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Andrew J Ball

On Construction Domestic Energy Assessor (OCDEA) for new-build home energy SAP ratings, providing On Construction Energy Performance Certificates (OCEPCs)

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Water Efficiency Calculations


The new revisions to the Building Regulations and the associated new Approved Document (Part G - Sanitation, hot water safety and water efficiency) came into force on 6th April 2010.


The new requirements will involve the calculation of water efficiency at both the Design and As-built stages and form part of the data entry for SAP 2009 calculations.


Part G now contains six requirements (G1 to G6). Requirement G2 requires that the consumption of potable water in a dwelling must not exceed 125 litres per person per day as calculated in accordance with the methodology set out by the government in its document 'The Water Efficiency Calculator for New Dwellings' available at


G2 is applicable only to new dwellings or newly formed dwellings as part of a conversion.


Please contact us  for details of Water Efficiency Calculations.