When most people think of a Passive House, they picture a brand-new, purpose-built home with ultra-modern detailing. But what if you already live in a house you love, or you’ve bought a character property with potential and you want to make it more energy-efficient?
The good news is: yes, you can retrofit an existing home to Passive House standards. In fact, there’s a specific pathway designed for exactly that - it’s called EnerPHit.
What is EnerPHit?
EnerPHit is the official Passive House retrofit standard. It acknowledges that older properties often have quirks and constraints like solid stone walls, unusual layouts, or conservation area rules that make full Passive House certification more challenging.
The EnerPHit standard sets a high bar for performance, but allows a little more flexibility. It still focuses on the core benefits that make Passive House so appealing:
- Very low energy use
- Exceptional airtightness
- Balanced temperatures and no draughts
- Excellent indoor air quality via mechanical ventilation with heat recovery (MVHR)
Our Experience: Retrofitting with Purpose
At Inspired Builds, we’ve worked on a number of retrofits that apply sustainable principles, even if they’re not always certified as Passive House. One standout example is a stone cottage in Ilkley, where we're currently carrying out an extensive reconfiguration and refurbishment, with very strong emphasis on sustainability.
This project includes:
✅ A new insulated ground floor slab with underfloor heating
✅ Preparation for solar battery storage and EV charging
✅ Ready for a future air source heat pump
✅ Full disconnection from the existing gas supply
While this particular home wasn’t originally designed for Passive House, we’ve approached the build with the same level of detail, thinking carefully about airtightness, thermal performance, and long-term sustainability.
What Does a Passive House Retrofit Typically Include?
Every property is different, but some of the most common upgrades we make to improve energy performance and meet EnerPHit standards include:
- External insulation – Often applied to solid walls or roofs to reduce heat loss, particularly useful in homes where internal insulation would impact floor space or finishes.
- High-performance windows and doors – Triple-glazed units with airtight detailing around frames are key to minimising thermal bridges.
- Mechanical Ventilation with Heat Recovery (MVHR) – This system extracts stale air while recovering heat to pre-warm the fresh air coming in.
- Airtightness measures – This might include membranes, tapes, or specific building techniques to reduce uncontrolled air leakage. This is greatly improved by including external insulation in your plans.
- Renewable energy sources – Solar PV panels and solar battery storage can support a low-energy lifestyle and offset any remaining demand.
- Heat pump systems – Air or ground source heat pumps replace gas boilers and offer a more sustainable source of heating and hot water.
- Slab insulation – Where the floor is being replaced or upgraded, high-quality insulation helps eliminate cold bridging and improve comfort.
The goal is to dramatically reduce the energy needed to heat and cool the home while maintaining excellent air quality and comfort, all without compromising the original character of the property where possible.
Is It Worth It?
We think so, but particularly if you intend to stay in your home for a long time. Whether you fully certify under EnerPHit or not, applying Passive House principles to a retrofit offers serious long-term benefits:
- 🔥 Lower energy bills
- 🌡️ More comfortable living, year-round
- 🌍 A reduced environmental footprint
- 🏡 Increased property value
Importantly, you don’t have to do everything at once. Many of our clients work with us in stages, prioritising the most impactful upgrades and planning for future improvements.
Although you do not need to upgrade everything at once, it is vital that any retrofit plans are designed holitically, making sure you consider all aspects of the upgrades at once.
Planning a Retrofit?
If you’re thinking about improving the energy efficiency of your existing home, we’d be happy to talk. Whether your goal is full Passive House performance or simply a warmer, more sustainable space, we can help you take the right steps.
Passive House isn’t just for new builds. It’s a smarter way to breathe new life into the homes we already have.
