Resources
Every RetrofitROI decision engine leans on a handful of durable ideas: how payback and NPV differ, how to read a utility bill, how financing changes a total-cost comparison. These resources explain those ideas once, in depth, and link out to the specific engines that put them to work.
All resources
Payback, NPV, and ROI Are Different Questions
How simple payback, discounted NPV, and ROI each answer a different home-energy purchase question, and when to reach for which one.
Cross-cuttingUsing Incentives Without Double-Counting Them
How to apply a confirmed rebate or tax credit to a purchase decision correctly, and the double-counting mistakes that inflate a payback.
Utility Rate OptimizationTurning a Utility Bill Into Usable Inputs
How to pull the specific numbers a home-energy decision tool needs out of a real electric or gas bill, and what a bill cannot tell you.
SolarCash, Loan, Lease, and PPA Solar Economics
How buying solar with cash, financing it with a loan, leasing the system, or signing a PPA change who owns the savings and by how much.
Insulation & EnvelopeWhy Climate Zone Changes the Math
Why the same envelope or heat-pump purchase pays back on a different timeline in a cold climate than a mild one, and how to use that context honestly.
HVACThe Heat-Pump Decision Beyond the Equipment Label
What actually drives a heat-pump purchase decision beyond the SEER or HSPF sticker: fuel cost, climate, backup strategy, and installed cost.
ElectrificationHow a Budget Changes Electrification Order
How to sequence a multi-appliance electrification project when you cannot fund every swap at once, and where a panel upgrade fits in that order.
Battery & Backup PowerBackup Power Economics Without One Price
Why a home battery or generator does not have a single price for resilience, and how to separate outage protection value from fuel-cost savings.
Water HeatingWater-Heater Economics and Replacement Timing
How to compare heat-pump, gas, and tankless water heaters on real operating cost, and when replacing before failure actually pays.
EV Home ChargingHome Charging, Public Charging, and Rate Plans
How a Level 2 charger install compares to relying on public charging, and how a rate plan changes the true cost of charging at home.
Utility Rate OptimizationRate Plans, Load Timing, and Demand Charges
How time-of-use pricing and demand charges actually work on a bill, and which home-energy purchases change your exposure to each.
SolarSolar Output and Export Value Are Different Questions
Why how much a solar system produces and what the utility pays for the excess are two separate questions with two separate answers.
Cross-cuttingHow Financing and Discounting Change the Decision
How a loan's interest rate and a discounted cash-flow rate each pull a home-energy purchase decision in a different direction.
HVACRepair-or-Replace as an Economic Decision
Why a repair-or-replace call is a total-cost comparison over your ownership horizon, not just today's repair bill against today's quote.
Cross-cuttingComparing Competing Home-Energy Investments
How to compare solar against a heat pump, insulation against equipment, or backup power against efficiency, when a budget cannot fund all of them.
Utility Rate OptimizationRates, Escalation, and Uncertainty in Planning Estimates
How a rate-escalation or degradation assumption changes a long-horizon payback, and how to use one without pretending it is a forecast.
Insulation & EnvelopeWhy the Envelope Can Change Later Economics
Why sealing and insulating a home before sizing a heat pump or solar system can change the economics of the equipment purchase that follows.
SolarWhat Actually Moves Solar Payback
The handful of inputs that actually move a rooftop solar payback: system cost, your rate, your incentive stack, and how long you plan to own the home.
Battery & Backup PowerSeparating Resilience Value From Fuel Savings
How to budget for outage resilience as its own line item, separate from any fuel-cost savings a battery or generator might also produce.
Cross-cuttingComparing Fuel Switching Without Hiding the Rate
Why a gas-to-electric switch decision lives or dies on the specific electricity and gas rates you enter, not on a general electrification claim.
Cross-cuttingUsing Bills and Quotes as Decision Evidence
How to turn a real utility bill and a contractor quote into evidence for a purchase decision, instead of relying on a marketing estimate.
Cross-cuttingUsing a Breakeven Without Treating It as a Forecast
What a breakeven rate or cost actually tells you, why it is not a forecast, and how to read one alongside a sensitivity range instead of alone.
Cross-cuttingMaintenance, Repair, and Lifetime Framing
Why an honest purchase comparison has to include maintenance and degradation over the full ownership horizon, not just the upfront price.
Cross-cuttingHow RetrofitROI Builds an Answer
The calculation boundaries, decision language, and honesty rules RetrofitROI applies to every home-energy purchase decision on the site.