Section G2 Water efficiency

The Requirement G2 and Regulation 36

This Approved Document deals with the following Requirement from Part G of Schedule 1 and regulation 36 to the Building Regulations 2010, as amended.

Requirement

Water efficiency

G2 Reasonable provision must be made by the installation of fittings and fixed appliances that use water efficiently for the prevention of undue consumption of water.

Water efficiency of new dwellings

36.—(1) The potential consumption of wholesome water by persons occupying a new dwelling must not exceed the requirement in paragraph (2).

(2) The requirement referred to in paragraph (1) is either—

(a) 125 litres per person per day; or

(b) in a case to which paragraph (3) applies, the optional requirement of 110 litres per person per day,

as measured in either case in accordance with a methodology approved by the Secretary of State.

(3) This paragraph applies where the planning permission under which the building work is carried out—

(a) specifies the optional requirement in paragraph (2)(b); and

(b) makes it a condition that that requirement must be complied with.

(4) In this Part, “new dwelling” does not include a dwelling that is formed by a material change of use of a building within the meaning of regulation 5(g).

Wholesome water consumption calculation

37.—(1) Where regulation 36 applies, the person carrying out the work must give the local authority a notice which specifies—

(a) which of the requirements in regulation 36(2)(a) or (b) applies to the dwelling; and

(b) the potential consumption of wholesome water per person per day in relation to the completed dwelling.

Building (Approved Inspectors) Regulations 2010

Application of Provisions of the Principal Regulations

20.—(1) Regulation 20 (provisions applicable to self certification schemes), 27 (CO2 emission rate calculations), 29 (energy performance certificates), 37 (wholesome water consumption calculation), 41 (sound insulation testing), 42 (mechanical ventilation air flow rate testing), 43 (pressure testing) and 44 (commissioning) of the Principal Regulations apply in relation to building work which is the subject of an initial notice as if references to the local authority were references to the approved inspector.

(4) Regulation 37(2) of the Principal Regulations applies in relation to building work which is the subject of an initial notice as if after “work has been completed” there were inserted, “or, if earlier the date on which in accordance with regulation 17 of the Building (Approved Inspectors etc.) Regulations 2010 the initial notice ceases to be in force”.

Limits on Application

Requirement G2 applies only when a dwelling is—

(a) erected; or

(b) formed by a material change of use of a building within the meaning of regulation 5(a) or (b).

 

  1. Performance
    1. General
      1. Fittings Approach
        1. Optional requirement
          1. Notification of water efficiency calculation to the BCB

            Performance

            In the Secretary of State’s view Requirement G2 will be met for new dwellings if:

            a. the estimated consumption of wholesome water resulting from the design of cold and hot water systems (calculated in accordance with the methodology set out in Appendix A to this approved document and taking into account the use of any alternative sources of water provided in accordance with G1(2)) is not greater than the standard set by the Secretary of State of 125 litres/person/day of wholesome water or 110 litres/person/day where the optional requirement applies;

            b. the manner in which sanitary appliances and white goods used in the design calculation undertaken to demonstrate compliance with paragraph (a) are provided and installed in the dwelling takes account of the other provisions in this approved document;

            c. the manner in which any alternative sources of water used in the design calculation undertaken to demonstrate compliance with paragraph (a) are supplied to the dwelling, takes account of other provisions in this approved document;

            d. a record of the sanitary appliances and white goods used in the water consumption calculation and installed in the dwelling is provided along with sufficient other information enabling building owners or occupiers to maintain the building and its services so as to maintain the water efficiency of the building. In this context, relevant white goods are washing machines and dishwashers;

            e. a record of the alternative sources of water used in the water consumption calculation and supplied to the dwelling is provided along with sufficient other information enabling building owners or occupiers to maintain the building and its services so as to maintain the water efficiency of the building.

            Where a building consists of more than one dwelling (such as a block of flats) it should be designed so that the estimated consumption of wholesome water resulting from the design of the cold and hot water systems for each individual dwelling should be no greater than the target.

            General

            2.1 The water used by sanitary appliances and relevant white goods in a new dwelling should be calculated using the manufacturer’s declared value for water consumption of each of those appliances and white goods.

            2.2 The estimated water consumption of a new dwelling should be calculated in accordance with the methodology set out in Appendix A, referred to as the water efficiency calculator.

            2.3 The estimated consumption of wholesome water of a new dwelling should be no more than 125 litres/person/day or 110 litres/person/day where the optional requirement applies. This includes a fixed factor of water for outdoor use of 5 litres/ person/day.

            2.4 Where alternative sources of water are to be used in the dwelling design, this should be reflected in the estimate of water use.

            Fittings Approach

            2.5 As an alternative to calculating the water consumption (as paragraph 2.2), a fittings approach that is based on the water efficiency calculator methodology may be used.

            2.6 Where the fittings approach is used, the water consumption of the fittings provided must not exceed the values in Table 1. If they do, the water efficiency calculator must be completed to demonstrate compliance. Similarly, where a shower is not to be provided or where a waste disposal unit, a water softener or water re-use is to be provided the water efficiency calculator must be completed.

            Table 2.1 Maximum fittings consumption

            Table 2.1 Maximum fittings consumption

            2.7 Where the fittings approach is used, the notice given under regulation 37 should state “Less than 125 litres/person/day using fittings approach”.

            Optional requirement

            2.8 The optional requirement only applies where a condition that the dwelling should meet the optional requirement is imposed as part of the process of granting planning Where it applies, the estimated consumption of wholesome water calculated in accordance with the methodology in the water  efficiency calculator, should not exceed 110  litres/person/day.

            2.9 The person carrying out the work must inform the BCB where the optional requirement applies.

            2.10 As an alternative to calculating the water consumption (as paragraph 2.8), a fittings approach that is based on the water efficiency calculator methodology may be used.

            2.11 Where the fittings approach is used, the water consumption of the fittings provided must not exceed the values in Table 2. If they do, the water efficiency calculator must be completed to demonstrate compliance. Similarly, where a shower is not to be provided or where a waste disposal unit, a water softener or water re-use is to be provided the water efficiency calculator must be completed.

            2.12 Where the fittings approach is used, the notice given under regulation 37 should state “Less than 110 litres/person/day using fittings approach”.

            Table 2.2 Maximum fittings consumption optional requirement level

            Table 2.2 Maximum fittings consumption optional requirement level

            Notification of water efficiency calculation to the BCB

            2.13 Where regulation 36 applies, regulation 37 of the Building Regulations and regulation 20(1) and (4) of the Building (Approved Inspectors etc.) Regulations require that a notice specifying the calculated potential consumption of wholesome water per person per day relating to the dwelling as constructed be given to the appropriate BCB.

            2.14 In most cases, this notice must be given to the BCB no later than five days after the completion of the building work. However, where the BCB is an Approved Inspector and the dwelling is occupied before completion, the notice must be given no later than the day that the initial notice ceases to be in force in consequence of regulation 18 of the Building (Approved Inspectors etc) Regulations when this is earlier than five days after the completion of the work.

            2.15 It is permissible for the notice to be served on the BCB electronically provided the BCB has stated its willingness to receive the document by those means and it is delivered to the electronic address that the body has specified.

            2.16 Local authorities are unlikely to be able to give a completion certificate for the building until the notice required under regulation 37 of the Building Regulations has been received. Approved Inspectors are unlikely to be able to give a final certificate until the equivalent notice under regulation 20(1) and (4) of the Building (Approved Inspectors etc.) Regulations has been received.