Energy & Efficiency Calculators & Estimators
Solar, insulation R-values, rainwater and cost-per-square-foot. Built for homeowners planning a project and contractors preparing a bid: enter dimensions, get the quantities and budget ranges suppliers actually quote in.
Stormwater Fee Savings Calculator
Estimate your stormwater utility fee by impervious area and model the savings and payback from converting pavement to permeable surfaces.
Permeable Pavement Reservoir Calculator
Size the stone reservoir under permeable pavement: storage depth, drawdown time, run-on ratio checks and aggregate tonnage.
Stormwater Runoff Calculator
Calculate annual and design-storm runoff volume from roof, paved and lawn areas, plus your impervious percentage and required storage.
Solar Panel Calculator
Panel count and system kW from monthly bill and local sun hours.
Solar ROI Calculator
Payback years and 25-year savings from system cost and bill offset.
Rainwater Harvesting Calculator
Collectable gallons from roof area and rainfall.
R-Value Calculator
Insulation depth needed to hit target R-value by material.
Cost Per Square Foot Calculator
Compare project quotes on a per-square-foot basis.
When to use which calculator
Efficiency first, generation second: establish targets with the R-Value Calculator and Insulation Calculator, see the load impact in the BTU Calculator, then size the array with the Solar Panel Calculator and test the investment with the Solar ROI Calculator.