Passive Design
Oct 2024
Part 2 of a series exploring passive building design.
The case for passive design used to live in glossy magazines and government brochures. Now it lives on your power bill. Energy in Queensland has risen roughly 38% in real terms across the past decade, and the federal Trajectory for Low Energy Buildings projects continued upward pressure as the grid electrifies. For a Brisbane homeowner, the question is no longer whether to design for energy — it's how aggressively to overshoot the current minimum.
The 7-star floor, in dollars
From 1 May 2024, every new Class 1 home in Queensland must achieve a minimum 7-star NatHERS thermal rating. ClimateWorks Centre modelling of an average new Australian home suggests moving from 6 stars to 7 stars reduces predicted annual heating and cooling energy by roughly 22%. On a typical Brisbane 200 m² home, that's a $400–$700 annual saving at 2026 retail rates — and the gap widens as electricity prices climb.
The Whole-of-Home rating (introduced alongside the thermal change) folds in your appliances, hot water, solar, and any battery. A high Whole-of-Home score can push the lived utility cost of a well-designed Brisbane home below $1,000 a year. Some go further: net-export, where the home produces more electricity than it consumes annually, is now achievable on a standard suburban lot with a competent solar/battery sizing and a tight envelope.
The valuation premium is real, and rising
The Domain Sustainability in Property report tracks sustainability-feature uplift on asking prices and time-on-market. In their 2024 dataset, Brisbane houses listed with solar, double glazing, and efficient heating/cooling sold roughly 6–9 days faster and at 2–3% higher median price than comparable homes without. As mandatory disclosure of energy efficiency at sale gains traction federally (the ACT already requires it; Victoria is consulting; Queensland is monitoring), expect that premium to harden.
Insurance is repricing the buildings you can't see
The flip side of valuation premium is insurance pricing. Following Brisbane's 2022 floods and the 2019–20 fire season, insurers have repriced flood and bushfire exposure substantially — the Insurance Council of Australia has flagged some river-bend Brisbane streets as effectively uninsurable at retail premiums. A passively-designed house with a thoughtfully elevated finished floor level, good drainage, and bushfire-resilient detailing is materially cheaper to insure over its life than the same house built to bare-minimum code. The savings compound silently, year after year.
Government support — what's real, what's not
Be careful here: there is no single "passive design rebate" in Queensland. What does exist:
The federal Small-scale Renewable Energy Scheme (STCs), which discounts rooftop solar by typically $2,500–$4,000 on a 6.6 kW system.
The Queensland Battery Booster Program (subject to budget cycles; check current funding before promising clients anything).
The Energy Saver Scheme mechanisms covering specific appliance upgrades.
The biggest financial lever is the design itself, not the rebate. A 7.5-star home that hits Whole-of-Home 75 will save its occupant five-figure sums over its first decade — without needing a single grant.
What it costs to build past the minimum
Common builder pushback: "going past 7 stars adds X% to the build cost." The honest answer for Brisbane is closer to 1–3% of base build cost if the passive logic is baked into orientation and form from day one, rising to 6–8% if you're trying to retrofit performance into a poorly-oriented design with feature glazing facing west. The cheapest performance is the performance you draw in at concept stage, before the slab is set.
The next compliance frontier — embodied carbon
NCC 2025 introduces voluntary embodied carbon reporting for commercial buildings; the residential pathway is widely expected to follow in NCC 2028. The carbon emitted to manufacture and transport your building's materials — concrete slabs, brick, steel, aluminium glazing frames — is increasingly counted alongside operational energy. Passive design that reduces operational energy and uses lower-embodied-carbon materials (timber framing, recycled content, locally sourced) hits both ledgers. Designers thinking five years ahead are already specifying with this in mind.
In the next instalment we move from why to how — the practical design moves that take a Brisbane house from 5 stars to 8.
By Ashton Genrich — Building Design — Open, QBCC 15387939