A product described as green may use less energy during operation, contain recycled material or support a lower-carbon system. These are different claims, and each requires different evidence.
Operational efficiency is often easiest to measure. A new device may consume less electricity than an older model. But manufacturing emissions, mining, transport and disposal can still represent a large share of its total impact.
Life-cycle analysis attempts to include these stages. The result depends on assumptions about product lifetime, electricity sources and recycling. Two studies can reach different conclusions without either being fraudulent if their boundaries differ.
Comparisons should use the same functional unit. A battery, vehicle or data center must be evaluated by the service it provides, not only by its weight or headline energy use.
Offsets deserve particular caution. A company may report a net-zero activity while continuing to emit and purchasing credits elsewhere. Readers should ask which emissions were reduced directly and which were balanced through another project.
The most credible environmental claim states its scope, method and limitations. Precision is more informative than a broad label that suggests an entire product has no impact.