Methodology & data sources.
Our estimates are planning benchmarks, not contractor bids. Here is what goes into them and where uncertainty remains.
Cost model
HomeCostGrid starts with a national project baseline, then applies a state installation factor, home-size factor, project-specific range, and selected scope. The low and high values account for typical variation in equipment, labor, access, electrical work, and permits.
Electricity and climate inputs
State electricity inputs are indicative residential planning values informed by U.S. Energy Information Administration state data. Climate classifications follow broad U.S. building-climate patterns. They are not a replacement for a utility bill, Manual J load calculation, or local design temperature.
Savings and payback
Savings are scenario estimates based on the user’s current monthly energy spending, project category, climate factor, and indicative electricity input. Actual savings depend on existing fuel, equipment efficiency, thermostat behavior, weather, rate design, and installation quality.
Review standard
- Every state page shows the model year.
- Programs are linked to official sources rather than presented as guaranteed rebates.
- Incentives are not deducted from headline cost ranges.
- Material corrections are applied when authoritative sources change.
Limitations
HomeCostGrid does not provide engineering, tax, legal, financial, or contractor services. Always obtain a load calculation, written scope, current incentive confirmation, and local permit guidance before purchasing equipment.