Sustainability & Passivhaus
We care deeply about designing and creating genuinely durable and resilient architecture. That’s why we design to the Passivhaus standard, and go even further with our own set of rigorous sustainability standards.
We care deeply about designing and creating genuinely durable and resilient architecture. That’s why we design to the Passivhaus standard, and go even further with our own set of rigorous sustainability standards.
Both the terms Passivhaus and Passive House refer to the voluntary low-energy construction standard developed in Europe in the 90s. The concept has a set of clearly defined empirical criteria that a building can be measured against. And there’s a separate third party Certification process, ensuring a rigorous and impartial assessment of the design – serving as a form of quality assurance for the whole team.
Passivhaus buildings are defined as those that have extremely low energy demand, and meet high standards for thermal comfort and good indoor air quality – even in very cold weather, like a Scottish winter that can get as low as -10°C.
The word ‘passive’ is used because the aim is to eliminate the need for an ‘active’ heating system. Instead, Passivhaus buildings utilise internal heat gains and solar energy entering through the glazed windows and doors, while simultaneously minimally heating the incoming fresh air. This reduces the demand for heating energy to its lowest level – no matter where the home is built.
It’s a fabric-first approach. The idea is to optimise the building’s inherent qualities, reducing the need for expensive or energy intensive ‘bolt-on’ technologies. The building fabric itself must perform to a very high standard first and foremost – even when renewable systems are incorporated into the design. And that’s exactly what Passivhaus certified builds ensure.
The Passivhaus Standard has three certification classes – Classic, Plus, and Premium – each with increasing energy efficiency and renewable energy goals. Except for the primary energy renewable, the technical criteria are consistent.
Keeping energy costs extremely low, and indoor spaces warm at 20°C, the building must not use more than 15kWh per square metre of usable floor area for heating or cooling annually.
The heating system must need no more than 10W per meter squared of usable floor area, during the coldest months, to keep indoor spaces at 20°C. This means the inside stays a comfortable temperature, without costing lots of money.
For a Passivhaus Classic, the total energy demand for heating, hot water, lighting and all appliances must be below 60 kWh per square meter of usable floor area per year. This can include any on-site renewable energy, so varies with each of the classes.
The building fabric must be very air tight. The measured level can’t be above 0.6 air changes per hour at 50Pa. This way, the building is draught free – making it very comfortable, while minimising lost energy through air leaks.
The risk of the building overheating (getting above 25°C internally) must be minimised to less than 10% of the year. By designing the ventilation strategy properly, internal spaces stay comfortable – no matter the weather.
The design process for a Passivhaus is a little bit different. Instead of treating it as an afterthought, a Passivhaus design integrates energy efficiency at every stage – from initial concept, all the way through to construction.
With over a decade of experience, we know how to handle the technical aspects – all while delivering beautiful architectural design. We use the Passivhaus approach in three key ways:
When designing a building or renovation, selecting the right components is essential to meeting your low-energy, low-carbon goals – from windows to MVHR units.
Because the Passivhaus standard is a performance driven approach, rather than being aesthetically driven, we ensure that high quality materials and components are embedded into our designs from the outset. When your building is finished, it’ll perform as expected – combining beauty and comfort seamlessly.
Under standard building regulations, a building’s energy balance is calculated using the Standard Assessment Procedure (SAP). In contrast, Passivhaus designs are validated with the Passivhaus Planning Package (PHPP) – a highly effective design and verification tool created by the Passivhaus Institute.
Using PHPP ensures a building’s anticipated energy performance is kept on track. In a typical architectural workflow, this level of assessment is often missing. Design changes that affect performance may go unexamined, leading to underestimated impacts and a significant performance gap. By using PHPP, this gap can be minimised – or even eliminated altogether.
We’ve been designing to the Passivhaus Standard since 2013, with our in-house Certified Passivhaus Designer handling all technical analysis. That means a more efficient design process for you, with every design change assessed and verified for the best possible outcome.
Passivhaus requires stricter quality control than a standard build – with rigorous checks at every stage. From concept design, where aspects like orientation and form are established, to detailed design, where materials and component specifications are defined – and finally to construction, where meticulous quality control ensures the highest standards are met.
At Paper Igloo, we make achieving the final Passivhaus Certification a straightforward process. We gather the information needed and conduct thorough checks in tandem with the Passivhaus Certifier at key stages – keeping you in the loop throughout.
There are five set principles that define a Passivhaus build – all designed to maximise energy efficiency and comfort.
High levels of insulation in the walls, roof, and floors reduce heat loss and maintain a comfortable indoor temperature with minimal energy use.
Opaque building envelope elements in contact with the ground or external air must be continuously insulated to minimise heat loss at the junctions.
In European climates, U-values of 0.15W/(m²K) or better are ideal. Sometimes a thicker wall (400-500mm) is needed for bio-based insulation, but this only leads to the striking detail of deeper sills.
