What is Insulation R-Value? How Does it Affect Comfort?
September 27, 2019
What is Insulation R-Value?
The R-Value is the measurement of how effective material is at resisting the flow of heat energy. The higher the R-value, the more resistant it is to heat transfer. In other words, material with a high R-Value is a better insulator than material with a lower value. This means that a high R-Value material is better at retaining heat, making it more desirable to have within a home to increase energy efficiency and comfort.
Any material that adds insulation or thermal protection to your home has an R-Value. This includes: all types of insulation (such as fibreglass batts or spray foam), along with any windows, doors, or the framing and drywall in finished walls. A home that uses effective insulation and/or has been renovated to increase energy efficiency will likely have a well sealed and insulated building envelope (walls, windows, and doors) with a high R-Value.
Every bit of insulation and airtightness within a home contributes to the home’s building envelope (the protective shell that separates a home’s occupants from the outdoor elements). As the R-Value of walls, doors, etc. improve, so too does the strength of the home’s building envelope. This means a more energy efficient home that has: lower utility payments, fewer drafts, a more comfortable living environment, and a higher market value.
If you have any questions about R-Value that we do not touch on here, or if you would like to take the first steps towards a more energy efficient home, feel free to give our Customer Experience Team a call at 1-800-265-1914, or send us a message online at www.gni.ca/contact.
What Does the R Stand for in R-Value?
The “R” in R-Value stands for absolute thermal resistance, and is the measurement that indicates how much heat energy is able to pass through the object in question. Any walls windows or ceilings that have a high R-Value will be very useful in the battle to maintain a comfortable interior temperature all year long.
In many cases, a home can become much more insulated without much hassle or up-front investment. For example, a home that has fairly well insulated walls would normally be quite effective at keeping its interior a comfortable temperature, but if the home has leaky and poorly insulated windows, it will almost certainly struggle. This is due to the significant drop in R-Value that occurs at each leaky window, in comparison to the fairly well insulated wall.
However, if the home was to be properly air sealed (which starts with a blower door test), and the R-Value of the windows were to be increased (through a full replacement or cost-effective retrofit), it would be much easier for the home to maintain a comfortable interior temperature all year long, and utility costs would be significantly lower at every payment.
How is R-Value Calculated?
R-Value is measured in Kelvin·square-metre per Watt (K·M2 / W). The main factors that affect R-Value are the type of insulation used, its density, and its thickness. Age and the accumulation of moisture also play a role, meaning that older insulation will not perform as well as new insulation.
To calculate R-Value, a mathematical formula is used: R-Value = The difference in temperature on either side of the insulation (ΔT) ➗ the rate at which heat can flow through the object (heat flux, Q).
In other words, R-Value is calculated by measuring how capable a certain object is at resisting the transfer of heat, while accounting for the specific properties of that certain object itself.
For example, spray foam is a better thermal insulator per inch of thickness when compared to fibreglass batts. This means that a thicker layer of fibreglass batts will be required to achieve the same R-Value as a thinner layer of spray foam.
If you would like to learn more about how R-Value is calculated, our Customer Experience Team will be happy to help! Give us a call at 1-800-265-1914 or send us a message online at www.gni.ca/contact.
What Type of Insulation has the Highest R-Value?
Without question, spray foam insulation has the highest R-Value per inch of thickness. It is very dense, making for a good insulator without the need for extra-thick walls. Spray foam can also act an effective air and moisture barrier depending on the climate, making it extremely effective at improving airtightness and helping to prevent moisture accumulation - without requiring the same amount of additional air sealing as other forms of insulation.
While spray foam insulation may be the best insulator per inch of application, it may not be the best choice for every application in terms of cost-effectiveness. Since the needs of every home and every homeowner are different, each home has a different way of improving energy efficiency in the most cost-effective manner possible. This means that both fibreglass batts and blown-in fibre insulation can be effective options, as they are both able to make a home more energy efficient and comfortable, while also helping to reduce the up-front investment costs of larger renovations.
With a home energy audit, every aspect of your home’s energy performance is identified and analyzed. This means that you not only see how well your home performs right now, but you also see the areas where energy efficiency could be most cost-effectively improved. These potential improvements come in the form of a list of suggested renovations / retrofits that are ordered in terms of their cost effectiveness, allowing you to target the problem areas directly and for the lowest cost.
Additionally, GNI can help you understand and qualify for up to $5000 of home renovation rebates that are currently available to both Union Gas and Enbridge Gas Customers. For more information, call our Customer Experience Team at 1-800-265-1914, or visit us online at www.gni.ca/contact.
What are Some Common R-Values?
There are many different factors that affect the R-Value of a product, and many different products are commonly used within the building industry. Depending on the application, the total R-Value of a wall or ceiling may need to be higher, in which case a thicker layer of insulation (or a more effective type) will be required. This will lead to a higher overall R-Value within the home.
The R-Value of an insulative material is often measured ‘per inch’, meaning that it indicates the insulative material’s ability to resist heat per inch of thickness. The R-Value of a wall or ceiling however, is measured in terms of total R-Value. This is a measurement of the wall or ceiling’s complete ability to resist heat flow, while also accounting for all the thickness of the insulative material itself. In other words: R-Value of insulative material X inches of thickness = total R-Value.
When measuring by inch, spray foam has the highest R-Value at about 3.7 - 6.5 per inch (open cell and closed cell respectively), blown-in fibre insulation is at about 3.5 per inch, and fibreglass batts are at about 2.9 per inch. If an Ontario homeowner was to improve the level of insulation and airtightness within their home so that it was entirely at R20, then they would be eligible for a $2000 rebate from the Home Efficiency Rebate Program.
If you would like to learn more about R-Values, the Home Efficiency Rebate Program, or about any of our products or services, give us a call at 1-800-265-1914, or visit us online at www.gni.ca/contact and our Customer Experience Team will be happy to assist you.