Manual J is the name for a specific protocol (often called “Heat Load Calculation” or “Cooling Load Calculation“) used to determine how much heating/cooling a home needs to stay cool and dry in the summer and warm in the winter.

There are books, certifications, software to compute the design parameters of the home — insulation, window U-factor and SHGC, roof type, house wrap, and more.

To a layman, it’s right up there with smoke and mirrors, and Arthur C. Clarke reciting “Any sufficiently advanced technology is indistinguishable from magic.”

But Texas would not be habitable if not for the invention of air conditioning.

Kyle Bacon at Elite Heating & Air Conditioning calculated the Manual J for Emerald Hill at 5 tons. Ross Britton, the consultant, agreed.

Today, however, Austin Energy Green Building messaged, reporting they calculate Manual J at 4 tons — and they ask us to “please revise” the HVAC system accordingly.

Steven alerted Kyle and Ross. Steven asked Kyle to check his numbers and contact Austin Green Building to compare his math with AEGB, “to reach agreement via collaboration.”

Stay tuned.