Tag Archives: Attic and Attic Insulation

What Caused the Ice in my Attic

Why is there ICE in my Attic and where did it come from?

  • ICE DAMS ARE CREATED WHEN THE HOT MOIST AIR RISES FROM THE INTERIOR OF THE BUILDING.

  • As the Hot Moist Air Rises into the Attic and meets the Roof Framing System.  Condensation Occurs on the Cold Framing Members consisting of: Rafters, Roof Trusses, Roof Decking

  • As the Condensation Cools the Moisture in the Air Freezes on the Roof System.

Ice Dams1-CAD Drawing by Scotts Contracting
Example 1 of how Ice Dams Form in the Attic
Ice Dams-CAD Drawing by Scotts Contracting
Example 2 of How Ice Dams Form in the Attic
Read how Ice Dams are Prevented in upcoming Blog Post or
view prior Green Blog Posts on Attic and Attic Insulation
Scotts Contracting is Available to Discuss “Energy Saving Alternatives for your Home in St Louis.  Please use the contact form to schedule an appoint for Money Saving Actions for your Home.

The construction industry’s leading researcher explains why what we think is true often isn’t, and how some of our best hunches, based on observation of field performance, have paid off with problem-free attic assemblies. by William B. Rose 
-Attic Insulation-I’ve put a little information to help assist in explaining ‘Attic Insulation for a Home’. I take a whole house approach to improve a Home’s Energy Reduction Needs. The Attic Area and Attic insulation being just 
Attic Insulation. – Proper Insulation Levels in your Attic coupled with Ventilation will save you Money on your Energy Bills. Certified Insulation Installer for: Batt Type, Spray Foam, Loose Fill-. Green and Eco Friendly options are always available.
Lack of Insulation In the Attic; Air Infiltration from the Interior of the House into the Attic Area; Uninsulated Heating Ducts inside the Attic. Scotts Contracting can Inspect your Attic for Proper: Insulation Levels; Adequate Ventilation; Uninsulated 
Jul 03, 2011
Attic Insulation-I’ve put a little information to explain Attic Insulation for a Home. It takes a whole house approach to Reduce a Home’s Energy Needs. The Attic Area and Attic insulation being just one area. When Combined with a Green 
Snow on Roof-Opportunity to Check Insulation Level. This last snow we received yesterday is the perfect opportunity to see if your attic is properly insulated. Take a look at the Roof of your Home. -Lack of Snow on your Roof is a sure indication 
With my Preliminary Figures using a Guesstimate ($400) on your current Energy Bill and using the Dept of Energy’s Estimate of 20% Savings for attic retrofits. I’ve determined that by Sealing your Air Leaks and Adding Insulation to the Attic the 

 

Add Curb Appeal and Save on Home Energy Needs


Both of which will Add Value to your Home in Comfort and Appraisal Value
This Green Build Wrap Around Porch was

Designed and Built by Scotty, Scotts Contracting
View the Power Point (with Before and After Photos) presentation here: How To Add Curb Appeal and Save on Home Energy Needs

 

Frost or Snow on Roof or Lack Snow is a sure sign…

Snow on Roof or Lack Snow is a sure sign….

On the Frosty Mornings when you are outside your house scraping your cars windshield to prepare for your drive to work. Take a look at the Roof of your Home. -Lack of Frost or Snow on your Roof is a sure indication that it was melted by the Heat as it rises from the Interior of your House into the Attic Area-

Snow on Roof or Lack Snow is a sure sign…

  • Does the Frost or Snow cover the whole roof?
  • Are there places where the snow and frost melt first? (not caused by the Suns Rays)
  • Is there Frost and Snow on the Garage Roof but not on the House Roof?
  • Does your Neighbors House have Frost and Snow on their Roof- but-Your Roof Doesn’t?

Any or All the above may mean that:

  1. Lack of Insulation In the Attic
  2. Air Infiltration from the Interior of the House into the Attic Area
  3. Uninsulated Heating Ducts inside the Attic

Scotts Contracting can Inspect your Attic for Proper:

  1. Insulation Levels
  2. Adequate Ventilation
  3. Uninsulated Heating Ducts
  4. Air Infiltration

Email scottscontracting@gmail.com and Scotty will provide a Free Estimate to Fix any of the Above Issues on your Home. I will also provide a Cost Saving Analysis that will provide a ROI on your Investment. 

Weatherization doesn’t cost it Saves! - Rule of Thumb: For Every $1 Spent on weatherization You will Save $2-$3 on your Home’s Energy Bills

  • Example: By adding the suggested Inches of Insulation you will save 10-30% amount on the Energy needed to heat your Home= Lower Heating Bills and Greater Comfort Levels for you and your family

Additional Green Blog Posts:Energy Star Home Improvement Tips ,Insulation and Thermal Performance ,Which Kind Of Insulation Is Best? ,Radiant Barriersfor your Attic,Insulating Roofs, Walls, and Floors, Roof and Attic Ventilation ,


Email scottscontracting@gmail.com or use the contact form below and Scotty will provide a Free Estimate to Fix any of the Above Issues on your Home. – Scotty, Scott’s Contracting

Air Sealing a Ceiling Electrical Junction Box

CAD Design-Weatherize-Insulate-Fire Block-Electrical Junction Box

Air Sealing Ceiling Electrical Junction Box
CAD Diagram explains how to Build and Air Tight Electrical Junction Box located in most Attics

Sealing Air Leaks

Warm air leaking into your home during the summer and out of your home during the winter and can waste a lot of your energy dollars. One of the quickest dollar-saving tasks you can do is caulk, seal, and weatherstrip all seams, cracks, and openings to the outside. You can save on your heating and cooling bill by reducing the air leaks in your home.

