Insulation

Insulation
Sandy Do
Anthony Hoac
David Leung
Linda Dix-Cooper
The envelope of insulation has grown since the 1920s Victorian age. When housing
construction materials became lighter, thermal envelops developed to insulate the floors,
walls, and roof. Use of building insulation was first made mandatory in the United States
during WWII to conserve fuel for the war effort.
In the U.S., energy in the form of heated or cooled air escapes through cracks and holes
in residential buildings, worth $13 billion every year. A properly insulated house can
save a homeowner a great deal of money. If one pays for the insulation on the front end,
the homeowner will recover savings in the long term over utility bills. It can also reduce
capacity and maintenance of HVAC equipment. Insulating material protects health from
mold, airborne pollutants, and allergens. This report considers three main common types
of insulation: fiberglass, cellulose, and spray foam insulations.
For the comparison of the three types of insulation, eight different categories are
considered. These categories are: cost, thermal efficiency, sound transmission, health
impacts, ease of installation, resiliency to water, environmental impacts and the
flammability of each type. The cost of each is normalized by square footage per inch and
also in accordance with an R-value of 13 (corresponding to the recommended R-value for
Berkeley homes). The thermal efficiency is measure by the R-value. The ability to
block sound is measured by the sound transmission coefficient, with a value of 36 for
bare walls. Health and environmental impacts, safety in terms of flammability is how
fireproof the material is, and the ease of installation corresponds to how easy it is for the
homeowner to install it themselves will be discussed.
Foam Insulation
The most effective foam insulation is spray foam. Spray foam material flows into cracks
and crevices, then expands and seals. Once cured it glues everything together to stand
severe conditions. Urethane expands 30 times its liquid form. This was developed in the
1940s for military and aviation applications, and in the 1950s, its use became widespread.
1970s innovations spawned a foam spray application method.
An open-cell or close-cell foam product makes a significant difference in cost,
application, and performance. Open-cell foam has tiny cells that are broken, with air
filling the space inside the material. Open-cell foam is softer and weaker than closed-cell,
and ranges from 0.4-0.5 lb/cu ft density. Closed-cell foam is filled with enclosed gas that
allows expansion, and is a better insulator. It ranges from 1.7-2.0 lb/cu ft. Roofing foam
is of higher 2.8-3.0 lb/cu ft density to support traffic. Both cell-types can be formulated
for different size and density. The closed-cell foam has higher strength, R-value, and

greater resistance to air and water vapor flows. Because the closed-cell foam is denser it
requires more material and thus expenses. Closed-cell foam is recommended for use over
open-cell below grade, especially in conditions of high water tables.
Spray polyurethane foam seals the entire building envelope of the home to prevent air
and moisture infiltration. Specifically polyurethane maintains a permanent shape and will
not sag or deform. In addition, it adds strength to the building structure. Lateral
movement by strong winds and storms create shearing forces on the home. Foam
insulation is monolithic and capable of reducing racking and shearing. Closed-cell spray
foam reinforces rigidity of the studs and sheathing.
In terms of installation and application, the foam is formed by trapping many gas forms
into a liquid or solid. One of the most popular foam insulations is polyurethane. It
contains polyol (a petroleum product), a surfactant, and a catalyst (to control reaction
rate). The size of the bubbles differs based on reaction rate and it dictates the density of
the foam product. Roofing foam must be denser than wall foam for higher strength. The
bubbles come from a blowing agent which is a liquid with a low boiling point, which is
capable of producing pockets of a gas. The last ingredient is isocyanate, which is highly
reactive. Isocyanate is separated from all components until dispensed through the hose
gun. Once it hits the substrate it drives the expansion reaction very quickly. Spray foam
insulation is applied to walls with an 80% pass. A downside to spray foam insulation is it
requires a skilled installer to prevent overspray.
Spray polyurethane foam has an R-value of approximately 6.0-7.0 per inch, depending on
formulation. This R-value is significantly higher than glass fiber, wool, and cellulose
insulations. It is adequate for residential, commercial, and industrial buildings. Spray
Polyurethane Foam provides more thermal resistance with less material than any other
commercial insulation material. It has a fairly low sound transmission coefficient of 37.
Spray polyurethane foam costs roughly $1.25-$2.25 per square foot. It forms to walls,
floors, and roofs as a tight seal, stopping air leakage as well as moisture infiltration.
Traditional fiberglass insulation stapled or placed into wall cavities does not seal the stud
and wall cavities, and gaps remain. For homes with crawl spaces and basements, high
humidity brings trouble for standard fiberglass insulation. Fiberglass absorbs moisture; it
may get heavy and fall from sub-flooring. Spray foam contractors are often hired to
remove old and wet fiberglass, and use spray foam as replacement. Spray foam maintains
its physical properties over time.
Oftentimes, no additional vapor barrier is required when using Spray Polyurethane Foam,
saving an additional item cost. Performance studies in the field suggest Spray
Polyurethane Foam systems used for roofing can last thirty or more years. Walls have a
longer lifetime exists due to its lack of exposure. Spray foam insulation increases a
home’s energy performance, structural integrity and air quality; and is increasingly used
to insulate walls, basements, and attics of homes.
Hurricane Katrina destroyed the original roof of the Superdome in New Orleans and
caused $250 million in damages to the structure. The state of Louisiana demanded a roof

