Understanding the Basics of Passive House Design
This is part 1 of a 3-part series on Passive House.
***Stay tuned for the next blog, where I will cover how Passive House design contributes to reducing mold risk, further highlighting the health benefits of this approach to building. In the final blog of this series, I will explain in more detail how this methodology is tested to ensure the measures that make this a better way to build are actually achieved.
Photograph by PassiveHouseAccelerator.com
What is Passive House?
The Passive House methodology was developed in Germany in the 1990s and adapted for North American climates by the Passive House Institute US (PHIUS), this approach to building design and construction is revolutionizing how we think about energy-efficient, healthy homes.
A Passive House is a building that adheres to a set of strict energy efficiency principles. The goal is to create a structure that is durable, resilient, and maintains a comfortable indoor temperature year-round with minimal active heating or cooling. This is achieved through a combination of superior insulation, airtight/watertight construction, and strategic use of passive solar gain.
Key Principles of Passive House Design
Superinsulation
Passive Houses feature extremely well-insulated walls, roofs, and floors. This thick insulation blanket significantly reduces heat transfer between the interior and exterior of the building.
Airtight Construction
A continuous air barrier is created around the entire building envelope, minimizing air leakage and associated energy losses.
Watertight Construction
The two equally important goals of moisture management are to: 1) prevent bulk water intrusion into the home and 2) avoid condensation where it can harm building assemblies.
Some components that impact how heat and moisture flow through a wall assembly include: the control layers (weather resistive barrier, the air barrier, vapor control layers), the structure, window openings, and the climate zone impacts of heat and moisture.
High-Performance Windows and Doors
Windows can significantly decrease the overall R-value of a wall assembly. In Passive House design, triple-paned windows and well-insulated doors are used to minimize heat loss while maximizing solar heat gain in colder climates.
Balanced Ventilation with Heat Recovery
A mechanical ventilation system with heat recovery ensures a constant supply of fresh air while recapturing the energy from exhaust air.
Thermal Bridge-Free Design
Special attention is paid to eliminating thermal bridges – areas where heat can easily escape the building envelope.
Wait … What is a thermal bridge?
So glad you asked.
A thermal bridge is a weak point in a building's construction that allows heat to pass through more easily. Thermal bridges occur when materials with higher thermal conductivity form a bridge between the inside and outside of a building.
Thermal bridges can cause:
Increased energy use: Thermal bridges can significantly reduce a building's thermal performance, which can lead to higher energy use for heating and cooling.
Condensation: Thermal bridges can cause unwanted condensation in a building.
Comfort issues: Thermal bridges can make it unpleasant to be close to walls on cold days, making parts of a home unusable.
Thermal bridges can be caused by:
Breaks in insulation,
Less/inconsistently applied insulation, and
Insulation penetrated by elements with higher thermal conductivity.
In residential construction, wood studs in walls can create significant thermal bridges because they are more conductive than the insulation around them.
Benefits of Passive House Design
- **Energy Efficiency**: Passive Houses can reduce energy consumption for heating and cooling by up to 90% compared to conventional buildings.
- **Comfort**: Consistent indoor temperatures and excellent air quality create a supremely comfortable living environment.
- **Durability**: The high-quality building envelope leads to increased durability and reduced maintenance costs.
- **Environmental Impact**: Reduced energy consumption translates to a significantly lower carbon footprint.
PHIUS Certification
The Passive House Institute US (PHIUS) has adapted the original Passive House standards to suit North American climates and construction practices. PHIUS offers certification for buildings that meet their rigorous standards, ensuring that these structures truly deliver on the promises of extreme energy efficiency and comfort.
I will cover these testing methodologies in detail in the final blog of this series.
Spoiler: You test! You do not guess!
Challenges and Considerations
While the benefits of Passive House design are numerous, there are challenges to consider:
Upfront costs may increase if the builder/team are not skilled in this approach due to specialized materials and construction techniques that require expertise to achieve
Note this does NOT mean that Passive House is automatically more expensive. This means that if a professional has not yet undertaken this level of detail, there may be a learning curve that costs SOMEONE more $ if adjustments need to be made.
Need for skilled professionals (builder/architect/trades professionals) familiar with Passive House principles
Potential limitations on design flexibility due to strict energy performance requirements (this may not be an issue for folks with a lower risk-profile who do not mind trading some design features for increased efficiency)
However, as the methodology gains popularity and more professionals become trained in these techniques, many of these challenges are being addressed.
Conclusion
The Passive House methodology represents a significant leap forward in sustainable building design. By focusing on creating an extremely efficient building envelope and utilizing passive strategies for temperature control, this approach not only reduces energy consumption but also creates healthier, more comfortable, durable, and resilient living spaces. As we continue to grapple with the challenges of climate change, resource conservation, and merely “code compliant” building practices, the principles of Passive House design offer a promising path forward for the future of architecture, construction, and homeowners in pursuit of healthier homes.
*All infographics pictured here are by PassiveHouseAccelerator.com
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If you need help putting these concepts into practice in your own build, apply to work with me 1:1 by visiting the link, here.
Stay conscious and curious, friend.
♥️C