Hint: Use Fire Rated: 5/8″Fire Rated Drywall or Sheetrock with Fire Proof Caulking to Create the Air Tight Seal

Fire Proof /Air Tight Electrical Junction Box Cover used in Attics

Tips for Sealing Air Leaks

re-posted from:http://www.energysavers.gov/tips/insulation_sealing.cfm

Pie chart shows how air escapes from a typical home: 31% floors, ceiling, walls; 15% ducts; 14% fireplace; 13% plumbing penetrations, 11% doors; 10% windows; 4% fans and vents; 2% electric outlets.How Does the Air Escape?
Air infiltrates into and out of your home through every hole and crack. About one-third of this air infiltrates through openings in your ceilings, walls, and floors.
  • First, test your home for air tightness. On a windy day, carefully hold a lit incense stick or a smoke pen next to your windows, doors, electrical boxes, plumbing fixtures, electrical outlets, ceiling fixtures, attic hatches, and other locations where there is a possible air path to the outside. If the smoke stream travels horizontally, you have located an air leak that may need caulking, sealing, or weatherstripping.
  • Caulk and weatherstrip doors and windows that leak air.
  • Caulk and seal air leaks where plumbing, ducting, or electrical wiring penetrates through walls, floors, ceilings, and soffits over cabinets.
  • Install foam gaskets behind outlet and switch plates on walls.
  • Look for dirty spots in your insulation, which often indicate holes where air leaks into and out of your house. You can seal the holes with low-expansion spray foam made for this purpose.
  • Look for dirty spots on your ceiling paint and carpet, which may indicate air leaks at interior wall/ceiling joints and wall/floor joists. These joints can be caulked.
  • Install storm windows over single-pane windows or replace them with more efficient windows, such as double-pane. See Windows on page 18 for more information.
  • When the fireplace is not in use, keep the flue damper tightly closed. A chimney is designed specifically for smoke to escape, so until you close it, warm air escapes—24 hours a day!
  • For new construction, reduce exterior wall leaks by installing house wrap, taping the joints of exterior sheathing, and comprehensively caulking and sealing the exterior walls.
  • Use foam sealant around larger gaps around windows, baseboards, and other places where warm air may be leaking out.
  • Kitchen exhaust fan covers can keep air from leaking in when the exhaust fan is not in use. The covers typically attach via magnets for ease of replacement.
  • Replacing existing door bottoms and thresholds with ones that have pliable sealing gaskets is a great way to eliminate conditioned air leaking out from underneath the doors.
  • Fireplace flues are made from metal, and over time repeated heating and cooling can cause the metal to warp or break, creating a channel for hot or cold air loss. Inflatable chimney balloons are designed to fit beneath your fireplace flue during periods of non-use. They are made from several layers of durable plastic and can be removed easily and reused hundreds of times. Should you forget to remove the balloon before making a fire, the balloon will automatically deflate within seconds of coming into contact with heat.
Cutaway house illustration showing areas of home where air leaks. Refer to caption for list.Sources of Air Leaks in Your Home
Areas that leak air into and out of your home cost you lots of money. Check the areas listed below.

  1. Dropped ceiling
  2. Recessed light
  3. Attic entrance
  4. Sill plates
  1. Water and furnace flues
  2. All ducts
  3. Door frames
  4. Chimney flashing
  1. Window frames
  2. Electrical outlets and switches
  3. Plumbing and utility access
Scotts Contracting is available to assist you in improving your Home or Business Energy Demands.  Please use this form to Contact Scotty, Scotts Contracting to schedule a FREE Energy Analysis for your Property.

CAD Detail Heat and Cold Loss-2×4 Wall

Rockwool Thermal insulation, scanned @ 1600dpi...
Rock Wool Insulation (Fire Resistant) Image via Wikipedia

If you have the question: Why is my house so Cold? Why are the walls so cold? Why are the outer rooms of my house so cold?  Where are these cold air drafts coming from? Why is it costing me so much to heat my house? Why is my Heating Bill so high? How do I lower my heating bills? What are the recommended ways to lower my heating bills?

Answer: I’ve designed this CAD Diagram to explain how hot & cold temperature seeps into a building and vice-versa

Example: a home with 2×4 walls with 0 (zero) insulation.

You can see by the blue areas how solid materials transfer the hot/cold temperature.

  • Standard Minimum Code Wall Framing consisting of

  • Siding on Exterior of Building
  • 1/2 in Plywood or OSB Particle Board
  • 2×4 Framing Member Wall Stud
  • 1/2 in Drywall or Sheet Rock

The hot/cold temperature (Blue Areas in Diagram) on the Exterior of the Building is transferred to the Interior of the Building by Conduction. This works both

Ways as Interior Temperature in transferred out-wards.

The simplest explanation I can use to demonstrate and explain this is too use this example: when you are using a Metal Cooking Utensil to stir a pot of chili. If the utensil is left in the pot of chilli for any length of time. The heat will eventually transfer up the utensil handle and will usually burn your hand or fingers. Heat and Cold enter a Building in the same way; unless, there is some form of Insulation or Thermal Break to prevent the conduction of energy.

Now that your understand how Energy is transferred thru building materials

I’ll explain the various ways that Insulation:

Slows down and Reduces this form of Energy Loss in an upcoming post.

If you have any questions or comments about this article or schedule an appointment use this link to schedule a

Free Proposal on Weatherizing your Building to save money and reduce your Winter-Time Energy Bills

and Scotty, Scotts Contracting will return your Weatherization request asap. scottscontracting@gmail.com

CAD Diagram courtesy of Scotty, Scotts Contracting explaining how cold temperature is transferred
thru building materials into your home.

Weatherization for the Attic

Attic Insulation-Energy Solutions

  • Part 1 on Home Weatherization Series

Attic Insulation-I’ve put a little information to explain Attic Insulation for a Home. It takes a whole house approach to Reduce a Home’s Energy Needs.

  • The Attic Area and Attic insulation being just one area.  When Combined with a Green Roofing System- The pair combined are your First Defense Against Rising Energy Costs.

Air Infiltration areas be resolved before adding insulation- Stop the Air (Hot or Cold) From Entering or Leaving a Home.

  • This includes: proper attic ventilation, ceiling protrusions(Light Boxes / Ceiling Fan), access points, mechanical and electric points, Attic Knee Walls, Obtrusion’s-
  • Anything that will allow the unconditioned air from the Exterior of the Home

Adding Radiant Barriers for Existing Buildings-in a nutshell this bounces the Exterior Temperature back outside. Radiant Barriers are being used in more Construction Projects in today’s construction techniques to assist homeowners with additional savings on utility bills.

  • Attached to the Underneath Side of Existing Rafters- Best Option for Retrofits
  • Reflective Radiant Barriers have R-Values that range from R-3.7 to R-17

Prior Experience: R30 2×4 Vaulted Roof System Example #105:

  • Light Color Shingles on Exterior
  • 1 in roof decking
  • 2×4 Rafters 16″ Space
  • R13 Batt Insulation
  • Double Sided Radiant Barier
    • Also Acts as Vapor Barrier
  • Adequate Ventilation Provided by
    • Automatic Power Attic Fan Peak of Roof
    • Proper Vents in Soffits and Gable Ends

Energy Savings:

  • Reduced the Need for 1 window AC unit in Typical Two Story Stick Built Home-
  • This translates to a Savings of $30 / Month during Cooling Months or $120-$160 / Year.
    • This Application Payed for itself in the 1st Summer 06. At the time of writing this article the estimated savings for 5 yrs is $600.  This Pays for 100% of the Materials used in the Green Roof System for the Upstairs Bedroom Remodel.
  • The Only drawback reported by owner (which wasn’t really a drawback since it was his teen-age sons room) was the decrease in cell phone reception,
    • This is caused by the Reflective Nature of the Reflective Foil Radiant Barrier.

