Let’s talk about R Values

R Values in Insulation: What They Mean and Why They Matter

When it comes to choosing the best type of insulation for your home or building, you may have heard of the term R-value. But what does it mean, and why is it important?

What is R-value?

R-value is a measure of how well a certain type of insulation can resist heat flow. The higher the R-value, the more effective the insulation is at preventing heat transfer. R-value is short for Resistance value, and is closely related to the metric unit of RSI (Resistance System International).

R-value is usually expressed per inch of thickness, which means that thicker insulation materials will have higher R-values than thinner ones. For example, a 2-inch thick foam board insulation may have an R-value of 10, while a 4-inch thick one may have an R-value of 20.

R-value is also affected by other factors, such as temperature, moisture, air leakage, and compression. For instance, if insulation is compressed or wet, its R-value will decrease. If there are gaps or cracks in the insulation or around it, heat will escape more easily and reduce the overall effectiveness of the insulation.

How is R-value measured?

R-value is measured by using a standardized, but unfair test method called ASTM C518 . This method involves placing a sample of insulation between two plates that have different temperatures. The heat flow through the sample is measured and used to calculate the R-value.

However, this test method has some limitations. It only measures the heat flow in one direction (usually horizontal), and it does not account for the effects of wind, moisture, air infiltration, or installation quality. Therefore, the R-value obtained from this test may not reflect the actual performance of the insulation in real-world conditions.

Why is R-value not enough?

R-value is a useful indicator of the thermal performance of insulation, but it is not the only factor to consider when choosing the best type of insulation for your project. Think of it as a minimum threshold and standardised starting point. There are other properties that affect how well insulation works in different situations like we mentioned, such as:

• Moisture resistance: Insulation that can resist moisture and prevent mold growth will last longer and maintain its R-value better than insulation that absorbs water and deteriorates over time.
• Durability: Insulation that can withstand physical damage, such as impact, puncture, or compression, will retain its shape and function better than insulation that breaks or deforms easily.
• Fire resistance: Insulation that can resist ignition and limit flame spread will provide more safety and protection than insulation that burns or melts easily.
• Environmental impact: Insulation that is made from renewable or recycled materials, has low global warming potential (GWP) and greenhouse gas (GHG) emissions, and can be disposed of safely will have less negative impact on the environment than insulation that is made from non-renewable or harmful materials.

One example of a type of insulation that has low R-value but high performance in other aspects is extruded polystyrene foam (XPS). XPS is a type of rigid foam board insulation that has a closed-cell structure and smooth surface. It has an average R-value of 5 per inch, which is lower than some other types of foam board insulation, such as polyisocyanurate (PIR) or expanded polystyrene (EPS).

However, XPS has several advantages over other types of foam board insulation, such as:

• Higher moisture resistance: XPS has very low water absorption rate and vapor permeability, which means that it can resist moisture penetration and prevent mold growth better than other types of foam board insulation.
• Higher durability: XPS has high compressive strength and impact resistance, which means that it can withstand physical damage better than other types of foam board insulation.
• Higher fire resistance: XPS has higher ignition temperature and lower flame spread index than other types of foam board insulation , which means that it can resist fire better than other types of foam board insulation.
• Lower environmental impact: XPS has lower GWP and GHG emissions than other types of foam board insulation , which means that it has a less negative impact on the environment than other types of foam board insulation.

Another example, and really the option I’m the most interested in but is still too expensive is Aerogel. It’s a type of ultra-light and porous material that is made from silica or other substances. It has an average R-value of 10 per inch and has several advantages over other types of insulation, such as:

• Higher thermal performance: Aerogel has very low thermal conductivity and high infrared reflectivity , which means that it can prevent heat transfer better than other types of insulation.
• Higher moisture resistance: Aerogel has very low water absorption rate and vapor permeability , which means that it can resist moisture penetration and prevent mold growth better than other types of insulation.
• Higher fire resistance: Aerogel has very high ignition temperature and very low flame spread index , which means that it can resist fire better than other types of insulation.
• Lower environmental impact: Aerogel is made from abundant and renewable materials, has low GWP and GHG emissions, and can be recycled or disposed of safely , which means that it has less negative impact on the environment than other types of insulation.

Why is it important?

Canada has four climate zones: A, B, C, and D. Zone A is the warmest and covers the southernmost parts of British Columbia, Ontario, Quebec, and the Atlantic provinces. Zone B is slightly cooler and covers most of the populated areas of Canada, except for the northern regions. Zone C is colder and covers parts of Alberta, Saskatchewan, Manitoba, Ontario, Quebec, Newfoundland and Labrador, and the territories. Zone D is the coldest and covers the Arctic regions of Canada.

The minimum R-values for each zone depend on the type of building and the component of the building envelope (walls, roof, floor, etc.) by code. The National Building Code (NBC) sets the minimum R-values for houses and small buildings, while the National Energy Code for Buildings (NECB) sets the minimum R-values for larger buildings. What does this really mean? Here’s the shittiest, cheapest, legal thing you can build.

