Insulation & Loads

Air sealing, insulation, and the blower door numbers behind them — the measures that usually pay back before the first panel goes on the roof.

Insulation & Loads August 23, 2026 Blower Door Report: CFM50 Is Measured, ACH50 Is Not A blower door report shows two numbers and only one came off the gauge. What volume, the one-point 1.1 factor, and your climate zone do to the other. 13 min read
Insulation & Loads August 18, 2026 Insulation Before Panels: The Audit That Sets the Order Solar quotes skip the measures that pay back sooner. Here is the federal rule that ranks them, and how to test one against your own gas and electric rates. 11 min read

About this section

Three quotes for the same roof came back with three different payback figures — seven years, nine, and fourteen. Priya Raghunathan rebuilt all three in a spreadsheet to find where they diverged, and the spreadsheet turned into this site. She does not work in the energy industry and has never sold, financed, or installed a system. Every number here is traced to a utility tariff sheet, a regulator's decision, or a published standard, and the arithmetic is written out so you can redo it on your own bill.

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Every guide cites the agency, statute, or document it was checked against, and carries the date it was checked. Rules change — if something here is out of date, tell us and it gets corrected.