Attic Add Insulation to meet Suggested Guidelines for the St Louis Area

Energy Star, Department of Energy, US Government Suggestions for Optimum Home Energy Savings (Reference Links Below)

  • w/ no insulation Add Insulation to achieve=R38 to R60
  • If existing 3-4 inches Add Insulation to achieve=R38
  • Suggested needed R value of Insulation on Attic Floor=R25 to R30

Insulation when used in conjunction with a Radiant Barrier can lower the Cost of Insulation by reducing the Amount of Insulation Needed

Scotts Contracting is Available to assist you in improving your “Homes Energy Efficiency”

When Scotty comes over to perform an estimate.

  1. He will inspect for the above mentioned problem areas.
  2. Discuss the various solutions.
  3. Next-Determine the Materials and Labor Needed to Complete and Fix the Areas Quoted in the Project.
  4. I’ll then submit a Project Proposal that will discuss project in detail.
  5. Answer any Questions, Explain Procedures, and determine the least obtrusive time to Weatherize your Home.
  6. Computerized Energy Audits for your Home for Estimated Energy Savings are also available- [Equest, Sam, HEED are just a few of the programs I am currently using. The Latest Simulated Advisory Model Beta is in the testing stages and being offered by the US Department of Energy].

Looking forward to meeting you and discussing the ways I can help with Lowering your Energy Bills for your Home or Business.Green Me UP-Scotty
Scotty 

Feel free to utilize the above information to Weatherize Your Home or Schedule a Free Green site evaluation-

Scotts Contracting will Weatherize Your Building Against the High Energy Costs of the Summer Time Cooling Costs

I will Save You $Money$!!!!


Scott’s Contracting

Green Me UP-Scotty

scottscontracting@gmail.com
http://stlouisrenewableenergy.blogspot.com
http://scottscontracting.wordpress.com
http://twitter.com/StLHandyMan

Referrence Materials:

http://www.ornl.gov/sci/roofs+walls/radiant/rb_fig2.html

http://www.ornl.gov/sci/roofs+walls/radiant/rb_02.html

http://www.ornl.gov/sci/roofs+walls/radiant/rb_tables.html#table1

http://www.ornl.gov/sci/roofs+walls/insulation/ins_07.html

http://www.greenfiber.com/step_one_-_calculate_your_need_how_to_install.html

http://www.homedepot.com/Building-Materials-Insulation-Radiant-Barrier/h_d1/N-5yc1vZ1xjlZbedf/R-100052556/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Which Spray Foam Insulation is Best-Open Cell or Closed Cell

Scotty writes: In response to prior questions:

Q:Which Spray Foam Insulation is Best, Open Cell or Closed Cell?

Open-Cell Vs. Closed-Cell

The real distinction between types of foam insulation focuses on whether they are open- or closed-cell. In general, both are made from the same materials and work in the same way, trapping air or gas in a plastic matrix. The differences start with the “blowing agents” used to create bubbles and end with both varied performance and cost.

Open-cell foam costs slightly less for the same thickness, but offers lower per-inch R-values than closed-cell products. In some instances, this is a disadvantage, but where thickness is less relevant, or where higher R-values are not needed, then open-cell can provide the better choice. It also has some green advantages over closed-cell: The blowing agent used to install open-cell insulation is water, which reacts with air to become CO2—while closed-cell products use HFCs.

Because CO2 expands quickly, the bubbles tend to burst before the plastic sets, and hence the “open cells,” which produce a spongy, lightweight foam. The industry describes the foam as “half-pound” material, which simply means the foam has a mass that weighs 0.5 pounds per cubic foot. This density yields an R-value of approximately 3.6 per inch, equivalent to most traditional insulations. Because of the open cell structure, open-cell foam allows some vapor to pass through, making it a good choice in hot, humid climates, and under roof sheathing, such as in conditioned attics, where water vapor caught between insulation and sheathing could promote wood rot.

In short, open-cell foam, tested in accordance with ASTM E 283, provides an air barrier with vapor breathability. Water-blown solutions have less environmental impact than the current HFCs used for most closed-cell spray-foam insulation. And open-cell has about twice the noise reduction coefficient in normal frequency ranges as closed-cell foam. Because the blowing agent in open-cell insulation dissipates as it sets, instead of slowly over time, there is no degeneration of the R-value—a minor point given aged closed-cell R-values still trump open-cell R-values by a magnitude of nearly 100%.

Unlike open-cell foam, closed-cell foam uses chemical blowing agents that come in liquid form and become gasses as they are applied. These gasses expand, but not as quickly as CO2, allowing the polyurethane plastic to set before the bubbles burst. This yields dense foam weighing nearly 2 pounds per cubic foot, and without the capillary characteristics of open-cell, it remains impermeable. The blowing agents used perform like the inert gasses between the panes of high-performance windows, adding to the insulating qualities of the foam. Unlike open-cell foam, closed-cell foam rarely requires any trimming, with little or no jobsite waste.

Closed-cell has more obvious advantages over open-cell, and a slightly higher price tag (20% to 30% for the same thickness). It provides both a vapor and air barrier and offers an aged R-value of a whopping 6.5 per inch. Because of its density and glue-like consistency, it remains very strong, providing both compressive and tensile strength to structure comparable to added sheathing, increasing the racking strength of walls by as much as 300%, according to the NAHB Research Center. Because water does not penetrate or degrade the product, FEMA recommends closed-cell foam as a suitable insulation material for flood regions.

The principle disadvantage of closed-cell foam comes with overkill. If you do not require the extra vapor barrier, structural strength, and R-value per inch, then you may be wasting money. As for the added wall strength, while real and substantial, it’s not acknowledged by building codes currently, so you can’t reduce the structural bracing as a tradeoff.

—————

Information found at: http://www.ecohomemagazine.com

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Scott’s Contracting
scottscontracting@gmail.com
http://stlouisrenewableenergy.blogspot.com
http://scottscontracting.wordpress.com


Frost on Roof or Lack of Frost is a sure sign…

On the Frosty Mornings when you are outside your house scraping your cars windshield to prepare for your drive to work. Take a look at the Roof of your Home. -Lack of Frost or Snow on your Roof is a sure indication that it was melted by the Heat as it rises from the Interior of your House into the Attic Area-

Frost on Roof or Lack of Frost is a sure sign…

  • Does the Frost or Snow cover the whole roof?
  • Are there places where the snow and frost melt first? (not caused by the Suns Rays)
  • Is there Frost and Snow on the Garage Roof but not on the House Roof?
  • Does your Neighbors House have Frost and Snow on their Roof- but-Your Roof Doesn’t?

