In February this year, I authored the article: NatHERS: Are we on the Road to Ruin?

The premise was to cast question (and perhaps doubt) onto the NatHERS compliance process for assessing multi-residential (Class 2 buildings). Under the backdrop of disjointed management, improvements to the calculation engine, poor market communication and value to the end user, one of the more interesting comments posted questioned my assertions and understanding regarding the simplification of glazing via the WERS database.

For those unfamiliar with it, the WERS database is a system to enable windows to be rated and labeled for their annual energy impact on Australian dwellings (primarily Class 1 buildings) so consumers can understand the significant impact of glass and frames on the performance of their homes. By gathering data from glass and fabricators, WERS uses typical module sizes to allow consumers to assess performance on a like by like basis, simplifying glass performance for the wider non-technical market.

It’s intended to work like an energy rating of a home appliance but for window systems that makes life easier for Class 1 consumers. Well, while it may be fit for purpose for the Class 1 construction market, where homeowners are looking for typical, off-the-shelf products, it is very rarely the case when we procure bespoke glazing systems for the Class 2 mid to high-rise construction market.

Titled Response to NatHERS: Are we on the Road to Ruin?, the rebuttal to my article aimed to ‘highlight the extent of the misunderstanding of the compliance paths available within the regulated tools.’ Inadvertently, it has gone on to illustrate a lack of understanding in regard to planning, design and procurement of façade systems on multi-residential (Class 2 buildings) construction projects by the WERS administrators.

Stating two different compliance mechanisms for glazing products (drop-down menus within NatHERS-accredited software), it articulates that:

  • a ‘default window database’ is intended for use where the final window product is not known and uses performance values as a stand in for real products until the final decisions on product procurement are made, and
  • a ‘full Australian Fenestration Rating Council (AFRC) database’ can also be used, which includes products which 'are real product performances which have been calculated in accordance with the AFRC protocols and procedures.'

The challenge is that in planning, products from a ‘default window database’ are quickly assumed by an ESD consultant to gain a preliminary compliance solution, often regardless of performance knowledge, façade cost or practical feasibility. To be clear, these assumptions are not related to stand-in products, these are nearly always the products that get a design over the line in the DA process. Not disappearing, these products remain in focus until the tender stage, where the actual performance values, based on clear budgets and market constraints are first obtained via the façade fabricators or façade consultants.

As we head into the design process, where system dimensions often change or become further refined, the actual system performance is often reduced. Put simply, the WERS default window database uses custom frame sizes that are often advantageous from a performance point of view for DA but unlikely so beneficial from an architectural point of view once we get to tender and thus pricing.

If we work through a quick example, WERS assumes a curtain wall system default module size of 2,000 millimetres by 2,000 millimetres. For benchmarking, why not use these measurements? But where a commonly designed system from a price and architectural standpoint is 2,600 millimetres by 1,200 millimetres, this reality changes the performance playing field. Due to the increase in frame to glass ratio in the actual system, our thermal performance is decreasing and putting pressure on the design team to ‘make it work’ by re-running the numbers and holding up construction!

From a procurement point of view, as indicated above, today’s mid to high-rise Class 2 construction market is dominated by bespoke fabrication and not those listed in the Certified Products area of the WERS website. Often designed and procured from international markets, Class 2 construction fabrication needs the economies of scale and price points not commonly available due to local labour and operational costs.

All of this is not new, and it is often passed onto the main contractor in a D&C procurement process. As we witness the continual rise of Class 2, glass-dominated construction and the need for hard and fast economies of scale that can nearly only be found through access to international procurement chains, the WERS database we will continue to be disconnected from the planning, design and procurement of façade systems.

As Albert Einstein once said, “doing the same thing over and over again and expecting different results is equal to insanity.” If the WERS database is to be used for Class 2, make it more relevant of actual procurement processes and performance opportunities for a higher performing built environment. Surely the inclusion of actual values within the NatHERS compliance process based on experience and market awareness is a better resolution than depending on inflexible and overstated WERS products?

  • "[ … ] these products remain in focus until the tender stage, where the actual performance values, based on clear budgets and market constraints are first obtained via the façade fabricators or façade consultants."
    If the economics of the system is left this late to test then surely management of the design is incompetent. In high-rise design development, the costs of facades is substantial and the project manager and design team should, through the quantity surveyor, already have a strong view of the cost long before any project procurement process. Using a D&C process with early contractor engagement is no different.

  • D&C or otherwise: I reckon part of the flaw is building procurement is when we have project managers/main-contractors/subcontractors/suppliers as***INSTALLERS ONLY***, thus negating their responsibilities. Sorta: tell me what you want – we'll price and deliver it. By default; statute requirements/compliance is the responsibility of everyone from designer down the food chain. Designers cannot be exhaustive in documenting all regulatory requirements – e.g. cannot list every item in the BCA. For instance: if they do not document tactile floor indicators, does not mean it is not in the Contract Sum since the contractor is contractually bound to the BCA – any mention by designer serves as a reminder or that the designer wants to control the appearance of it. I'm finding contractors and window fabricators not up to speed with window thermal performance figures. They need to be educated via building industry associations [e.g.MBA, HIA, ACC etc] or AWA RWA etc. They must have the WERS website as part of their office culture. Too often, they look up glass figures only than for total window. And window fabricators do not provide proper certificates covering NatHERS or Section J compliance [at least by citing manufacturer's WERS ID codes]. Probably can be more problematic with imported windows.

  • It remains the case that the NatHERs framework allows for either a specific window product to be used or default window systems that closely mirror the actual performance of actual windows can be used. These "default" system have a broad range to choose from and the NatHERs system does really provide an important assessment to determine the energy efficiency of the building envelope -that assesses both Class 1 and class 2 buildings.NatHERs is a good system -we are fortunate to be able to make use of it.

  • This article raises areas for the industry to consider such as potential improvement and development, but there are also a number of issues of concern that it raises from the glazing industries perspective. The description of WERS as a system allowing the assessment of performance on “a like for like basis” is correct, comparative size ratings do indeed simplify the process in order to reduce the number of ratings that are required for compliance purposes and reduce the unsubstantiated claims that are out in the market. In many of the comments made in the article the one area that is not covered adequately is the compliance requirements. By selecting a default window in an initial simulation for DA, the only way to achieve the compliance in the built site is to by providing a product according to the compliance rules as stated on the certificate. This is down to a performance stated in the default window (note the default windows are not owned or developed by WERS, they were developed by the AFRC for the NatHERS administrator), the issue here is not with the WERS database but with the default windows and their ability to accurately reflect real windows. Suggestions have been made for other methods of default windows. Compliance is also an issue in the use of “bespoke fabrication and not those listed in the Certified Products area of the WERS website” as the NCC calls for products that measure “combined glass and frame performance according to AFRC requirements” and at this point in time WERS is currently the only AFRC certified energy rating publisher. The substitution of products and use of products with European, glass only or other performance figures is putting the end sustainability of the final building at risk.

    • While the author has not contacted the Australian Window Association, Window Energy Rating Scheme or the Australian Fenestration Rating Council for clarification, explanation or comment regarding this but we agree that it is time that the industry work together to achieve an outcome that will provide the best sustainability outcomes, ease of use for all parties and move forward collaboratively.

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