The Hidden Danger in Every Old House

**“If you can’t hit 0.6 ACH on a brand-new build, you probably shouldn’t be building.”** Let’s stop tip-toeing around the reality of the Australian housing market. We are throwing up volume-built boxes and high-density apartments that are practically end-of-life before they’ve even seen their first winter. We sat down with Linden Thorley, architect, Passive House designer, and chair of the Australian Passive House Association Retrofit Committee. We take a look into why retrofitting the existing 9.5 million homes in Australia is the single biggest business opportunity for trades over the next decade. Linden walks us through the differences between a cosmetic renovation and a high-performance retrofit, detailing how his team utilises the PHPP (Passive House Planning Package) to model data and manage moisture, insulation, and ventilation risks case-by-case. We don't hold back on the real pain points of the industry either. We talk about the skyrocketing costs of business insurance, why Australian labour rates are fundamentally shifting project costs, and how to structure building contracts using provisional sums for airtightness so builders aren't crushed by unexpected site variations. Linden also breaks down his frustrations with legacy bank valuations that prioritise bloated 300-square-meter floor plans over highly efficient, smaller family homes. Finally, we hit the political wall: how heritage advisors and council planners are actively preventing energy efficiency upgrades, and the clever, practical drawing tricks **CHAPTER MARKERS** **00:00** – Introduction **02:08** – The Passive House Association Retrofit Committee & Playbook **04:12** – Finding the Ideal Market: How Long Does the Shift Take? **05:45** – Passive House as a Design-Agnostic Calculation Tool **07:11** – Can a House Be Great If It Doesn’t Reach Certified EnerPHit? **09:00** – Retrofitting Multi-Story Blocks vs. Standard Residential **10:38** – Managing Airtightness Expectations with the Builder **13:36** – How to Contract for Airtightness: The Provisional Sum Solution **15:21** – Dealing with Double Brick and Suspended Timber Floors **16:23** – The Spray Foam Debate in Subfloors vs. Walls **18:41** – The New Build Advantage vs. Retrofit Blind Spots **19:16** – A Case Study: Turning a 25 ACH House into an 8 ACH Home **22:27** – Threading Centralized MVHR Systems Through Bulkheads **23:28** – The Necessity of the ECI Process for Architects **26:16** – Why Don’t We Just Knock Them All Down? **27:43** – Renovation vs. Extension vs. Retrofit **29:47** – Do We Overcomplicate the Carbon Conversation? **31:14** – Lessons from Toronto: The 100 Macnab High-Rise Retrofit **32:38** – Drawing the Line: When to Demolish an Existing Fabric **37:28** – Forcing Council’s Hand with Legal NCC Clauses **39:34** – Is Passive House Actually a Premium-Priced Product? **41:11** – Breaking Down the True Cost of Australian Site Labour **44:46** – Linden’s Fire Loss & Installing His Own INTELLO Membrane **48:26** – Thermal Envelope vs. High-End Cabinetry **53:03** – The Intensity Slump on Modern Australian Building Sites **55:26** – Overheads, Insurance Hikes, and Free Market Economics **57:41** – The 3-Story Walk-Up: How Codes Limit Small Footprint Living **58:21** – Why Banks Hate Small Homes and Force Massive Floorplates **01:01:45** – Macroeconomics, Inflation, and Building for the Top 10% **01:08:37** – MEGT Mindful Moment: Harnessing the Un-Jaded Apprentice Mindset **01:11:16** – Connect with Linden Thorley **LINKS:** **Our Sponsors:** Pro Clima - https://mindful-builder.captivate.fm/proclima MEGT - https://mindful-builder.captivate.fm/megt **Connect with us on Instagram:** @themindfulbuilderpod **Connect with Hamish:** Instagram: @sanctumhomes Website: https://www.yoursanctum.com.au/www.yoursanctum.com.au/ **Connect with Matt:** Instagram: @carlandconstructions Website: https://www.carlandconstructions.com/www.carlandconstructions.com/ Mentioned in this episode: Proclima Sponsor