Apportioning Water Consumption – common areas only assessment

For assets where only the common areas are being assessed, the water consumption targets and actual figures reported should be based on the water used within the assessed areas only.

Therefore, where metering is provided for the whole building consumption and no separate metering of common areas is available, a logical assessment of the energy and sanitary (and other) water use and distribution should be carried out so that the figures are based on an accurate estimation of water usage within the common areas. Apportioning must not be based purely on the percentage of floor area.

A logical assessment could be based, for example, on the percentage of water using equipment installed, such as the proportion of toilets/taps/dishwashers etc within the scope of the assessment against those outside of the scope.

Justification and calculations should be provided within the evidence to support the reported figures.