How figures get onto this site, and how they come off

The rule

A number may appear on this site only if it is one of four things: arithmetic on a visitor's own input, a figure attributed to a named publisher with the date it was retrieved, an assumption labelled as such with its reasoning and plausible range, or one of the three install-cost starting values on the payback page, which are labelled there as illustrative, not market data, and meant to be replaced with your own quotes. Sourced figures and assumptions are read from a registry, and the build fails if a page asks for one the registry does not hold. The illustrative install values are typed into the payback page directly, so for those the safeguard is the label on that page rather than the build.

Sourcing

• Primary sources only for energy prices, climate data and regulatory requirements — the agency that publishes the series, not an aggregator that republished it.
• A raw copy of each source as fetched is kept in this project's evidence archive, which is not part of the published site, so a figure can be checked against what the publisher actually said. Where the raw copy of a figure's original retrieval was not kept, the copy on file is a later capture, and the methodology page gives both dates.
• Where a published figure has a known weakness for the pool case — a state average standing in for a marginal rate, an annual figure standing in for a summer one — that weakness is printed next to the figure, not buried in a disclaimer.

Assumptions

Where no publisher supplies a number for a residential pool, the assumption is written down with the reasoning that produced it and the range within which we believe it sits, and it is listed on the methodology page. All but one can be changed or bypassed by the reader on a page the methodology page names for it, directly or by picking a different option such as a cover type; not every page that uses an assumption offers a control for it. The exception is the 12-hour daylight window used to split cover hours, which cannot be edited; the methodology page says so and gives its reasoning and range, because an assumption the reader can neither see nor change would be a hidden claim.

Independence

No manufacturer, installer or retailer pays for placement, review or mention. No product is recommended by name. Where a category has a genuine weakness — the running cost of gas, the shoulder-season collapse of a heat pump, the disappointment of solar in April — it is stated in the same terms as its strengths.

Who writes this

Andrew Flores, working alone, with AI assistance used for drafting and checking and never as a source. For pool heating estimates, he is responsible for the evidence behind energy prices, heater performance assumptions, and any corrections to the published arithmetic. A registered figure must carry a named publisher and retrieval date, documented arithmetic, or a visibly stated assumption; the policy allows no unlabeled fourth category.

Editorial responsibility for every page sits with a named person rather than a masthead, and the corrections address on the contact page reaches him. Nathan Management, a California publisher of single-purpose calculators, is the publisher of record.

Staleness

Energy prices go out of date, and the natural gas series used here is an annual figure that will be superseded by a later year. Every sourced figure is therefore listed with its retrieval date on the methodology page, rather than hidden in a build log, and with the date of the later capture where that is the copy on file, so a reader can judge for themselves whether a figure is old enough to distrust. A stale figure with a visible date is a manageable problem; an undated figure is not, because nobody can tell whether it is a week old or three years old.

Where a figure has a natural revision cycle — monthly for electricity, annual for gas — the retrieval date is the honest description of what the site knows, not the publication date of the underlying series.

What is not published here

Three categories are excluded on principle. Installed prices, because they are local and any national figure would be invented. Product recommendations, because there is no way to rank equipment without either testing it or taking somebody's word, and this site does neither. And projections — of energy prices, of equipment life, of savings over a decade — because a projection dressed as a calculation is the most persuasive kind of made-up number.

Where a reader plainly needs a number in one of those categories, the site asks them for it and does the arithmetic around it. That is why the payback page takes two quotes rather than publishing a price table, and why it offers a price-sensitivity table rather than an escalation rate.

Language

Figures are stated with the precision the underlying source supports and no more. Where the model's output is uncertain, the page says which input drives the uncertainty rather than attaching a vague caveat to everything. Claims about what equipment does are written in terms of the physics that produces the behaviour, so that a reader can check the reasoning rather than take it on trust.

Corrections

Errors are corrected in the registry, which propagates to every page that used the figure. Where a correction changes a headline number materially, the change is noted on the methodology page rather than made silently. A correction is never made by quietly deleting the sentence that was wrong.