Choosing Best Airtight Options in Japan

What kind of materials are available in Japan, where are they found, are they safe, how are they installed….?

 

If you are looking to design, build or own a comfortable healthy house that consumes minimal amounts of energy then you may have searched and come across the following basic formula (no rocket science involved):

1. Airtight
2. Super insulated
3. Thermal bridge free (minimal moisture risk and heat or cooling energy loss at vulnerable spots in the assembly)
4. Optimal solar orientation (sun in winter and shade in summer)
5. Air ventilated (i.e., mechanically controlled fresh air!)

1    Passivhaus Consultants can help with this but of course, correct and healthy doses of the above cannot be achieved without the expertise of engineers, architects and builders or without the proper materials. 

Onto the topic of choosing the best airtight products (1 above) in Japan. First, let me start by showing an image of the effect on moisture infiltration of even a small (25mm or 1") hole in the airtight layer:

Thirty litres a year is a lot of moisture from one little hole, for example untaped seams or punctures from staples not covered up! It doesn't take much to imagine how this adds up and what the average home lets in these days, despite being more airtight than before. What does this cause? Mold, structural deterioration, and drafts which are not comfortable, conducive to build longevity, healthy, or energy efficient. Adequate and proper installation is paramount.

Next let's outline how these products should look in relation to a global society conscious of energy use and carbon footprint along with changing building codes around the world, such as the BC Step Code Canada.

 

Products should be VOC free, have a low carbon footprint, superior sticking properties where applicable in weather extremes, be robust during rigors of construction, smarter with regards to permeability in different directions, and have reputable certification that shows they meet the above conditions. Simply put, ones that are healthy and do a great job at keeping the energy and moisture where you want them. 

 

In my experience these sorts of products are difficult to find in Japan. For example, I recently did a search in Japan for foundation sealing tapes.

 

The first step was checking Japanese distributor sites based on known products readily available in Canadian, US, UK, and European markets—where Passivhaus is well established. What I found was 3M 8067 which hits a couple of the targets but not all. Beyond that not much else besides standard ¥599 rolls on the big sites and the same at local distributor’s shop. Translating and reading up on one "Eco" labelled product's JIS safety data sheet I was not convinced of its safety. So, what about tapes that ensure health, comfort, product longevity and energy reduction, aka lower energy bill? 

 

For products that deliver on the above I have turned my attention to one producer, Siga Swiss, for an upcoming Passive House project in Hokkaido. Why? Because they hit all of the above targets and more. The additional parts: Siga Swiss offers customizable solutions, transparent product info, computer simulated evaluations of your project followed by recommendations, and provide training on best methods of application. They are committed to doing their part globally and making sure it is done right.

 

These are the kinds of products we need to be using on our projects in Japan to get ahead and help push the world out of the dinosaur climate age. To do this, when speaking with suppliers, architects, and engineers ask whether a specific high performance product is available in Japan. like Siga Swiss for airtightness. This will get conversations started and ideas flowing as well as help toward a better educated industry along with comfier, cheaper, and better-built homes. Demand for better products can positively affect availability here in Japan. 

Of course, regarding any products that are pushing for similar goals already here in Japan please share and let’s discuss those too! Positive change works a lot better helping each other out. 

 

One final note. Alluding to traditional builds in a previous article on this site: “Yes we can!” If we keep these themes while blending traditional styles with new building techniques, technologies and products that make homes hit higher targets, specifically high-performance airtight tapes and membranes. These targets will be on the way to “2050 goals” rather than just words.

Are you positive wool is carbon negative?

I'm trying to understand the carbon footprint of buildings, and I always hit a mental roadblock when I see negative numbers. This just struck me on a list of insulation materials where wool was sticking out of the wrong side of the graph. There are also negative carbon footprints for cellulose fibre and cork. This negative accounting applies not only to insulation products but also structural materials such as wood.

Wood is certainly a great material to build with, and is definitely going to emit less carbon into the atmosphere than concrete, steel or glass. It also contains more carbon, and any atom of carbon in the building is one less molecule of carbon dioxide or methane in the atmosphere. But does that make its impact negative?

I have a couple of thought experiments that make me skeptical. First, what if you used twice as much wood on a building project?

If wood is carbon negative, then more wood would reduce the carbon footprint of the building. So just sticking a load of extra planks around the building would make it more "green", even if you use the same amount of concrete, steel and glass. Or you could just deliver the wood to the site and leave it in a pile on the ground. But you've cut down twice as many trees, so how can that be better?

Next thought experiment: what if every man-made structure used wood?

This would be impossible because human structures outweigh biomass. You would run out of trees, and all other living things. The planet is not a factory and you can't just increase production because there is more demand. Tree growth is limited by the amount of sunlight that falls on the trees, the area their roots have to grow into, and their access to water. Trees can take decades to grow and absorb the carbon stored in them. We have to be careful with our applications of economic calculations on natural systems.

So I'm starting off sceptical of a negative carbon impact for wood, which is made from plants that spend their life absorbing carbon from the atmosphere. What about wool? That comes from animals which spend their life emitting carbon dioxide and methane. But wool is also listed on the negative side of the carbon impacts.