Any or All the above may mean that:

  1. Lack of Insulation In the Attic
  2. Air Infiltration from the Interior of the House into the Attic Area
  3. Uninsulated Heating Ducts inside the Attic

Scotts Contracting can Inspect your Attic for Proper:

  1. Insulation Levels
  2. Adequate Ventilation
  3. Uninsulated Heating Ducts
  4. Air Infiltration

Email scottscontracting and Scotty will provide a Free Estimate to Fix any of the Above Issues on your Home. I will also provide a Cost Saving Analysis that will provide a ROI on your Investment.

Weatherization doesn’t cost it Saves! - Rule of Thumb: For Every $1 Spent on Weatherization- You will Save $2 on your Home’s Energy Bills

  • Example: By adding ___ Inches of Insulation you will save $__ amount on the Energy needed to heat your Home= Lower Heating Bills and Greater Comfort Levels

Additional Green Blog Posts:Energy Star Home Improvement Tips ,Insulation and Thermal Performance ,Which Kind Of Insulation Is Best? ,Radiant Barriers for your Attic,Insulating Roofs, Walls, and Floors, Roof and Attic Ventilation ,

Email scottscontracting and Scotty will provide a Free Estimate to Fix any of the Above Issues on your Home.

Radiation, Convection, Conduction-Warm to Cold

Convection is the movement of air in response to heat Convection happens inside walls too

Warm air rises, cool air sinks. Because walls and windows are usually cooler than the middle of a room, they spur convective loops that can feel like a draft. A similar thing can happen inside a wall cavity.

When air is heated, it expands, and therefore becomes less dense, so it rises. The rising warm air displaces cooler air, which sinks. When the motion is constant, it’s called a convective loop.

Woodstoves and windows cause convective loops by heating or cooling (respectively) the air closest to them.

Even in homes with airtight walls and ceilings, convective loops can feel like a cool draft and be uncomfortable to the people in the room.

Convective loops can occur inside poorly insulated wall cavities, too, degrading the performance of the insulation.

Heat flows through materials by conduction

thermal bridge - wood Wood is a better insulator than nothing at all. Snow melts off the uninsulated rafter bays more quickly than directly above the wooden trusses, which have an R-valuearound 1.1 per inch, or R-4 for a 2×4 top chord.

Conduction is the flow of heat energy by direct contact, through a single material or through materials that are touching.
Substances that conduct heat readily are called conductors, while substances that don’t conduct heat readily are called insulators. Metal is a good conductor; foam is a good insulator. Wood falls somewhere in between.

Radiation heats objects, not air

Solar radiation Solar radiation. Solar heat radiates through the vacuum of space and warms the earth.

Radiation is the transfer of heat by electromagnetic waves that travel through a vacuum (like space) or air.

Radiation cannot pass through a solid object like plywood roof sheathing. When the sun shines on asphalt shingles, heat is transferred to the plywood sheathing by conduction. After the plywood has been warmed by conduction, it can radiate heat into the attic.

Radiant barriers are materials (for example, aluminum foil) with a low-emissivity (low-e) surface. Although radiant barriers have a few applications in residential construction—they are sometimes integrated with roof sheathing—they are rarely cost-effective when compared to conventional insulation options.

Insulation and Thermal Performance

On Mon, Oct 25, 2010 at 9:50 AM, Scott’s Contracting <scottscontracting> wrote:

Insulation:
Thermal Performance is Just the Beginning

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attic_blow.jpg InsulSafe ® 4, made by CertainTeed Corporation, is a formaldehyde-free, loose-fill, fiberglass insulation suitable for open-blow attic applications. The product contains recycled glass cullet and carries Greenguard™ certification for low emissions.

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We last took a broad look at insulation materials exactly ten years ago: in the January/February 1995 issue. A lot has happened since then—manufacturers have introduced new insulation materials, new product formulations have eliminated problem materials such as HCFCs, and improved understanding of performance and health risks has informed our building practices.

But the fundamental issues have not changed over ten years. Insulation remains a critically important component of any green building—whether residential or commercial. No matter the type of insulation used, if it is used appropriately, its environmental benefits over a building’s life will almost certainly far outweigh any negatives—and dwarf any environmental differences among the alternative materials.

This article provides a survey of insulation materials, beginning with an examination of what insulation is and how it works. Much of the article focuses on life-cycle considerations for different insulation materials: environmental and health issues associated with resource extraction, manufacture, use, and disposal.

Understanding Insulation

To really understand insulation materials, you have to understand the basics of heat flow. There are three primary mechanisms of heat flow:

  1. conduction,
  2. convection, and
  3. radiation.

Thermal conduction is the movement of heat from direct contact: one molecule is activated (excited) by heat and transfers that kinetic energy to an adjacent molecule. We generally think of conduction occurring between solid materials—the handle of a hot skillet conducting its heat to your hand, for example—but thermal conduction also occurs with liquids and gases.

Convection is the transfer of heat in liquids and gases by the movement of those molecules from one place to another. As air is warmed, it expands, becomes more buoyant, and rises—a process called natural convection. Forced convection is the distribution of warm air by use of a fan or air handler.

 Finally, radiation is the transfer of heat from one body to another via the propagation of electromagnetic waves. A warmer body will radiate heat to a cooler body. When you sit in front of a fireplace and look into the fire, your face is warmed by the radiant transfer of energy from that heat source to your face. That radiant energy is not affected by air currents and occurs even across a vacuum—as we know from lying in the sun!

 Most insulation materials function by slowing the conductive flow of heat. Materials with low thermal conductivity more effectively block heat flow than materials with high thermal conductivity.

The R-value of an insulation material measures its resistance to heat flow. R-value is the inverse of U-factor, which is a measure of heat transfer, usually measured in Btu/hr·ft 2·°F or W/m 2·°C. Most insulation materials work by trapping tiny pockets of air (or some other gas).

The performance of that insulation material is determined primarily by the conductivity of the air, or other gas, in those spaces. If convection is prevented, a 1” (25 mm) air space has a conductivity of about 0.18 Btu/hr·ft 2·°F (1.02 W/m 2·°C). Its resistance to conductive heat loss, the inverse of that value, is R-5.5 per inch (RSI-38/m).

With fiber insulation materials, such as fiberglass, cellulose, and cotton, pockets of air are trapped between the fibers.