At Paper Igloo, we specialise in using natural, minimally processed materials that are recyclable, repurposable, or biodegradable.
A highly airtight thermal envelope prevents drafts and heat loss, improving energy efficiency and comfort.
There’s a common misconception that airtight buildings feel stale. A constant fresh air supply is essential in any healthy building, so in a Passivhaus airflow is controlled, rather than relying on ad-hoc leaks.
Placed on the warm side of the insulation, the airtight layer must be continuous to prevent heat loss – while the exterior should be windtight. The airtight layer can be made from membranes, boards or plasters, often serving dual purposes to reduce costs. Proper detailing and installation are key.
To comply with Passivhaus standards, the mandatory airtightness test must be performed using both pressurisation and depressurisation.
High-quality, triple-glazed windows and doors minimise heat loss while maximising natural daylight and ventilation.
Passivhaus suitable windows come in many aesthetic options. But in our climate, they share three key features:
– The frame must be robust with a thermal break
– The glazing should be triple-pane with Low-E coatings to retain solar heat
– The spacer around the glass must be made from a material that has a low thermal conductivity
Together, these elements don’t just mean optimal performance – it means you can sit near any window and feel comfortable, no matter the weather.
An energy efficient ventilation system, like Mechanical Ventilation with Heat Recovery (MVHR), provides constant fresh air and heat recovery from outgoing air – maintaining good indoor air quality, without wasting energy.
Working with a simple duct system, the unit runs at very slow speeds – making it completely silent. An added benefit to city dwellers or allergy sufferers, it also filters the air.
While fresh, gently warmed air flows into living and sleeping spaces, stale air is extracted from kitchens, bathrooms, and utility rooms. Hallways act as transitional zones, and the system automatically regulates humidity, preventing mould when drying clothes indoors.
Consistent insulation throughout the building is achieved by avoiding thermal bridges (areas of higher heat loss) in design and construction.
Poorly designed junctions can lose heat at an alarming rate. By also minimising heat loss at these connections, your home stays warm with very little heating needed.
In Passivhaus buildings, a thermal bridge-free construction means the calculated heat loss (PSI value) from each junction is ≤ 0.01W/(mK) – or better.
In short, there are three key reasons: reduced costs, durability and sustainability. There are clear perks to reducing energy costs. And building a durable home that stands the test of time – benefitting both you and the planet – just makes sense.
When it comes to sustainability, we feel strongly that contributing towards a lower energy future during a climate emergency is essential.
The question is, why would you not design to the Passivhaus standard?
If you couldn’t already tell, we’re really passionate about helping people to live comfortably while caring for our planet. So you won’t be surprised to learn that we’ve gone one step further in creating our very own Paper Igloo sustainability standards.
Ensuring low embodied carbon reduces the environmental impact of our buildings over their lifetime. Using Embodied or Whole Life Carbon (WLC) Assessments lets us benchmark our projects against one another and industry standards.
We create flexible, adaptable spaces that evolve with the building’s lifespan. This means our new homes can accommodate lifestyle changes – from prams, to bikes, to wheelchairs, and even areas for homeworking – so you don’t have to extend, rebuild or move.
We aim for the Passivhaus Standard on all of our new build projects. Not only does this mean significant reductions in operational energy, but a lower carbon footprint overall.
From simple, low-tech solutions like waste water heat recovery units, to onsite electricity generation through PV panels – we’ll help you choose the right renewable technology for your home so you can keep costs down and use less energy from the grid.
We prioritise bio-based materials – using timber frames and natural insulation whenever possible – and aim to use all resources efficiently. These materials manage moisture effectively, are recyclable, and support both environmental and human health.
By designing green roofs and landscaping schemes, we enhance the local ecosystem – especially when a building occupies a previously natural, rural area. Boosting biodiversity is vital for strengthening ecosystems, supporting climate resilience, and creating a healthier environment for both wildlife and people.
To us, enhanced acoustic protection between spaces is essential in every home – regardless of lifestyle or hobbies. With relatively simple measures and careful detailing, we can significantly improve sound control for a more enjoyable, relaxing living environment.
We design primary spaces with higher daylight levels than the minimum standards, carefully balancing larger windows to prevent overheating. Buildings with strong visual connections to the outside world massively benefit our health – reducing stress and improving overall wellbeing.
We design water systems with low-flow fixtures and fittings to reduce hot water consumption, and use water butts in landscaping to minimise or eliminate the need for potable water in the garden. Avoiding excessive use of non-free-draining materials in hard landscaping improves both the quantity and quality of surface water flow from the building into the wider environment.
We design for deconstruction whenever possible, using timber frames to create a demountable superstructure. Loose-fill insulation makes it easy to separate the building’s main components at the end of its life, promoting material reuse and reducing waste.
We’re always keen to talk about Passivhaus and sustainability in architecture – let us know if you have any questions or want to find out more.
