Passive House: What It Is and What It Means for Your Home

The Passive House standard originated in Germany in the early 1990s and has since become one of the most rigorous and well-respected benchmarks for energy efficiency in buildings worldwide. It is not a style of architecture, it is a performance standard, and one that demands a fundamentally different approach to how a building is designed and built.

At its core, the standard focuses on three things: exceptional insulation, airtightness, and controlled ventilation. Buildings that meet it can use up to 90% less energy for heating and cooling than a conventionally built equivalent. The result is a home that is dramatically cheaper to run, significantly more comfortable to live in, and considerably kinder to the environment.

Is it relevant to London’s older housing stock?

This is a question we are asked regularly, and the honest answer is: yes, but with some important caveats.

London’s Victorian and Edwardian terraced houses were built at a time when energy was cheap and insulation was not a consideration. Solid brick walls, single-glazed sash windows, suspended timber floors, and high ceilings all create significant heat loss. Achieving full Passive House certification in a property like this is genuinely challenging and in some cases not feasible without compromising the character of the building. However, applying Passive House principles, even partially, can make a profound difference.

Where to focus your effort

Insulation is almost always the starting point. Victorian homes lose the most heat through their walls and roofs, so improving insulation in these areas delivers the greatest impact. Internal wall insulation is less disruptive to the exterior appearance of the property, though it does reduce floor area slightly. External insulation is more effective thermally but will change the look of the building, which may not be appropriate in conservation areas or for listed properties. Aerogel-based insulation products are worth considering in situations where space is tight, as they offer excellent thermal performance at a fraction of the thickness of conventional materials.

Airtightness comes next. Draughts through floorboards, around window frames, and through unused fireplaces account for a surprisingly large proportion of heat loss in older properties. Systematic draught-proofing, combined with an airtightness test to identify and address the worst areas, can make a noticeable difference to both comfort and energy bills.

Window upgrades are often the most visible intervention. Original single-glazed sash windows are thermally very poor, but they are also one of the defining features of a Victorian home. Where planning restrictions allow, replacing them with high-performance double or triple-glazed units is the most effective option. Where the original windows must be retained, well-fitted secondary glazing is a practical and less disruptive alternative.

Ventilation requires particular care. As you improve airtightness, you need to ensure the building can still breathe properly. Mechanical ventilation with heat recovery, known as MVHR, is the Passive House solution to this: it continuously supplies fresh filtered air while capturing most of the heat from the air being expelled. Installing an MVHR system in an older property requires careful planning to route the ducting without causing unnecessary disruption, but it transforms the air quality and comfort of the home considerably.

Finally, renewable energy. Solar panels and heat pumps are not required for Passive House certification, but they complement the approach well, further reducing reliance on the grid and helping to future-proof the property as energy costs continue to rise.

Is it worth it?

In our experience, the homes that have been thoughtfully upgraded along Passive House principles are noticeably more pleasant to live in. The temperature is more consistent, draughts are gone, and the reduction in energy bills is real. For clients who are undertaking a significant renovation, it is always worth considering how many of these measures can be incorporated at the outset, as retrofitting them later is invariably more expensive and disruptive.

Full certification may not always be achievable or appropriate, particularly in historic properties, but the principles themselves are always worth applying as far as the building allows.

For further reading, the RIBA has published a useful overview of the benefits of Passive House design, which is worth exploring if you are considering this approach for your own home.