Energy Efficiency Measurements
BCA Volume 1 & 2

Building Fabric
External Glazing
Building Sealing
Air Movement
Air-conditioning and Ventilating Systems
Artificial Lighting and Power
Hot water Supply
Access for Maintenance
Verification methods

VOLUME ONE:   pertains primarily to Class 2 to 9 buildings.
VOLUME TWO:  pertains primarily to Class 1 and 10 buildings (houses, sheds, carports, etc)

Overview of requirements

  • Utilise natural ventilation
  • Turn off systems when not in use
  • Occupants are responsible for paying energy bills


    The aim is to treat the building fabric to reduce heat gain and heat loss and to reduce the need for conditioning.

    Building envelope or fabric is a term used to describe the roof, walls, windows, floors and internal walls of a home. The envelope controls heat gain in summer and heat loss in winter.
    Building fabric separating heated or cooled interior spaces from the exterior of the building or unconditioned spaces i.e. spaces that:

  • Are habitable rooms
  • Are conditioned
  • Can be conditioned

    The envelope may comprise internal or external elements


    Sole occupancy unit conditioned: The walls, roof, ceiling and floor may be part of the building envelope. Includes non-habitable rooms such as the ensuite.

    Corridor: The walls, etc of this area are part of the envelope where there is conditioning on one side of an element and no conditioning on the other.

         Envelope definition



    Plant room ceiling not insulated as the ceiling is not part of the building envelope

    SOU below non-conditioned
    space: Ceiling is insulated
    as it is part of the envelope

    Building envelope: Between conditioned spaces and non- conditioned spaces

    Buildings, both internal & external elements (part of the building envelope)
    like roof and ceilings, roof lights, wall and floor construction. Ensure that insulation is installed correctly and properly tested. Also make sure it has the required fire properties.



    Good glazing design contributes to energy efficiency by:
  •  Allowing in natural light
  •  Enhancing solar heat gains in winter
  •  Restricting heat losses through the glazing in winter

    Restricting unwanted heat gains in summer or in hotter climates
    Relevant definitions: Glazing , Conductance, U-Value, Solar heat gain, SHGC, Exposure factor

    Glazing (BCA):

    U-Value (Watts/m˛.K):

    Solar Heat Gain Heating:
    Exposure factors (E):
    “Glazing, for the purposes of Section J, means a transparent or translucent element and its supporting frame located in the external fabric of the building.”
    heat transferred from a warmer to a colder surface
    measures the rate of heat conduction through a material or assembly for each degree of temperature difference
    caused by direct solar radiation,
    Solar Heat Gain Coefficient
    measure exposure to summertime solar radiation

    Glazing is assessed separately for each sole-occupancy unit and each public area.
    This Section considers the glazing area in each storey (glazing aggregates should not exceed each of the BCA allowances)
    Calculations can be completed by: Equations or ABCB glazing calculator

    ABCB glazing calculator
    Excel spreadsheet determines the BCA glazing allowances, aggregate glazing conductance and aggregate glazing solar heat gain.
    Automatically carries out calculations and compares results for compliance



    Applies to rooms with artificial heating and cooling i.e. a BCA defined conditioned space
    Buildings using evaporative coolers inclimate zones 1, 2, 3 and 5 and for ventilation required for gas appliances




    Reasons for air movement measures is to reduce the use of air-conditioning by taking advantage of the cooling effect provided by natural cross flow ventilation, ceiling fans and evaporative coolers.
    Reduced use means reduced greenhouse gas emissions!

    Ventilation openings - Clause J4.3

    Breeze-Path Breeze Path
    • Internal doors must have a minimum area of 1.5m²
    • Breeze path not greater than 20m
    • Openings to bathroom comply withTable J4.2



    Reasons for measures
  •  To allow air-conditioning and ventilation systems to use energy more efficiently
  •  To ensure that inefficient equipment is not chosen
  •  To take a whole-of-building approach rather than a developer & tenant approach


  •  Air-conditioning systems
          - Including systems that heat, cool or both
  •  Mechanical ventilation systems Section F4 compliance
          - May be part of air-conditioning system
  •  Heating and cooling systems
          - May be part of an air-conditioning system
          - May directly heat or cool a space

  •  Introduces BCA requirements
  •  Extensively covers air-conditioning, ventilation, heating and cooling plant
  •  Requires design and testing documents
  •  Certificates from experts to verify installation



    Relevant definitions
  •  Lamp power density
        Calculates amount of lighting power used in a room (lamp capacity & numbers) and is specified in the BCA. Maximum value specified is determined by total of lamp Watts divided by room floor area.
  •  Light source efficacy (effectiveness)
        Calculates the energy efficiency of the lamps. Applies to bathrooms, dressing rooms, etc. Minimum value specified is determined by luminous flux of the lamps divided by the electric power ratings (Lumens/Watt).

  •  Individual switching of lighting
  •  Limit the power that may be used by lighting systems (Capacity and number of fittings)
  •  Use of occupant activated device for all powered items sole-occupancy units



    A hot water supply system for food preparation and sanitary purposes, other than a solar hot water supply system in climate zones 1, 2 and 3, must be designed and installed in accordance with Section 8 of AS/NZS 3500.4.

  •  Applies to sanitary and cooking hot water piping systems
  •  Requirements in AS/NZS 3500.4
  •  Exemptions for solar water heaters in climate zones 1, 2 & 3



    Access must be provided to all plant, equipment and components that require maintenance.


    Assessment/Verification Methods

    There are several means by which an approval authority can assess whether a building solution, complies with the BCA. These are referred to as assessment methods and include the following:

    a.) The use of clause A2.2 of the BCA. This clause allows the following evidence (in some cases subject to conditions) to be submitted in support of a proposal that a material, form of construction or design meets a performance requirement.

    b.) Another assessment method is referred to as a verification method. Verification methods.

    Designers are not restricted to using a listed verification method. Any other method may be used if the approval authority is satisfied that it establishes compliance with the BCA.


    Karl Boing