What is Passive House?

August 10, 2017 Anthony Naimo

When it comes to energy efficient or “green” design, Passive House (or PassivHaus depending on where you live) is one of the most rigorous building standards around. However, it is also arguably one of the most successful in achieving energy efficiency living standards and reducing the ecological footprint of a building.

Originally conceived in the late 1980s, the first Passive House project was the construction of four row houses in Darmstadt, Germany in 1990. Since then, the Passive House approach has exploded across the globe with thousands of Passive House buildings being constructed in Europe, North America, Australia and beyond. The term itself derives from “passive energy source”, whereby the energy source does not come from fossil fuels but rather natural sources such as sunlight, water, air and thermal mass.

The Passive House approach focuses on energy efficiency while lowering energy consumption and introduces ultra-low energy buildings that require very little for heating and cooling. In fact, according to Matthew Sachs, a Toronto-based green building specialist, heating in a Passive House building can be reduced by an incredible 90%. 

Generally speaking, Passive House regulations and standards revolve around the following: 

  • High insulation values
  • Superior air tightness of the building envelope
  • The use of sunlight by orienting and designing the building to maximize solar
  • Ventilation that allows for the natural flow of fresh air through the building


How does Icynene spray foam insulation play a role in Passive House design?

As noted, a Passive House design relies on high insulation values and superior air tightness of the building envelope. High performance insulation works to reduce heat transfer through walls, roof and floor. While some critics of the Passive House approach suggest that thick walls are required to contain enough insulation to achieve the right R-value or U-value (depending on where you live), a high performance spray foam insulation material like Icynene ProSeal offers a high insulating value (in this case R-7.1 per inch) while also performing as an air barrier material that addresses the superior air tightness requirement.

Is it important to note that the Passive House Institute U.S. (PHIUS) banned the use of spray foam insulation products that have high global warming potential in early 2012.  With this in mind, it is important to source spray foam insulation products from manufacturers such as Icynene that have introduced low GWP, low VOC and GREENGUARD Gold certified foam insulation. Icynene has a suite of high performance closed-cell and open-cell foam insulation products that address this including Icynene ProSeal Eco which is 100% water blown closed cell spray foam insulation.

The image below, courtesy of Home Logic UK – a licensed Icynene contractor in the United Kingdom, shows how Icynene can play a role in the design and construction of a Passive House home. 

Passive House with Icynene spray foam insulation installed

Image courtesy of Home Logic UK.

Icynene Spray Foam in Passive House projects

Icynene spray foam insulation has been used in several projects that were originally designed according to the Passive House approach or have worked towards Passive House.

3 Palms Project
Built in Southern California, the 3Palms Project brings together the best in green sustainable design and functionality in a 2,450 sq. ft., three-bedroom family home.   With a focus on sustainability and sustainable practices, the design and construction teams had to pay strict attention to material durability, economic feasibility, occupant comfort and indoor air quality. Additionally, in order to achieve net-zero status, the architectural firm needed to consider high-performance materials or processes that optimized energy efficiency. The emphasis on sustainable design was pushed to the max. Of the many energy efficient technologies included into the design, photovoltaïc solar panels were included to generate 100% of the home’s electricity while solar thermal units contributed to generating a hot water supply. A highly efficient SIP wall system was used while any lumber used had to be sourced from a FSC certified, sustainably harvested forest. All the concrete used throughout the property had to have a 50% fly ash mix.

Inside the home, designers had included radiant heated floors to help keep the occupants comfortable without excessive energy use. The inclusion of LED lighting solutions and Energy Star rated appliances helped the home adhere to the design goals of energy efficiency. A rainwater collection system for irrigation was included. High-performance windows and doors were included to address the long-term weather durability.


3 Palms Home in California features Icynene spray foam insulation

To address the criteria of air tightness, occupant comfort, indoor air quality and super insulation the design team used Icynene spray foam insulation to insulate the home. With all of the work, technologies and considerations that the 3 Palms Project took, the project received Passive House certification and LEED for Homes Platinum certification.

 

Dursley Tree House
This Bed & Breakfast escape in Gloustershire in the United Kingdom is another example of how Icynene spray foam insulation played a role in reaching Passive House standards. The architect had specifically chosen Icynene spray foam insulation based on its high insulating performance and air sealing properties. The three storey building features windows and decking to preserve and enjoy the hundreds of trees surrounding the property. 

In order to further protect the trees, the structure was built without the use of concrete. Nine meter long screw-in piles were used for the foundations. To meet the Passive House requirement, almost 16” of high performance open cell Icynene foam insulation, triple glazed windows, MVHR , solar PV and solar thermal technologies were integrated into the design. Upon completion, the treehouse was opened up to others as a bed and breakfast retreat allowing visitors to learn and appreciate the concept of sustainable building and living. Due to the project’s uniqueness and Passive House design, it was featured on the UK’s Grand Designs television program.

Passive House in the United Kingdom featuring icynene spray foam insulation

 

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