Nasa’s Aerogel material, which it uses to collect space dust – also makes a great insulating material for your house!

Since we’ve recently discussed energy consumption and indoor air quality on Inhabitat, we figured now would be a great time to talk about insulation. Don’t run away! We realize that insulation is not a sexy subject matter. Nevertheless, insulation is crucial to your energy consumption, comfort, health, and ultimate happiness – so don’t flee just yet…

As you all know, having good insulation is critical to having an energy efficient house, and proper insulation can save you loads of money with your heating and cooling bills. What you may not know, however, is that most mainstream, commercially-available insulation is pretty nasty stuff that you probably don’t want anywhere near the air you breathe all day. Many people believe that nasty chemical insulation (the kind that is in most people’s houses) can contribute to cancer, asthma, and a whole host of other health problems. That’s why we highly recommend checking out some of the newest types of eco-friendly insulation, such as recycled denim, wool, icynene, and nanogel.

Here are some of the traditional choices for insulation…

The most common insulation in the US is fiberglass – the pink stuff that looks like cotton candy. This is the Pink Panther of insulation, and it comes in batts and blankets. It has long held a pseudo-monopoly in residential insulation, but its negative aspects are beginning to catch up with it. It’s a health hazard, has been connected with black mold, and is difficult to work with – yet it is still the cheapest choice in today’s market.

The problem is that fiberglass is similar in structure to asbestos (made up of tiny little fibers) and thus raises similar health concerns. Tiny sharp particles break off into the air and can lodge in your skin, eyes and lungs, causing small abrasions which lead to irritation. The evidence is unclear, but there are many groups who claim the health problems caused by fiberglass are just as bad as asbestos. This is why anyone who installs fiberglass insulation has to wear heavy duty clothes, gloves and a face mask. My personal feeling is, if you need to take this much precaution when installing a material, do you really want it sitting in your house, leeching into the air you breathe for 20 years?

This is basically bits of newspaper shredded up and sprayed into a space. It is cheap, effective and easy to install. Recycled newspaper you say? Recycled = eco-friendly, right? In this case, not really. Shredded-up newspaper is highly flammable, pests like it, water loves it, and it can get nasty and moldy.

Polystyrene – You’ve likely seen these sheets of cut-to-fit Styrofoam. This product has the best R-value of the bunch, it’s relatively affordable, and takes a physical beating fairly well. Of course, with Styrofoam, there are long standing issues with CFC’s and the other hazardous chemical components that go into the production of these panels.


There are a lot of promising new materials being used for insulation these days. Some, like wool and cotton (above), have been used successfully for thousands of years and are finally being rediscovered by mainstream markets for their combination of high R values and simple, natural organic qualities. Other substances like Nanogel and Icyene are patently high-tech and non-organic, yet their special qualities permit new developments in insulation such as spray-in-place quick fixes, and translucent insulating walls.


This is my favorite choice by far! This organic insulation is made from recycled blue jeans – how cool is that? Bonded Logic’s UltraTouch brand of denim insulation is 100% recycled, and since its good old fashioned cotton, you know its not going to off-gas any nasty chemicals into your house. Better yet, it installs quickly, comfortably and easily – requiring no special equipment and no protective clothing. As these photos attest, you can even get your kids to help install it!

+ Bonded Logic UltraTouch


People have known for thousands of years that sheep’s wool has excellent insulation qualities. We’ve been making garments out of wool for centuries, so it is surprising that it’s taken this long for wool to be considered a viable insulation for buildings. Thermafleece is a patented sheep’s wool insulation material for buildings, produced by Second Nature in northern England. Unfortunately for Americans, Sheep’s wool doesn’t seem to be too easy to come by in the US at this moment. Fortunately for us, we can stick with the all-American blue jean insulation.


There are a several varieties of spray-in foam. They start out in liquid form, and expand and solidify almost instantaneously to fill minute cracks and crevices. These high-tech foams are more flexible than the “Great Stuff” you’ve seen at Home Depot, and also allow trapped moisture to evaporate. Not all of these products are the same, though. Some of these formulas are chemical minefields, while others such as Icynene, are water blown and produce no off-gasses whatsoever. Additionally, these usually cost three to four times more than traditional fiberglass and must be done by professionals. (Oh, and it ain’t fun if it dries in your hair – ask Nicki!)


Aerogel is a super-futuristic form of “frozen silica smoke” – made of a special type of super-porous silicon foam that is 99% air. It’s incredibly strong, incredibly insulating and incredibly light. This stuff has to be seen to be believed! Check out this crazy photo from wikipedia >

Aerogels have extremely small pores, which makes them one the best thermal insulators in the world. Nanogel® is Cabot Corporation’s trademark name for its family of translucent silica aerogels. The great thing about Nanogel is that it is light and transparent, while being extremely insulating – so you can use it to create insulating windows and skylights, as well as translucent walls and ceilings that will let the light in, but keep the heat out.

As you might expect, this silica foam isn’t inherently any better for your health than fiberglass when exposed to skin and lungs. (Just like fiberglass and asbestos, microscopic pieces can break off and lodge in your skin, creating health problems). Fortunately, however, Nanogel is never sold loose – it is always prepackaged and sealed into polycarbonate or fiberglass panels under trade names like Kalwall and Supersky Systems. These prefab panels are completely safe to work with, and make up for any possible health concerns with their very healthy advantage of allowing natural light into homes. Aerogels are revolutionizing a new era in residential daylighting. Viva la insulation revolution!


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  1. Richard Beyer April 15, 2014 at 2:55 pm

    I think what readers are failing to understand here is the year (2006) this article was published. During 2006 most of the published information was fact for that time period. We were also in a building boom and no one cared to know fact from fiction with all that money changing hands. Now that the recession cured us all from the financial drive and brought most back to reality we all in the building trades are taking a hard look at the numerous failures and illnesses we are faced with today.

