How we research costs
Last updated
Every cost on this site should be something you can check. This page explains where the numbers come from and how they are worked out.
Which sources do we use?
We start with public data from U.S. government agencies and national programs, because they publish their methods and update on a known schedule:
- U.S. Energy Information Administration (EIA): electricity and natural gas prices, bills and household energy use by state.
- Energy Star and the U.S. Department of Energy (DOE): appliance and equipment efficiency, typical energy use and operating costs.
- National Renewable Energy Laboratory (NREL): solar production estimates and installed-cost research.
- U.S. Census Bureau and Bureau of Labor Statistics: housing and price data when a topic needs it.
When a cost has no good public source, such as a repair price, we say where the range comes from and how wide it is, instead of giving a single number that looks more precise than it is.
How are averages calculated?
We use the agency's own definitions. For example, an average monthly electric bill is the residential revenue reported to the EIA divided by the number of residential customers, month by month, then averaged over the last 12 months available. The article always says which months the data covers and whether the numbers are preliminary.
When we run our own calculation, like the cost of running an appliance, the article shows the formula and the inputs (watts, hours, price per kWh) so you can redo it with your own numbers.
How often are articles updated?
When a source publishes new data that changes a figure, the article is updated and the "Updated" date at the top changes. We don't change dates for edits that leave the content the same.
How is AI used?
AI tools help with research and first drafts. A person, Marcos Salles, checks every figure against its source and edits every article before it goes live. Read more on the About page.
Who decides what is covered?
Only the editor. The site may show ads served by Google; advertisers have no say in topics or numbers, and there are no sponsored articles.
What if you find an error?
Write to talk2marcvs@gmail.com. Corrections are checked against the source and fixed as soon as possible.