Passivhaus and low energy design service

At OCRA we always strive to design responsibly, ensuring each scheme meets the client brief, maximises the site and is as sustainable and responsible as the site and client will allow. We realise the benefits of Passivhaus and sustainable design and enjoy the opportunity to develop projects with these principles and their core, however we also understand that a fully certified Passivhaus is not right for every client and plot. Unlike some designers we work with you and encourage the best design to be achieved but we do not subscribe in a ‘All or nothing’ approach to sustainable design.

Many of our commercial clients have to balance commercial pressures of development against a sustainable agenda, however by working with them we can incorporate passive sustainable benefits into schemes, such as larger plot sizes that improves natural light and ventilation in properties whilst ensuring the overall commercial viability is maintained.

On our one of house we often have more scope to include more detailed Passivhaus and sustainable designs into the scheme but whatever the project we can tailor our services and design to suit your needs and aspirations to get the best out of the site and get the right building for you.

Why Passivhaus


Passivhaus dwellings are the epitome of low-energy living, with an emphasis on reducing energy use before offsetting this with renewable technologies. Passivhauses have vastly lower in-use energy demands (typically reduced by 90%), keep warm over winter and reduce overheating over summer, have better internal air quality (filtered air is distributed through the house to where it’s needed), better sound insulation (triple glazed windows and increased airtightness levels reduce external noise pollution), and increased levels of natural daylight.

Passivhaus design can also be combined with an emphasis on sustainable materials (to reduce the building’s carbon footprint), and eco-friendly internal finishes (to create a healthier internal environment).

The Passivhaus trust provide a useful detailed guide for further reading.

Our Services


We offer a wide range of Passivhaus and low-energy design services on an individual project basis to suit our clients’ specific requirements, ranging from a low-energy assessment of existing and in-progress designs, to a complete Passivhaus design service from concept through to a completed project.

Designing low-energy buildings is an integral part of our ethos, and the majority of our projects are designed with the Passivhaus Principles in mind, and assessed by our in-house Certified European Passivhaus Designer.

Whether you are looking to reduce your energy bills, go above and beyond the current UK standards, or live in an accredited Passivhaus, we have a service to suit you:

Level 1: Concept Assessment

We assess your preferred concept design against the Passivhaus Principles and advise how the project could evolve to include low-energy design features and even achieve Passivhaus accreditation. This is a top-level overview at an early stage to check that the design is on the right track.

Level 2: Detailed Assessment

We model and assess a detailed design (or an existing design you may already have) using our PHPP software, and advise in greater detail how the project could be adapted or redesigned to meet low-energy or Passivhaus standards. This also allows us to design out potential problems (i.e. reducing summer overheating) before they become an issue.

Level 3: AECB Building Standard

Whilst not as rigorous as the Passivhaus requirements, the AECB Building Standard is still a much higher level of accreditation than current UK Building Regulations, and shows that low-energy design has been considered and achieved.

We model and assess the design using our PHPP software, following this up on-site by overseeing the construction, to ensure that the AECB Building Standard requirements are delivered.

Level 4: Certified Passivhaus / EnerPHit

The pinnacle of low-energy design, we develop, model and assess the design to ensure that it meets the strict Passivhaus requirements, followed up with rigorous on-site quality control to ensure that the Passivhaus accreditation is met. Passivhaus Plus and Passivhaus Premium accreditation is also available for clients wishing to include renewable technologies and further push the boundaries of low-energy design.

EnerPHit is a similar accreditation for existing buildings and retro-fit projects (with slightly more lenient standards) where clients are looking to upgrade their existing property to the highest UK energy standard for refurbishment projects.

Passivhaus