Q&A | What is Passivhaus?

What is Passivhaus?

Passivhaus is an international standard that adopts a whole-building approach with a focus upon high-quality construction and rigorous evidence-based certification. Passivhaus buildings are designed and constructed as high-performance yet simple, well insulated, airtight envelopes working in unison with heat recovery ventilation systems, ensuring air quality and comfort within a building of very low energy demand.

What needs to happen to make a building Passivhaus?

Passivhaus buildings must be considered from first principles, early in the briefing and concept design stage. Form and orientation are key early considerations, avoiding complex shapes and optimising the ratio between external surface area and internal floor area, all to minimise heat loss, risk of thermal bridges and airtightness breaches. A careful balance of windows on southern elevations to capitalise on heat gains, and a considered limit of windows on shaded northern elevations to minimise heat loss is also a key consideration.

In addition, there are five key principles to Passivhaus design and construction:

• Insulation: The building must be well insulated as a continuous high-performance envelope, minimising heat loss
• Airtight Construction: Airtightness is critical to ensure air leakages are prevented
• High Performance Windows and Doors: As a continuation of the building envelope, windows and doors must also be high-performance to minimise heat loss
• Thermal Bridges: Thermal bridges must be avoided. Thermal bridges are breaches in the building’s insulated envelope which permit heat loss if not designed out
• Ventilation and Heat Recovery: The air-tight construction of the building works in harmony with the ventilation system, controlling air flow, environmental conditions and user comfort

Why have we chosen to achieve Passivhaus for the visitor centre?

In 2019, Hull City Council declared a climate emergency and committed to doing all in its power to becoming carbon neutral by 2030. At the same time, the proposed visitor centre at the North End Shipyard was emerging, and offered the ideal opportunity for Hull City Council to lead by example and develop the new visitor centre as a sustainable exemplar. Adopting a Passivhaus approach achieves a route to reduced energy demand within a highly insulated building, and allows for that reduced energy demand to be generated by on-site renewable means. In pursuance of the 2030 carbon neutral target, and aligning with Purcell’s values of championing sustainable architecture, the new visitor centre will operate at net zero carbon emissions.

What are the benefits?

Adopting Passivhaus standards brings with it many benefits, including:

• Low energy consumption: The highly insulated thermal envelope can reduce heating demand by up to 90% over standard construction methods
• Reduced Energy bills: As a result, energy bills can be significantly lower
• Reduced carbon emissions: The North End Shipyard will operate at net zero carbon emissions
• No reliance upon fossil fuels: The building is powered purely by electricity, including on-site renewable energy, and ability to adopt green tariffs
• Optimal user comfort: The ventilation and heat recovery systems monitor and maintain a constant comfortable, healthy environment within the building
• Building and user health: By maintaining constant environmental quality, the building eliminates the possibility of condensation and mould growth
• Quality: Adopting Passivhaus principles demands high quality, proven by rigorous evidence-based processes
• Teamwork and collaboration: There is a critical link between design and construction that must be maintained throughout, instilling healthy teamwork towards a common goal

Are there any challenges?

A commonly faced challenge of Passivhaus is one of misconception. It can be heard that Passivhaus buildings are more complicated, less user friendly, appropriate only for housing, and more costly. These myths are not accurate, but lead to the challenge of communicating and convincing clients, consultants and contractors of the appropriateness of Passivhaus for a given project.

Challenges which can manifest, however, include experience, mindset and a project ethos which may be unfamiliar to some. Passivhaus demands high principles and rigour be embedded from the outset and throughout the project, ensuring all are on the journey together is critical.

Technical detailing requires careful thought, and product selection also is key to achieving a palette of products and materials which achieve project requirements, which doesn’t solely include sustainability criteria. Such specialist products may be unfamiliar to some, however, this can also be beneficial as a tool for learning. Operational needs and flood resilience, for instance, at the North End Shipyard required dedicated consideration to meet project expectation.

What do we hope to learn from this project?

Commitment to carbon neutrality and the impact that the construction industry has on climate change not static; we constantly learn and evolve, taking lessons from ourselves and each other, implementing our developing understanding. We hope that this project does the same, learning from the buildings which we create, and gathering data on performance and energy usage to inform and enhance future schemes.

The project also holds the potential to dispel myths, demonstrating the simplicity of the designed scheme, and the importance that simple yet considered design decisions such as form and orientation can have on building performance.

We continue to learn enhancement of robust and high-quality detailing and workmanship. A well detailed, reduced thermal bridge design and construction does cost more, but it does drive high quality design and workmanship.

We hope too that, whilst the works at the North End Shipyard are part of a major capital investment, it inspires others, clients, designers, and homeowners, to embed sustainable measures in decision making, whether that be in briefing for future major projects, or homeowners inspired to make affordable improvements.

Learn more about Earth Day 2025 here.