    Today (2014) after much research of modern building materials we now know most of what is stated in this article is no longer valid information and is misleading. Today those concerned with building product safety are now looking at the health effects of isocyanate (A-side used in spray foam), flame retardants (used in most modern insulation, except for mineral wool), Glycols, Amines, Blowing Agents (used in spray foam) and other volotile compounds. With insulation each has it’s place to be used.

    There is no single size shoe that fits all and careful consideration needs to be used when health and safety is a priority, as it should be in all homes. Moderation may be the best solution when selecting insulation. (a little of this with that)This may be the safer alternative than pumping a home with to much of one product with so much of one or two hazardous chemicals for the well being of the individuals residing in the home. People with chemical sesitivities need to be more concerned and those of the population living with asthma. These folks need to seek safer alternatives and seriously consider safer ventilation techniques. A wise choice would be to spend the money on an Industrial Hygentist to advise them in the proper building materials selection process.

  2. James O'Shea June 11, 2013 at 11:44 am

    As an energy auditor who has conducted over 500 Comprehensive Home Assessments to BPI Standards and over 2,000 quality assurance observations for the Department of Energy after 10 years in the Green construction industry, I have to ask you to either re-write this or remove it for being Highly Biased, Incomplete (You don’t talk about Hot vs. Cold Climates and how materials perform in them respectively), and based on opinion NOT fact (Although many of the statements can be put in a context where they’re not TECHNICALLY wrong, they are still misleading).

    As Robert pointed out Cellulose is actually one of the BEST insulating materials, NOT the worst ( And I’m a spray foam guy for most applications )

    Spray foam is typically 1.5 – 2 times the cost of fiberglass not 4 unless you’re talking about simply buying the materials, and a Foam Contractor operating off of a spray rig (not the 5 gallon 2 part foam kits) will give you a COMPLETE finished product including cleanup for LESS THAN THE MATERIAL YOU CAN BUY YOURSELF.

    And if you want to talk about expensive, try pricing out Cabot’s Aerogel product. It works out to around 3-5 times the cost of cellulose while providing only twice the insulation value (Cellulose 3.7/Inch Aerogel 8.8 based on my 2011 Technical Data Sheet), and good luck finding someone to install it that actually returns phone calls.

    For facts, #’s, technical data sheets, specifics about most things related to green construction (Insulation, Air-Sealing, Renewable Energy, Heating, A/C, etc.) my E-Mail address is and I enjoy spreading knowledge to help the environment.

  3. TTT-A.RU February 5, 2012 at 10:04 am

    Interesting Information –

  4. Robert Riversong October 14, 2011 at 12:25 pm

    I am a 30-year pioneer in super-insulated home design and construction, as well as an instructor in hygro-thermal engineering and have no stake in any facet of the insulation industry.

    However, there’s some strongly biased and false information here. “Shredded-up newspaper is highly flammable, pests like it, water loves it, and it can get nasty and moldy.” Cellulose insulation, in addition to having the lowest embodied energy, is treated with non-toxic (to humans) borate which is an excellent fire-retardant, kills most household insects, is an irritant to rodents and prevents mold growth. The fact that it is one of the most hygroscopic of all insulation materials means that it serves as a moisture buffer, absorbing and releasing excess humidity as necessary, and by distributing the moisture throughout its mass it prevents the localized high moisture content which leads to mold and rot in the wood framing and sheathing.

    Blue Jean batt “installs quickly, comfortably and easily – requiring no special equipment…” Recycled blue jeans create one of the most eco-friendly batt type insulations, but it’s susceptible to the installation problems of all batts – difficult to fit completely into cavities. Additionally, blue jean batts are nearly impossible to cut, even with the special knives and saws that are recommended for that purpose.

    Insulation overviews like this would be more useful if they were based on fact rather than opinion.

  5. Clare June 2, 2011 at 1:21 am

    Thank you for a most interesting and informative post! Thanks also to the many people who have contributed meaningful comments which have added to the knowledge base. I have learnt a lot today. It’s wonderful to see a post generating so much interest – good for you!

    EcoExpert tips on eco-friendly lifestyle, products, travel

  6. preciseenergy May 31, 2011 at 7:05 am

    Thanks for sharing the ideas with us…Please keep sharing this stuff.

  7. Johan April 30, 2011 at 2:12 pm

    The cellulose is the best. go on youtube to see it.

  8. rick Babtist February 25, 2011 at 12:55 am

    Great post on Green insulation. Materials used in green as mentioned are available in brand name insulation. A good directory of insulation is available at McGraw Hill. You can view a list of products, green description, manufacturer, product details and even download CAD files. I hope this information helps like it continues to for me. insulation

  9. CarrieMcM November 22, 2010 at 6:45 pm

    As an employee at a foam insulation company, I personally prefer to use icynene foam insulation. It’s so much greener than fiberglass. Though can be a bit pricey, it covers holes and cracks much more thoroughly.

  10. New rSTUD Significantly... November 3, 2010 at 3:30 pm

    […] building industry is that the promised r-value of a wall is usually just a measure of the cavity insulation in a perfect installation. Often the installation of insulation is not perfect, but just as […]

  11. Tania Parks September 3, 2010 at 2:15 pm

    Hi, I work for a Home Performance contractor in Portland, OR called Sustainable Solutions Unlimited. We do Home Performance with ENERGY STAR assessments and complete the associated whole home weatherization work. We install all kinds of insulation from blown in fiberglass to Eco Foam and Air Krete for walls to blown in cellulose.

    We are always open to trying something new for our customers yet unfortunately often the new/returning options are generally 2-4 times the cost of blown in cellulose. These include Eco Foam, Air Krete, Spray Foams, recycled denim batts, wool batts, etc. And Aerotech Gels are most likely going to be much more expensive. Most of our customers cannot afford these other options, especially with the way the economy is today.

