Residential Load Calculation (Manual J)


MJ8 produces equipment sizing loads for single-family-detached homes, small multi-unit structures, condo­miniums, town houses and manufactured homes. This new version incorporates the complete MJ8-AE volume in a user friendly format. It provides quick supplemental details and advanced topics as well as supporting reference tables and appendices.

Updated 2011 to version 2.10 which includes:

  • Encapsulated attic tables and instructions
  • Duct dew-point equations
  • Winter Humidification load for Duct leakage calculation procedures

MJ8 also accommodates homes that have excep­tional architectural features and life style accessories such as:

  • Dwellings that have limited exposure or no expo­sure diversity
  • Homes with large south-facing glass area or rooms with unusually large glass area
  • A thermally isolated solarium
  • Customized internal load estimates

MJ8 is sensitive to an increased variety of issues re­lated to construction materials and methods including:

  • Fenestration loads for glass rated by the National Fenestration Rating Council (NFRC)
  • Improved duct load models
  • Improved methods for estimating the effect of internal and external shading devices, including insect screens
  • Inïfiltration estimated based on blower door test
  • Sensitivity to latitude and altitude
  • Sensitivity to skylight glazing material, curb con­struction and light shaft construction
  • Heat gain sensitivity to roofing material, roof color and the use of radiant barrier
  • Heat loss and gain for log walls, structural foam panels, aerated autoclaved concrete block, insu­lated form concrete panels, brick walls, concrete walls, wood foundation walls, and any other types of walls and insulation options

Learn how to apply Manual J and Manual D when designing a quality residential HVAC system, and prove it with an ACCA Certificate! Click here to learn more about ACCA’s exclusive certificate program in Residential HVAC Design for Quality Installation. Available online 24/7 (plus get NATE and BPI CEUs).

ACCA Approved Manual J Software

Powered by Manual J – Full Load Calculation

Manual J Block Load Compliant

Wrightsoft Right-J Mobile Browser-Based (All Devices).  Note: This system can integrate with Wrightsoft Right-J to provide a full load calculation.
CalcuNow MJ8-Calc Browser-Based (All Devices).