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Introduction to Manual J load calculations and why they are important

Overview of Manual J

Manual J is designed to be used only for residential buildings that have three or fewer above-grade stories

Can I use Manual J for commercial buildings?

How design conditions are set automatically and how they can be adjusted per local code requirements

Design conditions - automatic settings and making edits

Set the construction type, tightness, wall insulation, floor insulation and finish so floor heat transfer is calculated correctly.

Floors - verify and edit

Set the construction, attic venting, roof material, and insulation so ceiling heat gain and loss are calculated correctly.

Ceilings - verify and edit

How to set infiltration load calculations with the tightness or blower door method

Air infiltration - verify and edit

Learn more about occupant, appliance and plant loads found in the Building Profile

Internal loads - verify and edit

Use a flash light, lighter or laser to quickly verify glass type

How to determine if you have "low-e" or "clear" windows

Learn how we set starting assumptions using the year built and location of a home

Smart starting assumptions for insulation, windows and air leakage

Background on how CFMs are calculated and how they should (and should not) be used

Approximate airflow CFMs for cooling or heating

A how-to video on our variable capacity heat pump Manual S tool

How to use the free Manual S Excel file

With a mixed application, you still only need a single Manual J. Here's how to do it.

How to model a mixed ducted + ductless system

Eric Fitz

Manual J background and how to fine tune your designs

Manual J & Load Calculations

Find answers and get help from Intercom Support and Community Experts

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