Healthy Insulation Materials

Insulating your house is one of the best passive energy-saving strategies available. However, choosing the best type of insulation material based on your construction, environmental impact, and your health, can be a daunting task. Furthermore, some types of insulation are more appropriate for new construction while other products can be easily installed in renovations. Let’s take a look at different building insulation materials, their properties, environmental impact, and consider how healthy we can get with some of the  options.

First off, why insulate? To either keep warm – or to keep cool! It works both ways! When we insulate the exterior walls and roof (and even foundations!) of our homes, we are preventing heat transfer to occur whenever there is a temperature difference between inside and outside. So, insulation of the building envelope (wall, roof, and slab) will either prevent heat from leaving the interior on cold days and nights or it will prevent heat from penetrating to the indoors on hot days and nights. Remember, heat transfer by conduction (through the molecules of a material) occurs in the direction from hot to cold.

Sometimes the exterior wall materials of homes are inherently insulative – such as super thick masonry or stone construction as well as straw-bale or insulated concrete block construction. These materials either have a high heat capacitance, which is the ability to store a lot of heat before releasing it back to cooler air surrounds, or they might have decent thickness combined with insulative properties of air or porosity inside the material system. These are helpful for construction because they combine the insulative property along with the primary role of load-bearing structural walls when building new homes or additions. For now, however, we will be reviewing insulation materials that are intended specifically to insulate as their primary role in building application.

As I write this, it is a cold November morning in the Catskills of New York, and we have the first frost of the year appearing across the landscape outside. It is so beautiful, and it also reminds me of the need for extra insulation this time of year. It is time for me to pull out my winter coat that is made like a giant puffy sleeping bag! Do you wear or see those puff-jackets during this time of year? I think they were popularized in contemporary society from rap music culture, but they are extremely utilitarian in cold winter locations. Why? Because they are filled with lots of air! Air is an excellent insulator because it is a gas and does not easily transfer heat energy. Let’s think about poof-jackets on our homes for a moment…

Okay, back to building materials for insulation – do they have to be super thick like the puffy jackets? Not necessarily, but each additional inch of insulation thickness adds more resistance to heat transfer. We identify this resistance as R-value in building materials, which is the inverse of conduction for a given thickness. R-value and thickness are not equal across different insulation products. Some products are in the form of blankets, others in boards, others in loose-fill, and others in spray-foam. Each form of insulation has its own attributes and properties based on the material chemistry and the composition. Oddly enough, the real estate market had influenced the development of thinner insulation materials that can provide higher R-values because of preferences to increase the livable square-footage of a home in relation to the allowable construction footprint. The desire for thinner walls by real estate conventions is that the resulting house can be marketed at a slightly higher square-footage and thus a higher price. Because of this, the insulation products such as spray-on polyurethane and denser rigid boards have become prevalent for providing higher R-value with a relatively minimal thickness. 

If we follow a strictly building science paradigm of construction, this might make sense. But the beauty of architecture is not even considered in this formula. The beauty of buildings is in many ways related to their inherent physiognomy – where the visual aesthetic becomes a direct story of how and why the building is composed in the way it is, with a transparency to the translation of its design. For the thermal and insulative behaviors of a house, we would almost imagine it to have super-thick walls, walls that speak to the time it might require for heat to transfer through. With thicker walls, there are so many other beautiful opportunities in the qualities of the design that can be activated – such as the placement of windows so that there will be a large window-sill and richer light and shadow interactions. When we move through a thick wall or threshold, we have a different experience of entry or transition from one space to another (inside to outside or vice versa). This creates an element of ritual and awareness from the body experiencing the delineation of space with more pronounced conditions. Insulation products that can fill the cavities of wall and roof systems in thicker ways include blanket forms as well as loose-fill.

Aside from the thickness of insulation materials, the chemical composition is a major factor to consider when selecting healthy building materials for your home. Some prevalent insulation products from the past are challenged with chemicals that directly affect our health. Fiberglass insulation blankets are problematic because of the small glass fiber particles that become airborne and impact our respiratory system. Some fiberglass and mineral wool products use formaldehyde, so be sure to look for toxin-free mineral wool if going that route! Formaldehyde in building materials can slowly release into the air over time and is a volatile organic compound (VOC) that negatively effects our central nervous system. 

Expanded polystyrene (EPS) or extruded polystyrene (XPS) foam sheets or boards are problematic because of the hydrofluorocarbons (HFCs) used in the manufacturing process. HFCs are a types of greenhouse gas and are being phased out from all contemporary refrigeration and cooling equipment. EPS and XPS will also release poisonous gases if they catch on fire. Given the increasing rates of forest fires reaching large swaths of American development (especially in California and the Pacific Northwest), all of the wood frame construction with EPS and XPS insulation is disastrous for the air quality and impacts the surrounding communities, animals, and firefighters. We can do better!!

Let’s discuss some of the wonderful insulation products that are healthy and also improving the material life-cycle by reducing overall environmental impacts. There are so many options emerging in different construction material markets around the world. One that is especially promising is the use of agro-byproducts for insulation boards. This type of insulation material utilizes agricultural waste (rice husks, corn husks, coconut coir, etc.) that would otherwise be burned as direct waste and contribute to carbon dioxide emissions. Agro-byproduct upcycling makes use of these secondary materials that were already harvested and produced and turns them into useful building materials. For insulation, there are a series of different agro-byproduct blanket and boards that are being developed and used in construction today. These include hemp insulation, the use of cattail fibers, wood waste, and others.

Another exciting new insulation material that is natural and healthy is mycelium, or mushroom insulation! This product was originally developed for packaging insulation materials and is now scaled for building integration (currently marketed in Ireland and New Zealand). One of the challenges to market with many cellulose-based products is the food source it might serve as to insects, microbes, and molds. While integrating natural and organic materials into our buildings is healthy for the environment, the secondary effect could be one that becomes unhealthy for human inhabitants. However, this problem is easily solved by incorporating the proper toxin-free fungicides and stabilizers into the composite material products when they are formed. In addition, boric acid is added to natural products to serve as a flame retardant and is natural and not harmful for the given function.

A super fun cellulose-based insulation product that I love is recycled blue-jean insulation! Yes! Our blue-jeans (well, actually the blue-jean scrap or waste material from the factory floor) are inside some of our buildings! This one is fashionably great as it is good for the environment by upcycling from an already challenged industry and makes use of the beneficial insulative properties of cotton.

Can we also envision building insulation from silkworm cocoons or other natural products in our region? The environmental footprint of our building industry can be reduced if we look close to home for resources and materials to upcycle into products for our dwellings. As a society at large, we have the scientific know-how to make the proper healthy materials with low carbon-footprints, we just have to demand the right stuff at the market level so that industry and manufacturers respond accordingly (as we see this is already happening!).

If you are interested in more information about designing or renovating your house with healthy insulation materials, reach out to AIDA, LLC today for a consultation.You can always find more information and healthy home resources at Aletheia Ida Design and Architecture, LLC (AIDA, LLC) at www.aletheiaida.com.