Facades are major determinants of building performance, however they can be a battleground for designers, engineers and clients to ensure great ideas are also compliant with Section J of the Building Code of Australia, which sets out requirements for building thermal efficiency.
Where outcomes don’t meet thermal performance standards, variations mean innovation often becomes a casualty. InEnergy, a new open-source software tool engineered by Inhabit Group, aims to prevent the dumbing down of designs and assist clients and designers to achieve higher performance outcomes without adding to costs.
Generally, assessing a design’s compliance requires that an architect have it assessed by a consulting engineer, Darren O’Dea, building physics (ESD) manager for Inhabit Group, told The Fifth Estate.
With the tool, designers can assess an early-stages facade design against the requirements of Section J – JV3, an alternative solution compliance pathway that uses a 3D energy model of the proposed building. It can also model the metrics for high performance solutions, and provide outputs for Green Star and NABERS energy calculations.
If the design is not going to achieve JV3 compliance, InEnergy offers an array of options for changing it to do so. This means an architect can be presenting designs to clients that are already likely to pass with consent authorities.
Smoothing out relationships
“It moves an aspect of detailed design up front,” Tai Hollingsbee, director and design research leader at Studio Huss told The Fifth Estate.
It also soothes out what he described as the “love triangle” between architect, engineer and client.
In the traditional workings of the triangle, he said, the architect proposes a design, the client goes “yeah!”, and the engineer says it doesn’t comply because energy performance and BCA compliance have often been left until the last stage of the design process.
The architect then has to explain this to the client, and propose a varied design, and the whole dance starts again. The other thing that sometimes happens is the designer, the client and the engineer are all happy, and it goes to lodgement but then the consent authority says it doesn’t comply, and then it’s back to the drawing board again.
This is why design solutions are often “dumbed down” to balance out the extra costs that are incurred during the to and fro process, Mr Hollingsbee said.
The other area for potential conflict is when a client is smitten by a design idea that is simply not going to comply, which is where showing them the metrics with the tool could really help the discussion along.
Performance and aesthetics
At stake is building performance. Mr O’Dea said 90 per cent of a building’s thermal performance comes down to the facade and building envelope. It’s also the crucial factor from an aesthetic point of view.
The facade design also determines whether it needs to achieve compliance via full JV3 modelling or if it can demonstrate its compliance via Deemed To Satisfy provisions.
The modelling required for the DTS path involves testing the design against a number of external standards including the Australian Fenestration Rating Council. The AFRC requires that glazing and framing be modelled against set boundary conditions to calculate the performance (U-value) of a particular glazing and framing combination. The U-value is how much heat it will transfer into the interior under specific conditions. Mr O’Dea said these standards have been “poorly communicated across the industry”.
And that’s where it can get interesting, as the performance is dictated by architectural intent – the amount of frame involved in the design – as well as engineering, Mr O’Dea said.
Aluminium framing – which is used extensively by many projects – performs 10 times worse than glass. And glass performs five times worse than wall. So the usual solution would be to tweak the existing design and make the frames and windows smaller or higher performing and increase the wall if the initial design proves non-compliant.
Running the initial design modelling through the new tool, however, generates options – for example swapping the aluminium framing for thermally enhanced framing or adding shading elements.
According to Mr Hollingsbee, the fact this can be done in real-time on a laptop or in a design meeting means an architect can also show a client why specific decisions are being made in the design, and can also test client-suggested variations on the spot.
There are also issues with changes to the code, and the difference between what models might say and what manufacturers might deliver.
“What we’re [also] finding is someone assumes a certain glass and frame from the NatHERS database [for the modelling] but they don’t buy the products from a database, they buy from a fabricator, so the end product may not meet specifications,” Mr O’Dea said.
“The tool will allow a user to generate values based on the actual design, not on a database.”
A user’s point of view
Mark Louw, director – architecture at Allen Jack + Cottier, told The Fifth Estate that his practice keeps samples of the palette of glazing products they use for projects and that each sample specifies its U-value. This will allow the firm’s architects to input the actual U-value of the product they plan on specifying for a design into InEnergy as part of the modelling process.
The practice works mainly across educational, retail and residential buildings, including the health and retirement sectors, which he said are building typologies where extensive glazing is a basic requirement. High performance facades, like the one recently unveiled for the new library at University of Western Sydney Penrith campus, have proven complex to model and achieve compliance on.
