About
HomeCostMage publishes evidence-backed United States national home-improvement cost guides. The current public set is ten certified project pages plus this site's supporting pages. Each guide answers one planning question with a dated source-year benchmark, not a live market feed.
What the estimates are
Solar totals and dollars-per-watt figures are copied from the DOE / NREL photovoltaic system cost benchmark (Q1 2025 release, reported in 2024 dollars). Water-heater, HVAC, 200A panel, and unfinished-attic figures are evaluated from NREL's Residential Efficiency Measures Database (REMDB 2024.12.23 workbook, 2023 dollars) using the published linear retail equation plus the retrofit multiplier and adder.
Interactive fields only change variables that the certified model already contains: system size for solar, in-domain performance metrics for REMDB rows, and an optional attic area you measure. The site does not invent city multipliers, inflation to 2026, or unpublished high bounds.
What the estimates are not
They are not contractor quotes, warranties, or licensed design advice. They are not Slovenia, Europe, or worldwide prices. A national unit wage, a federal fee, or a survey average that belongs on CostMage is not republished here as if it were a project bid.
How sources are updated
Certified numbers stay on the source year of the cited workbook or benchmark. A later calendar date is not substituted for a historical data year. If a source cannot be re-verified, the claim is flagged rather than silently replaced.
HomeCostMage is an independent publication. Citations are not endorsements or partnerships. This site does not publish a legal-entity name, street address, telephone number, or staff biography on these pages. Ownership details that are not verified here are omitted on purpose.