A Glass Facade on a Certified Passive House

I’m building my own home at the moment, to certified passive house standard, and for the glass facade I’ve gone with a system from Candour, the prefabrication company founded by the architects behind Archier. As far as I know, this is one of the first times their structural glass facade has been used on a certified passive house, which makes my build a bit of a test case, and this post is my working notes on why I chose it and how it actually goes together.

When the builder’s own home is the job, you get to make the choices you’d normally talk a client through. This was one of mine.

What Candour is

Candour was founded in 2022 by five architects, including the directors of Archier, the award-winning practice, and it grew out of their frustration with how hard it has become to deliver well-crafted, sustainable, healthy buildings. Their answer is a design-led prefabrication system: a suite of customisable building components, floor, walls, roof and facade, manufactured in their own facility, with CAD plugins for Archicad and Revit that give architects instant pricing and buildability feedback while they draft.

That last part deserves a moment. The plugin connects the drawing directly to the fabrication facility, so the designer knows what a facade costs as they design it, not three months later when the quotes come back wrong. Anyone who has watched a beautiful design get value-managed to death after tender understands what that solves. It’s the same shift I keep writing about with AI in this industry: close the gap between a decision and its consequences, and the whole process gets better.

The facade system itself

The system I’m installing is a structural glulam timber frame with face-fixed glazing. In plain terms: beautiful engineered timber mullions and transoms do the structural work, and the glass fixes to the face of the frame, held by mounting pins and then pressure plates with gaskets inside and out. Powder coated finish caps clip over the pressure plates as the final trim, so the fixings disappear.

A few details from the install that show the thinking in the system:

• The sub-sill does the hard work first. A machined LVL sub-sill goes down before any frame, setting out every connection point and letting you get the whole run dead level before the frames arrive on it. Custom washers drop into machined locations directly under each mullion.
• Frames arrive as loose members and assemble on site, then tilt up as complete units with a continuous seal across the bottom. Concealed dado bolts clamp them down through the sill into machined threaded barrels, corners laminate together with pre-piloted screws, and the holes get plugged with timber. No visible fixings.
• Joining members use factory-installed Knapp connectors that slide in from outside and clip between assembled frames. Precision joinery logic applied at building scale.
• For passive house spec, an additional insulation strip sits between the glass panels, on top of the standard gasket arrangement.

It’s a system clearly designed by people who have stood on site watching things not fit. Everything is machined, pre-piloted, located and levelled before the expensive, fragile parts arrive.

The airtightness game

Certification lives or dies on the blower door test, and here’s what experience teaches you: the taped membrane field is never the problem. Your Intello can be perfect across every wall. The leaks come through the details, and glazing is the detail that bites, so this is where my attention is going.

The approach on my build, for anyone attempting similar:

1. Slab to sub-sill: foam fill between packers, sealant behind, and a liquid membrane bonding the slab edge and wrapping up around the top of the sub-sill, one continuous connection from slab to system.
2. Window head: an airtight starter strip running along the full top plate, flashing tape up and over, with the joists then landing on top. Get this in before the joists and it’s easy; after, it’s misery.
3. Timber-to-timber joins: a sealant bead at mullion bases and around every bolt penetration. Every fixing that passes through the airtight layer is a hole unless you treat it as one.
4. Corners: the cruciform junctions rely on glazing tape rather than the internal gasket, which makes glazing day itself part of the airtightness work, not just the waterproofing.
5. Protect the gaskets during install. Internal gaskets roll aside and stay out of the way until the heavy work is done. A nicked gasket is a leak you’ll spend a day finding at test time.

The meta-lesson: on a passive house, airtightness isn’t a stage of the build, it’s a lens on every stage. Every trade, every penetration, every “she’ll be right” moment is a future smoke-pencil discovery.

Why this matters beyond my house

I write a lot about designing homes that make life better, and this build is me putting my own money where that philosophy is. A certified passive house wrapped in structural timber and glass: healthy, comfortable, almost no heating load, and genuinely beautiful. Ten years ago, getting that combination meant a bespoke facade engineered from scratch at eye-watering cost. A system like Candour’s, priced from within the CAD file and manufactured locally, is what it looks like when that becomes accessible.

That’s the direction I want this whole industry to move: better buildings, delivered through better process. I’ll report back after the blower door test, and I’ll be honest about the number either way.