Mr Louw said there were three recent projects where full JV3 modelling was required because the facade could not meet the requirements of the DTS model.
He said for a building like a retail shopfront or car showroom, where expansive and unshadowed glazing is imperative from the building user’s marketing point of view, his firm’s solution was generally to use double glazing instead of shading the glass. The new tool can account for these types of solutions, and for design decisions like using a blue feature glass in a facade.
“It resolves a big issue we have as a designer,” Mr Louw said. “The facade choice of materials is critical, it defines the form, function and appearance. And usually we have to pass it on to an engineer to get the modelling done, and the turnaround is not always fast enough.”
Getting the modelling done quickly is important so budgets can be created, cost-effective solutions developed and a final design agreed that will be compliant when it is lodged with the consent authority. This modelling, he said, has generally involved a large upfront cost, and it gets very expensive if the design doesn’t comply at DA stage.
“We have been working in a bit of a vacuum. We do the work, do the 3D model, show the client, then go to lodgement, then start preparing the detailed design, do the JV3, then it goes to the engineer, then it goes back to the client,” Mr Louw said. “The tool will facilitate the process.”
He said the tool would be useful for immediately assessing a design idea that arises during a meeting with a client, instead of saying to them, “I’ll have to get back to you on that”, and then emailing the consulting engineer and waiting for a reply.
The tool also has value from a risk management point of view.
“A lot of buildings are being costed at the preliminary stage, so the quantity surveyor asks, “What’s your facade?” Then it goes to JV3 and you find you have to change it – and no one likes a surprise,” Mr Louw said.
By enabling designs that depart from standard models to be quickly tested by designers against best-practice performance criteria, it will save time and design variation cost.
“As engineers, we see a lot of conflict over facades,” Mr O’Dea said. This leads to designs being “dumbed down and value-managed”. In many cases, the outcome of this is a loss in performance terms of being merely compliant, not a truly smart and sustainable building.
He said the tool gives architects an opportunity to retain the value in their designs, and will make it easier for younger architects who have not yet acquired the depth of understanding of the technical values of what they are creating to achieve compliant, high-performance results through exploring options. For senior architects, it also has a value in terms of assessing the ESD value of design decisions.
“If you can make sure the project is compliant up front, then you have extra dollars to invest in super-optimising the building,” Mr O’Dea said. “JV3 doesn’t super-optimise; it doesn’t look at the way services and new technology can add to performance outcomes.”
In other words, the budget that is not burned up to-ing and fro-ing on the facade can be used for a better mechanical services solution, or energy-efficient lighting, or other sustainability gains.
Inhabit has used the tool on numerous projects as part of the development process, approximately 30 in the past year alone.
Why make it open source?
The reason the company has chosen to provide the tool as an open-source resource to architects and others including builders and fabricators, is to simply assist the industry to achieve smarter, compliant outcomes in a more time and cost effective way.
“We are adding real value to the industry, and addressing a real concern in the industry,” he said.
Mr Hollingsbee said the tool would be “amazingly disruptive”, as it allows an architect to iterate things relating the facade performance very quickly and at the front end of the design process. This may, he said, take away a share of work from engineering consultants who specialise in analysing design proposals for JV3 compliance.
And he thinks it will force the industry to change.
“In the face of what’s happening now [with sustainability and building design], it is a tool for creativity, rather than limiting,” Mr Hollingsbee said.
“It’s an enormously useful tool, there is nothing else up there that can do this. That’s an exceptional game-changer.”
Having used the tool on a number of projects, Mr Hollingsbee said he believed it could also lead to improved compliance in the final building outcome, and also assist designs to achieve performance better than the BCA mandates.
“The BCA code is behind international best practice,” he said, “both in terms of standards of compliance and methods of compliance.”
One of these areas where it is behind is in building tightness and pressurisation. The tool, he said, could help designers appreciate both natural air change rates and air tightness of proposed facades.
In achieving a sustainable building, both natural ventilation through the operability of a facade and the air tightness of the construction are important, something Mr Hollingsbee described as “the idea of the dual in design”.
The other potential he sees is for the tool to assist architects with pushing the case for new materials such as engineered timber in innovative ways, and for it to be used fine-tuning design concepts involving prefabrication.