With cellular insulation materials, such as polystyrene, polyisocyanurate (polyiso), and polyurethane, the air—or other gas—is trapped within the plastic cells comprising the foam.

While resistance to conductive heat flow is the primary operative property of insulation materials, convection and radiation can come into play as well. With polyiso insulation, for example, according to Richard Roe of the Atlas Roofing Corporation in an August 2002 article in Interface magazine, 60–65% of the heat transfer is attributed to the conductivity of the blowing agent gases trapped in the cells, while 20–25% is attributed to the thermal conductivity of the solid polymer matrix, and 10–15% is attributed to radiation.

One key design features of an insulation material is keeping the air pockets small enough to limit convection within those spaces and radiation across those spaces.

With fiber insulation materials, the fibers have to be packed densely enough to effectively stop airflow through the material. (Air blowing through the insulation would carry heat by convection.)

With insulation materials that incorporate radiant barriers (foil-faced batt insulation, radiant-barrier bubble-pack insulation, and reflective barriers on rigid foam sheathing), the reflective surface functions by reducing radiant heat transfer. To function in this capacity, the reflective surface has to be next to an air space. The surface may function by reflecting heat radiation or (more commonly) by emitting less radiant energy from it. This is why a radiant barrier can reduce heat loss even when the reflective (low-emissivity) surface is facing the cold side.

Note that air leakage is a type of convection. Air leakage allows conditioned air to leak out of a building and unconditioned air to leak in—bypassing the insulated portions of the envelope. In older homes air leakage around windows, through poorly fitting doors, and across poorly detailed walls can sometimes account for over half of the total wintertime heat loss! Air leakage can also occur through an insulation material, which can reduce that material’s effective R-value. Loose-fill fiberglass, for example, usually allows more airflow than does cellulose insulation.

Life-Cycle Considerations with Insulation Materials

In this portion of the article, we examine the four primary life-cycle stages of any building material: raw material acquisition; manufacturing; the use phase, including indoor air quality concerns; and end-of-life disposal and recyclability.

 In each of these life-cycle stages we highlight key differences among insulation materials and discuss recent developments. Summaries of the key life-cycle considerations are presented by insulation material in the accompanying table.

Raw material acquisition

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JM_install.jpg All Johns Manville fiberglass insulation is now produced with formaldehyde-free binders.

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Fiberglass. The most prevalent type of insulation in North America, fiberglass is produced from silica sand with various additives, including boron. Most fiberglass also contains a fairly high percentage of recycled glass.

The recycled content can be pre-consumer (post-industrial) glass cullet from float-glass manufacture or post-consumer glass collected through bottle recycling programs.

In 2003 the fiberglass insulation industry used 1.1 billion pounds (500 million kg) of recycled glass, according to the North American Insulation Manufacturers Association (NAIMA), though the industry-wide split between pre-consumer and post-consumer recycled glass is not available.

 According to Robin Bectel of NAIMA, fiberglass insulation represents the second-largest market for recycled bottle glass (after the packaging industry).

Most U.S. fiberglass insulation has a minimum 20–30% recycled content. Owens Corning, for example, has been third-party certified by Scientific Certification Systems (SCS) to contain at least 30% recycled content—4% post-consumer and 26% pre-consumer, according to Jim Worden of the company. Johns Manville has an SCS-certified minimum recycled content of 25%; CertainTeed claims a minimum recycled content of 20–25% to meet U.S.

Environmental Protection Agency (EPA) requirements under the Comprehensive Procurement Guidelines (CPG); and Knauf Fiberglass claims a minimum 20% recycled content, all of it post-consumer. Recycled-content information for Guardian Fiberglass was not available.

Mineral wool. Mineral wool is made from both iron ore blast-furnace slag (an industrial waste product from steel production) and rock such as basalt. In 2003 the mineral-slag wool industry used 514 million pounds (233 million kg) of slag. This is down 45% from the slag use in 1992. Mineral-slag wool production is down in part because building codes are shifting away from the passive fire resistance that mineral wool provides toward active sprinklering of buildings.

Cellulose. Cellulose insulation is made primarily from post-consumer recycled newspaper, with up to 20% ammonium sulfate and/or borate flame retardants. While cellulose insulation used to be one of the highest-value uses of old newspaper, today dozens of de-inking plants in North America turn old newspaper into new newsprint. Producing cellulose insulation from old newspaper can be referred to as downcycling; from an environmental standpoint, turning a waste product back into a new form of the same material is preferable to turning it into a lower-grade material. (Note that producing fiberglass insulation from beverage bottles or glass cullet is also downcycling.)

Plastic foam insulation. Plastic foam insulation materials, including extruded polystyrene (XPS), expanded polystyrene (EPS), polyisocyanurate, and the various types of spray polyurethane insulation, are all produced primarily from petrochemicals. Both natural gas and petroleum are common feedstocks, and both have significant environmental impacts associated with their extraction, refining, and transport. At least two open-cell, spray polyurethane insulation products are manufactured in part from soybeans. Two-component BioBase 501 (see EBN Vol. 12, No. 9) and HealthySeal 500 are produced with soy oil comprising approximately 40% of the polyol component. (Polyurethanes are produced by reacting an isocyanate with a polyol, which is a type of alcohol.) The resultant polyurethane foam ends up being about 25% soy-derived and 75% petrochemical-derived.

Polystyrene. Recycled polystyrene can be incorporated into polystyrene foam insulation fairly easily, since polystyrene is a thermoplastic. At least one EPS insulation product contains recycled polystyrene: Polar 10 from Polar Industries is made with up to 40–60% post-industrial recycled content (see EBN Vol. 10, No. 2). The only XPS product that includes recycled content today is Owens Corning Foamular®, which is SCS-certified to contain a minimum of 15% pre-consumer recycled polystyrene.

Polyisocyanurate. Polyiso insulation incorporates a relatively small amount (9–10%) of recycled content to comply with CPG minimums. A portion of the polyol used in polyiso is produced from recycled PET bottles. The polyiso industry is one of the largest users of recycled, mixed-color PET bottles, according to the Polyisocyanurate Insulation Manufacturers Association (PIMA). The foil facings on many polyiso boardstock products may also contain some recycled content. header_left.gifheader_right.gif
Bonded_Logic.jpg Bonded Logic’s cotton insulation is manufactured from pre-consumer recycled denim waste.

