Transparent energy planning.

WattWise is a building energy investment screening tool by ArforEarth. It compares proposed upgrades using explicit inputs and deterministic calculations. The demonstration profile represents an illustrative grocery store in Pennsylvania, with values in USD.

How the calculation works

Electricity use multiplied by an end-use share gives a system baseline. Each efficiency measure reduces the remaining load. Two upgrades saving 50% each therefore save 75% together, rather than 100%. Optional lighting cooling credits and heating penalties are applied after efficiency.

Solar and emissions

Solar generation is capacity × yield, adjusted for degradation and the selected realization factor. Self-consumption is capped by remaining annual grid demand; excess receives an export credit. Avoided emissions use the fixed grid factor and subtract any extra gas emissions. Exports receive no emissions credit. This annual method does not model hourly matching or weather.

Financial returns

Net cost is installation cost minus the assumed year-zero incentive. Annual savings include electricity, exports and maintenance, less added heating costs. Utility prices change at the chosen escalation rate. NPV discounts the cash flows over the analysis horizon. Simple payback uses first-year savings; discounted payback uses cumulative discounted savings.

Benefits stop at equipment end-of-life. The model assumes no replacement, salvage value, financing or taxes. Demand charges contribute to baseline operating cost, but no demand-charge savings are assumed without interval data.

Optimization and uncertainty

Every combination of eligible measures is evaluated, up to 12 measures. The selected package maximizes NPV within budget, or maximizes lifetime avoided emissions among packages with nonnegative NPV. Conservative and optimistic cases scale all measures together using editable factors. These are sensitivity cases, not probabilities.

The public decision guide

The guide explains computed results using rules and templates. It is not a generative AI model and makes no paid AI API calls. Questions, building inputs and imported CSV files are processed in the browser.

What to verify before investing

Replace sample inputs with actual utility data, engineering estimates and vendor quotes. Confirm the applicability and timing of any incentives. Building type and location do not automatically adjust rates, savings or emissions. Indian tariffs, INR display, local rebates and weather normalization are not included in this release.