Is this the HVAC system of the future?

A research collaboration between architecture firm BVN and the University of Technology Sydney (UTS) has created a 3D-printed air-diffusion system that has the potential to slash embodied carbon and installation costs – and disrupt the status quo of mechanical services.

The Systems Reef 2 (SR2) is an alternative to traditional ductwork that is 3D printed by a robot using recycled plastic. The project team says it offers a 90 per cent reduction in embodied carbon when compared to existing systems.

As well as being shaped to facilitate airflow, the tubes that make up the system have thousands of pores, also placed by robot, to distribute air more effectively than traditional ductwork.

“Rather than dumping air at routine intervals across a floorplan, this design distributes the air evenly,” says Associate Professor Tim Schork from the School of Architecture at UTS, and Chief Investigator on the project. “There is a more consistent air temperature and flow and nobody needs to sit under the cold draught of a high-powered vent,”

Raising their sights

Fellow Chief Investigator and BVN Co-CEO Ninotschka Titchkosky says the idea for the project emerged from the work her firm has been doing on corporate offices over the past 20 years.

“There are certain problems that have not been solved,” she says. “One of them was how do you make people and furniture fully mobile within an office environment? Every time you want to adjust a bit of air conditioning duct or you want to move a desk it’s always costly and you have to bring in professionals to do that work. We find that adjusting the services and tidying them up can cost in the order of 45–50 per cent of the total fit-out costs.”

The firm also noted that although there had been some improvements, the fundamentals of ductwork systems had not changed for more than 50 years. It seemed like an area ripe for innovation.

This dovetailed into another piece of work BVN was doing around power and data services (SR1), in which the group was rethinking the “services ecology” in a building. They knew that air conditioning issues were typically in the top three complaints of tenants in commercial buildings, and that if they were to provide a holistic solution, they would have to tackle delivery of air.

Studying the status quo

Teaming up with UTS, BVN conducted a deep dive into the mechanical services industry. This discovery phase of the project looked at the changeovers between mechanical consultants, mechanical subcontractors and manufacturers in what Titchkosky describes as an often dissatisfying process.

“Sometimes the mechanical consultants will spend a year doing a whole design, and then the subcontractor will come in and completely change it, and then the manufacturer will tweak it again,” says Titchkosky. “Through that process we tried to look at the redundancy that is built into the current status quo.”

It was much greater than they had anticipated, and not only in terms of time wasted through the project life-cycle.

“We were discovering that duct manufacturers want to do it in 1,400mm lengths, they want to manufacture to these set sizes,” Titchkosky says. “Anything bespoke is basically handmade. And then every time you were connecting [parts of the system] you were getting air losses. So the system was sized to handle that level of redundancy, and that was in the order of 15 per cent.

“I guess the main point was that the systems were designed more for the manufacturing process rather than the way air wants to move.”

CFD analysis confirmed these inefficiencies.

“Air doesn’t move in right-angles,” Schork says, “so it’s not logical to design an air distribution system with square corners. We need to develop new approaches to design, materials and construction.”

Cutting down on carbon

During the research phase, the embodied carbon in existing systems also became apparent. According to The Footprint Company, services account for approximately 33 per cent of the total embodied carbon of a typical office building. Within that, the mechanical system represents about 25 per cent of the total embodied carbon of services, and ductwork makes up 60 per cent of that 25 per cent.

This finding tied in with the robotic fabrication work that BVN has been doing for several years. The team explored the option of creating forms that were not limited by traditional manufacturing processes. They also investigated printing with recycled plastics. The SR2’s elements are made of PETG – commonly used in water bottles – which can be crushed, melted and remade again, creating a closed loop of materials.

Because the system is relatively light and clicks together with rubber gaskets, it requires only half the number of fixings in the slab. The team estimates labour savings in installation of around 50 per cent.

Finally, the project team created tools to digitise the design and manufacture process.

An AI-based algorithm helps correctly size each of the components to a zone, and 3D printing can taper elements as they get further away from the VAV unit. In the “living lab” set up in the BVN office, the team achieved a 70 per cent overall reduction in cross-section of the duct, and a 30 per cent reduction in the length of the elements compared to conventional ductwork, because of the shaping and efficiencies of the system.

Next steps

Arup has provided mechanical engineering consulting on the project, and has helped identify areas where more testing, verification and certification work is required. But Titchkosky says any issues they have identified so far are solvable.

Now that the technology has been patented, the team is looking for potential partners such as impact investors, manufacturers, and even government.

“The good thing is we’re at sweet spot at the moment where everybody is more focused on issues of circular economy and material waste,” says Titchkosky. “There’s a spotlight on the construction industry and the contribution it makes to climate change.”

Titchkosky says the team is also aware of the need for mechanical engineers and subcontractors to engage in the new development.

“We’re really keen to share it with [the HVAC] industry, and understand the barriers that people think are out there to something like this, to see if we can pick through those,” she says. “Also to try and get everyone going in the conversation that the status quo doesn’t have to be the only way. We need to start thinking differently, and everyone’s got a role to play in that.”

For more information on the SR2 project, click here.

Image of SR2 installed in the BVN office courtesy of BVN