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BCA2011 Energy Efficiency Summary

The Code has changed many times over the years since this article was written and the information in here isn’t current for today’s requirements. We’re keeping it here for historical reference purposes and to assist others who may want to check an existing building meets the older standard. If you need a second opinion regarding if an older building actually met the then-current energy efficiency requirements we can still do the calculations for any class of building, for any year’s requirements ranging from all the way back to 1999 to the current draft proposal for next year. Contact us for more information!

With the commencement of the Building Code of Australia 2011 (National Construction Code, NCC Volumes 1 and 2) from 1 May 2011, there are some changes that affect the Requirements for Energy Efficiency of all classes of buildings. Most of the major changes to Energy Efficiency that affect the design of buildings are discussed here. For more information, consult the Codes.

Changes in Volume 1 include roof colour for the lower R-value concession, and Floor direction of heat flow is now specified. Installation of bulk insulation must avoid compression, or allowances are to be made for an increase in material R-value to compensate for the loss due to compression.

In Queensland, the Queensland Development Code MP4.1 – Sustainable Buildings, Performance Requirement P1 refers to the Energy Efficiency of Class 1 buildings and Performance Requirement P2 refers to Class 2 buildings. For the current version, check

To accommodate the new Building Code, we have a new check-list. This is available for download from our website. Please update your records to include the new check-list with future jobs.

Changes for Volume 1 (building classes 2 to 9) Section J

J1.3 (Roof+Ceiling insulation) in BCA Climate Zones 1, 2 and 3 the Solar Absorptance that achieves the very-light colour Total R-value concession has been reduced from α ≤ 0.5 to α ≤ 0.4 (e.g. Colorbond® Whitehaven™, Classic Cream™, Surf Mist® and Zincalume® only). Roof colours are now described as: very-light (α ≤ 0.4), light (0.4 < α ≤ 0.6) and dark (α > 0.6), with medium colour (e.g. darker than Pale Eucalypt®) classified as dark. If the exact roof colour is specified, a Verification Method JV3 assessment (thermal calculation) can take this into account. If you do not specify a roof colour on our Check List we have to assume the worst-case colour (dark).

Table J1.5a (External Walls) has only two options for External Wall total R-value. Option (a) has several combinations, depending on thermal mass (surface density), orientation, shade and colour (in BCA Climate Zones 1, 2 and 3). Option (b) with more stringent glazing should only be used where the insulation is being added to an otherwise structural wall. In this case the space available for the added insulation is limited by the thickness of the added lining (furring channel, top-hat section, batten or the like). If the insulation is to be added between the studs of an external wall, then Option (a) should be used.

Table J1.5b (Envelope Walls) – as a clarification, the non-conditioned space still needs glazing to comply with Part J2 to qualify for the lower wall Total R-value.

Table J1.6 (Floors) Floor Total R-value is now calculated for Upwards heat flow for BCA Climate Zones 1, 2 and 3 and Downwards for Climate Zones 2 to 8. For Climate Zones 2 and 3 the Upwards heat flow will be less due to lower internal air-film resistance.

J5.2(a)(vii) (Air-conditioning and ventilation systems) allows exemption from requiring an outdoor air economy cycle for applications needing humidity control such as a laboratory, a paper store, a frozen food area of a supermarket or the like.

J5.4(b)(ii)(H) (Heating systems) allows for limited size of electric heaters in BCA Climate Zones 1 and 2, or where reticulated gas is not available in BCA Climate Zones 3 to 7 (Table J5.4c), with limited annual energy consumption (<15 kWh/m²) in BCA Climate Zones 1 to 5.

Changes for Volume 2 (building classes 1 and 10) Section 3.12

Part (Building fabric thermal insulation) Explanatory information has been added such that the R-value of bulk insulation is reduced to account for any compression. A discussion on fibre insulation compression is below.

Table (Adjustment of minimum R-value for loss of ceiling insulation) Explanatory information #3 indicates an insulation increase is not required for roof lights and #4 indicates that some insulation at roof level moderates the temperature in the roof-space reducing extremes in temperature, including condensation risk in cold climates. Serious condensation risk occurs from the loss of insulation due to moisture, with the consequent increase in heat transfer resulting in further condensation. Porous insulation should be kept dry by other building elements or membranes.

Table (External glazing) Explanatory information #5 has added “The provisions of 3.12.2 assume that internal window coverings will be installed for privacy reasons. This assumption is already incorporated in the allowances for glazing.”