    The one we have found that makes the investment worth it in terms of energy savings/payback is the Eco Foam for walls. It provides the air sealing, insulation, and sound reduction qualities that we are looking for as a Home Performance contractor.

    Also the issues I have seen mentioned in the comments such as indoor air quality and moisture issues of cellulose or fiberglass – these are issues with any insulation. Any fiberous items floating around in your home\’s air is not good to breathe, and there is a simple and highly cost effective answer – air sealing. Air sealing is part of Home Performance 101 and goes hand in hand with any insulation product that is not sprayed into place. Any type of batt or loose fill insulation has millions of air spaces that allows air to leak in/out of homes by traveling through and around the insulation. Air sealing with a combo of caulk, spray foam or rigid foam board insulation should happen first before any batt or loose fill insulation is installed. It is the air sealing that will keep any nasties from migrating from your attic, walls and crawlspace from making into your home.

    Pest are another indoor air quality issue that has nothing to do with insulation. If you have pests in the attic or crawl, then they need to be removed and you need to find where they are coming in and block off the hole(s).

    Regarding insulation and moisture issues, almost all types of insulation will get moldy and nasty if water penetrates and sits around in the material. Think about having soaked denim cotton jeans and cotton sleeping bag on backpacking trip where its pouring down rain – they don\’t dry out until it stops raining and the sun comes out. If your walls, attic, and crawlspaces are getting that much water, then you have another issue that has nothing to do with the insulation. Insulation is NOT an air or moisture barrier, you have to take into account your climate and region in order to design in where the vapor barriers are installed in the roof and walls. If they are on the wrong side then your home will experience the diaper effect – moisture locked in and no where for it to go.

    By far the most common insulation we use for attics and walls is cellulose for several reasons:
    1. Its about the same price as blown in fiberglass so its an easy & comparable sell to home owners that believe in more traditional products such as blown in fiberglass. And it is much more environmentally friendly and non-toxic for the home.
    2. It has a high R-value at approx. 3.7 per sq inch
    3. It deals with moisture by dispersing it over a larger area which dries out more quickly later, whereas fiberglass and wool products wick it to the edges where it can pool up in the lowspot and stay stagnant for a long time depending on how much moisture is leaking in.
    4. Cellulose is treated with a boric acid solution – the type and toxicity depends on the boric solution used & there is more than one out there. Ask your insulation manufacturer or contractor about seeing an MSDS sheet. In general boric acid solution is non-toxic as compared to the bromines and other fire retardants out there. It also is used to deter insects (a great natural remedy for ants & other small insects that infest our walls)
    5. Cellulose can be dense packed into walls and there are less air spaces than with blown in fiberglass, wool or denim batts. This means it has better sound reduction and air sealing properties.

  12. America's First Zero En... September 2, 2010 at 2:23 pm

    […] are shaded by light shelves that reflect sun into the celestry windows, providing ample daylighting. Nanogel translucent panels line the celestry window in the main hall. Their ability to provide lots of […]

  13. Mickey August 26, 2009 at 6:11 pm

    I am sure that things have changed since we put cellulose in our house about 30 years ago but I would never put it in any house of mine or recommend it to anyone. We blew it into an existing 70 to 80 year old farm house ever since I have had the insulation sifting out of window frames and any and all cracks that it could find. It has been a pain in my backside for 30 years. If you are not putting it into a new house don’t do it!!!!!!!!!!!!!!!!!!!!1

  14. pickle.face May 4, 2009 at 2:40 pm

    what are the best materials for an insulator in a box??

  15. datudean October 9, 2008 at 3:41 pm

    I think you forgot to include the cheapest and yet highly effective insulation (and 100% absolutely green).

    we people living in the tropics utilize the use of air as insulation to walls and roof. as much as possible we integrate it to our designs. air is abundant and it is always free to use.

  16. datudean October 9, 2008 at 3:32 pm

    i think you forgot to include the cheapest, lightest and greenest kind of insulation.

    we people living in the tropics, we utilize air spaces as insulation. you can verify it. air is still the best insulation.

  17. Jeanne September 13, 2008 at 2:15 am

    I\’d like to know anything anyone out there knows about the potential toxicity/pluses/minuses of Icynene. It is listed as \”green\” on its own and some other websites, but I can\’t find more than brief mentions of it. I\’m thinking of using it to insulate my home.

    A company I have talked to here in Oregon, Phelps, that uses it, says that moisture is not as much of a problem because water slowly passes through it. So if your roof is leaking, you\’re going to see the leak, but the icynene doesn\’t retain the water the way the way

    Lastly:Good article. I am not an insulation contractor, I\’m a nurse practitioner, and did my master\’s on a subject related to home air pollution (chlorpyrifos exposure). Most people don\’t realize they get most toxic exposure inside, not outside, their homes, so it is important to consider the toxicity of anything you use/bring into your home. Remember that substances you use indoors are going to be MUCH more concentrated than those you use outside. Personally I try not to get paranoid, but I avoid anything containing old-fashioned particle board (offgases formaldehyde and other things) and I painted my rooms with low voc paint.

    It\’s important to consider Hypocrates\’ maxim: the difference between a medicine and a poison is in the dose. Regarding cellulose and their borate content: Boric acid is fine if you use a bit of it for medicinal purposes or to kill ants. I don\’t know if it has health effects if it is floating around in your indoor air constantly. I wish it was easier to get information on the toxicity of everyday products. Seems there should be some trusted website you could go to. If you know of one, please tell me! And info on icynene, please!