However, these are only the minimum requirements and will not be sufficient for achieving a passive or off-grid home design. A passive house design is a design standard that achieves thermal comfort with minimal heating and cooling by using insulation, airtightness, appropriate window and door design, ventilation systems with heat recovery, and elimination of thermal bridges. As a great side effect, over time these places can be more environmentally friendly and much cheaper to run. A passive house design can reduce energy consumption by up to 90% compared to a conventional house. 90%! A passive house in zone B may need an R-value of at least R-40 for walls, R-60 for roof, and R-50 for floors, but again this can be better, and also doesn’t have to be achieved using man-made parts.

A thermal battery is a physical structure used for storing and releasing thermal energy. Heat is energy. To gather a better idea, thermal batteries can use different materials and methods to store heat, such as water tanks, phase change materials (such as wax or salt), or earth tubes. The benefits of thermal batteries include:

• Reducing or eliminating the need for additional heating or cooling systems, by relying on it’s heat dissipation
• Saving money on energy bills
• Increasing comfort and indoor air quality
• Reducing greenhouse gas emissions and environmental impact

Building into a hill can also act as a thermal battery, as it can provide insulation and thermal mass to the house. The earth around the house can absorb heat from the sun during the day and release it at night, or vice versa. The earth can also moderate the temperature fluctuations between seasons. The R-value of earth depends on its moisture content, density, and composition. Generally speaking, dry earth has an R-value of about 0.25 per inch, while moist earth has an R-value of about 0.5 per inch, this doesn’t sound great until you start to think about a 50ft dirt wall for part of your house and realise that’s an R-Value of 150, plus all the other added benefits and headaches that will come with using that as a wall.

Overall this is a large and expansive topic to cover, but we think it’s safe to say we need to rethink the way we design and use houses, our resources, etc. This is where the idea of earthships can get very interesting.

Earthships are a type of sustainable architecture that combine passive solar design, natural and recycled materials, and self-reliance systems to create homes that are independent from the grid and have minimal environmental impact. Earthships are typically built with earth-filled tires, which provide thermal mass and structural support, as well as recycled cans, bottles, and wood. Earthships also feature south-facing windows and skylights that allow natural light and heat to enter the building, as well as a greenhouse that can grow food and filter greywater. Earthships use solar panels, wind turbines, and batteries to generate and store electricity, and collect rainwater and snowmelt for domestic use. Earthships can also have composting toilets that turn human waste into fertilizer for plants.

Earthships by this design, tend to have lower R-values, but as we said, they do not account for other factors such as thermal mass, air infiltration, humidity, and solar gain. Earthships have low R-values because they use materials such as earth and glass that conduct heat easily, but they also have high thermal mass, which means they can store and release heat over time. This allows earthships to maintain comfortable indoor temperatures throughout the year, regardless of the external climate. For example, in New Mexico, where the Greater World Earthship Community is located, the average temperature in an earthship is 22 degrees Celcius, while the outdoor temperature can range from -34 to 38 degrees Celcius. That pretty much covers Canada’s climate. Earthships also use passive ventilation techniques such as operable skylights and windows to regulate the airflow and humidity in the building.

Earthships are not only energy-efficient and environmentally friendly, but they also offer a variety of social and economic benefits. Earthships are designed to be affordable and accessible to anyone who wants to build their own home, using mostly local and recycled materials and simple construction methods. Earthships can also foster a sense of community and self-reliance among their inhabitants, who share common values and lifestyles based on sustainability and harmony with nature. Earthships can also provide food security and health benefits by growing organic produce and herbs in their greenhouses, as well as reducing exposure to toxins and pollutants that are often found in conventional buildings.

Earthships are not only suitable for individual homes, but they can also form the basis of micro-communities that can transform the future of suburban development. Instead of relying on centralized infrastructure and services that are often costly, inefficient, and unsustainable, earthship micro-communities can create their own decentralized networks of energy, water, waste management, and food production. These networks can be powered by renewable sources such as solar parks and wind turbines, accompanied by backup batteries for storage. They can also incorporate rooftop farms that can grow more food on top of the earthship buildings, using the earth as thermal walls to protect the plants from extreme weather conditions. Rooftop farms can also reduce the urban heat island effect by cooling the air and absorbing carbon dioxide. Earthship micro-communities can also promote social cohesion and cooperation among their residents, who can share resources, skills, knowledge, and experiences in a mutually supportive environment. Earthships can also look modern and use new build materials.

Earthships and the right idea are a visionary and practical solution to many of the challenges facing humanity in the 21st century. They demonstrate how we can live in harmony with nature and each other, while enjoying a high quality of life that is not dependent on external factors. Earthships are more than just buildings; they are living systems that can adapt to any climate and culture, and inspire us to create the same around our housing to eventually create a more sustainable and resilient future.

We truly think this is an answer to not only affordable housing, but food production, recycling, our energy crisis, our resource crsisis, our dependance on large companies raising our cost of living and holding power and water production with antiquated equipment over our heads and much more. This idea can also help developing countries and aid in their current North American trash issues.