Youre building this to the Passive House standard used in Europe. Can you give us some background on this system?
The Passive House concept looks at reducing the amount of energy used in heating and cooling. In a European context this means reducing energy consumption for heating to less that 15kwhr per square metre, per annum. This is incredibly small. You effectively do this by building a highly efficient thermal building with an efficient skin, through which you can completely control what comes in and what goes out. Solar heat comes in through the windows and is retained within the building. Basically, with this system, the overall calculation of what comes in and what goes out is at a much finer degree than what we are used to in Australia.
And does this code need to be adapted for the Australian context?
The skin is highly insulated, which means it creates a completely different type of living. The one large glazed façade you find in older apartment buildings brings in a cold draft in winter even when it is double glazed. You tend not to live near the window in winter. But that is totally different in a Passive House. The external skin has almost the same insulative characteristics as an internal wall so you can really live with it in winter.
In winter, well use hardly any auxiliary energy for heating. In summer, well use some additional cooling energy by pulling in the cooler air, and perhaps a hydronic cooling system but were still researching this. The aim is to have as little temperature differentials as possible all the surfaces should be the same temperature. In Australia, we have the reverse of Europe: well use little energy in winter, and more in summer.
Youre bringing in the prefabricated panels from Europe for this project, is that right?
Yes the façade skin, as well as the cross-laminated timber (CLT) structure. At the moment, its a huge technology transfer. Our consultant team here is learning from the consultant team in Europe. Doing this type of building for the first time in Australia, and on this scale, we have to rely on the expertise of those who have done this before. The objective is, further down the line with projects two and three, the technology transfer has happened so we can do this ourselves and use local knowledge.
Is it a modular design that is easily adaptable?
It is modular, because its prefabricated, but it takes full advantage of the flexibility of timber. Its much cheaper to saw cut a large piece of timber into shape, than it is to laser cut a piece of steel. The speed of assembly and prefabrication associated with that is quite great.
How much of the building structure will be timber? Are you looking at a hybrid structure that also includes steel or concrete?
There is a reinforced concrete podium structure that sits behind the CUB bluestone wall that we have to preserve. This is part of the podium that sits in front of ARMs building [the Portrait tower]. Our timber building will sit above the podium. Were aiming to have everything above that point built in timber, if we can. On a structural level, its all possible but we need to comply with acoustic codes, fire codes and so on and that might have an impact.
Will the timber also be expressed on the façade?
Were still going through design variations. We havent made a final decision but we dont want it to look like the classic, minimalist timber boxes that you see in Europe. We want it to be an aesthetic challenge so that a European designer might see it and say, wow, thats a Passive House? And its in Australia? We want to push the boundaries. The façade systems that are highly insulated use a lot of timber and recycled pulp, but the external skin could be coloured glass, metal, anything. We want to use sustainable materials, but its important that the final skin deals with water run-off so it might be more efficient to use another material.
The huge advantage of working with timber is, as a porous material, it doesnt transmit coolth or warmth through it unlike a concrete slab. That allows us to be much more flexible in the interface design between the main structure and the façade. It also means the timber elements can be profile cut to a particular geometry at almost no extra cost this is much cheaper than creating a free-flowing edge in concrete.
Its given you more freedom than expected with prefab, then?
The freedom is fascinating. Were trying to find where these particular technologies are freeing us up as designers.
And actually, the notion that pre-fabrication is restrictive has totally changed. The highly influential thinkers from the 1960s and 1970s Buckminster Fuller, Konrad Wachsmann in the last 10-15 years, their vision of what could be possible in pre-fabrication has come into play. There is much more liberation with design, we can create freer forms to a much higher quality. We can do everything in a pre-manufactured way more precisely, and to more exacting standards, than is possible on site.
Seeing these factories and what they do [in Europe], I was amazed at how competent they are when it comes to really complex geometric structures. Its now simpler and cheaper for these companies to build complex forms, such as rollercoaster rails that have to curve in two directions, in timber than in steel. Technology is almost reversing.
Have you found they are surprised we dont use similar methods in Australia?
The cross-laminated timber is an engineered product. It uses standard timber elements and bonds them together to form these thick, strong structural panels. What doesnt exist in Australia is a factory to carry out that process it relies on a large amount of space, and big machines, and it only makes sense when you have the demand for such a product in high volume.
But there is a future for it here. It needs some big thinking. Timber is a wholly sustainable source: it re-grows, and as it grows it consumes carbon. If we can grow this industry in Australia, were doing something good for the environment. The Canadian architect Michael Green is working on timber high-rise buildings too he spoke at Green Cities in Melbourne recently. He says we need to use plantation timber that is being replanted it can be harvested in 5-10 years, making it a predictable and sustainable cycle for the timber industry.
The most advanced country when it comes to this is Austria, which has created a goldmine for itself through government regulation. Whenever they fell a tree, they have to replace it. They cant reduce the overall timber stock and Austrian companies are now the leaders in this industry. Their business growth depends on planting more trees. Through the government directive, forest stock in Austria has actually increased, to meet the demand of this new technology.
So a government incentive would help grow this industry locally?
Hopefully. We have the space and we have the environment. And with New Zealand not far away, its only a matter of time until the technology makes its way over here. And some of these CLT structures because of their inherent flexibility can be highly efficient in earthquake zones. So there could be a huge future for it, especially in New Zealand.
Image courtesy studio505