  18. garyo July 12, 2008 at 1:37 am

    As Eric has mentioned,
    The effect of fiberglass insulation on humans or the environment is limited. When installing fiberglass insulation I wear an appropriate mask, eye protection, long sleeve shirt, nitrile gloves (they seem tougher), and of course, long pants. A Tyvek painter\\\’s suit would work well. A cool shower after handling fiberglass seems to help wash off any fibers that have penetrated my protective layers.
    Once installed in a building, fiberglass insulation is contained within the walls, ceilings, etc. It\\\’s toxic effect upon humans or our environment is non-existent at this point. Which other insulating products can the same be said for? Foams can emit gasses over their lifetime, blue jeans have what in them? I do remodeling in the Northeast, I have worked on houses that have had \\\”state of the art\\\” insulation from all eras since the late 1800\\\’s.The oldest had no actual insulation, but were well built with interior plaster walls. Houses built in the 30\\\’s -50\\\’s often have fiber building board behind their siding and sometimes bats of \\\”rockwool\\\” insulation. Newer homes usually sport fiberglass in various thicknesses. The goal no matter the age of the house however, is to make a home more comfortable while expending less energy ($) in doing so. Use the insulation of your choice, look at the big picture people, use of any insulation saves energy. Let\\\’s work together on this.

  19. andrej April 15, 2008 at 4:23 am

    Just wander if you came across some European manufacturers of eco insulation?

  20. kevin March 5, 2008 at 3:21 pm

    i’m a international business man from china,and we have developped a kind of super material for insulation,and it’s not the same as fiberglass and rockwool,it’s 19 layers,and we export it to the uk,but we donot know how to get a new order,it’s cheap if you buy it from us,and it’s better than any other if there are any business people will be interested in it,pls tell me or contact with me,and hope some one will help email is

  21. JB December 25, 2007 at 12:31 am

    I am building larger cedar planter boxes in my business. I’ve seen several spray in gels discussed but I’m not sure if I would have to have a licensed applicator do it, get a license myself or if I need a license at all?
    Any other options that would be cost effective? The purpose is to avoid wide temperature fluctuations and most of all prevent freeze damage to the roots. Any ideas conventional or on the edge are welcome. Thank you.
    Whoever is paying for this site BRAVO!

  22. John Peters November 18, 2007 at 10:34 pm

    Everyone brings up good points in the article, but no one has bothered to address the science of thernal energy transfer. If your talking about insulation you need to talk about how heat and cold move. There are a lot of statements about various product benefits versus other products but all I read is marketing bullets. Lets cut the fat and look at the science of the matter.

    Thermal energy (heat or cold) moves in three ways; conductivity, radiation and convection. Unfortunately, our present building code only address’s radiation (R value). A truly effective insulation material should be able to mitigate all three of these. When taking a closer look at convection we find the biggest culprit of thermal energy loss; air infiltration. Only spray foam insulation can address all three forms of thermal energy transfer (especially air infiltration) while still maintaining Class I fire rating.

    I pose no marketing bullets here or try to make something out that it is not. Science is science. Adhesion and expansion is how spray foam performs the best.

    I own a spray foam insulation company ( You can call my above statement biased because of this or lift the vail from your eyes and see the light. If you want to save money on heating and cooling bills and reduce your pollution output spray foam is the answer.

  23. Dare November 16, 2007 at 12:17 pm

    Does anyone have any experience with Sealection 500? I’ve read the wikipedia entry on it: mostly positive except for mentioning that it’s an Isocyanate.

    I’m insulating the floor of an old Victorian in Savannah, GA. Anyone know of any other green insulation companies down here?


  24. Andrew Carson November 12, 2007 at 3:15 am

    Hi use sheep wool insulation blown supa_fill its cheap here in New Zealand and if someone wanted to import and install in quantity the cost wouls be very similar i.e 70usc per sq ft installed

  25. Callie September 19, 2007 at 7:17 pm

    It is about time people speak up and get away from the “way it has always been done” ideas! We are all in this together and it is about conserving energy, recycling and having a healtier place to live. I grew up in a home with fiberglass and some other “poured bagged stuff” that as kids, we used to play in, now we learn it probably accounts for my lungs being like a smoker even tho I have never smoked! Radiant Barriers prevent heat from entering building, less strain on A/C units. etc etc etc

  26. Len Mecca September 9, 2007 at 6:43 pm

    Obviously you didn’t do your research when you reviewed cellulose. You have it wrong by a wide margin. it’s NOT highly flamable . Try burning it with a blow torch – nothing happens. It has a class A fire rating – one of the highest. Pests to NOT like it. The fire treatment is borate which is used extensively to treat for insects and mold. It DOESN’T grow mold – borates again. When you mention water, you must be talking about buckets of water? That’s a problem fscenario for all insulations. I did my research and have used cellulose in my home long ago with no regrets.

  27. Peter Hewlett August 23, 2007 at 11:40 pm

    Used carpet underfelt is discarded and replaced by foam underlay when old carpets are replaced. Has anyone investigated the feasibility of re-using it as roof-insulation? It looks as if it would insulate very well, and I presume it is already treated against fire and pests. It also has the great virtues of being readily available and free. Great website!

  28. callie barrett August 20, 2007 at 6:50 am

    Radiant barriers and reflective foam/foil insulation varies. our products use polypropylene whish has the highest fire rating. Class A/Class I fire rated. MicroLt is a high performance reflective foil radiant barrier and vapor barrier. It is energy saving, labor saving due to self taping seams, extra tough, high quality pure aluminum foil. Great condensation contol. shipped factory direct to your project. All products are not equal.

  29. Callie Barrett August 9, 2007 at 6:46 am

    Radiant barriers are necessary to stop Radiant Energy which accounts for over 90% of summer heat gain and over 50% of heat loss in the winter. It is easy to apply, doesnt tear, no special tools to apply. Our products do not contain air but the Core is ¼”thick microfoam polypropylene with
    high purity Aluminum foil with reincorced scrim and patented self taped edges are on both sides.

