Flick the Switch: Monash University has set itself the challenging target of getting its campuses to net zero by 2030 and unlike some other organisations that set similar goals, it has a plan to get there.
Top of the list for Monash is the low hanging fruit of energy efficiency, followed by building electrification and procuring/using 100 per cent renewable energy. Once the building has its emissions profile as low as possible, remaining emissions will be offset.
One new build that neatly captures this vision is award winning student accommodation building Gillies Hall at Monash University.
Gillies Hall has attracted lots of attention – and a couple of awards – for taking two major risks: going for the ultra-low energy use Passive House certification on a large building (the first in Australia) and using cross laminated timber (CLT), a low carbon material that was fairly new to the industry at the time.
The gamble has paid off financially. Recent lifecycle assessments show that over a 30-year period the student accommodation building will cost less than a standard build.
According to building services engineer on the project, AECOM associate director Nick Bamford, it was a marginal cost improvement but for a building that came with high risk premiums attached, it’s a win.
“It’s still a thumbs up for Passive House on a 30-year lifecycle basis,” he told The Fifth Estate.
Interestingly, despite using an unfamiliar construction technique and material, the build itself was only slightly more expensive than a traditional build. One reason for this, according to Bamford, is that the lower floor to façade ratio Passive House requires for thermal performance reasons also means significant savings on expensive façades.
Crunching the numbers revealed that the building was consuming more electricity than expected.
The likely explanation is the building’s operability and a massive variation in temperature in student rooms, with students choosing to heat rooms anywhere between 17 to 27 degrees overnight.
According to Rob Brimblecombe, the head of the university’s net zero program, while there’s no “active” heating or cooling in the accommodation, the university wanted students to have choice and control over their thermal comfort.
He says that while PH’s heat recovery ventilation system provides excellent air quality even without relying on occupants to open windows and doors, the university wants students to be able to open windows or use supplementary heating such as a panel heater if they wish.
And it’s clear the students have made full use of the operability.
Even so, and even with this wide temperature range, Brimblecombe says the building is still “outperforming by a long shot”.
An ongoing education program for residents of the building includes offering students ways to manage energy use in both cool and warm seasons to more effectively use the natural ventilation and passive heating and cooling.
Timber and Passive House – a winning combo
While Passive House was always part of the plan for Gillies Hall, timber wasn’t. Pretty late in the design process, the university took the opportunity to try this low embodied carbon material.
According to Nick Bamford the choice of timber aligned with time constraints and the desire to minimise disruption. In addition, the choice of cross laminated timber (CLT) in particular, offered a much quicker and quieter construction material than steel or concrete.
But the late decision on timber meant going back to the drawing board on the design.
“It was right back to first principles, which was good and bad,” Brimblecombe explains. “It meant more work but also that the building was designed from the ground up.”
Timber turned out to be super compatible with Passive House requirements around airtightness, insulation and thermal bridging. It has inherent insulating properties and low thermal conductivity, which made the material more forgiving in the few instances construction didn’t go to plan and the interior was pegged right back to the timber façade.
CLT also comes as an airtight product, which de-risks and speeds up the task of achieving airtightness.
Compared to the upper floors that relied on timber for airtightness, it took far longer to achieve airtightness on the ground floor podium made of concrete, metal studs and precast.
The façade, made of CLT panels with a continuous moisture barrier, cladding of cement sheeting and shading structures, also works hard to deliver a high thermal performance.
It took a couple of attempts but in the end, the building comfortably passed Passive House airtightness benchmarks with 0.53 air changes per hour (buildings must be below 0.6 air changes per hour to pass).
The building also has an all electric thermal plant and rooftop solar. For the remainder of its energy needs, it relies on the university’s power purchase agreement with the Murra Warra Wind farm – making the residences powered 100 per cent by renewable energy.