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Passivhaus . a low carbon future for our homes?

While the climate crisis is often framed through the lens of renewable energy grids or electric vehicles, Dave Borlace zeroes in on a far more stubborn culprit: the very walls we live behind. He argues that the building sector's 39 percent share of global greenhouse gas emissions is not a technological failure, but a design one, rooted in the "appalling inefficiencies" of modern construction. For busy leaders and homeowners alike, the piece offers a startling proposition: we don't need to wait for a miracle battery to solve our carbon footprint; we simply need to stop building houses that leak heat like sieves.

The Cost of Leaking Heat

Borlace opens by dismantling the status quo of residential construction, noting that current methods force us to "spend oodles of cash putting heat back into our living spaces just so it can leak straight back outside again." This framing is effective because it shifts the narrative from abstract environmentalism to immediate economic waste. The logic is sound: if a building is poorly sealed, no amount of green energy generation can fully offset the energy required to compensate for its structural flaws.

Passivhaus . a low carbon future for our homes?

He introduces Dr. Wolfgang Feist, the architect behind the Passive House movement, who proved nearly three decades ago that a home could use "about 90 less energy than a traditional house." Borlace uses this historical anchor to challenge the industry's inertia. If the technology has existed for 30 years and the savings are that dramatic, why hasn't it become the default? The answer, Borlace suggests, lies in the complexity of the build process, yet he reframes this complexity as a necessary investment. He posits that in construction, "the more time and care they give to the design details before starting the build the less time and money they'll need to spend later on expensive remedials and retrofits."

"It's all a little bit stupid."

This blunt assessment of current building practices serves as the piece's emotional hook. It cuts through the technical jargon to highlight a fundamental absurdity: we are paying to heat the outdoors. Borlace's argument holds up because it aligns with basic physics and economics, making the resistance to Passive House standards seem less like a prudent caution and more like a failure of imagination.

The Four Pillars of Efficiency

The core of Borlace's analysis breaks down the Passive House standard into four non-negotiable principles, moving beyond vague promises of "green building" to specific, measurable criteria. First is the "super insulated envelope," which requires doubling or tripling the thermal insulation of standard codes. He emphasizes that this isn't just about keeping heat in; it's about creating a "completely continuous unbroken wrap of materials around the structure."

However, Borlace acknowledges that even the best insulation fails if the design ignores thermal bridging. He explains that "steel joists and lintels are the worst offenders because of the inherent conductivity of metal," turning structural necessities into energy leaks. The solution involves intricate architectural detailing to "break the continuity of heat flow." This level of specificity is crucial; it moves the conversation from general sustainability to rigorous engineering.

The third principle, airtightness, is perhaps the most counterintuitive for the average homeowner. Borlace notes that a certified Passive House must have "fewer than 0.6 air changes per hour." He addresses the obvious fear of suffocation by introducing the fourth principle: heat recovery ventilation. These systems extract heat from exhaust air and transfer it to incoming fresh air, achieving "at least 75 percent heat recovery." Critics might note that such strict airtightness requires a complete reliance on mechanical systems, which could be a vulnerability if the power grid fails, though Borlace counters this by highlighting modern battery-integrated solutions.

"The standard that a passive house hrv system must achieve is at least 75 percent heat recovery."

Windows and the Future of Materials

Finally, Borlace tackles the weakest link in any building: the window. He admits that windows "obviously can't be insulated to the same degree as a wall," but argues that Passive House standards mitigate this through triple glazing, inert gas fills, and non-conductive framing. Beyond the glass, he highlights how the industry is evolving with "ultra slim insulation panels" that offer traditional insulation values at a fraction of the thickness, addressing the common concern that high efficiency means sacrificing living space.

He also points to emerging smart technologies, such as DC-powered lighting systems that run directly from solar batteries, eliminating the energy loss of converting power to AC and back again. These innovations suggest that the Passive House standard is not a static relic of the 1990s but a dynamic framework that absorbs new tech. Borlace concludes by noting that what was once an "expensive indulgence for very wealthy people" is now "very competitively priced compared to a traditional construction," provided the project is well-planned.

Bottom Line

Dave Borlace's strongest argument is the reframing of energy efficiency from a moral obligation to a financial imperative, proving that the most effective way to cut carbon is to stop wasting energy on bad design. The piece's biggest vulnerability is the assumption that the construction industry can rapidly scale these high-precision techniques without significant labor shortages or regulatory hurdles. For the reader, the takeaway is clear: the technology for a low-carbon future exists today, but it requires a fundamental shift in how we value the design phase of building.

"The more time and care they give to the design details before starting the build the less time and money they'll need to spend later on expensive remedials and retrofits."

The most critical next step for policymakers and developers is not just to mandate these standards, but to incentivize the upfront design investment that makes them possible. Without that shift, the 90 percent energy savings Borlace describes will remain a niche luxury rather than a global necessity.

Sources

Passivhaus . a low carbon future for our homes?

by Dave Borlace · Just Have a Think · Watch video

as you regular viewers will know i'm always going on about stuff in our modern world contributing to our ever worsening climate crisis one of the areas we haven't looked at in any great detail yet is the building sector and that's a bit of an omission because according to the international energy agency it's responsible for no less than 39 of total global greenhouse gas emissions those emissions are created by running machinery that compensates for the appalling inefficiencies in the way we currently build houses heat energy escapes from our homes through badly sealed windows and poorly insulated walls and roof spaces and then we spend oodles of cash putting heat back into our living spaces just so it can leak straight back outside again and in the hotter months those gaps in our buildings fabric let all the outside heat inside too so we spend even more money on machines that pull that heat out of our spaces while more warm air continues to come back in through the holes in our walls and windows it's all a little bit stupid this guy isn't stupid he's called dr wolfgang feist and back in 1991 he built a new home using materials and techniques that he developed through many years of research and consultation with leaders in the building industry that single construction spawned a global movement that's come to be known as passive house the home that dr feist built nearly 30 years ago was so well constructed and insulated that it still meets the now very stringent requirements of the international passivhaus institute by which it uses about 90 less energy than a traditional house the consequence of that is that there's virtually no requirement for expensive electrical heating and cooling systems which saves a good deal of money and prevents quite a lot of carbon dioxide going up into the atmosphere so surely by now after 30 odd years the construction industry builds all new houses to these specifications right hello and welcome to just ever think anyone who's tried to build a house will no doubt tell you that it's a pretty complicated time-consuming and expensive business self-builders are often advised to calculate a budget and timeline as carefully as possible and then double it for the real world one piece of advice that all builders understand though is that the more time and ...