  30. Jevin Dornic July 16, 2007 at 1:36 am

    I’m surprised to see that inhabitat is promoting the use of aerogel. It seems premature to support the use of nano-technology as an effective solution. The effects of nano-particles on the human body and environment are still un-known, and if the product had been researched in depth, you would have discovered that the company mentions a “nuisance dust” when the product is disturbed. When I called to ask about the material in late May, the information regarding the additives to silica product were described as proprietary. Nano-particles used in other products have been shown to cause adverse effects on the human body when airborne. “In May 2006, Magic Nano, a household cleaning solution, was introduced in Germany… Within 72 hours of product rollout, however, 97 consumers had been hospitalized with breathing difficulties, some in danger of death due to lung edema.” -Jean-Yves Poirier

  31. Jeff Rodman July 4, 2007 at 1:27 pm

    Thanks for an excellent article, with some very illuminating comments following. I have one comment: once installed, fiberglass does not release particulates into the air, because it is sealed in place and not disturbed. This is also true of asbestos. The issue comes during installation and removal, when particles are broken free through agitation and can be ingested or inhaled. In actual use, they are not “sitting in your house, leeching into the air you breathe for 20 years.”


  32. p.v.parameswaran June 10, 2007 at 12:56 am

    I would like to know the negative factors of reflective bubble wrap insulation material

  33. Green" Insulation &laqu... June 5, 2007 at 4:32 pm

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  34. Callie May 27, 2007 at 8:13 am

    sorry for more info please see

  35. Callie May 27, 2007 at 8:13 am

    radiant barriers prevent up to 97% heat from entering the space . It is the perfect addition to insulation that only slows conduction heat transfer. We ship factory direct the finest green insulation product available with pure AL foil ,with reinforced scrim and self seaming taped sides. Has a polypropelene core, same kind of material underwater divers adn mountain climbers use! Easy to install.

  36. Eric W. May 23, 2007 at 4:47 pm

    It’s too bad that the insulation choices that are “greenest” (cellulose, blue jean) are ones that are “downcycled.”

    Does anyone have more detail about the environmental impact of icynene? How different is it from Spray Polyurethane Foam (SPF)? Is it made from petrochemicals? What’s the embodied energy? Are there off-gassing issues? It’s hard to find info that isn’t from the manufacturer…

  37. Eric W. May 23, 2007 at 4:39 pm

    @ dug-

    you asked about the toxicity of fiberglass insulation. Essentially, it is made from silica, or sand, in a furnace, so it is not toxic to the environment, except for the breathing in issue already mentioned. It is therefore “all natural” and made from a plentiful resource, but it has a high embodied energy, because it is made in a high-temp furnace.

    As for the black mold issue, there’s nothing about fiberglass insulation that makes it any more supportive of black mold than cellulose or drywall (or any organic material or inorganic material that can collect organic material) The problem behind any mold growth is moisture

    The soy-based spray foams are 50% soy and 50% petrochemical (at least the stuff I’ve come across), so they aren’t 100% renewable,

  38. john roberts May 17, 2007 at 10:15 pm

    I am refurbing several older homes and building some new ones………all with existing different methods that interest me as well as some that are my own design…For those of you who have logged on saying that you were building a new home and WHAT insulation do I use????? need to first deal with several things….Where are you (What works here in the S.W. may not work as well In the N.E….If you are still kicking around they type of house, your choice should have an influence on what you use as well. Michelle has in my opinion come up with the insulation that we all should be considering due to the properties she mentions that it possesses…..I have dealt with moisture in walls which reduce the insulative qualitys of fiberglass batts to nil and seen the mold grow on cellulose that has gotten damp and etc. etc. with the other types. If you are going to build the house yourself you have one up on one that someone else is going to build for you as you can make sure all those cavitys are filled and the thickness in the ceiling is what is called for….and maybe a little more. You caulked or foamed around the fixtures and pipes and didn’t miss any cracks. The type and care in which the house is built should enter into your insulation figuring. I am building one house with 2 foot thick soil (65% sand/gravel, 30% clay, and 3-5% cement….rammed earth or poured. There will be little insulation needed and then only in the ceiling…..but thats here in the s.w….New England or the Oregon Coast will require a different approach…..The innovators and contributors of this website deserve much credit….It is only in forums like this that we will change our society to include everyone and for the better…….Michelle….you and I may have to start thebig polyester insulation company……doesn’t seem like much available…….eep us informed as to what you find…..I’ll do the same…….

  39. michelle May 16, 2007 at 5:07 pm

    Nobody has mentioned polyester batting insulation. They apparently use it in Australia (under the name “green stuff”. It’s similar to fiberglass batting in terms of how it’s used, but (like cotton or wool) it doesn’t have the health issues (no sharp, tiny particles to lodge in your lungs or skin), and (unlike cotton and maybe wool) it’s not attractive to pests or bacteria, is hypoallergenic and possibly less water absorbing.

    At least that’s what I can glean from the few websites I’ve found that discuss it. I’d certainly be interested in hearing anyone’s practical experiences with it. It would be nice to have a fairly low-tech, user friendly insulating alternative. To me, cotton and wool seem like potential problems in terms of dampness and critter appeal, so polyester seems like a potentially attractive alternative.

  40. Mike April 23, 2007 at 11:52 pm
    All soy based foams are about same, except we are going to blend in the front range. Call for application and foam sales.

  41. Raymond Pritchard February 26, 2007 at 3:51 pm

    We are building a new house in Texas, it is a ranch, silver metal roof….

    Should we us the cell insulation? Reflective barrier insulation? Both?

    Does anyone have any comments…HELP!


  42. Kris February 24, 2007 at 8:25 am

    I am a homeowner without insulation experience. I have an old English Tudor with a high ceiling, the attic currently has cellulose on the horizontal surface above the ceiling. The cellulose has been there a very long time and is super dusty. I have allergies so when using the attic for storage I have trouble with the dust from the unfinished part of the attic getting over to the finished part. If money were no object I think I would use a soy based professionally sprayed insulation, to insulate the roof. We live in California and it gets hot. However one of your bloggers mentioned foil, should we be putting foil on the roof inside the attic before we add any type of insulation? Also I am considering blue jean insulation and air krete insulation. I am concerned about weight of the insulation, weight of dryall, etc. on the open beam ceiling. Is there a website that lets me know how to calculate if my structure can hold insulation on a roof safely? I have run into a number of bozos who I paid big dollars for consultation and they said something that made me mistrust their advice. This includes a so called engineer. It seems that the engineer architect planner types I have met do not know as much as the roofers and insulation contractors. Any pros out there that can refer me to structural concerns 101 type website, etc. I also have allergies so I need to keep a low dust environment.

