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BCA2010 Energy Efficiency Summary


NOTE:
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 We’re keeping it here for historical reference purposes and to assist others who may want to check an existing building meets the older standard.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!

The Proposals for changes to BCA2010 Section J and Part 3.12 have passed a significant milestone with the joint media release on 22 January 2010. Consequently, Building Approvals from 1 May 2010 will have a further tightening in the stringency to comply with the new Energy Efficiency Measures. A Summary of the proposals is available from the ABCB. Below is our own summary and observations of the changes.

In Summary:

All buildings will require significantly more roof/ceiling, external wall & suspended floor insulation and have much lower glazing allowances. The following highlights some of the major changes that are expected to increase construction costs.

Residential Buildings:

EITHER – Except for NSW (BASIX), the Northern Territory, Tasmania, Victoria and Western Australia (who stay with BCA2009), Houses (Class 1 buildings) will require 6 Stars with half Star concessions available in Climate Zones 1 and 2 for each of a complying Outdoor Living Area with an insulated roof and/or a ceiling fan in the Outdoor Living Area. Additional Deemed-To-Satisfy (DTS) requirements now apply to Star Ratings (insulation installation, thermal breaks etc.). For more information see the Queensland Development Code MP4.1 Sustainable Buildings.

OR – In Climate Zones 1 to 7, DTS Roof+Ceiling total insulation R-Value increases to R5.1 for medium-dark coloured roofs (solar absorptance > 0.6); R4.6 for light coloured roofs (solar absorptance > 0.4 to 0.6); R4.1 for very-light coloured roofs (solar absorptance < 0.4). An additional R0.5 reduction is available in Climate Zones 1 to 5 for ceiling-only added insulation and adequate roof-space ventilation. Climate Zone 8 must have R6.3 (upwards) roof+ceiling insulation. With a flat ceiling and a pitched roof, at least 50% of the added insulation MUST be on the ceiling. Insulation needs to be further increased for ceiling insulation penetrations around recessed downlights, flues and exhaust fans.

In Climate Zones 1 to 7, DTS External Wall insulation options include a total R-Value of R2.8 (R3.8 in Climate 8) and in Climate Zones 1 to 5 the option of a total R-Value of R2.4 and 15° shade. Other external wall options apply to heavy construction (surface density > 220kg/m², e.g. filled concrete block) including shade, added insulation, lower glazing Solar Heat Gain allowance in Climates 1, 2, 3 & 5 with lower glazing Conductance allowance in Climates 4, 6 & 7, and slab on ground for the lowest storey.

External glazing DTS allowances are tighter with the addition of shade influencing the Aggregate Conductance (except for Climate Zone 1). Options for compliant glazing at more than about 20% glass area to floor area ratio include performance glazing (e.g. low-E, double-glazed, or thermally improved frames) in all Climate Zones. In warm to hot climates (Climate Zones 1, 2 and 4) less glass will be the lowest cost solution (consistent with the minimum ventilation opening area to room floor area ratio requirement). Full-opening glazing (casement, louvre, hopper) should be considered with ceiling fans. In colder climates (Climate Zones 3, 5 to 8) taller, narrower, clear glass, facing North with little shade is preferred. Different glass types with orientation and storey (on ground/suspended) will allow more glass area. Light-weight construction must have either less glass or better performance glass than brick or concrete slab construction.

For the first time suspended floors in all Climate Zones must achieve a minimum total R-Value (including the R-Value of the sub-floor perimeter walls). Total R-Values vary from R1.0 in Climate Zones 2 & 5, R1.5 in Zones 1 & 3, R2.25 in Zones 4 & 6, R2.75 and R3.25 in Zones 7 & 8 respectively. QDC MP4.1 excludes additional floor insulation in Queensland Climate Zones 1 and 2.

In Climate Zone 5, Class 10a buildings (e.g. attached garages) must have masonry walls including to the house, have the same roof insulation as the house and, if the garage door faces East or West, the whole house has a lower glazing Conductance allowance.

For more information on the comparison between BCA2010 DTS and Star Ratings for Queensland see the ABCB Research Report “Testing of Proposed BCA2010 Volume 2 House Energy Efficiency Deemed-to-Satisfy Measures with BERS Pro Energy Ratings”. A copy is available on the ABCB Energy Efficiency Research Reports page, or our copy here.

