 3C-5 (Tinted plastic dome - skylights)
    • 3C-6 (Milky plastic dome – skylights)
    • 3E-2 (Latitude adjustment for generic fenestration)
    • 3E-4 (SHGC values for light and dark shading devices used with generic fenestration)
    • 8B (Moisture content of sea level air)
  • Revisions to varied Worksheets - Various revisions have been made to Worksheet E (Infiltration Loads), Worksheet GS (Duct Runs in Unconditioned Space), and Worksheet H (Ventilation Loads) in Appendix 10. These changes reflect the revised guidance on each subject, and have been incorporated into example problems throughout the informative portion of the Manual.
  • Informative Appendices - The following changes have been made:
    • Appendix 13 (ANSI ASHRAE Standard 62.2) in the 2011 Manual J has been deleted
    • New Appendix 13 (Load Calculations for Energy Efficient Homes)
    • New Appendix 14 (MJ8 Duct Loads for a Duct Leakage Test Specification)
    • New Appendix 15 (Load Calculations for Large Multifamily Dwellings)

Manual J 8th Edition is divided into five parts across the informative sections, and an additional normative section, for a total of twenty-eight sections and fifteen appendices.

Normative Section

  • Section N - Normative Requirements

Informative Sections 

Part 1 - Core Training

Part 1 consists of entry level training and basic calculation tools for Manual J users.

  • Section 1 - Types of Heating and Cooling Loads
  • Section 2 - Making an Accurate Load Estimate
  • Section 3 - Important Issues and Concepts
  • Section 4 - Component Heating Loads
  • Section 5 - Component Cooling Loads
  • Section 6 - Instructions for Using Form J1AE  and the MJ8AE Worksheets
  • Section 7 - Vatilo Residence - Block Load
  • Section 8 - Victor Residence - Block Load
  • Section 9 - Long Residence - Block and Room Loads
  • Section 10 - What to Do Next

Part 2 - Topics for Instructors and Practitioners that use Manual J Software

Part 2 features calculations and procedures present throughout Manual J.

  • Section 11 - Issues and Concepts
  • Section 12 - Smith Residence - Single Family Detached Example
  • Section 13 - Walker Residence - Single Family Detached Example
  • Section 14 - Cobb Residence - Inadequate Exposure Diversity
  • Section 15 - Bell Residence - Multi Zone System
  • Section 16 - Home Addition with Large South Glass Area
  • Section 17 - Solarium Heat Transfer Multipliers

Part 3 - Details of Manual J Procedures for Instructor and Software Programmer Reference

Part 3 provides a detailed explanation of Manual J procedures and related technical issues.

  • Section 18 - Design Conditions
  • Section 19 - Fenestration Load Procedures
  • Section 20 - Opaque Panel Load Procedures
  • Section 21 - Infiltration Load Procedures / Infiltration Principles
  • Section 22 - Internal Load Procedures
  • Section 23 - Duct Load Procedures
  • Section 24 - Ventilation Load Procedures
  • Section 25 - Blower Heat
  • Section 26 - Hot Water Piping Load
  • Section 27 - Winter Humidification Load
  • Section 28 - Moisture Migration Load

Part 4 - Normative Tables

Part 4 presents weather data and building component performance information for use in various Manual J procedures and calculations.

Part 5 - Documentation and Guidance

Part 5 provides guidelines, help, and pertinent information around information and procedures in Manual J.

  • Appendix 1 - Notes for Instructors
  • Appendix 2 - MJ8AE Capabilities and Sensitivities
  • Appendix 3 - Adequate Exposure Diversity and System Compatibility
  • Appendix 4 - Physical Principles and Mathematics
  • Appendix 5 - Survey
  • Appendix 6 - Troubleshooting System Design Problems
  • Appendix 7 - Summary of Equations
  • Appendix 8 - Glossary
  • Appendix 9 - Symbols and Abbreviations
  • Appendix 10 - Forms and Worksheets
  • Appendix 11 - Software Protocol for Fenestration Loads
  • Appendix 12 - Software Protocol for Tables 4A and 4B
  • Appendix 13 - Load Calculations for Energy Efficient Homes
  • Appendix 14 - Manual J 8th Edition Duct Loads for a Duct Leakage Test Specification
  • Appendix 15 - Load Calculations for Large Multifamily Dwellings


Additional Manual J 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

Understanding Manual J - HVAC Essentials

Instructions for ACCA Manual Jae Speedsheet

Approved Software

ACCA has approved software that works in conjunction with regulations, tables, procedures and worksheets that appear in Manual J.

Learn more about ACCA’s Approved Software here.

ACCA Members-Only Resources

Get connected to your National HVACR Community.

ACCA Membership gives you access to a wide variety of exclusive HVAC resources, including hundreds of hours of exclusive webinars, informational videos, access to downloadable templates, articles, and customizable marketing materials.

Learn more about becoming an ACCA Member »

Members-Only Manual J Resources

Design Essentials - Manual J Residential Load Calculation
This informative video by Ed Janowiak, Manager of HVACR Design Education, goes over all of the intricate details of residential load calculations as detailed in Manual J.

Predictable Comfort - Manual J Shading
Need 10 minutes or less to catch-up on a Manual J topic? This episode of ACCA’s Predictable Comfort briefly goes over proper shading as per Manual J regulations.

Predictable Comfort - Manual J Opaque Panels
Need 10 minutes or less to catch-up on a Manual J topic? This episode of ACCA’s Predictable Comfort briefly goes over how to handle and measure opaque windows in residential homes.

Predictable Comfort - Manual J and Solar Panels
Need 10 minutes or less to catch-up on a Manual J topic? This episode of ACCA’s Predictable Comfort goes over how Solar Panels interact with Manual J regulations, calculations and operations.

Predictable Comfort - Manual J Shading… From Trees
Need 10 minutes or less to catch-up on a Manual J topic? This episode of ACCA’s Predictable Comfort briefly goes over how to handle structures with adjacent trees and how the shade affects load calculations.

Predictable Comfort - Manual J: Block Load vs Room-by-Room Load
Need 10 minutes or less to catch-up on a Manual J topic? This episode of ACCA’s Predictable Comfort briefly goes over Block Loads vs. Room-by-Room Loads for calculations.

become an acca member

And Get Member Exclusives

learn more

PLUS It's Risk-Free!

Connect with ACCA

Corporate Partners