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Cotton insulation. Cotton insulation is made today by two manufacturers. Bonded Logic, Inc. and Inno-Therm, Inc. make batt insulation products from pre-consumer recycled denim scrap. The cotton or cotton-polyester fibers are treated with a nonhalogenated flame retardant. UltraTouch, produced by Bonded Logic, contains approximately 85% pre-consumer recycled fiber saturated with borate flame retardants to provide fire resistance. Inno-Therm is believed to be using a mix of borate and ammonium sulfate flame retardants. In addition to its use in batt insulation products, cotton insulation is used by Payless Insulation, Inc. in insulated flexible duct products; Bonded Logic supplies the cotton insulation for these products.

Cementitious foam insulation. The totally inorganic, cementitious Air Krete ® is produced from magnesium oxide, derived from seawater, and from a ceramic talc mined in Governor, New York. While essentially the same material as it was when last covered in EBN ( Vol. 6, No. 7), Air Krete has undergone some modest refinements, according to vice-president Bruce Christopher. “We have continued to improve both the product and the equipment for installation,” he told EBN. But he noted that friability—the fragility of the cured foam—remains their biggest challenge. “If there is a downside to Air Krete, it’s its friability.” Despite its resistance to the idea, the company may decide to add a little plastic to make it less friable, said Christopher. The challenge in adding plastic would be maintaining the superb fire resistance of the insulation material. While cost is highly variable, depending on location, size of the job, and other factors, it averages 30–50¢ per board foot, according to Christopher. Air Krete remains a very good alternative to another foamed-in-place insulation material used primarily for insulating masonry block, Tripolymer ® foam, produced by the C. P. Chemical Company. Tripolymer foam is a foamed phenol-formaldehyde insulation—a material that some manufacturers of urea-formaldehyde foam insulation (UFFI) switched to after formaldehyde emissions from UFFI led to its discontinuance in the 1970s.

Radiant barriers. Radiant barriers could be produced with recycled aluminum, but this is rarely if ever done, because very pure aluminum is needed to achieve the thin foils. Recycled polyethylene, however, can be used for the foam that is sometimes used with radiant barriers. Low-E ® Insulation, produced by Environmentally Safe Products, Inc., uses polyethylene foam with 40% post-consumer recycled content. In its TempShield™ radiant insulation product, Sealed Air Corporation uses 20% recycled-content cellular polyethylene for the insulation laminated between layers of reflective foil. A number of manufactured panel products have reflective facings glued to one side.

Manufacturing and transport

Fiberglass. Fiberglass insulation is manufactured with binders (typically phenol-formaldehyde) that hold the glass fibers together. The only fiberglass insulation material that did not contain a binder, Owens Corning’s Miraflex™ (see EBN Vol. 4, No. 1) was pulled off the market late in 2004. Manufacture of Miraflex was actually discontinued at the beginning of 2003, according to Gale Tedhams, Owens Corning’s product manager for residential insulation, but enough material had been stockpiled to sell it through 2004—mostly through Lowe’s stores. “It just had a very limited market,” Tedhams told EBN. Owens Corning did not promote the health benefits of not having a binder but focused on the packaging benefits—rolls of the insulation take up half the space of standard fiberglass. While the product carried a “slight price premium,” according to Tedhams, it was “very expensive to manufacture.” See additional discussion of binders used in fiberglass insulation under “Use phase and IAQ concerns.”

Cellulose. Because cellulose is inherently combustible, flame retardants are required to make it an acceptable material for building insulation. As has been the case for the past ten years, the primary flame retardants used in cellulose insulation are ammonium sulfate, borax, and boric acid. According to Daniel Lea, executive director of the Cellulose Insulation Manufacturers Association (CIMA), these additives are typically used in combination, though a few manufacturers offer products that use all-borate retardants.

Polyisocyanurate. The biggest environmental news in foam boardstock insulation has been the elimination of HCFC-141b in polyiso. The industry completed the transition from that ozone-depleting compound to the blowing agent pentane at the end of 2002. (Some manufacturers continued using stockpiled HCFC-141b in early 2003 while plant modifications were completed.) The transition to an ozone-safe formulation was a big step for polyiso, and it renders the product significantly better environmentally than extruded polystyrene (XPS), which in North America is still made with an HCFC blowing agent. In an industry that is generally slow to change, these changes in polyiso have been dramatic. In 1992 polyiso was all produced with CFC-11. By mid-1993 the polyiso industry had shifted completely to HCFC-141b, which has only about 10% the ozone depletion potential of CFC-11. Atlas Industries then led the transition away from HCFCs, introducing its ozone-friendly AC-Ultra™ in February 1998 (see EBN Vol. 7, No. 5). By May 2001 the company had fully converted three of its plants to pentane (see EBN Vol. 10, No. 5), with others converted early in 2002.

Polystyrene. Polystyrene has some fairly troubling chemical precursors in its production. The polystyrene used in both XPS and EPS is made by reacting ethylene (from natural gas or crude oil) with benzene (from crude oil, via naphtha catalytic reforming) to produce ethyl-benzene. The ethyl-benzene is converted into vinyl-benzene or styrene monomer, which is then polymerized into polystyrene. Benzene is listed in the 10th Report on Carcinogens, put out by the National Toxicology Program of the U.S. Department of Health and Human Services, as a “known carcinogen.” The International Agency for Research on Cancer (IARC) of the World Health Organization lists benzene as a “confirmed human carcinogen” and styrene monomer as a “possible human carcinogen.” Some material safety data sheets (MSDS) for polystyrene list residual styrene monomer as a constituent of the foam at levels up to 0.2%. While benzene is also used in polyiso and polyurethane production, these insulation materials are less likely than polystyrene to contain residual toxic chemicals.

Extruded polystyrene. XPS and EPS differ in how the foam is expanded—and they use quite different blowing agents. EPS has long been made with non-ozone-depleting pentane, but XPS still relies on HCFCs. Though the XPS industry led the charge in replacing CFCs with far-less-damaging HCFCs, it is today the only type of boardstock insulation that remains harmful to stratospheric ozone. Amofoam (now Pactiv) was the first company to switch from CFC-12 to HCFC-142b, in 1990, and the entire XPS industry completed that transition in 1992. The transition away from HCFC-142b is not likely in the U.S. until close to the 2010 EPA deadline for doing so (see EBN Vol. 11, No. 7), according to Worden at Owens Corning. While European manufacturers of XPS shifted to either HFC-134A or carbon dioxide in 2002, more stringent energy standards and different construction systems in North America make the same sort of conversion more difficult here, says Worden. European XPS is a higher-density product with a lower R-value.

Expanded polystyrene. Expanded polystyrene (EPS) continues to be made with non-ozone-depleting pentane as the expanding agent. Some manufacturers are using a low-pentane formulation that results in lower pentane emissions. (While not an ozone-depleting compound, pentane can generate ground-level smog.) The more distributed production of EPS, compared with XPS, may reduce shipping energy consumption to some extent.