Of course wool contains carbon and that carbon comes from grass, and the grass has captured the carbon from the atmosphere. So I guess you could argue that the carbon is being sequestered and stored in the building rather than being left in the atmosphere. That's lovely, but at what cost?

Sheep are warm-blooded animals, which means that most of the calories they consume go into maintaining their body heat. Even though they are wearing highly insulating fleeces over 80% of their calorie intake goes into keeping warm. Given that they are walking around and growing fat and muscle, it's hard to imagine more than a couple of percent of those green carbs they are eating going into wool.

I could do some calculations on the back of an envelope, but instead I looked at published research papers. Brock et al. (2013) looked at a farm in New South Wales and estimated 25 kg of CO2e (carbon dioxide equivalent) per kg of wool at the farm gate. A study on farms in Patagonia by Peri et al. (2020) estimated around 8-19 kg CO2e per kg of wool. 

CO2 is made up of one carbon atom and two oxygen atoms, so burning a kilogram of carbon will give us about 3.7 kg of carbon dioxide, or living things will turn 3.7kg of atmospheric carbon dioxide into one kilogram of biological carbon. So even on a good day, assuming that sheep's wool is 100% carbon, taking the lowest figure in those studies, and ignoring manufacture and transport, for each kg of wool in the building there would be well over two kg going into the atmosphere. Am I missing something? 

I was only thinking about sheep working to produce wool, but of course they produce meat as well. Both papers note that meat production changes the estimate, which accounts for some of the range in the second study.

Sheep not only produce wool and meat, they also have other effects for land management. They are excellent at deforestation. Even if they cannot cut down trees, they will eat any saplings before they can grow and make sure that the trees never grow back.

Sheep farming:
Causing deforestation for at least six millennia 

You can see in the background of this picture from the Campaign for Wool "Why to use wool insulation." It should be titled, "Sheep farming: Causing deforestation for at least six millennia!" People talk about wolves in sheep's clothing, but in terms of ecological impact: compared to sheep the wolf is a lamb. Historically speaking this has been very helpful as sheep have cleared the way for other kinds of agriculture and for urban development. We are now in different times. As an Englishman these rolling hills with drystone walls and woolly sheep seem like a perfect rural scene, but it is as man-made as a concrete jungle.

Of course using wool insulation in a building is going to lead to less energy use in your house, like any other insulation. Using insulation is almost certainly a better choice than not using insulation, which would force the inhabitants of the building to use more energy to stay warm or cool. But that is a choice between two different energy uses. You can use all the insulation in the world, and your heating bills are never going to be negative.

And wool may be a lower-carbon option than other insulation materials such as polyurethane or extruded polystyrene. But you may not want to use wool underneath your foundation, and you may find that higher performing insulators can be thinner, which may reduce the need for other building materials.

I don't want to suggest that wool is a bad insulator. Just let's be honest about its carbon impact, think a bit more about the ecological impact of sheep farming and give up with the brownie points.

Sequestering carbon is a good idea, and if we can find places to store carbon, that will help keep it out of the atmosphere. But negative numbers don't exist in the real world. I don't think we can ever make a truly carbon-negative building, any more than we can generate energy by taking carbon out of the atmosphere.

We can just try to reduce the impact as much as possible.

References

Photo from: 

Campaign for Wool (2020). Why use wool insulation in your home? http://www.campaignforwool.org/why-use-wool-insulation-in-your-home/

Jan Zalasiewicz, Mark Williams, Colin N Waters, Anthony D Barnosky, John Palmesino, Ann-Sofi Rönnskog, Matt Edgeworth, Cath Neal, Alejandro Cearreta, Erle C Ellis, Jacques Grinevald, Peter Haff, Juliana A Ivar do Sul, Catherine Jeandel, Reinhold Leinfelder, John R McNeill, Eric Odada, Naomi Oreskes, Simon James Price, Andrew Revkin, Will Steffen, Colin Summerhayes, Davor Vidas, Scott Wing, & Alexander P Wolfe (2016) Scale and diversity of the physical technosphere: A geological perspective. The Anthropocene Review, vol. 4(1), 9-22. https://journals.sagepub.com/doi/full/10.1177/2053019616677743

Yinon M. Bar-On, Rob Phillips, & Ron Milo (2018) The biomass distribution on Earth. PNAS, 115 (25) 6506-6511; first published May 21, 2018; https://doi.org/10.1073/pnas.1711842115 https://www.pnas.org/content/115/25/6506 

Brock, Philippa M., Graham, Phillip, Madden, Patrick, & Alcock, Douglas J. (2014). Greenhouse gas emissions profile for 1 kg of wool produced in the Yass Region, New South Wales: A Life Cycle Assessment approach. Animal production science, 53(6). https://www.researchgate.net/publication/268631844_Greenhouse_gas_emissions_profile_for_1_kg_of_wool_produced_in_the_Yass_Region_New_South_Wales_A_Life_Cycle_Assessment_approach 

Pablo L. Peri, Yamina M. Rosas, Brenton Ladd, Ricardo Díaz-Delgado, & Guillermo Martínez Pastur (2020). Carbon Footprint of Lamb and Wool Production at Farm Gate and the Regional Scale in Southern Patagonia. Sustainability,12(8), 3077. https://www.mdpi.com/2071-1050/12/8/3077