Where the Numbers Come From
Short answer
Penny Damper's figures come from federal agencies, federal rules and equipment makers' manuals, read in October 2026, plus one supply house's listed part prices with the date they were read.
Updated
Sources
Most figures link to the document they came from, and the rest name it. The main sources are the U.S. Department of Energy, ENERGY STAR, the Environmental Protection Agency, the IRS, the Department of Health and Human Services and its LIHEAP Clearinghouse, the CPSC, the U.S. Fire Administration, the CDC, the Energy Information Administration, the Bureau of Labor Statistics, the FTC, the Consumer Financial Protection Bureau and the federal efficiency rules in the Code of Federal Regulations. Equipment makers' manuals and homeowner pages are used for how a specific kind of equipment works, and the maker is named.
When two agencies give different figures, the page names which one it uses. ENERGY STAR, for example, puts heating and cooling at "nearly half" of a home's energy, while the Energy Information Administration measured 52% in 2020.
Prices and dates
Part prices are the listed prices at PlumbingSupplyAndMore on October 27, 2026, for the part only. That supply house is under the same ownership as this site, which the ownership page explains. Prices change, and other sellers charge more or less.
Labor is never guessed. Pages explain what a labor charge covers, such as the trip, diagnosis, time, refrigerant certification and warranty, and quote the Bureau of Labor Statistics median pay for HVAC mechanics: $29.33 an hour in May 2025. A company's hourly rate is higher than a technician's pay because it also covers the vehicle, insurance, tools and overhead.
Electricity math uses the Energy Information Administration's U.S. average residential price for August 2026, 18.16 cents per kWh, and shows the arithmetic.
What is left out
No lab tests, because none were run. No forum anecdotes, reviews or contractor price surveys. No lifespans stated as fact; where a maker publishes one, the page names the maker. No savings claims an agency did not make, and no phone numbers: every program is linked to its own web page.
Corrections
When an error is found, the page is corrected and the figure is checked again against its source. Rules that changed in 2025 and 2026, such as the end of the 25C and 25D tax credits and the renamed federal rebate programs, are the ones most likely to move, so each page says when its figures were read. See the bill help hub for the current program status.