We're Certified! Your Guide to Passivhaus Homes
Approx. 4 min read
Designing a building goes far beyond the visual aesthetic; it demands all-encompassing principles to create a truly well-rounded result.
Passivhaus design embodies this philosophy, addressing common issues like inconsistent temperatures and poor air quality. This standard creates homes where comfort and health are paramount, achieved through a meticulously integrated approach that also delivers exceptional energy efficiency.
So, what exactly is Passivhaus?
At its core, it's a design approach that prioritises energy efficiency. Think of it like this: a conventional building is a leaky bucket. Passivhaus is a bucket with almost no holes. We achieve this through a "fabric first" approach, focusing on super-insulation and airtightness. And yes, you can still open your windows (More on that later).
The design of a Passivhaus is meticulously done using the Passivhaus Planning Package (PHPP). Think of it as a super-accurate energy balance spreadsheet. It ensures every aspect of the design contributes to optimal energy efficiency. The following principles are the foundation of this design process.
What are the Principles of Passivhaus?
An AI imagination of “the perfect Passivhaus natural material home of the future” - those with a keen eye can spot the glaringly obvious issues and potential flaws with this one!
Highly Insulated Building Envelope: Super Snug Insulation!
When we talk about the building envelope, we mean everything that separates the inside from the outside: walls, roof, floor, windows, doors – the whole shebang! In a Passivhaus, these elements are packed with seriously thick high-performance insulation, carefully placed to prevent heat loss.
Eliminate Thermal Bridges: Bye Bye Heat Leaking Gaps! Thermal bridges are essentially pathways for heat to escape. They create a continuous path for energy to travel from the warm inside to the cold outside – a major source of heat loss! In a Passivhaus, layered insulation, when done correctly, breaks these pathways, preventing heat loss and ensuring consistent temperatures.
Airtightness: Airtight not Airless!
There's a common misconception that airtightness means living in a sealed bubble. That couldn't be further from the truth. Yes, Passivhaus buildings are airtight, but that's what allows the mechanical ventilation with heat recovery (MVHR) system to work its magic. This system recycles heat from outgoing air and transfers it to incoming fresh air, which is filtered, creating a healthier living environment. And yes, you can absolutely open your windows! In fact, we wholeheartedly encourage you to open your windows regularly and connect to the external atmosphere, but with a Passivhaus, there is just not 100% reliance on opening a window in order to retain a healthy environment.
Ventilation: Fresh Air Smart Savings!
Passivhaus prioritises controlled ventilation to remove smells, air pollutants (such as VOCs), and humidity, preventing moisture damage to the building structure. Instead of uncontrolled heat loss from simply opening a window, we use heat recovery ventilation systems. These systems feature cross-flow heat exchangers, efficiently recovering heat from outgoing air and transferring it to fresh, incoming air. In fact, 80-90% of the heat extracted is put back in, so very minimal reheating is required.
High-Performing Glazing: Peek Inside The Future of Comfort!
Windows are truly remarkable components. They act as water-shedding surfaces, water-resistant barriers, air barriers, vapor barriers, and insulators. Achieving year-round comfort in a Passivhaus demands a nuanced approach to glazing, going beyond the essential pre-requisite of triple glazing. Strategic orientation, optimised size, and high-performance glazing are vital for balancing solar gain. We design to maximise beneficial solar heat during winter, reducing reliance on conventional heating, while simultaneously preventing overheating in summer. This involves careful consideration of seasonal changes, surrounding infrastructure, and shading strategies to assess and manage heating and cooling potentials. While some believe Passivhaus is about eliminating windows, it's actually about optimising their placement and size for maximum effectiveness. We focus on removing unnecessary windows and strategically placing those that provide optimal performance. Importantly, a well-designed Passivhaus also considers future climate adaptation, ensuring long-term climate resilience. The window frame is often the weakest point in the building envelope, which is why we strongly recommend timber frames. Timber's excellent thermal properties provide natural insulation and structural strength.
There’s a bit of a misconception around windows and Passivhaus buildings, that’s for sure. Some folks will tell you that you can’t open them at all! However you’ll be glad to know that this couldn’t be further from the truth!
Just like all building’s, a dose of fresh air is thoroughly recommended! It’s just that Passivhaus goes multiple steps further than conventional modern buildings in helping to regulate and monitor the internal environment with a view to optimising health and energy consumption.
The Benefits Beyond Energy Savings
Of course the reduced energy demand results in a more efficient building with lower carbon emissions than a conventional build but that's not all...
Reduced Energy Costs: Passivhaus standard can reduce your heating energy consumption by up to 90% . That's a huge saving, and in today's climate, a no-brainer!
Healthier Living Environment: Experience a significant improvement in indoor air quality with Passivhaus. The advanced ventilation systems not only provide a continuous flow of fresh air but also actively filters out pollutants and allergens, leading to a healthier living environment with direct positive impacts on your physical well-being.
Year-Round Comfort: Thanks to their superior insulation and airtight construction, Passivhaus homes maintain consistent temperatures year-round, eliminating cold drafts in winter and excessive heat in summer. It's important to clarify two common misconceptions here: Firstly, while Passivhaus dramatically reduces heating needs, it doesn't eliminate them entirely. A small amount of supplementary heating is still required to fine-tune the balance of the internal temperature. Secondly, a well considered Passivhaus home should not be prone to overheating. Careful design, including strategic orientation and shading, ensures that the building benefits from solar gain in winter without becoming too hot in summer.
Improved Wellbeing: A comfortable, healthy home has a profound impact on your mental wellbeing. The added benefit of reduced external noise, thanks to the airtight construction and high-performance glazing, creates a more peaceful and relaxing environment. It's hard to put a monetary value on feeling good in your own space.
Is Passivhaus worth it?
So whilst yes, Passivhaus construction can cost between 3-10% more upfront due to the higher quality materials like windows and insulation, the long-term savings in running costs and some of the immeasurable benefits to your health and wellbeing far outweigh the initial investment. In addition, Passivhaus homes often command a higher capital value due to their superior performance and energy efficiency. Ultimately, Passivhaus represents not just a home, but a long-term investment in your comfort, health, and financial well-being.
Passivhaus Design Services at OSOTIMBER
Whilst OSOTIMBER have consistently adopted many passivhaus principles into project designs, this year, Jordan took that passion to the next level by becoming a certified Passivhaus designer. Spending the last 3 months training with Coaction Training CIC (an independent and not for profit organisation driving upskilling for low energy building in the construction industry), has allowed Jordan to deepen his knowledge and be able to expand on his offering. We are pleased to say Jordan is now officially certified as a Passivahaus designer putting OSOTIMBER in a strong position to work alongside architects or self builders in Scotland, UK and beyond to refine their plans to the Passivhaus standard!
For self-builders and architects alike, OSOTIMBER is ready to partner with you on your Passivhaus journey. Reach out to us to explore how we can collaborate on your next project.
Written by Natalie Ross