FAVOURITES – May 5 2010 – The Building Code of Australia 2010 has been in effect from 1 May. Section J, dealing with energy efficiency, has been updated but few people understand what is involved. The way buildings are designed, documented, cost estimated and constructed will need to change.
Several of the significant amendments to Section J are outlined below.
General increases in stringency across all areas of insulation requirements.
Far higher thermal resistance (R-Values) are included for wall and roof/ceiling insulation. These elements will need to be factored in prior to detailed design development to avoid potentially incorrect documentation. This is particularly relevant for wall insulation where, for instance, in a
Climate Zone 6 (such as Melbourne), Class 5 – Office Building:
• The thermal resistance base value under Section J – Table J1.5b(a) increased from R1.8 in 2009 to R2.8 in 2010.
• In addition, roof insulation performance is now linked to roof colours (solar absorption values). There are also now roof insulation adjustment factors for loss of ceiling insulation such as exhaust fans, flues or recessed downlights.
Glazing indices have been made more stringent for all Building Classifications 3 – 9 (excluding display glazing in a shop or showroom).
An example to illustrate the potential implications is provided below, with building specifications:
• Climate Zone 6
• Class 5 – Office Building
• Level 3 floor area: 1095 square metres
• Shading device to the north facade
The above table and scenario demonstrates that under the new provisions there is a requirement to go from a single glazed solution, clear finish product to double glazed tint finish if the same 2009 design was maintained.
The science of fenestration needs to be reintroduced into the building design. A far more strategic approach is required to passive solar design. This may include using:
• Less glass in more creative ways,
• Appropriate placement of glass,
• High thermal performance glazing systems,
• High performance films,
• Application of effective shading mechanisms.
Designers are urged to have preliminary Part J2 glazing assessments undertaken prior to seeking Town Planning Phase development approval, as facade treatments become more difficult to alter at a later stage.
Alternative Solutions to the DTS Provisions
It is anticipated that Alternative Solutions will become a more common approach to achieving compliance under Section J. The alternative solutions approach includes the following assessment methods:
• Documentary evidence,
• Verification Method JV3 (Reference Building) – Energy Modelling,
• Comparative Analysis to the DTS provisions
• Expert judgement.
Architects and designers who seek to drive their creative response beyond the capabilities of the DTS provisions should expect to factor in compliance using an Alternative Solution. Practitioners who continue with the status quo approach with no regard for Section J may find the design process onerous.
A change in the primary focus from energy efficiency to greenhouse gas emissions reduction
Under the previous versions of Section J, the emphasis had been on efficiently using energy. Greenhouse gas emission reduction is now recognised in the Objective, Functional Statement and some Performance Requirements. The added weighting on greenhouse gas emission reduction will provide the impetus for the implementation of low greenhouse gas intensity energy sources and renewable energy technologies.
This recognition will be particularly beneficial where a proposed building does not achieve compliance under the Deemed-to-Satisfy provisions, and seek compliance via the Alternative Solution pathway. For example, when incorporating co – or tri-generation plant, renewable energy technologies or the like, weighting can be assigned to a design solution that may enable a compliance result.
Class 2 and Class 4 Residential Units are now to achieve a minimum energy rating of 6 stars under Section J
To date, a Deemed-to-Satisfy provisions approach for Class 2 and Class 4 Residential Units was permissible. Under the new framework a House Energy Rating Scheme (HERS) approach for such dwellings is to be adopted. Critically, reference needs to be drawn to the BCA 2010 Volume 1 – Appendices: Variations and Additions for State-by-State adoption. In the majority of states, compliance adopts BCA 2009 Section J (and BASIX in NSW). For example, in Victoria, a 5 Star building average with no unit rating less than 3 Stars will remain the base requirement for 2010.
Roof lighting (sky lighting) provisions have been reduced from a maximum of 10 per cent down to 5 per cent.
Previously the total area of roof lights serving the room or space as a percentage of the floor area of the room or space was ten per change. This requirement has now been reduced to 5 per cent. The Deemed-to-Satisfy provisions seek to discourage large expanses of roof lights and skylights. A clause reference to Part F4 is provided for additional flexibility. In scenarios such as shopping centres and aquatic centres it is likely that the Alternative Solution pathways to compliance will be utilised.
Metering of Energy Usage
New provisions have been added for the metering of energy usage of various services. This is aimed at providing greater accountability and control over individual services within a building. These provisions will be beneficial in the adoption of the NABERS mandatory disclosure scheme.
General increases in stringency across all areas of airconditioning and ventilation systems
Amendments to reflect increased energy provisions apply to:
• Maximum allowable fan power;
• Maximum pump power;
• Water heating
• Refrigerant chillers system efficiencies
Practitioners are encouraged to adopt design briefs which take the principles of ESD into consideration. The BCA Section J 2010 compliance reporting process can be streamlined if addressed strategically. Awareness and pre-emptive consideration is imperative in navigating the new regulations and avoiding the potentially costly hurdles which confront the development team.
This article aims to provide industry with an insight into a number of the major changes to the BCA 2010 Volume One Section J. For a comprehensive list of amendments to the BCA Section J 2010 please refer to the Australian Building Codes Board (ABCB) website. www.abcb.gov.au
Gary Wertheimer is director of GIW Environment Solutions. He has been involved in the field of ESD and sustainable buildings for over eight years both locally and overseas. Gary has worked as an Environmental Building Scientist in Australia, has held membership with Urban Ecology (Vic) and has been a primary judge at the 2001 and 2003 Banksia Environmental Awards – “Sustainable Buildings Category.”