Services/Passivhaus
Passivhaus consultancy
The standard that takes the fabric-first approach and delivers it in operation.
With several in-house Passivhaus accredited designers and consultants, we manage the certification process from the earliest stages of design to site completion, ensuring the effective delivery of targeted energy performance.
Winner
CIBSE Building Performance Consultancy of the Year2022, 2023, 2024, 2025, 2026
Passivhaus Designers and in-house MEP engineers, seeing schemes through to certification and operation
Passivhaus is an ultra low energy standard that can be applied to a variety of building types and sizes, not only houses as the name implies. Through a stringent modelling, measurement and verification process, it aims to bridge the gap between estimated and actual energy performance.
It sets limits on space heating demand, primary energy and airtightness, which are achieved through a fabric-first approach (carefully considered openings, increased insulation levels, minimised thermal bridging and air permeability) combined with efficient ventilation (MVHR, or mechanical ventilation with heat recovery).
The deciding factors for achieving the standard are mostly determined at the start: form factor, orientation, the ratio of glazing to wall, expected penetrations through the insulation layer, and the viability of achieving airtightness on site. That is why XCO2 is usually involved at the earliest design stages, using PHPP modelling to guide clients on cost benefit decisions. Complementing that, our in-house MEP team supports our Passivhaus Designers on a strategy for achievable, highly efficient building services, a joint capability that sets us apart.
However, the design stage is only part of the process. Construction support is key to ensuring Passivhaus is actually achieved, and our consultants stay heavily involved during construction, visiting site, witnessing installation, highlighting areas of concern and guiding the contractors. Through this combined teamwork, we achieve truly energy efficient buildings that operate as designed.
What we do
Scope is set around the scheme and the stage it has reached. Most commissions combine several of the following.
Passivhaus feasibility and option appraisal
Passivhaus design services through RIBA stages
PHPP energy balance modelling
Thermal bridge and junction analysis
Airtightness strategy and testing support
MVHR and low temperature heating design
EnerPHit and Passivhaus retrofit assessment
Passivhaus construction inspections
Certification evidence and certifier liaison
Golf Links Estate under construction in Ealing, and Taylor House and Peebles House for Westminster City Council. Passivhaus is won or lost during construction, which is why our consultants stay involved through installation and testing.
How we work
01
Feasibility and target setting
Whether the standard is achievable on this site and this form, tested at RIBA Stage 1 to 2, with the cost and design implications set out before it is committed to.
02
PHPP modelling
Energy balance modelling through design stages, with fabric, glazing, ventilation and heat source options compared against the criteria rather than assumed.
03
Detailing and coordination
Thermal bridge assessment, airtightness strategy and junction detailing worked through with the architect and the services design, which is where most schemes lose the standard.
04
Construction and certification
Site support, quality assurance and the evidence pack the certifier needs, including airtightness testing and as built verification against the model.
Who we work with
01Local authorities and housing associations
02Estate regeneration and masterplans
03Private residential developers
04Architects and design teams
05Education and public buildings
06Private clients and individual houses
Selected projects
Schemes designed to the standard
Golf Links Estate
MEP, environmental and Passivhaus consultancy supporting the reserved matters application, on a fabric first scheme designed to meet the Passivhaus Standard.
147 affordable homes, expected to be one of the largest certified schemes in the UK on completion
Lexden Road and Steyne Road
Passivhaus consultancy alongside environmental consultancy and MEP engineering, from early planning and design through construction, with two 1960s towers retained.
188 mixed tenure homes, including a 20 storey residential block
Taylor House and Peebles House
Passivhaus and AECB consultancy for Westminster City Council, using PHPP modelling to cut operational energy through a simple form, a high performance fabric and minimised thermal bridging.
88 homes, 80% improvement over Part L
Works with
Common questions
What is Passivhaus?
Passivhaus is a voluntary international standard for energy use and comfort in buildings, developed by the Passivhaus Institut in Germany. It sets limits on space heating and cooling demand, primary energy use and air leakage, and it applies to new build and existing buildings, residential and non residential. Its distinguishing feature is the quality assurance process attached to it: the design is modelled, the construction is tested, and certification depends on the finished building meeting the criteria rather than on the design intending to.
What does a Passivhaus consultant actually do?
A Passivhaus consultant establishes whether the standard is achievable for a specific scheme, models it in PHPP through the design stages, and works with the architect and contractor on the fabric, junction detailing and airtightness that determine whether it is met. The consultant is not the certifier. Certification is carried out by an independent certifier, and our role is to get the building and its evidence to the point where it passes.
Do we need a certified Passivhaus designer on the project team?
For certification the design work has to be done to the Passivhaus Institut methodology, and clients and funders increasingly ask for a certified Passivhaus designer to be named in the team. We have that qualification in the practice, held alongside our building services engineering, which is the combination that matters on housing schemes where the ventilation and heat source have to be designed as part of meeting the standard rather than after it.
Can Passivhaus be applied to an existing building?
Yes, through EnerPHit, the Passivhaus Institut’s standard for retrofit, which recognises that an existing form and structure cannot always reach the new build criteria. In practice much of our work on existing housing is fabric first improvement measured against Passivhaus and LETI targets rather than full certification, as at Styles House, where the question was what level of performance the retained building could reach without decanting residents.
How does Passivhaus sit alongside Part L, Part O and the London Plan?
They are separate requirements and a Passivhaus scheme still has to satisfy all of them. Passivhaus is not a compliance route: the building regulations calculation, the Part O overheating assessment and the London Plan energy hierarchy are demonstrated on their own terms. In practice a scheme designed to the standard usually clears Part L comfortably, while Part O needs care, because a highly insulated airtight envelope has to be modelled for summer as well as winter.
How does Passivhaus compare with BREEAM or LEED?
Passivhaus measures one thing to a hard limit: the energy performance of the building and the comfort it delivers, verified as built. BREEAM, LEED and WELL are broader assessment frameworks covering materials, water, ecology, transport, health and management, scored across categories to reach a rating. Schemes often carry both, and they answer different questions, so neither substitutes for the other.
Does Passivhaus cost more to build?
There is usually a capital uplift, and how large it is depends almost entirely on when the standard was adopted. Set at feasibility, much of it is absorbed into decisions being taken anyway, on form, glazing ratio and structure. Introduced after the design is fixed, the same performance has to be bought through specification and remedial detailing, which is where the expensive version of Passivhaus comes from. The counterweight is a permanent reduction in heating demand and a verified rather than assumed performance in use.
Where do you work?
We are based in London and work across the UK, with a second office serving projects in Singapore and the wider Asia Pacific region. Contact us to discuss a scheme in either region.