Resource, Energy and Material Intensity

Why it matters

If a flow can produce more good products with the same resources, the way resources are used may have improved. To make this visible, energy or material consumption is divided by accepted output. But if the two quantities forming the ratio are not within the same boundary, the result is not reliable. Dividing the electricity consumption of a whole building by the output of a single line, or comparing monthly material input with weekly production, gives no meaningful intensity. First, which processes, which products and which time interval are monitored is determined. The intensity figure is reported together with this scope; it is not compared alone as a label.

Having good output as the denominator keeps quality loss visible. A defective product can also consume material, energy and human time. Even so, counting it as an accepted product adds production that cannot meet the same customer need to the success indicator. Counting a reworked product twice, on the first pass and after rework, leads to the same problem. If the meter consumption includes rework, this consumption must not be hidden by a denominator error. Each accepted physical product is counted once. The quantity awaiting a decision and the defective quantity are shown separately. That way the effect of a quality improvement on resource intensity can really be followed.

Total consumption and intensity answer different questions. Total kWh shows how much electricity was used in the period. kWh/unit explains the average consumption for each good product. When production grows, intensity can fall while total consumption rises. When production falls, the total can fall while intensity worsens. Energy expense also depends on the tariff and the payment structure; fewer kWh does not in every case mean a proportionally lower bill. The unit price change, the fixed payment and the consumption effect must be separated. For material too, a reduction in kilograms and a reduction in cost rest on different assumptions.

When resource indicators are tied to an improvement decision, service, quality and safety must be protected. Cutting heating or ventilation can show a fall on the meter in the short term; if the required working condition is damaged, it is not counted as an acceptable improvement. A design that reduces material use is not chosen on kilograms alone if it lowers strength. Likewise, moving material loss to another process is not a saving for the whole flow. A correct assessment tracks the total, the intensity and the required acceptance conditions together. This lesson builds the calculation for electricity and a single material; from these, a whole environmental impact or life-cycle result is not automatically inferred. Every extended claim needs separate data and a boundary.

Base consumption that continues even without production is divided by fewer good products at low production and raises the ratio. It is not correct to attribute such a change wholly to the speed at which people work. First, the relationship between consumption and time by operating state is examined. If ready standby is unnecessary, reducing it can be considered; but the energy and quality effect of restarting must also be assessed. The operating pattern, the product changeovers and the ambient conditions of the periods to be compared are therefore entered in the record.

Formula