ECO.10:4 - Solution

ECO.10:4.1 - State the comparison

Name the service or other useful result in units that preserve the needed performance. Identify the resource whose total matters, the affected activities, the period and the situation without the proposed improvement. A cost reduction, an energy reduction and an emissions reduction are different claims.

Use three totals under the same resource account: use without the improvement, use after the improvement at the counterfactual output without an induced response, and use after the response. The first minus the second is the fixed-output saving; the third minus the second is the response-induced change. Include equipment, infrastructure or transition burdens in the relevant totals when they matter to the claimed scope. A burden that arises even at unchanged output belongs in the second total, not in the demand response. Reuse the relevant PHY, MMP, OPS, MA or FIN result.

ECO.10:4.2 - Follow the responses that can change the answer

Ask how the improvement changes attainable action. Can users buy more of the same service, providers expand output, released funds support other activity, or a previously infeasible use become practical? Do prices, capacity, time, access rules or a resource cap limit these responses? Trace the mechanism before choosing a demand estimate.

Keep resource use within the focal activity separate from consequential use elsewhere. Add effects only within the declared total, avoid counting the same effect twice, and retain uncertainty where the effect is not known. Consider a new model, causal study or measurement only when its result can change the choice, supported conclusion or warranted use, and its attainable value warrants the burden.

For a simple unchanged service with resource use per unit e and volume q, total use is e × q. Compare improved total use with the counterfactual total, not just with last year’s observed value. If per-unit use falls from e0 to e1, the fixed-boundary break-even volume is q0 × e0/e1 when e1 is positive. This is a threshold under the stated assumptions, not a demand forecast. When additional terms matter, compare the full totals instead of extending this simple threshold unchanged.

ECO.10:4.3 - Return the consequence to the actual purpose

First state whether total use after the response is lower than, equal to or higher than use without the improvement. Then, if useful, report the fraction of the fixed-output saving offset by the induced response: divide the response-induced change by the fixed-output saving. This percentage requires a positive, well-defined saving. Otherwise report the separate totals and the induced change. The percentage here uses the declared resource account; an operating-only rebound estimate and an estimate including equipment or transition burdens have different bases. A response which exceeds a positive fixed-output saving is the backfire case.

Compare responses appropriate to the purpose. A growth objective may welcome more valuable output. A resource cap may require allocating the released capacity or controlling aggregate use as well as improving efficiency. Each intervention has its own feasibility, cost and affected interests; the rebound calculation does not select a policy automatically.

Return a choice, a conditional operating limit or the observation that would change it. Stop when the comparison already distinguishes the feasible alternatives.