Part (Shading) Explanatory information #1 has added “Winter access refers to the availability of winter solar gains to offset conducted heat losses” and #2 has added “The impact of shading is assessed with respect to the solar heat gain for the window. The requirements of consider solar heat gain to be either beneficial or detrimental to the energy efficiency of a building based on seasonal variation (summer/winter), climate zone, orientation and P/H. Higher P/H values are more beneficial in minimising summer solar heat gain whereas lower P/H values are more beneficial in allowing winter access.”

Part 3.12.5 (Services) now applies to Class 10b swimming pools (and spas).

The Queensland Development Code MP4.1 – Sustainable Buildings, Performance Requirement P1 refers to the Energy Efficiency of Class 1 buildings and Performance Requirement P2 refers to the Energy Efficiency of Class 2 buildings. For more information visit While QDC MP4.1 addresses the Energy Efficiency of dwellings, it takes precedence over NCC Volumes 1 and 2.

The additional requirements of NCC Volume 1 Part J0.2 (b) to (f) and NCC Volume 2 Part 3.12.0(a)(i)(B) to (F) apply in addition to Star Ratings. These parts address: general thermal construction, thermal breaks, compensation for loss of ceiling insulation, floor edge insulation, and building sealing. These five requirements are therefore generic assumptions for the Star Rating of all Class 1 and Class 2 dwellings. A thermal model of a building can be adjusted if any of these five requirements is not present, but the Star Rating should be lower and other elements may need to be improved to compensate.

Further information on Sustainable Housing provides information on Energy equivalence rating, Air conditioners, Sustainability declaration, Lighting, Hot water systems, Covenants and body corporate by-laws, Water, Electricity sub-metering and Incentive programs.

Visiting the following link and typing in the Postcode will give helpful hints on achieving an Energy Efficient 5 Star House in the relevant Climate Zone. Sustainability Victoria’s Energy Smart Housing Manual addresses: Benefits of energy smart housing, Energy smart design, Sun, climate & comfort, Siting & solar access, Windows, Thermal mass, Insulation, Air movement, Services, lighting & appliances, and Landscape Design. Many technologies can improve the Energy Efficiency of a building by reducing artificial lighting, heating, cooling and electricity consumption.

Compression of Insulation


As an example, consider a roof with Polyester fibre insulation compressed 80% at the battens (5% of length) with relaxation of 40% either side (20% of length) and uncompressed for the remaining 75%. The average R-value is 1 / (sum of conductances for each length): R = 1 / (0.05/0.42 + 0.20/0.82 + 0.75/1), which is an average R-value of 90% of the uncompressed material. Bulk insulation that is compressed must have more R-value to compensate.

Changes at Clyde Anderson Pty Ltd

We’ve moved! Our new office is located at Unit 13, 264 Old Cleveland Road, Coorparoo QLD 4151. Our postal address is still PO Box 12, COORPAROO QLD 4151. Deliveries will need to be during office hours, 9am to 5pm (or by arrangement). Our Telephone number, Fax number, Email and web addresses are still the same. If you come to visit, we are in the old Coorparoo Mall building with parking in the basement off Harries Road.

Thanks to steady, strong business, the move was necessary to accommodate additional staff to help with our increasing workload. Two new staff members now complement our existing Professional Engineering consulting services: Mr Peter Vance (MIEAust, CPEng, RPEQ 7103) has over 29 years construction industry experience as an Electrical Engineer and Project Manager. Mr Juancho Bauyon (MIEAust, MAIRAH, Member Philippine Society of Mechanical Engineers) has been a Professional Engineer for 14 years working in Macau, Philippines, Singapore, Algeria and Japan before settling in Australia. You may see their signatures on Reports issued by Clyde Anderson Pty Ltd. Dr Clyde Anderson has been supervising their on-the-job training for over three months and is satisfied that they are “Competent Persons” as defined in the Queensland Building Regulations 2006 for Building Energy Efficiency Assessments to the Performance Requirements of the Building Code of Australia, Volume 1. For more information contact Clyde Anderson Pty Ltd.

Original Energy Efficiency Reports issued with Form 15 Design Compliance Certificates by Clyde Anderson Pty Ltd have a unique hologram security sticker placed beside the signature. This additional security measure is proof that the Report was issued by Clyde Anderson Pty Ltd, giving clients confidence that the Report and calculations are genuine.

Clyde Anderson Pty Ltd has successfully completed the annual independent Audit for compliance to the requirements of ISO 9001:2008 for an operational Quality Management System for the provision of energy efficiency assessments and consulting.

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