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SCIENCE · INVESTIGATE AND EXPLAIN

Separate service demand from engineering efficiency

Energy intensity describes energy per unit of service; total energy also depends on the amount of service. An efficient transport, cooling or water system can still use more total energy when activity expands. Whether expanded service meets unmet needs is a social question distinct from the energy arithmetic.

Learning outcome: Hold efficiency reduction 0.2 while increasing service demand. Find the break-even point, then identify an independent observation needed to attribute demand change to efficiency.

Starting recap

Fix the useful service, lifecycle boundary and scenario; distinguish a conditional model result from an observed causal improvement.

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Try

With intensity reduction 0.2 and service growth 0.25, energy is 1000×0.8×1.25=1000 kWh. Engineering saving was 200 but actual saving is zero; the defined rebound fraction is 1.

Open the experiment

Predict

Rebound above one in this defined comparison means:

Experiment

Hold efficiency reduction 0.2 while increasing service demand. Find the break-even point, then identify an independent observation needed to attribute demand change to efficiency.

Separate engineering efficiency from total demand

Worked teaching model · synthetic values · Original service uses 1000 kWh. New energy=1000×(1−intensity reduction)×(1+service increase). Rebound fraction=(engineering saving−actual saving)/engineering saving. Supplied independent changes do not establish a causal demand response to prices or predict economy-wide rebound.

Reset keeps your prediction, captures and practice history.

Original synthetic system; units differ by row
QuantityValueUnit
Engineering saving at fixed service200kWh
Actual energy after service change1000kWh
Actual saving versus baseline0kWh
Rebound fraction1fraction
New service / original service1.25ratio

Lower intensity does not alone guarantee lower total energy.

A rebound fraction above one indicates backfire in this supplied comparison. It does not prove efficiency caused the demand change; independent population, access, prices and other mechanisms need evidence.

Predict, change one control, and save contrasting captures. Reconstruct the balance with units; then explain a process the ledger deliberately leaves out. Display precision is not measurement precision.

Lower intensity does not alone guarantee lower total energy.

A rebound fraction above one indicates backfire in this supplied comparison. It does not prove efficiency caused the demand change; independent population, access, prices and other mechanisms need evidence.

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

Define the useful service

Energy intensity describes energy per unit of service; total energy also depends on the amount of service. An efficient transport, cooling or water system can still use more total energy when activity expands. Whether expanded service meets unmet needs is a social question distinct from the energy arithmetic.

Construct the comparable ledger

The original reference uses 1000 kWh. An intensity reduction e at unchanged service would save 1000 e. With service growth g, actual energy is 1000(1−e)(1+g), not 1000(1−e−g). Multiplicative factors preserve the different denominators: efficiency acts per unit of the new service quantity.

Interpret the competing metrics

Rebound here is defined as the fraction of engineering savings offset: one minus actual savings divided by engineering savings. Zero means engineering savings are fully realized, one means no net saving, and a value above one means actual energy exceeds baseline. A negative actual saving is an increase, not an impossible energy amount.

Challenge the boundary and scenario

These supplied changes do not prove that efficiency caused demand growth. Prices, population, weather, access and other activity changes could contribute. Causal direct rebound, indirect spending responses and economy-wide effects require different evidence. The exercise labels the arithmetic measure rather than claiming a universal empirical rebound rate.

Worked original packet

With intensity reduction 0.2 and service growth 0.25, energy is 1000×0.8×1.25=1000 kWh. Engineering saving was 200 but actual saving is zero; the defined rebound fraction is 1.

Investigation

Hold efficiency reduction 0.2 while increasing service demand. Find the break-even point, then identify an independent observation needed to attribute demand change to efficiency.

Changed-case transfer

At intensity reduction 0.4 and service growth 0.5, compute energy, actual saving and rebound fraction.

Feedback

Energy 900 kWh, actual saving 100, engineering saving 400; rebound 1−100/400=0.75. This is 75% of engineering savings offset, not 75% growth in demand.

Sources and evidence boundary

Original prose, numerical packets and exercises. Primary method/mechanism source, checked 30 October 2026. Supplied values are not measured operating data, universal coefficients or recommendations. No physical equipment work, chemical application, organism manipulation or water extraction is requested. Retain first reasoning and critique in the course workspace; public feedback is practice, not independent assessment.

Apply

Rebound above one in this defined comparison means:

Public practice checks a specific claim. It does not establish independent mastery.

At intensity reduction 0.4 and service growth 0.5, compute energy, actual saving and rebound fraction.

Continue

Completion requires a saved prediction, at least one capture and a reflection. Presence checks do not grade your reasoning.

Skipping retains experiments and awards no mastery.

Previous: Match renewable energy to the time of serviceNext: Track return flows before claiming real water savings
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