Hello All and Happy Earth day to everyone,
I wanted to chat today about a very important issue when building a home or commercial building. The most important element in a green construction in my mind is the insulation. Why is this? Well for a starting point,buildings will use a tremendous amount less energy for its lifetime to operate. The USGBC (United States Green Building Council) has reported that 30 to 40 percent of total energy use is from buildings. 60 to 70 percent of the total electricity consumed is from buildings. 10 to 20 percent for water consumption and 30 to 40 percent carbon dioxide emissions are the result from yes buildings.
When designing an HVAC system engineers will look at the cubic volume of conditioned space with solar exposure and window verses wall area. Look for windows with low U value of .30 or better. The r- value would be important for the wall area.
The u value is the inverse of r-value check same link below.
The R-value is
http://en.wikipedia.org/wiki/R-value_(insulation) check this out for a more detail explanation of r-value.
Most popular option for insulating a home was fiberglass batt insulation. A 2x6 stud wall would give you an R-value of R-19 or if you had specified a higher density batt you may achieve R-22. This product would sometimes incorporate a kraft type paper vapor barrier that would be stapled gun to the inside face of the stud. A performance issue with this was mainly by poor installation practices but even a very good installation would result in marginal performance. The issue is with air tightness. Fiberglass and kraft face vapor retarder is difficult to create air tight structures that can maintain conditioned space in the home. Some designers would specify un-faced batts and specify a polyethylene vapor retarder toward the warm side of the insulation to provide a tighter installation. The studs at 16" o.c. is also fighting with the r-value. Sure your may be getting r-19 in the cavity but the stud is an r-7. Thermal breaks with continuous insulation as done in the commercial world works much better.
So what is the buzz on the street today?
Open cell vs Closed cell spray spray on foam insulation. You have probably heard many people in the construction industry talking about this insulation. Just goggle this and you will see what I mean.
What is Open Cell spray insulation? The foam cell is open basically so it can contain air and is less dense approximately 0.5 lb./cu. ft. I do not want to explain all the aspects of the open cell so please visit some good product web sites for more exhaustive descriptions of their products.
Some leading manufacturers of open cell foam are Icynene.
Check it out Below.
Open cell product is Castor Oil based water blown application.
R-value per inch 3.5 so 2x6 wall is 19.25
http://www.icynene.com/icynene-ld-r-50/Bio-Based 501 - soy bean based and water blown application.
R-value per inch 3.5 so 2x6 wall is 19.25
another good open cell manufacturer is
http://www.biobased.net/As you can see in terms of r-value the product compares with the much less expensive fiberglass batt insulation but with this product the air tightness is dramatically improved. We are going to be hearing much more about air tightness in construction and why this is a good thing if properly design with a good HVAC system that exchanges fresh air and handles interior moisture build up.
Now we will discuss closed cell insulation. The product is basically closed cell in nature not allow air into it and denser then open cell foam. The density of closed cell is approximately 2 lb./cu. ft much denser then open cell and it does not expand as quickly.
Some good first looks at closed cell insulation manufacturers would be Insulstar
Closed Cell product Polyol Resin System - Petrochemical -
http://www.insulstar.com/Thier product has a an excellent r value of 6 per inch. Check out msds sheet.
http://www.insulstar.com/uploads/11-009%20MSDS.pdfBASF Comfort Foam
Closed Cell product Polyol Resin System - Petrochemical
Thier product has a an excellent r value of 6 per inch. Check out msds sheet.
http://www.basf-pfe.com/index.php?location=RPR§ion=comfortfoamSome people ask my opionion on what product I think is greener.
My opinion is that the r-value is very good with closed cell but I do not like some of the chemicals in the mix.
Closed cell manufacturers have been recognized by the USGBC on stratospheric awards.
Having a higher r-value results in lower tonnage needed to condition the space resulting lower operating cost and less energy and fossil fuels to run equipment and reducing green house gas emissions.
I do like the soy bean open cell and Icynene's castor oil water based products.
It is all in the details for your architect and engineer for your project specific goals.
If someone told me I had to eat a plate or closed cell or open cell insulation I would probably go for the open cell.
Not recommending you eat insulation. You should insulate your home or commercial building with it.
Remember not to eat insulation.
Remember to Tread Lightly or Less
Be Green
Be Happy
Eric H. Gjerde AIA
Architect.
