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):
- Airtight
- Super insulated
- Thermal bridge free (minimal moisture risk and heat or cooling energy loss at vulnerable spots in the assembly)
- Optimal solar orientation (sun in winter and shade in summer)
- 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.
