In the constant quest for a greener insulation I have considered many options.
– Cellulose is good but messy and dusty.
– Isonyne spray foam or Demilec spray foam is good but not that cheap and quite honestly not as green as they say. It takes huge amounts of energy and petroleum to create the main ingredient isocyanate.
– Formaldehyde free fiberglass is ok but still fiberglass (scratch, scratch).
– Solid foam is good and in my opinion under valued by the green community.

THEN you have RECYCLED SOLID FOAM, which I am starting to think is the way to go.
It comes out at the same price as normal fiberglass batts but is way better R value when you air seal the boards correctly. And it is RECYCLED.

In my opinion normal (non-green) recycled materials is better than new green material. Why make more when it has already been made.

ALSO, foam board does off gas a little BUT almost all of that happens in the first few months or year. And since it is recycled it has already off gassed! Now that is a fantastic side benefit of recycling!

Further info I found on the web

Whether it takes the form of batt, loose fill, sprayed-in foam, or rigid foam, insulation is an essential part of any housing. Insulation slows the transfer of heat (energy) from warmer areas to colder areas. It can also serve to reduce noise. Insulation effectiveness is typically measured in R-value. A higher R-value for insulation is better. A well-constructed insulation system will help reduce air infiltration and heat transfer and help control moisture. All of these factors need to come together to produce a comfortable and healthy living environment. The following analysis examines the relative economic, energy, and environmental impacts of the following insulation types: fiberglass batt, blown and loose fill cellulose, blown fiberglass, foamed-in-place polyisocyanurate or polyicynene, extruded polystyrene, expanded polystyrene, and rigid polyisocyanurate.

Loose fill, blown and batt insulation is more cost effective in walls and attics than rigid board insulation. Foamed-in-place insulation should be used when budget permits, its high R-value combined with excellent air sealing increase the overall performance of the assembly. Look for insulation materials that have stable R-values over time.
Extruded polystyrene (XPS) insulation with CFC or HCFC’s as blowing agents should not be used. Rigid insulation alternatives include: wood fiberboard, (some made entirely from recycled cellulose), expanded polystyrene (EPS), fiberglass board, or cellular glass board.

Insulation Fact Sheet:


cost/sq. ft./R (materials & labor)

energy (R- value per inch)


expected product life (years)

life cycle thinking


fiberglass batt







cellulose blown and loose fill







fiberglass blown







foamed-in-place polyisocyanurate
or polyicynene

not available





requires trained installer

rigid perimeter: extruded







rigid perimeter: expanded







rigid perimeter: polyisocyanurate







Criteria Summaries
Cost: Loose fill, blown and batt insulation materials have a low cost per R-value and rigid board materials. Higher first costs associated with increased insulation thickness of any type may be recouped over the life cycle of the building through reduced heating and cooling costs. Premium costs associated with insulation with higher R-values per inch not only reduce operating costs but also use less material.
Energy: Rigid insulations typically have a higher R-value per inch than batt or blown insulations.
IAQ: If left undisturbed in wall cavities and attic spaces insulation poses no threat to human health. Respiratory masks should be worn when handling fiberglass and mineral wool batts, since they may potentially release fibers into the air during handling.
Expected Product Life: The R-value of most insulation materials decreases with aging. Polyisocyanurate and polyicynene have the longest expected life with the greatest R-value stability. Loss of R-value can be attributed to several different factors. Batt insulation can slump in cavities, or become damaged by moisture. These effects can be limited by proper construction and detailing. Rigid insulation can shrink and or dry over time, while loose fill insulation can settle, decreasing its effectiveness.

Life Cycle Thinking:
• Energy consumption (non-renewable, fossil fuel energy): The manufacturing process for fiberglass and mineral wool batts is energy intensive although less than for rigid products. Where recycled content is higher, energy impacts related to manufacture are further reduced. Rigid insulations have high embodied energy from extraction through production, though they offer higher R-value per inch thickness, and require less material overall.
• Pollutants generated in production: Extruded polystyrenes still use HCFC’s, while expanded and some polyisocyanurates use alternative agents.
• Potential for off-gassing: Not an issue when insulation is not exposed to the interior.
• Durability of the product: Prolonged contact with moisture can cause the paper backing on batt insulation to deteriorate, and also mat down batt and blown insulation, reducing the effective R-value of the material.
• Potential for future recycling: Blown insulation suffers from settlement, but can be recovered easily for reuse. Certain expanded polystyrene rigid insulation products use recycled content in their products (or at least reused waste products).
Practice: With the exception of sprayed-in-place insulations, which require training and professional installers, all insulation types are considered common practice.

