Which building standard is right for your project?

very project has to decide how hard it's going to work on energy and comfort, and that decision shapes how the building feels and what it costs to run for decades. Choosing a standard isn't only about clearing the regulations.

It's about matching the level of performance to your priorities, your budget and the building you've got. Here's how the main standards compare, and how we use them.

A low-energy rear extension and retrofit of a London home, detailed to EnerPHit principles. RISE Design Studio.

The baseline: Building Regulations, Part L

Part L of the Building Regulations (Conservation of Fuel and Power) sets the legal minimum for insulation, energy efficiency and carbon emissions. It's the floor, not the target. It'll get you a compliant building, but compliant and comfortable aren't the same thing, and Part L on its own won't give you the low bills or the absence of draughts that people actually notice. We design well beyond it as a matter of course.

Part L of the UK Building Regulations sets the legal minimum for energy efficiency—but at RISE, we see it as just the starting point for sustainable architecture.

Passivhaus: performance you can measure

Passivhaus is the benchmark for ultra-low-energy buildings. It isn't about gadgets or green badges, it's about getting the fundamentals right: airtightness, insulation, orientation, solar gain and ventilation, modelled carefully and then tested. A certified Passivhaus building has a space heating demand at or below 15 kWh/m² a year and an airtightness of no more than 0.6 air changes an hour at 50 pascals, which is far tighter than the regulations ask for.

What sets it apart is the accountability. Certification checks the building at every stage, the design model, the construction detailing and on-site testing, so what gets built actually performs as designed. That's rarer than it should be, and it's why a Passivhaus home stays warm and well-ventilated on heating bills that barely register.

Passivhaus Certification sets a benchmark for thermal comfort, airtightness and energy use, ensuring your building performs exactly as it was designed to.

EnerPHit: Passivhaus for existing buildings

You can't usually hit full Passivhaus on an old house, because the existing structure, orientation and party walls limit what's achievable. EnerPHit is the Passivhaus Institute's retrofit standard, which takes the same method and applies realistic targets to existing buildings, typically a space heating demand around 25 kWh/m² a year.

It's demanding but achievable, and it's the standard we'd point most serious retrofits toward, because the results show up clearly in comfort, air quality and running cost.

EnerPHit is the Passivhaus standard for retrofit projects, designed to elevate existing buildings to exceptional levels of energy performance and comfort.

The AECB standard: a pragmatic step up

Where full Passivhaus certification isn't the right fit, the AECB's standard (its CarbonLite framework) is a sensible step above Building Regulations. It uses the same modelling engine as Passivhaus, PHPP, but with more flexibility and less process. It's performance-based rather than points-based, which is why we like it: it's judged on outcomes, not a checklist.

It's also grounded in real construction costs, so for smaller homes or tighter budgets it often strikes the right balance between ambition and what's affordable.

The AECB CarbonLite standards offer a pragmatic approach to low-energy design, with separate pathways for new builds and retrofits grounded in real-world performance.

Building Biology: health as well as energy

Not every standard is about kilowatt-hours. Building Biology, developed in Germany, is concerned with how a building affects the people in it: indoor pollutants, moisture, daylight, electromagnetic fields and the materials you're surrounded by.

It treats a building as a habitat rather than just shelter. It's part of why we favour natural finishes, breathable construction and VOC-free materials where we can, because energy performance and a healthy interior should come together rather than at each other's expense.

BREEAM: sustainability at scale

For larger and commercial schemes, BREEAM is the established framework. It assesses sustainability across a broad range of categories, from water and waste to biodiversity and adaptability to a changing climate, and it pushes cross-discipline collaboration from early design through to post-occupancy.

It's broad rather than simple, and used well it keeps clients, consultants and contractors accountable for the sustainability of the whole project rather than treating it as a finishing touch. We work alongside BREEAM assessors on our larger and institutional work.

BREEAM takes a broad-spectrum view of sustainability—assessing buildings across categories like energy, transport, materials, ecology and wellbeing to ensure long-term environmental resilience.

Do you need to certify?

Not always. A building designed to Passivhaus standards but not formally certified can still perform well, provided the right modelling and testing are done along the way. What certification adds is independent scrutiny: it checks that the building delivers what the design promised, which protects both the design intent and your investment.

For us it's a quality-assurance tool rather than a marketing badge. The value is in how the building performs in January, not the certificate on the wall.

So which one is right for you?

There's no single answer. The right standard depends on your priorities, your budget, the constraints of your site, and how you want to live or work in the building. A tight budget on a small terrace points one way; a new build with room to optimise orientation points another; a large commercial scheme points somewhere else again.

The useful thing is to weigh the trade-offs honestly, test a couple of options, and find the point where performance and buildability meet. That's the conversation we'd have with you at the start.

If you're weighing up which standard fits your project, we'd be glad to talk it through.

→ Email us at architects@risedesignstudio.co.uk
→ Or call the studio on 020 3947 5886

RISE Design Studio, Architects, Interior Designers + Sustainability Experts

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