  43. Tom Sanders February 10, 2007 at 12:27 am

    We’ve lived in a super insulated home for 10 years and thoroughly enjoyed it. Especially, the low amount of heating oil consumed and the summer cooling costs. The house was insulated with fiberglass, constructed with double side walls and site orientation for the winter solar gain.

    Now our present home is insulated with Icyene and I think the stuff is great. The Icyene makes the house extremely tight. I did get some Icyene overspray on my glasses and it never came off. I am convinced the Icyene has kept our energy bills down. Our living room has a 15ft vault with and 8ft drop on the fan. Very confortable. The issue I have is we have not installed a proper air to air exchanger and that may be costing us. In the construction of this home, we were lucky to have a builder who worked with us on the Icyene. The mechanical was already in place and he wouldn’t budge.

  44. STEVE January 31, 2007 at 5:57 pm

    Oh one more thing about cellulose. The manufacturers mix in some starch to make the cellulose slightly sticky. When it is blown in it is damp. The installer controls the amount of dampness in the mix, so it is important to get this right. The building owner needs to insist that the wall cavity stay open long enough for drying to occur. Use of a humidity probe is a good idea to gauge when it is okay to close the wall cavities.

  45. STEVE January 31, 2007 at 5:52 pm

    The information on cellulose insulation is a bit misleading. Cellulose insulation is treated with boric acid to impart fire, mold, and pest resistance. Its burn characteristics are similar to strawbale; ie it smolders rather than burst into flames as the summary suggests. The beauty of blown in insulations like cellulose is that it fills a cavity completely, without requiring the kind of detailing required to make batt insulation perform as advertized.

  46. gernot January 30, 2007 at 12:06 pm

    Hi erica, hi feile !

    for those who are interested in real eco-friendly insulation check out this new project from good old europe.
    it´s a “factor 10″-house (uses 10% resources and energy compared to a conventional construction)

    so here is a link to a short presentation in english:

    …kind a interesting i think!

  47. feile January 24, 2007 at 7:53 am

    I would just like to query the environmental impact of the aerogels when looked at from “the cradle to the grave”. It seems like the kind of product that would have high embodied energy in its manufacturing process. Maybe you can enlighten me. I would also wonder about its recyclability. Does it ever break down? Or will it get dumped in landfill when its job is done? For this reason I would always prefer organic materials whenever possible.

    And just a small point – it’s straw bales, not hay bales – straw is a hollow structure with a lot more strength and a lot longer shelf life than hay. And they are a brilliant way to insulate, if you are not too close to the sea and can seriously protect your walls from rain.

  48. Inhabitat » ILLUM... January 16, 2007 at 1:27 am

    […] We’ve been singing the praises of daylighting and translucent architecture ever since we began preaching the green design gospel here at Inhabitat. Using translucent daylight panels, you can fill your house with diffused sunlight during the day — aiding your health and well-being, and cutting down your electricity bills at the same time. There are plenty of building companies that have been making polycarbonate, nanogel-filled “Daylighting Panels” for awhile now, but Duo-Gard is the first company to push the envelope to its logical discotheque conclusion by bringing colored LED lights into the mix. Now with Duo-Gard’s new IllumaWALL, not only can you flood your house with sunlight during the day, but you can light up your house like a big jack-o-lantern at night: in pink, yellow, green or blue light — or even a pulsating spectrum of colors if you want to be that annoying. […]

  49. Hugh Loebner January 14, 2007 at 8:54 pm

    What about ordinary bubble wrap? It is cheap, and translucent. I have used it and it works well. I use 3 layers..

  50. Linda December 17, 2006 at 9:40 pm

    I am building a house and am trying to decide between insulating with blown cellulose or icynene?
    I am worried that icynene may not breath and can trap moisture and rot the walls.
    Any comments?

  51. E. Johansson November 27, 2006 at 1:07 pm

    Very interesting site & great that you update it so often!

    A question regarding the silica foam insulation – if it “isn’t inherently any better for your health than fiberglass when exposed to skin and lungs…….” what about worker exposure & health?

  52. Gil November 14, 2006 at 9:22 pm

    Check out soy-based spray foam.

    Same properties as other foams, even better when considering environmental aspects, comes in open and closed cell versions (.5lbs/cubic foot or 1.7lbs/cubic foot).

    Dealers across the country.

  53. testus October 19, 2006 at 7:39 am

    Very good read! If anyone could point me to similar informational articles please let me know on my small website about insulation:

  54. sarah October 17, 2006 at 2:02 am

    I am seriously considering using Icynene in a renovation in Brooklyn, NY. I am very curious about the R value issue though. I am told that Icynene with a value of R23 holds up to the saem standards of insulation as other options at R38 (ie 6″ of icynene with a “true ” R value of 23 will be sufficient in my roof). Has anyone had any experience with it? Believe /not believe this? Would love feedback from anyone out there who has.

  55. erica October 5, 2006 at 12:54 am

    I am glad to see that new, eco-friendly insulation options are being utilized.

    however, there was recently an article in the paper of another material which i would urge you to investigate. “hay bales”. They can retain heat or keep heat out of a house, and are much less expensive than other insulating options. The house which i read about was located in Rhode Island, and seems to be drawing attention for many positive reasons.

