Tackling the carbon challenge in new build schools

Timber can be a flexible, attractive and most importantly, sustainable building material if used in the right way. Beca’s Jared Keen talks about how the design team on the Waimea College project redefined the priorities for the new teaching block - creating a timber superstructure and saving 270 tonnes of CO2e in the process.

We love it when our projects and our communities align. That is what happened on the Waimea College project. While our design team were putting the finishing touches on drawings for the new engineered timber superstructure for the college’s new teaching block, down the road from Beca’s Nelson office; school students were beginning their own passion project – striking for action on Climate Change. Their message: Those of us with the power to shape our built environment aren’t acting with the broader environment in mind.

In these debates, a defense of the status quo is sometimes put forward claiming that the students don’t understand - they don’t see the challenges. As a structural engineer, I don’t buy that defense. It’s my job to see those challenges, and they are the same challenges the students see. They’re not simple challenges to overcome. But they certainly can be overcome, and with the Client and Design team all pushing in the same direction, it need not be an insurmountable obstacle.

Those who work on schools projects know them to be at the pointy end of building design, where tight budget constraints meet the Ministry of Education’s rigorous design guidelines. There exists a perceived wisdom that trying to do a New Zealand two story school in timber is just too hard.

Waimea College is located just south of Nelson.That’s engineered timber country. Nelson Pine’s main factory is just short stroll from the school. The Waimea team, led by Jasper van der Lingen of Sheppard and Rout Architects, Rachel Dodd of Arthouse Architects, and Jared Keen and Georgia Whitla of Beca determined if ever there was a school to be done better (in timber) - this was it. The Ministry of Education approved the plan, initially alongside a concrete and steel option (just in case).

The design process involved the team redefining the priorities for the building. To make timber structures work in an area with the seismicity of Nelson, and without budget increases, requires the building layouts to be shaped by sympathy for how timber behaves. Rather than the traditional approach of starting with an open layout, and threading a structure through, instead it is necessary to take a layout that suits timber and peel that back until functional layouts appear. When Beca asked our architectural partners if they (and the school) were willing to make the necessary layout sacrifices on the altar of sustainability, the answer was a firm ‘Yes!’.

As a result, the superstructure of the building is now timber, consisting of Laminated Veneer Lumber (LVL) beams, LVL and ply hybrid walls, and Potius floor. Superstructure concrete has been removed completely, and steel is limited to the connections. The result is a significant reduction in embodied carbon and a rather lovely building to boot.

This move to timber means Waimea College's new teaching block superstructure has approximately 82 tonnes of CO2e sequestered from the atmosphere into sustainably forested timber, and a further 190 tonnes CO2e of emissions avoided by removing the concrete and steel from the superstructure. 270 tonnes of CO2e all up.

What does 270 tonnes CO2e look like? To give a sense of scale, that represents around 110,000 school drop-offs worth of carbon savings (assuming a 15km round trip).  

Much more importantly, we believe it represents a new way forward for Australasian schools, and a part of the answer to the challenge being put to us by the students in those schools. It’s going to take a lot of concerted effort and some clever ideas to shape a better world. Shaping a better school building? That can be done now.