Environmental Context
Reducing the amount of fuel to heat and cool also reduces environmental damage and costs. Insulation effectiveness is usually measured in R-value (thermal resistance) – the higher the R-value, the better the insulation value. Other considerations include the amount of recycled content, the ability to reuse or recycle the insulation, the ability to meet code requirements (in Minnesota amendments to the Uniform Building Code and the residential building code), and off-gassing of the products in place. Batt and blown insulation materials will generally have lower embodied energy than rigid insulation materials.

Here is some more info on Rigid Foam Board Insulation from my research

Rigid foam board insulation is a popular mass insulation product used to insulate all parts of homes, metal buildings and commercial buildings against the movement of conductive and convective heat transfer. A high insulating value for relatively little thickness makes rigid foam ideal for insulating roofs and exterior walls. Rigid insulation also substitutes well for other forms of insulation like fiberglass blankets and loose-fill cellulose in attics and floors. The water resistant nature of foam makes it well suited for use under slabs and in the ground around foundation walls.

Types of Foam Board
Rigid insulation is made of air-entrained plastic that is either extruded or pressed into sheets. There are three types of rigid foam insulation: expanded polystyrene (EPS), extruded polystyrene (XPS) and polyisocyanurate (polyiso), each varying in cost and R-value. Boards are available with a reflective foil facing that reduces radiant heat flow when installed next to an air space for total insulation against the three types of heat transfer, conduction, convection and radiation. If properly sealed, foil faced boards can also be used to form a vapor barrier in areas where moisture and condensation are an issue. Alternately, rigid foam can be installed in combination with reflective insulation to add a radiant or vapor barrier.

Insulation is rated by its ability to resist convective heat flow in units called R-value. R-value gives the insulation resistance per inch of material. Construction materials with higher R-value ratings are more effective insulators than materials with lower ratings for the same thickness. The R-value is a function of the material type, thickness and density. The R-value of an insulation system is calculated by adding the R-values of the individual components together to achieve the recommended insulation protection based on climate.

R-value is helpful in comparing different types of insulation as well as different brands of the same type of insulation. Rigid foam insulation has insulation values that are almost double the R-value per inch of fiberglass or cellulose insulation. R-values for rigid foam range from 3.6 – 8 per inch. Note that R-value is not used to rate a material`s ability to resist radiant heat.

Rigid Insulation Type R-value per inch
Expanded polystyrene board 3.6 to 4
Extruded polystyrene board 4.5 to 5
Polyisocyanurate board, unfaced 5.6 to 6.3
Polyisocyanurate board, foil-faced 7-8
(Source: US Department of Energy Insulation Fact Sheet)

State and federal agencies recommend insulation R-values for different areas inside of a building based on local climate conditions with the attic requiring the most insulation. Divide the recommended R-value by the R-value per inch of the type of insulation you want to use to determine the necessary insulation thickness. If you use reflective insulation in combination, you can add in up to an additional 14.5 R depending on whether the reflective insulation has foam, plastic bubbles or fiberglass for its central layer. Foam core reflective insulation (like foam board insulation) has the highest R-value. If you use foil faced rigid insulation facing an air space, you can add an additional R-value of 2.8 without increasing the insulation thickness.

Moisture Considerations
Preventing condensation in building cavities is a major consideration for an insulation system. Rigid foam board insulation resists absorption of moisture from the atmosphere in the form of humidity and also has a low water vapor transmission rate. However, rigid foam alone cannot be used as a vapor barrier. A vapor barrier should have a permeance rating of less than 1. The permeance of 1 inch of expanded polystyrene is 2 and the permeance of 1 inch of extruded polystyrene board is 1.2. In contrast, the permeance of aluminum foil is .001. Reflective insulation or foil facing is commonly used in combination with rigid insulation to create the vapor barrier necessary to keep moisture out of the walls and ceilings where it can cause rot, mold, mildew, odors, condensation and dripping. To create the vapor barrier, all seams are tightly sealed with aluminum tape.

Moisture also creates a heat transfer problem of decreasing efficiency when insulation gets wet as water is a good conductor of heat. Rigid foam board has been shown to retain its structural integrity through freeze-and-thaw cycles. It retains very little moisture in comparison with other types of insulation like fiberglass or cellulose. The Energy Division of the Minnesota Department of Public Service found that Expanded polystyrene used in exterior foundation insulation showed moisture levels of only 0.13% after 7 years of use. They concluded that the damp insulation board still maintained between 95 and 97 percent of its original thermal efficiency and compressive strength.