that “will never blow off again”. In repair of the Superdome in September 2006, the
Texas-based contractor Brazos Urethane, used a closed-cell polyurethane spray foam for
the 9.7-acre metal roof decking of its 70,000-seat domed stadium. The spray foam
provides insulation, and will protect from severe storms and high winds. The
polyurethane was capable of sealing the roof surface and irregular shapes. The
manufacturer was BaySystems, a subsidiary of Bayer MaterialScience LLC, and the
blowing agent was supplied by Honeywell. The product performance stands wind uplift,
and BaySystems provided a hurricane-proof warranty.
Fiberglass Insulation
The most common type of insulation today is fiberglass insulation. This type of
insulation has a fluffy and spongy look and comes in mainly two colors: pink and yellow.
Fiberglass insulation is made up of small fibers of glass. Due to recent consumer
awareness for conservation, manufacturers have been increasing the amount of recycled
glass used in production. Currently, approximately 40% of the fiberglass by weight is
made up from recycled glass. Fiberglass insulation, when installed, saves more than 12
times the production energy cost, within the first year in use.
At home improvement stores, the most common type of insulation in stock will most
likely be fiberglass. This is due to its ease of installation and cost effectiveness in
comparison with other insulation types such as cellulose and spray foam. Fiberglass
comes in two different types: batts and rolls. Batts are sheets of fiberglass made
especially for large flat areas such as walls. Rolls are similar to batts except rolled up so
homeowners or installers can easily unroll the insulation for roofs or ground areas.
Fiberglass also comes in specified sizes--pre-cut lengths and widths. The thickness of the
fiberglass is dependent on the R-value. The chart below (Table 1) shows the average Rvalue
associated with the thickness of the fiberglass.
Table 1. Fiberglass Batt Insulation Characteristics
Thickness (inches) R-Value Cost (cents/sq. ft.)
3 1/2 11 12-16
3 5/8 13 15-20
3 1/2 (high density) 15 34-40
6 to 6 1/4 19 27-34
5 1/4 (high density) 21 33-39
8 to 8 1/2 2-5 37-45
8 (high density) 30 45-49
9 1/2 (standard) 30 39-43
12 38 55-60
Installation of the fiberglass is relatively straight forward. The sheets or rolls are
unraveled and stapled or glued to studs and the interiors of the wall. Another advantage
of fiberglass insulation includes the fact that it is a natural flame retardant therefore noncombustible
due to its make-up of mainly recycled glass and sand. As a sound insulator,
fiberglass is also relatively effective. The sounds transmission coefficient of fiberglass
has been shown to be approximately 40, with bare wall at 36. This means that fiberglass
will block sixteen times more sound than not having any type of insulation.

