Energy intensity at constant structure is the fictive value which indicates how energy intensity would have evolved if the structure of industry had not changed: it is calculated at year t using the structure of year t-1 as a reference, applying the Divisia method. The annual variation in this intensity at constant structure is then expressed in the form of an index taking one year as a reference (currently 2000). For this reason, the actual intensity and the intensity at constant structure are equal for the year 2000.
Comparing the variation in actual intensity with the variation in intensity at constant structure shows the impact of structural changes on the variation in intensity.
For instance, if actual intensity over a period decreases by 1%/year and intensity at constant structure decreases by 0.6%/year, this means that structural changes explain a reduction in intensity of 0.4%/year. This implies a growing share of low-energy-intensity branches (e.g. equipment) in industry value added.
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