For Class 2 and 4 buildings there is no longer a DTS Building Solution; these Units are required to achieve a building average of 6 Stars with no Unit below 5 Stars. Additional DTS requirements now apply to Star Ratings (insulation installation, thermal breaks etc.). From the 1st of March 2010 Queensland Development Code MP4.1 requires a Class 2 building average of 5 stars with a minimum of 4 stars for any Unit and up to 1 Star concession for Units with complying Outdoor Living Areas.

Residential Artificial Lighting must meet either a W/m² Allowance or have 80% of the total as energy efficient lighting. Where the W/m² calculation is performed, this will be included in the Energy Efficiency Report. A lighting plan will be required for Residential assessments outside of Queensland.

Commercial (Class 3 and 5-9) Buildings:

DTS Roof+Ceiling total insulation R-Value increases from R3.2 for Climate Zones 4, 5 and 6 and for light coloured roofs (solar absorptance < 0.5) in Climate Zones 1, 2 and 3; to R3.7 for in Climate Zone 7 and for medium coloured roofs (solar absorptance > 0.5 to 0.6) in Climate Zones 1, 2 & 3; and to R4.2 for medium-dark coloured roofs (solar absorptance > 0.6) in Climate Zones 1, 2 & 3. Insulation needs to be further increased for ceiling insulation penetrations around recessed downlights, flues and exhaust fans.

External wall DTS total R-Value is increased to be at least R3.3 in Climate Zones 1, 2 and 3;
reduced by R0.5 if the surface density is >220kg/m², facing South, and
reduced if the wall is shaded (R0.5 less if more than 15° shade and R1.0 less if more than 45° shade), and reduced by R0.5 if light or medium coloured (solar absorptance <0.6). In Climate Zones 4, 5 and 6 the external wall total R-Value is to be at least R2.8, with the same reductions as Climate Zones 1, 2 and 3 with the R1.0 concession for shade more than 60° and without the medium-colour concession.

For external walls with insulation provided by a furring channel or batten, the total R-Value must be at least R1.4, and have lower glazing allowance (Option B).

Internal walls that are part of the building envelope must satisfy total R-Value requirements and the internal glazing is counted as South orientation.

Suspended floors (as part of the envelope) that are unenclosed or enclosed with ventilation more than 1.5 air-changes/hour must now be insulated total R-Value R2.0 in Climate Zones 1 to 7. For enclosed suspended floors with less ventilation a total R-Value of at least R1.0 is required in Climate Zones 1, 2, 5 and 6. Slab on ground is required to be insulated in Climate Zones 7 and 8.

DTS Glazing – there is no change from BCA2009 for shop-front and display glazing. For Class 3 and 9c the Glazing Energy Index has been reduced by about 40% to 75% (varies by Climate), and for Class 5-9 the Energy Index has been reduced by about 20% to 65%. There will need to be much more attention to the size, type, location and shade of glazing. Large glass areas will most likely require performance glazing (e.g. lowE, double-glazed or thermally improved frames).

Verification Method JV3 may become more popular for commercial buildings as the additional costs of insulation and complying glazing will be many times more than the extra Energy Efficiency consulting cost. Clients regularly report cost savings of tens of thousands of dollars using JV3 Assessments. The JV3 Reference Building “allowance” is calculated for a similar building that complies with DTS in all elements, and some degree of trading between wall type and insulation with glazing is possible.

In Conclusion:

Energy Efficiency Requirements for BCA 2010 are more stringent. A higher construction cost is most likely required for most building types, especially the cost of glazing if sizes are not reduced.

Based on the experience of assessing thousands of buildings of all Classes, more designs as delivered for Energy Efficiency Assessment are expected to not comply and longer turn-around times should be expected, with higher consulting fees. At this stage we are hoping to contain the additional Energy Efficiency consulting cost to within 30%. Building Designers and Architects who don’t improve current designs enough can expect longer delays and more changes required, so plan to send the project for assessment 1-2 weeks earlier.

A new Energy Efficiency Check List will be required for BCA 2010 assessments and is now available. A guide for completing the Check List is also available to assist in filling out the Check List.

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