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Passivhaus Q&A Series: Does a house have to be a new build to be a Passivhaus?

This post is part of our series that shares questions we regularly receive about Passivhaus and low energy construction. We will be posting a new one every week. Explore our Blog to learn all about why designing buildings to low energy standards like Passivhaus delivers a lot more than just energy savings.


Passivhaus for New. Enerphit for Retrofit.
Passivhaus for New. Enerphit for Retrofit.

In recent years, there has been a growing interest in sustainable and energy-efficient building design. One concept that has gained significant attention is the Passivhaus standard, which originated in Germany and has since been adopted worldwide. Passivhaus buildings are known for their exceptional energy efficiency and comfort, but there is a common misconception that they can only be newly constructed. In this blog post, we will explore whether a building has to be a new build to be a Passivhaus and delve into the possibilities of retrofitting existing structures to meet this rigorous standard.


Understanding the Passivhaus Standard:


Before we dive into the question at hand, let's first understand what the Passivhaus standard entails. Passivhaus, which translates to "passive house" in German, is a building performance standard that focuses on achieving ultra-low energy consumption and excellent indoor comfort. The key principles include airtightness, high levels of insulation, mechanical ventilation with heat recovery, and minimal thermal bridging.


New Builds and the Passivhaus Standard:


New construction projects are often the ideal candidates for achieving Passivhaus certification. Designing a building from scratch allows for careful planning and integration of Passivhaus principles right from the beginning. We optimise the building's orientation, select the most appropriate materials, and install the necessary systems to meet the standard's strict criteria.


New builds can achieve airtightness easily, which is a fundamental requirement for a Passivhaus. They can also incorporate the best insulation materials and design features to minimise energy demand. Furthermore, new constructions can take full advantage of the latest advancements in energy-efficient technologies, making it more feasible to reach the Passivhaus standard.


Retrofitting Existing Buildings to Passivhaus Standard


While new builds may have certain advantages, it's important to note that existing buildings can also be retrofitted to meet the Passivhaus standard. This is known as an 'Enerphit' renovation. Retrofitting involves making substantial upgrades to the building envelope, heating, and ventilation systems to significantly reduce energy consumption while improving comfort.


Retrofitting existing structures presents unique challenges, such as dealing with structural constraints, working around existing infrastructure, and maintaining the building's historical or architectural value. However, with careful planning and a committed team of professionals, it is possible to transform older buildings into Passivhaus-certified ones.


Key Considerations for Retrofitting

  1. Insulation: Retrofit projects often involve adding insulation to the existing walls, roof, and floor. High-performance insulation materials can be applied internally or externally to improve thermal performance.

  2. Windows and Doors: Replacing old, inefficient windows and doors with Passivhaus-certified alternatives is crucial for achieving airtightness and thermal comfort.

  3. Ventilation: Installing a mechanical ventilation system with heat recovery is essential for ensuring a constant supply of fresh air while recovering heat from exhaust air.

  4. Airtightness: Careful attention must be paid to sealing gaps and cracks in the building envelope to achieve the required level of airtightness.

  5. Heating and Cooling: High-efficiency heating and cooling systems, such as heat pumps, can be integrated to meet the remaining heating and cooling demands.

  6. Moisture management: Ensuring that there is no risk of interstitial condensation or mould growth at interfaces between new and old construction.

Conclusion


While new builds may have inherent advantages when it comes to achieving the Passivhaus standard, it is entirely possible to retrofit existing buildings to meet this rigorous energy-efficiency standard. Retrofitting poses unique challenges, but with the right expertise and commitment, it can be a sustainable way to transform older structures into high-performance, eco-friendly Passivhaus buildings.


Ultimately, whether a building is new or existing, the key to success lies in a holistic approach that combines advanced building science, efficient technologies, and a deep commitment to sustainability. Passivhaus principles can benefit not only the environment but also the occupants by providing superior indoor comfort and significantly reducing energy bills.

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