Flame retardants and polystyrene. All foam plastic insulation materials rely on flame retardants to meet fire-resistance standards. EPS and XPS are produced using the brominated flame retardant HBCD (hexabromocyclododecane) at concentrations of 0.5–2.0% by weight. HBCD is not the focus of as much attention as another class of brominated flame retardants (PBDEs), but some evidence indicates that it is more bioaccumulative than PBDEs and just as likely to be toxic to humans (see EBN Vol. 13, No. 6).

Flame retardants and polyisocyanurate. Ironically, until recently flame retardants were not used in most polyiso insulation. With HCFC blowing agents, this thermoset plastic foam was able to achieve the required Class I fire ratings without any added flame retardant. But with the substitution of pentane blowing agents for HCFC-141b, manufacturers now must add flame retardants. Although manufacturers rarely divulge their formulations (and can apparently get around the requirement to list the flame retardant in the MSDS because it is part of one component or the other (the polyol or isocyanate), the most common flame retardant used in polyiso today is believed to be TCPP (tris(chloropropyl) phosphate), a compound that relies on both phosphorous and chlorine as the fire-retarding components. The typical concentration in the foam insulation is 5–14% by weight. While a halogenated compound, TCPP is much less likely to be a persistent bioaccumulative toxin than HBCD, according to the PBT Profiler software from EPA.

Spray polyurethane. While polyiso manufacturers had to eliminate their use of HCFC-141b by January 1, 2003, manufacturers of closed-cell (high-density) spray polyurethane were given an extension for the transition to non-ozone-depleting blowing agents. HCFC-141b for spray polyurethane cannot be sold after December 31, 2004, though polyurethane installers can use inventoried HCFC-based chemicals until July 1, 2005, according to Ken Gayer, the global business manager for foam blowing agents at Honeywell Specialty Materials, which produces the non-ozone-depleting blowing agent HFC-245fa under the tradename Enovate 3000. Most spray polyurethane companies are converting to Honeywell’s HFC-245fa. While significantly more expensive than HCFC-141b, the resultant foam achieves similar energy performance. The ozone depletion potential of HFC-245fa is zero, but the global warming potential is similar to that of HCFC-141b. Hydrocarbon blowing agents are avoided with spray polyurethane because of flammability concerns and difficulties with the vapor pressure, according to Gayer. header_left.gifheader_right.gif
Icynene.jpg Low-density, open-cell polyurethane produced by Icynene is material-
efficient and uses water as the blowing agent.

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Open-cell polyurethane, including the products made by Icynene, Inc. and Demilec, Inc. as well as the newer soy-based foams, are produced with water as the blowing agent. They do not achieve R-values as high as those of closed-cell polyurethane, but they are more resource-efficient, using just one-fourth to one-third the material used for a comparable volume of closed-cell polyurethane.

Flame retardants and spray polyurethane. Both closed-cell (high-density) and open-cell (low-density) polyurethane insulation contain flame retardants, but these are non-brominated flame retardants. While manufacturers are reluctant to share this information, the best available information indicates that the two flame retardants most commonly used in spray polyurethane are TCPP, which contains chlorine but not bromine, and RDP (resorcinol-bis-diphenylphosphate), which is totally halogen-free.

Use phase and IAQ concerns

Fiberglass and mineral wool. Concerns about mineral and glass fibers possibly being carcinogenic have been widely publicized over the past ten years—especially by competing industries. These concerns resulted in cancer warning labels being required for most products, but more recently these concerns are waning. In October 2001, IARC changed its classification for fiberglass and mineral wool from “possible human carcinogen” to “not a known human carcinogen.” This change has allowed mineral wool (slag wool and rock wool) manufacturers to drop the warning labels. Fiberglass insulation continues to carry the cancer warnings because, in addition to the IARC listing, the National Toxicology Program added glass fibers to its Report on Carcinogens in 1990. According to Angus Crane, the vice president and general council for NAIMA, glass fibers were added to the NTP possible-carcinogen list because of the IARC-reported studies. Now that IARC has dropped the possible-carcinogen listing for glass fibers, the material is likely to be dropped from the NTP list. NAIMA has petitioned NTP to delist glass fibers, but that process typically takes several years. Crane hopes to see the listing removed in late 2005 or early 2006. If and when that happens, the industry will petition the State of California to remove the requirement under Proposition 65 that fiberglass insulation products include a warning about cancer. Meanwhile, the carcinogenicity of formaldehyde, which could be released in very small quantities from the phenol-formaldehyde binder used in most fiberglass insulation, has recently been upgraded. In June 2004, IARC changed its classification of formaldehyde from a “probable human carcinogen” to a “confirmed human carcinogen.” Most of this binder is volatized and dissipated during a baking stage of the manufacturing process, but residual formaldehyde may remain in the product. Johns Manville, one of the five major producers of fiberglass insulation in North America, switched to 100% acrylic binder for its fiberglass insulation product line in 2002 (see EBN Vol. 11, No. 3). The other major fiberglass insulation manufacturers have all had their products certified as low-emitting by Greenguard™.

 Mineral wool. For cavity-fill and attic applications, rock wool and slag wool are similar to fiberglass in look and feel, though the density is greater and the sound control better. The fire resistance of mineral wool is also significantly better than that of fiberglass, because of both the higher density and the significantly higher temperatures required for melting. While these fire-resistance properties used to be a major selling point, greater reliance on sprinklers in buildings, rather than passive fire resistance, is resulting in decreased use of mineral wool, according to Crane of NAIMA. For below-grade applications, one rigid mineral-wool product, Roxul drainboard, offers superb performance, owing to its hydrophobic properties and its excellent drainage characteristics (see EBN Vol. 4, No. 6). This material has never been actively marketed in the U.S., but Roxul products in general are becoming more widely available here.