Benefits of using Rigid Foam Board Insulation

* Density – Density provides hi R-value with minimum thickness making rigid insulation more resistant to air and water vapor movement than fiberglass batts or cellulose.
* High compressive strength – rigid insulation provides a solid structure under the roof deck that can withstand the weight of both equipment and light foot traffic.
* Low weight makes rigid insulation boards easy to install and less expensive to ship.
* Resists outside air infiltration when joints are sealed with tape or caulk.
* New products are made without ozone depleting chemicals for virtually no global warming impact.
* Can be installed with full coverage over studs instead of just between them to eliminate the heat loss path through framing members.
* Non-hazardous to install – no fibers or fumes to inhale, non-irritating to skin.
* No deterioration of R-value over time – rigid insulation does not lose R-Value over its service life.
* Green – A manufacturing study showed that the energy required producing polystyrene foam insulation is 24 percent less than the energy required to make the equivalent R-value of fiberglass insulation.
* Rigid insulation “breathes” instead of trapping moisture like fiberglass or cellulose and therefore does not require the venting methods used for other insulation materials to prevent trapped moisture within walls, ceilings and roofs.
* Highly resistant to mold
* Not a food for insects
* Good acoustical insulation properties
* Can be used in structural insulated panels or for insulating concrete forms.

Expanded polystyrene (EPS) or beadboard, has been used as common household insulation since the 1950s. EPS is environmentally friendly as it is not manufactured using CFCs or HCFCs- both ozone-depleting chemicals. In addition to insulation, EPS is commonly used to make coffee cups and packing peanuts for shipping.

EPS is closed-cell foam made from polystyrene (a type of plastic) beads mixed with pentane and steam, used as a blowing agent, to expand the beads under pressure into foam, which forms thousands of tiny air pockets in the finished board. As air is a poor conductor of heat, these tiny air pockets will block the transfer of heat through the foam and trap expanding warm air.

EPS is molded into large sheets with R-values ranging from 3.8 to 4.4 per inch, depending on the density of the material. However, air spaces in EPS can accumulate and retain water. Because water is a good conductor of heat, some form of moisture barrier may be required to prevent this problem in high humidity areas, especially when EPS is used around foundations. To make the insulation more waterproof, EPS boards are available with optional thin foil or plastic facings.

Extruded polystyrene (XPS) or blueboard, is also a closed-cell foam insulation made from polystyrene plastic beads mixed with chemicals to turn them into a liquid before using a blowing agent to turn it into foam. The foam is forced through a shaping die, cooled and cut into panels.

XPS is more consistent in density and has a higher compressive strength than EPS making it better suited for use in roof assemblies and structural insulation panels. Higher density makes it more resistant to moisture than EPS, and XPS has a slightly higher R-value of R-5 per inch. Because of its superior properties, XPS is more expensive than EPS.

Polyisocyanurate or Polyiso, has the highest R-value per inch of thickness of the different rigid foam insulation types with an average R-value between 5.6 and 8 depending on the facing material. Facings such as plastic or aluminum foil increase its resistance to both moisture and radiant heat transfer. Polyiso is commonly used in roofs and cavity walls because of its thinness.

Polyiso is touted for being an economical choice. Its higher R-values per inch allow for savings on other building materials like thinner walls and roofs and their associated shorter fasteners.

According to the Polyisocyanurate Insulation Manufacturers Association, polyiso is a completely green building product as it no longer is made with either of the ozone depleting chemicals – CFC and HCFC. In addition, construction site waste can be recycled. Other beneficial characteristics of polyiso include its resistance to solvents in common construction adhesives and high fire test ratings.

Foil faced polyiso insulation has the highest R-value per inch of any type of mass insulation currently produced. When installed facing an air space of at least 1″, the R-value will increase by 2.89. ASHRAE assigns a 1″ air space R- 2.77. The Masonry Advisory Council adds an additional R-2.89 to polyiso insulation for a foil facing.

Rigid foam insulation boards used to insulate the interior of masonry walls do not require an additional vapor barrier. Wood strapping is attached to the wall and the insulation is installed over the strapping. If a foil-faced board or reflective insulation is used also, the foil side should face the room and an additional layer of wood strapping is needed under the drywall to create an air space. Fire safety codes require that at least ½-inch thick gypsum board (dry-wall) be placed over rigid foam insulation. The drywall is then attached to the wood strapping or underlying masonry with nails or screws. For insulating an unventilated crawlspace, rigid insulation boards can be glued directly to the wall.