RAA IN PRACTICE | Could We? Should We? Inside the National True Zero Carbon Design of the Year

The Session
Sarah Lebner of Cooee Architecture and the team from Powerhaus Engineering share the thinking behind Could We? Should We?, a case study home named National True Zero Carbon Design of the Year 2026.

The True Zero Carbon Challenge, run by Design Matters National, asks entrants to balance three things in a single family home: budget, NatHERS energy efficiency, and embodied carbon measured with the EPiC database. Most designs perform well on one or two. Getting all three to work together is the real challenge.

The winning design is a compact two-storey home of 161m². It achieves an official 8.7 star NatHERS rating, lifting to 9 stars once 3ACH airtightness is accounted for. It uses conventional construction and materials at an estimated all-inclusive build cost of $800k.

Sarah and Powerhaus will walk through how the architecture and the building science informed each other, where the sweet spots sit between cost, performance and carbon, and why chasing a single metric isn’t the answer for most Australian homes. They’ll also share visual data and comparisons that test common myths and answer common questions about high-performance homes.

Sarah Lebner
Sarah Lebner is the Director of Cooee Architecture, a regional practice focusing on energy-efficient, resilient, and low-carbon homes. Cooee practices throughout the Victorian High Country, NSW Snowy Mountains, and surrounds. Prior to relocating, Sarah was the Principal Architect at Light House Architecture and Science in Canberra, a multidisciplinary practice focused on evidence-based retrofit and new-build affordability.

Sarah is also the author of 101 Things I Didn't Learn in Architecture School, recipient of the 2023 Dulux Study Tour Prize, and the Australian Institute of Architect’s 2020 National Emerging Architect Prize winner.

Andrew Pickard
Director, Powerhaus Engineering and founder of the Powerhaus app
Andrew Pickard is an engineer with more than 12 years’ building-performance experience, including optimising the Australian Government’s YourHome plans for 7-star performance across every climate zone. He co-founded Powerhaus to help architects cut through compliance red tape. His thinking behind the Powerhaus App turns clunky energy-rating processes into clear, practical feedback, helping architects design better homes for their local climate. Winner of the True Zero Carbon Challenge together with Cooee Architecture. 

Matt Godfrey
Solutions Development Engineer, Powerhaus Engineering
Matt Godfrey is a physicist and engineer developing the tools behind the Powerhaus App. He turns complex thermal modelling into clear comparisons, helping architects test how glazing, materials and specifications perform in local conditions. Combining physics with software development, Matt makes building-performance analysis faster and more useful while design options are still open.

CPD 1 formal point (performance criteria 3, 31, 33, 35, 41 and 45 / AACA National Standard of Competency for Architects 2021).

RAA members use the discount code from the member content area for free admission.