  56. marvin greenberg September 27, 2006 at 2:03 pm

    There is also cementious foam (AirKrete) which is an environmentally friendly fireproof insulating foam. Importantly for me, it can be blown in to existing structures (unlike most foams that expand on application and can only be sprayed.) Here are some links that mention it: (in blown in foams) (one company) (another company)

    My delicious links about insulation:

  57. Mirza Shahed Baig September 23, 2006 at 6:36 am

    can u provide me the monthly information about the nano technology applied to space

  58. adaminc September 7, 2006 at 3:33 am

    I think you are missing the most important insulation yet, VIP (Vacuum Insulated Panels), they byfar offer the best insulation, between R30 to R50 depending on the structure material, whereas that Aerogel does around R10 at best! Not only thermal insulation, but sound insulation as well. The only problem right now is I dont know how long they last, there is a company called AcuTemp that makes them, but no notion on how long they last.

  59. Joan August 29, 2006 at 1:27 pm

    Hi Peter,

    Where can I find more information on Insulsoy – there does not seem to be a website associated with it? Also, could you let me know the name of the company in NH?

    Thank you!


  60. Peter Cantone August 24, 2006 at 1:40 am

    Hi Joan,
    I am partners in a company that distributes Insulsoy- a soy-based insulation. We are located in CT and we work with a company in NH that could help you. It has a flame rating of 22 and a smoke rating of 360 – basically its much less flammable then the wood beams and the toxic fumes are less harmful than those of burning wood. In a nutshell- it’s safe. As far as out-gassing (many spray foams emit a gas or fumer that can be harmful) there is no out-gassing – its water-blown.

  61. Joan August 19, 2006 at 3:26 pm

    I have purchased an old farmhouse which has no insulation in the walls and little in the attic. It needs extensive renovation, so we will insulate it at the same time. I’m seriously considering the soy based spray-in-foam (assuming I can find someone to apply it here in Maine), but have searched and found nothing about how flammable it is, and whether it emits deadly fumes when burning. Can you help me with this?

    Thanks so much!

  62. Jill August 15, 2006 at 2:28 pm

    Hi Dug-

    Sorry about deleting your comment earlier – but the fake email address thing threw me off (we use people’s email addresses to verify they are real people and prevent spam – and also to correspond with commenters if the comment raises issues or we are considering deleting the comment). Anyways, I did the best I could in this appraisal of insulation options with the knowledge I have and the research that is available online. I have never installed insulation myself or compared many different types over the long run, so I am certainly not an expert in insulation. I am just going from the research that I have found. I am glad so many people are commenting, as there is certainly a lot of informed and useful opinions coming in. I am glad this post has generated such a spirited discussion – who would have thought people would find insulation so thought-provoking!!

    To answer your last question, Fiberglass is toxic to human health – please see the numerous studies I linked to in the post. I don’t know much about its environmental qualities (anyone else care to comment?) but I think frankly that the human health concerns are even more worrisome than being “toxic to the environment” as it is people who end up living with fiberglass in their houses for their whole lives. Also, I’m sure that anything this bad for people is not good for animals either when it gets out of houses and into landfills.

  63. Philip August 15, 2006 at 3:39 am

    It’s possibe that aerogels have some further properties that may single them out as uniquely desirable for use in construction applications.

    First, while I’m not confident of this, the nanogel product in particular may be effectively fireproof. I’ve seen no data relevant to it’s fire rating, but distinctly recall graphic demonstrations of the product’s capabilites as an insulator that involved applying torches to it, to no obvious destructive effect.

    Second, not all ultra small pore smart gels are deleterious to health. I recall that one of the earliest applications of the technology involved use in hospital bed cushioning. The material had a surface property that naturally retarded the propagation of bed sores.

    I wish I could provide you with harder data than this, but I’m suffering through some disorganization at the moment.

    I like your site. It’s my cup of tea exactly.

  64. dug August 14, 2006 at 9:41 pm

    i was the original author of the deleted post. there was nothing emotional and the only statement which might have been percieved as an attack was when i said it was “not a very accurate appraisal of the insulation options available.” i said that because i felt the post was misleading, particularly in regards to cellulose (reasons for which have since been reiterated by others). i don’t work for industry in any way, but i do build things that need insulated and i think it’s very important to get facts straight even if you’re only using them to back up opinions.

    it’s also one of my least favorite options, but i still wonder how fiberglass is toxic to the environment.

  65. Art Carlson August 13, 2006 at 3:08 am

    Over the years we notice different ways to add mass to cavities in the hope that conductivity will be diminished… AND it never worked! Its like doing the samething over and over, expecting a different result each time. The conductivity of AIR is .02 and the conductivity of everything else is greater.. including smoke! Even if the conductivity was diminished, buy some magic, the addition of insulation mass only deals with 20-25% of the heat transfer algorithm… 80+% is transfered radiantly…. Yes radiantly! So, lets manage the first order effect first, with Radiant Barriers, then manage remaning conductive heat .. the 2d order effect, and finally convection of heat, the 3d order!

    Yea Team!

  66. Christoper P. August 11, 2006 at 8:39 pm

    The more thorough commentary in the replies regarding recycled cellulose insulation is much appreciated. Similar commentary from experienced hands, regarding the cotton and wool fiber based products, would also be appreciated. Shredding and flocking ANY fiber, at least in the manufactoring phase, has to present some health hazard (“white lung disease” anyone?) With any of the blow-in technologies, there have to be precautionary measures taken, which are probably beyond the ken of DIYers. Cavity-wall moisture retention/transfer treated with moisture barriers such as foil is at the heart of the mold problem, regardless of the insulation medium, unless one wants to permeate the structure and insulation with fungicides…Battens with moisture barriers, caulking (including all those little holes from plumbing and electrical runs) per Jeff’s experience does wonders, according to my nephew Chip, who is also a contractor in the high-altitude ski resorts…

  67. Lee August 11, 2006 at 4:35 pm

    some one mentioned soy based foams, here is one source for information:

  68. JS August 11, 2006 at 4:20 pm


    Sorry for the quick post before…I definitely did not mean to imply your article lacked merit. You did an excellent summary for a tough topic, and other commentators are making great points too. I was just surprised to see that post deleted…but you’re right, it was a generic response.

