Demystifying Passivhaus

Passivhaus refers to buildings created to rigorous energy efficient design standards so that they maintain an almost constant temperature. Passivhaus buildings are so well constructed, insulated and ventilated that they retain heat from the sun and the activities of their occupants, requiring very little additional heating or cooling.

Five key principles:

• High quality continuous insulation
• Heat control and robust windows
• Airtight construction
• Heat recovery ventilation
• Thermal bridge free design

The EnerPHit standard

Additionally, Passivhaus has developed an EnerPHit standard which focuses on the same core criteria for the project as Passivhaus while accepting that meeting Passive requirements is generally not possible for a retrofit project. This is because important elements, like orientation and structural form, are already decided in an existing building.

There are significantly less EnerPHit projects than new build Passivhaus projects in the UK so we wanted to explore how EnerPHit standards could benefit the current public sector estate to achieve net carbon zero. Approximately 80% of the building stock likely to be required for 2050 government net zero target already exists. Therefore, the future is likely to have a greater number of retrofit projects to continue the UK's journey to net zero.

For more information on Passivhaus, please refer to this document on Retrofit in the UK.

The conversation followed by Pick Evered presenters showcasing a project we are currently working on which involves using EnerPHit standards to decarbonise an existing building. Our client’s primary focus is sustainability research, their target is to stop burning fossil fuels by 2030 and then achieve net zero by 2040. Luckily for us they didn’t need much convincing when it came to the benefits of EnerPHit standards.

Key points of discussion

Stakeholder engagement

Early stakeholder engagement was one of the most important strategies for this project. Engaging with all stakeholders to explain how EnerPHit standards would be beneficial to their project was key. It was extremely beneficial that Pick Everard has several Passivhaus accredited engineers and architects who are well versed in showcasing the benefits of Passivhaus principles.

Contractors

It is extremely important to engage with the right contractor in the early stages. They must share client aspirations from the start. Using Passivhaus and EnerPHit standards does come at a cost so typically contractors do like to value engineer this at an early stage. This is why design team, client engagement and collaborative effort is key to a successful project delivery. Experience within the group showed that the smaller contractors are more driven to achieve carbon zero for clients. They have less red tape and less lines of communication so can make decisions quickly.

Traditional approach is preferred over Design and Build procurement as quality of works drives the project and under traditional contract quality is better controlled.

Project Managers are the glue of the team and drive client aspiration. They are key to advising clients how to reduce risks and the importance of appointing the right contractor and design team.

Listed and protected building

The group then went into discussing historic buildings, how do we make these carbon neutral? One of the attendees commented on their positive involvement with Historic England and how much they strive to make their sites carbon neutral. After all, if they don’t modernise their estate then people will stop using them.

We discussed how we could adapt a tiered approach. The grand and famous buildings could undergo a simple gas boiler replacement for electric heating. However, the further down the line buildings such as barns could go a more strenuous retrofit works. Decisions need to be made for public benefit not architectural beauty, again engagement and collaboration is key.

Re-invent the standard design of a buildings - do we need ceilings, for example, just because it is the common thing to have, simple solutions such as this could help towards carbon reduction.

We need to improve spaces as a whole, not make sacrifices for carbon neutral purposes. A few years back the trend was to have concrete, sleek public spaces, now the trend is to have carbon natural spaces. We need to ensure we are not focusing on one thing only and look further to ensure we are considering wellbeing, green spaces, commercial value etc. public benefit.

One of the participants are currently developing a Passivhaus passport software which will guide users how to make the most of their building efficiency post occupancy. If we are building these extradentary buildings, we must ensure users understand how to use these in the most efficient way. The software will guide users how to continuously reduce carbon within their building.

If you would like any more information or would like to be involved in our next Roundtable series, please contact Diana Hawkins.