Walls used to be walls. A simple protector from the outside – wind, rain, cold, heat… you know the elements. Primitively, they were porous and inefficient though long-lasting given an inherent ability and opportunity to get wet and subsequently bake dry.

As we’ve evolved so too have building practices and a fairly new fangled interest in efficiency. What does efficiency mean in a structure? In short, it means less heating and cooling because the structure is less a sieve and more of an airtight environment. The development of Passivhaus is perhaps the best example of how efforts and attention have changed. For clarity, (German: Passivhaus) is a voluntary standard for energy efficiency in a building, which reduces the building’s ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling.

  • The international standard is further defined as follows:
    Use up to 15 kWh/m2 (4,755 BTU/sq ft; 5.017 MJ/sq ft) per year for heating and cooling as calculated by the Passivhaus Planning Package, or a peak heat load of 10 W/m2 (1.2 hp/1000 sq ft), based on local climate data.
  • Use up to 60 kWh/m2 (19,020 BTU/sq ft; 20.07 MJ/sq ft) per year primary energy (for heating, hot water and electricity).
  • Leak air up to 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (0.0073 psi) as tested by a blower door; or up to 0.05 cubic feet per minute (1.4 l/min) per square foot of the surface area of the enclosure.

For those newer to this discussion the above often gets summarized by <1 ACH 50, where air changes per hour (ACH) are less than one at 50 pascals of pressure. This is determined with a blower door test. And for those even newer, Passivhaus is about getting to a prescribed performance figure with arguably not enough consideration for how to arrive there.

We are not here to say there is anything wrong with Passivhaus (though we certainly would not advocate for oft-used spray foam insulation); we are simply here to say that it may not be the end all / be all of enclosure systems and that materials used should be more stringently considered.

Leading members of the Embodied Carbon Network will sight an operational mantra that focuses on using best in class materials and building practices and then allowing the applied result to define the outcome.

One could easily pause here and note there are loads of standards and organizations that were created to improve the built environment. It is fair to say that some do a better job than others. Subjective views and bias notwithstanding, there is a new kid on the block that we wanted to stop and recognize.

Foreverbreathe is a simple system created by Health Based Building, a firm in our favorite place: New Zealand. Like so many of our kiwi mates the offering is elegant, sensible and gets right to the point. From their site you will learn the following:

Sustainable Development is described in specific documents as development that meets the needs of the present without compromising the ability of future generations to meet their own needs…..It is Health Based Building’s (HBB) commitment to Sustainable Development that brought Foreverbreathe Specification to market.

Foreverbreathe Specification brings a combination of vapour permeable building materials together to ensure the built environment is able to migrate moisture away from the indoor space with minimum energy use. Adhering to aims of sustainable development ensures these materials do not contain chemicals or the ability to release chemicals that could impact indoor air quality and the environment.
Foreverbreathe Specification provides energy efficiency and air quality by not bringing Asthmagens to the built environment and not requiring whole home mechanical ventilation systems. The specification is based on the airtight principle to reduce air exchanges and natural infiltration of air and moisture to establish the required air quality and air exchanges per hour.
A vast percentage of moisture within air infiltration is managed via the specifications breathable components. These components, inclusive of insulation are built to manage moisture transfer and conversion within wall and ceiling cavities. Local exhaust ventilation (LEV) is included in locations that create high levels of moisture, kitchens, bathrooms etc. Velux solar powered window technology is included to further ventilate moisture and reduce temperature on demand
Foreverbreathe Specification positions “let the built environment do the work” as the first principle in design. Removing moisture via the built environment puts less dependency on heating and cooling systems. By this approach energy use is reduced with sustainable materials embedded to establish good air quality and sustainable outcomes.

It is fair enough to say that wall systems do not abound. But as they do evolve it just may be that Foreverbreath is not only one to consider but perhaps one to stick with.

As ever, we are here to share and hope you find this information useful. For more visit our site or HBBs per the links below:



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One comment on “The Wall System Evolution

  • Great blog article! I appreciate the comment “we are simply here to say that it may not be the end all / be all of enclosure systems and that materials used should be more stringently considered.”

    I like the Passivehaus goals, but their choice to make a very tight building envelope, but not recommend the use of very low toxicity materials that won’t offgas problematic compounds has been problematic to me. I’ve viewed Passivehaus certified buildings go up with loads of foam and OSB, and where for me the air quality during the construction was very poor, and was still less than optimal after it was completed. Materials, materials, materials.

    I hope in the future they will see the benefit of marrying their efficiency goals with the parallel goal of “a healthy house that lets the environment do the work”, to paraphrase what you describe above.

    We have the ability to build homes that will still be habitable when the power goes out…so why not do it?

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