Volume of buildings
The glossary of statistical terms, published by the Organisation for Economic Co-operation and Development (OECD), suggests that: ‘The volume of buildings is the total volume included between the outer surface of the outer walls measured from the level of the lowest storey to the roof of the building.’
It should be noted that there are sometimes differences in assumed internal volumes when calculating to various building standards. For example when calculating infiltration air change (or air leakage) rate per hour to Air Tightness Testing and Measurement Association (ATTMA) q50 standard (m3 per hour per m2 @50 Pascals) the internal walls within the envelope would be included in the volume calculation. If calculating air tightness to the Passivhaus (PH) n50 standard (air changes per hr @ 50 Pascals) then the thickness of internal walls within the envelope are excluded from the floor are and thus the overall volume. ie the calculation is the sum of the volumes of all internal rooms rather than the volume within the envelope.
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