What is Your R Value?
Posted by lindseyshoe
Reduce, reuse and recycle — but what is the other R and how does it help the environment? Find out what R values are and how it not only helps the environment but saves homeowners money.
When we think of Rs in going green; we usually think of recycling, reusing and reducing. Another R in going green is R-Value, but what is R Value?
R-value is a measure that represents a material’s resistance to heat flow. Having high R-value materials in your home slows the flow of heat through walls, floors and ceilings.
For example, heat flows through a wall with an R-value of 8, twice as fast as through a wall with an R-value of 16. Reducing heating or cooling losses can reduce energy needs and cut energy bills.
The History of R Value:
The Federal Trade Commission instituted the R-value rule in the 1970s following the “Energy Crisis.” When prices of oil, gas and electricity skyrocketed, (sound familiar?) insulation was in high demand. As demands grew, insulations prices rose as well and so did the claims of about the energy savings benefits of insulation. R-value was used as a standard measurement to help consumers compare different brands of insulation. The R-value rule is considered a good rule that has reduced misrepresentation and fraud in the insulation industry. It has been hailed as one of the “most important and successful consumer protection regulations ever enacted by the U.S. Federal Government.”
R-values are important but they can only tell only part of the story. R-value is a laboratory measurement so it can’t tell you exactly how well insulations will work in your home. Many factors will impact the actual performance of an R valued material:
* the total R-value of all system components
* air infiltration from gaps in the system
* air infiltration due to permeability of elements
* convective flows within insulated systems
* the thermal mass of building components
R-Value Comparisons for Insulation Materials:
In 1990 The University of Colorado School of Architecture and Planning put two insulations materials, cellulose wall spray and fiberglass. They built two identical structures. One with R-10 fiberglass in the walls and R-30 in the ceilings. The second structure utilized cellulose wall spray in the walls and loose-fill cellulose in the ceilings with identical R-values as the first structure.
Another the R-value for the insulation materials was identical, their performance was varied. The cellulose insulation required 26.4% less energy to heat than the structure insulated with fiberglass.
So as you can see, cellulose insulation, which is made from almost 85% recycled newspaper, can be a more eco-friendly and money saving choice, even compared to fiberglass options with the same R value.
The R-value of Windows Varies Greatly.
Most windows in the past were framed with aluminum, which is a great conductor and therefore a big source of heating or cooling loss, had very low R-values. Current windows have R-values of about R3 or R4. New window options have drastically higher R-values, some ranging from R12 to R20.
What Are the General Recommendations for R-values?
R-value recommendations will vary climate and will be impacted by the type of heating used and how a house is built but these are rule of thumb recommendations.
For mild climates, an R-11 for walls and floors and R-19 for ceilings and below ventilated attics.
For moderate climates, an R-19 for walls and floors and R-30 for ceilings and below ventilated attics.
For colder climates, R-19 in walls and under floors and R-38 to R-49 in ceilings below ventilated attics.
Why Should We Care About R-values?
Obviously, using materials with higher R-values will reduce your energy bills and save you money. Higher R-values can also make it easier to regulate your homes temperature, keeping you more comfortable.
Kevin Surace, the CEO of Serious Materials wants to bring attention to the importance of R-values in reducing our carbon footprints. Serious Materials, a green building materials company, is developing EcoRock, a recyclable material to be used in place of traditional dry wall and ThermaProof, a line of high R-value windows.
“Fifty two percent of all CO2 comes from building: 40% for heating and cooling buildings, and 12% for construction. Nobody wants to do anything about it; I was at the Fortune Brainstorm Green Conference and all anyone wanted to talk about is cars and fuel, when the biggies are cement, metal, glass and drywall,” says Surace.
So along with reducing, recycling and reusing, consider “resistance training.” Become aware of the R-values of the materials in your home. Making eco-friendly choices often reduces your energy bills while reducing your carbon footprint.
You have got your numbers on Rvalue of new windows completely unrealistic, the best you can hope for for very very expensive windows is approx R 4 . Even if they were a vacuum sealed air space window, they will be a key area houses lose heat. Please be responsible with your information that you post.
Liz
http://www.coloradoenergy.org/procorner/stuff/r-values.htm