Cellulose. Cellulose insulation has never been required to carry indoor air quality warnings, and the fiberglass and mineral wool industries remain upset that their products have come under greater scrutiny than cellulose. “Our competitors have not gone through the testing,” said Angus Crane of NAIMA. “It is dangerous to assume that an untested material is safe,” he told EBN. The editors at EBN continue to take the position that all fiber insulation products (fiberglass, mineral wool, and cellulose) are safe if properly installed, and we would much prefer to see insulation manufacturers focus on the positive benefits of all insulation, rather than potential risks of their competitors’ products. The health concerns with cellulose range from inhalation of dust during installation to VOC emissions from printing inks (which are now almost entirely vegetable-based) and limited evidence of toxicity of boric acid flame retardants. For more on health issues with cellulose insulation see EBN Vol. 2, No. 5. As for installation and performance, cellulose insulation has evolved considerably over the past 20 years. According to Daniel Lea of CIMA, the average installed density of cellulose insulation has dropped from 2.6 pounds per cubic foot (42 kg/m 3) in 1984 to 1.6 pcf (26 kg/m 3) today. “R for R, today’s cellulose insulation products are almost 40% lighter than those of 1984,” said Lea. Most cellulose insulation today is being installed as “cellulose wall-cavity spray,” a process that has sometimes been referred to as “wet-spray” cellulose. CIMA is trying to discourage the use of the term wet-spray because it implies a process that is far wetter than is the case. “I think there is a perception that the material is applied almost as a fibrous papier-mâché,” said Lea. “That is far from the case; if you were to touch wall spray seconds after it’s applied, you probably couldn’t tell that water was added during the installation process,” he said. The typical installed moisture content today is 30–35%, according to Lea, while a moisture content as high as 60% was not uncommon 15 years ago.

 Fiber insulation installation. Quality dust masks or respirators should be used while installing fiberglass, mineral wool, and cellulose. (Cotton insulation is the only fiber insulation material that can be installed safely without protective measures.) Building design and detailing should ensure that fibers cannot enter forced-air distribution or ventilation systems. Airtight construction practices should be used to ensure that fiber insulation stays where it was installed.

Polystyrene. Indoor air quality concerns with XPS and EPS are similar to concerns addressed previously relating to manufacturing: the potential release of residual styrene monomer and flame retardants. The brominated flame retardants used in polystyrene present a greater health concern than the nonbrominated flame retardants used in polyisocyanurate, spray polyurethane, and cellulose insulation.

Polyisocyanurate. Now that polyiso is no longer produced with HCFCs, it is the environmentally preferred rigid boardstock insulation for above-grade applications. (Polyiso is not recommended for below-grade applications because it can absorb moisture.) Polyiso manufacturers disagree as to whether rigid foam produced today with hydrocarbon blowing agents achieves an R-value comparable to that of the older material made with HCFC-141b. The conductivity of the hydrocarbon blowing agent is higher than that of HCFC-141b, and this has led Dow Chemical to downgrade the rated R-values for all of its polyiso insulation, including Thermax ®. However, Richard Roe of Atlas Roofing argues that the smaller cell size of foam produced with hydrocarbon blowing agents, the slower diffusion rate of the hydrocarbon out of the polymer cells, and the lower absorption of the hydrocarbon blowing agent by the polymer collectively result in better long-term R-value stability. Most polyiso manufacturers are now using new long-term thermal resistance (LTTR) values for reporting aged R-values. This method was adopted in Canada in mid-2002 and in the U.S. in January 2003. This method produces 5-year aged R-values that are lower than the 6-month aged R-values that had previously been reported. The bottom line is that the rated long-term stabilized R-value of polyiso is now between R-6 and 6.5 per inch (RSI-42 to 45 per meter), depending on thickness and facings.

Closed-cell polyurethane. Closed-cell, high-density polyurethane is a very good performer owing to the low-conductivity gas in the cellular structure. It is used both for cavity installation and as an insulating roofing material, which is typically referred to as spray polyurethane foam or SPF. The closed-cell structure gives SPF structural properties. There should be no significant impact on R-value with the shift to non-ozone-depleting HFC-245fa blowing agent, which is becoming the industry standard. Polyurethane also exhibits superb adhesive properties and good compressive strength.

Open-cell polyurethane. Open-cell polyurethane is most commonly installed into open cavities, though formulations are available for filling closed cavities from holes at the top. This is a nonstructural foam, though these materials seal very well, and their flexibility allows for some movement of the framing materials as shrinkage and expansion occur. These properties make them very effective insulation materials for older buildings. Both closed-cell and open-cell polyurethane must be installed by trained professionals. Special care is required to ensure the safety of insulation installers working with these materials; other people should not be in the space while polyurethane insulation is being installed. Once cured, polyurethane insulation is considered by most IAQ experts to be quite inert.

End-of-life reuse and recyclability

Loose-fill and batt insulation. It is difficult to salvage loose-fill or batt insulation and reuse it, though this can be done. Virtually no fiber insulation is recycled after use in buildings—due to contamination with dust and other materials. Scrap insulation generated during installation can be collected and reused quite easily. header_left.gifheader_right.gif

Insulation Materials – Summary of Environmental and Health Considerations

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Rigid boardstock insulation. Rigid insulation can be salvaged and reused if it is protected during removal. For roof insulation applications, reuse is most feasible when protected-membrane or inverted roof configurations are used (see EBN Vol. 7, No. 10). In this system, a non-water-absorbing rigid insulation, such as XPS, is laid on top of the roof membrane, and ballast is installed on top of the insulation. When re-roofing is required, the insulation can be removed and stored for safekeeping, then reinstalled after the new roof membrane is laid down. Of the rigid insulation materials, only polystyrene can be recycled. This thermoplastic can be melted and re-expanded into either polystyrene insulation or packaging. Unfortunately, very little polystyrene is being recycled currently. Polyiso and polyurethane cannot be recycled because these foams are thermoset plastics.

Final Thoughts and Recommendations

Insulation is a key component of any green building. More important than the decision of what type of insulation to install is the decision of how much insulation should be installed. From an environmental standpoint, a thicker layer of a relatively nongreen insulation material is almost always better than an inadequate thickness of the greenest insulation material available. This point cannot be over-emphasized. However, assuming that adequate R-values can be achieved, choosing a green insulation material over a nongreen one can be a very good decision. The accompanying table should help to identify materials that meet your needs and satisfy the environmental priorities of your project.

Summary recommendations:

• Provide the highest feasible insulation levels.

• With lower R-value materials, increase insulation thickness.

• Avoid extruded polystyrene due to the ozone-depletion potential of blowing agent.

• Except where moisture may be an issue, use polyiso instead of either XPS or EPS.

• Rigid mineral wool, such as that made by Roxul, is a very good foundation insulation material due to its superb drainage properties.

• With highly conductive framing systems, especially steel, minimize thermal bridging by wrapping the frame with a layer of rigid board insulation.

• Choose high-recycled-content insulation materials when doing so will not result in significant loss of R-value compared with other materials.

• With roof insulation, consider a protected-membrane roof so that insulation can be reused.

 • Address air leakage and moisture resistance in insulation detailing.

A good source of information on building science issues is www.BuildingScience.com.

• For chemically sensitive individuals, test potential insulation materials for reaction before installation.

• Choose an insulation contractor who recycles scrap insulation. – Alex Wilson

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