Passive House - a design guide - Vorbild Architecture

March 28, 2021

Passive House – a design guide

What is a Passive House?

The Passive House Standard is a rigorous, voluntary benchmark for energy efficiency in buildings that significantly reduces a structure’s ecological footprint. Originating in Germany, it emphasises exceptional thermal performance, airtightness, and mechanical ventilation. Buildings constructed or retrofitted to this standard can achieve energy savings of up to 90% compared to conventional buildings.

Adapting the Passive House Standard to Victorian Houses in the UK

Victorian houses in the UK are known for their solid brick walls, high ceilings, and ornate architectural detailing. However, these historic features also pose challenges when attempting to retrofit to meet the Passive House standard, due to the original construction methods and lack of insulation. Despite these challenges, applying Passive House principles to Victorian homes is a meaningful step towards improving sustainability and reducing energy demand.

Here are some key strategies for adapting Passive House principles to Victorian properties:

1. Insulation and Thermal Performance

Victorian homes often lack adequate insulation and are susceptible to heat loss. Enhancing insulation in walls, roofs, and floors is critical. This can be achieved through internal or external wall insulation. Innovative materials like aerogel offer high performance with minimal thickness—ideal for retrofits where space or aesthetics are a concern.

2. Airtightness

Airtightness is essential to meeting Passive House requirements. In Victorian homes, this involves sealing gaps in floorboards, windows, and doors, and adding draught-proofing measures. Airtightness testing followed by targeted sealing ensures that air leakage is reduced to acceptable levels.

3. Window Upgrades

Original sash windows, often single-glazed, are inefficient. Replacing them with high-performance double- or triple-glazed units improves thermal performance. Where preservation is a priority, secondary glazing offers a less intrusive yet effective solution.

4. Ventilation

Mechanical Ventilation with Heat Recovery (MVHR) is a core component of Passive House design, providing a constant supply of filtered fresh air while retaining warmth from the exhaust air. Installing an MVHR system in a Victorian house requires careful planning to integrate ducting in a way that respects the building’s historic character.

5. Renewable Energy Integration

To further reduce reliance on grid energy, renewable technologies such as solar panels or ground source heat pumps can be integrated. While not strictly required for Passive House certification, renewables contribute to overall sustainability and help offset remaining energy use.

6. Energy-Efficient Appliances and Lighting

Upgrading to energy-efficient appliances and LED lighting reduces operational energy demands and complements the building’s overall efficiency strategy.

7. Continuous Monitoring and Maintenance

Post-retrofit, ongoing monitoring of energy use, indoor temperature, and humidity helps ensure the home performs as expected. This allows for prompt identification and resolution of any issues, safeguarding the long-term benefits of the investment.

Conclusion

Retrofitting Victorian houses to the Passive House standard is complex but highly rewarding. While it requires sensitive and innovative solutions to respect the architectural heritage, it can greatly improve comfort, reduce environmental impact, and future-proof these iconic homes. By blending advanced energy-efficiency measures with conservation-led design, Victorian homes can become beacons of sustainable living for the modern era.