    Your team writes a fantastic blog here!

  69. Jeff August 11, 2006 at 2:28 pm

    I own an insulation company in a high end ski resort. We use all products listed in this well written article.
    We try to use anything that’s “better”. We face very difficult ice problems on roof’s due to snow sitting above holding in the heat if the roof isn’t vented properly. We use sprayed polyurethane foam, Blow-In-Blanket-System (BIBS), cellulose and are now using foils to wrap homes inside and out. The foil concept has been around for many years
    in commercial applications but just recently have we integrated it into most of our homes. We have found a combination of foil in attics above insulations AND below it at the sheetrock line – with an air cavity between foil and sheetrock- is an incredible upgrade to any insulation job. Simiple and not too expensive.

    The foil reflects heat out of an attic in the summer before it penetrates the home and keeps heat in in the winter if applied in exterior walls and ceilings. We use it now in sub-floors and the outside as a house wrap.
    We try to use GREEN products when possible and have used the cotton products. They are great but hard to get in volumn and are so far expensive.

    All of these products are only as good as the installer. Quality is key.
    Simple caulking will go far if done properly prior to sheetrocking.

    I hope I’ve helped. I know I’ve learned here.



  70. Gary Reysa August 11, 2006 at 1:29 pm

    Nice summary of information on some of the newer insulation types.

    But, I think your negative assessment of cellulose is unwarranted. It is treated with boric acid for fire and pest resistance. I’ve read extensively on cellulose, and have not seen any documented cases of the problems you mention — I’ve not seen a single source say that boric acid is harmful in any way to people as it is used on cellulose insulation.
    Cellulose insulation has a number of very good properties: it is made from recycled material, has low embedded energy content, has no adverse health effects, it fills cracks and openings very well, which reduces infiltration, it does not develop internal air circulation cells that can reduce the effective R value of fiberglass by a factor of 2, it has a much lower incidence of moisture problems than fiberglass, and it provides very good insulation at a very affordable price. It also lends itself to Do-It-Yourself installation, and works very well in retrofit situations (e.g. existing walls). It seems to me its a really fine product for homeowners and for the the planet.

    The Icynene foam you mention is a good product, but it provides little more R value per inch than cellulose, and is sereral times more expensive. It is expensive enough that many people will just opt not to upgrade their insulation.

    And, no I’m not on the payroll of the Cellulose Insulation Association :)



  71. Edie Kello August 11, 2006 at 3:33 am

    Facts on cellulose: Cellulose is made of 75% post consumer recycled paper fiber and up to 5% post industrial paper fiber. Cellulose is treated with borates and has a class 1 fire rating. It will not melt in the event of fire, but will smolder until it reaches wood framing members. See the “Big Burn Demo” at With cellulose in the walls and attic, you have more time to exit in the unfortunate event of a fire vs. other materials that melt or give off toxic gases in a fire. Pests do not like cellulose because of the borates. The FTC requires cellulose pass ASTM anti-fungal tests. As far as water is concerned, cellulose is hygroscopic and does a wonderful job handling humidity changes through a wall. It is an effective insulator that provides better sound attenuation and fire resistance than conventional and other insulation products.

  72. Jill August 11, 2006 at 1:41 am

    Hey Steven-

    We are having some problems with WP and bits of our posts disappearing. Thanks for pointing that out!

    Hey JB-

    I actually edited the post based on that original commenter’s comment, and that’s why I deleted it – because I tried to address his concerns, and once I did, the comment was no longer relevant. I attempted to contact the person and tell him this, but the email bounced back because the email address was fake. This, together with the commenter’s strangely emotional reaction to my personal opinions on insulation, made me think perhaps it was not an unbiased comment, but from someone with a vested interest in an insulation company or something.

    I do my best to cover as much information as I can, but I take personal offense at people who complain the article is useless and doesn’t provide any good information. I have spent countless days researching and putting together this post and its not like someone pays me to do this. Its fine to disagree with my opinions, conclusions or provide constructive criticism, but the commenter in question seemed less interested in expanding the discussion of insulation as in complaining about my post. There are certainly insulation choices that I have overlooked, but we can’t cover everything. That’s why we have the forums. Please comment again and expand upon soy-based and other types of spray insulation. I’m sure readers would like to hear more.

  73. Steven August 10, 2006 at 9:38 pm

    FYI, insulation if very sexy, and the page has suddenly gotten all broken-ey in the middle… I don’t know if the two issues are related or not.

  74. JS August 10, 2006 at 7:57 pm

    The comment that I read earlier (that you deleted) was a constructive criticism (my opinion…and I wasn’t the earlier poster). His point was valid…how about some discussion about open versus closed cell spray foam, or soy-based?

  75. MikeP August 10, 2006 at 6:29 pm

    I am about to begin a remodel and will need to insulate several internal walls. Apart from thermal insulation are there insulating products that offer better sound insulation? We want to dampen as much sound as possible.

  76. Andreas Paulsen August 10, 2006 at 5:14 pm

    It’s all “re-think”. The barrier is social acceptance. “Oh we’ve done it this way for years” attitude has to change. As the ideas and materials come to the “top”, building codes and other barriers have to change. Shelter is one of the basic human needs, we have to change concepts in order to grow.

  77. Jill August 10, 2006 at 4:13 pm

    Hi Musser-

    Rockwool is very similar to fiberglass in both insulation qualities and human health risks. Please see Wikipedia for more information:


  78. JustinThomas August 10, 2006 at 2:39 pm

    This is a great summary, thanks.

  79. musser August 10, 2006 at 2:07 pm

    Where is Rockwool’s Roxul mineral wool in your list? It’s available in the US as well as most other places in the world, and doesn’t grow mold, hold water, or catch on fire. Seems like a good option to me!

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