The downside of fiberglass comes with the insulation of small hard to reach areas of the
building. Because fiberglass normally comes in large pre-cut sizes, it is not as flexible as
cellulose or spray foam. Also it is resiliency to water or moisture is relatively weak.
During installation it’s important that the environment is controlled so that little or no
moisture leaks into the wall. When the fiberglass gets wet, it crunches up together and
starts sagging. This leaves gaps in the walls with for air and heat to penetrate. There are
also acute and long term health effects associated insulation. However, majority of
health effects are due to the exposure of fiberglass which affect mainly the installer or
contractor rather than the inhabitants of the home. Later sections of the paper will
explore the health effects in greater detail.
In summary, Fiberglass has an R-value of 2.9-3.8 m2-K/W per inch which is pretty
average in comparison with the other two types of insulations that were compared. The
STC for fiberglass is also pretty average, better than spray foam but clearly not as good
as cellulose. The advantages of fiberglass include ease of installation and cost, and these
are the primary reasons why fiberglass is still so popular in the market today. Though
fiberglass is falls short when it comes to insulating hard to reach places, often times
homeowners or contractors also use spray foam alongside fiberglass. Fiberglass
insulation is the homeowner’s choice when it comes to self performance, it’s relatively
inexpensive, effective and easy to install.
Cellulose Installation
As one of the primary form of home insulation, cellulose can either be purchased as a
spray-on insulator or in sheets. It is made from recycled newsprint and other paper
sources and accounts for 15% of the total insulation market. It is comprised of old
newspapers, telephone directories, borates, and ammonium sulfate, having a recycled
content up to 85%. Its strength is derived from its fibrous composition, which results
from the hydrogen bonding within the chain and maintains a linear conformation. It’s
typical R value per inch ranges from 3.6-4 m 2 -K/W. However, because of the fiber and
chemical constituents, it can become a source of irritants. The main attractiveness of
using cellulose is its high recycled content and very low embodied energy.
Embodied energy represents the non-renewable energy consumed in the acquisition of
raw materials and their processing and manufacturing. It comprises of direct energy (like
direct transportation of the insulation to the site) and indirect energy, which is the energy
associated with manufacturing of the product. It is a measure of non-renewable energy
per unit of building material. Usually, it is implicative of the environmental resource
depletion, greenhouse gases, environmental degradation, and reduction of biodiversity,
and research has been done to suggest that it can even be a reasonable indicator of the
overall environmental impact of building materials. However, because of building
performance, the embodied energy must be weighted against performance and durability.
From research done by several international sources, against fiberglass and foam,
cellulose has an embodied energy of only 3.3 MJ/kg, while the fiberglass has 30.3 and
polystyrene has 117 respectively, making cellulose a prime choice due to its recyclability.

In terms of sound, it has been argued that cellulose insulation has better STC (sound
transmission coefficient) than either fiberglass or foam as well. For cellulose, it is 44.
Fiberglass is 40, foam is 37, and nothing is 36. For every rise of 1 point in rating, it is
equates to twice the effectiveness. Therefore, cellulose is about 16 times better in
stopping sound transmission over fiberglass. For fire safety, cellulose, even though is
comprised of wood products, has been tested in the laboratory to be more fire spread
resistant than fiberglass. This is because cellulose is treated with fire retardants, which is
about 10-20% by weight in the form of boric acid. In fact, according to National Fire
Protection Association, flammability is rated as a 0, while in HMIS, it is rated as a 1.
Tests have shown, however, that when the cellulose insulation is heated to about 300
degrees F, it loses its fire retardant properties. However, in open flame, it may emit
carbon monoxide, boric acid, and other hazard particulates.
In terms of insulation, there are two main methods: dry (blow-in) or moisture-added. For
dry installation, a blower can be rented where one feeds the dry fiber into the blowing
machine while the other person operates a hose that is extended to the location where the
insulation will be deposited. For sprayed cellulose, a small amount of water is added to
moisten the cellulose, which activates the starches so it adheres to the surface within the
wall and ceiling cavities. The cavity is actually overfilled, then the excess is scrapped off
using a rotating brush. After it dries in about 1 to 2 days, drywall can be added.
In terms of durability, however, there have been numerous cases where cellulose
deterioration becomes a concern under the combined effects of thermal, oxidative, and
hydrolytic degradation. Widely used in power plants and high-voltage power cables,
cellulose’s deterioration because critical in determining the overall end-of-life.
For cost, one can purchase it at 40 sq ft package for $9.87.
Environmental Health Effects of Insulation:
In general, insulation is good for our health. It warms our living spaces and saves money
that could otherwise be spent on healthcare or other essential needs such as food.
Inadequate home insulation and warmth can impair the health of household inhabitants
by increasing mold and humidity-related allergen sensitizers as well as impair immune
response and the ability to fight illness during cold winter months (Jacobs et al., 2009).
Poor health can then affect important social outcomes such as educational success, job
retention, and family cohesiveness.
Particularly for low income populations living in areas of the US with harsh winter
climates, proper insulation is vital. Lack of access to healthcare and insurance, poor
housing quality, poor indoor air quality, housing instability, and household energy and
food insecurity are all associated with low socio-economic status (SES) and can be
adversely aggravated by high home energy costs due to poor insulation. Low SES
households are forced to make trade-off decisions between paying for household energy
and for health-related needs. For example, housing energy insecurity, defined as the

inability to pay monthly energy bills, is associated with greater odds of household and
child food insecurity, child developmental concerns, poor school performance, and
increased hospitalization (Cook et al., 2008). Furthermore, the 2005 National Energy
Assistance Directors (NAEDA) Program survey of low-income US households that were
eligible to receive federal home energy assistance found that 78% of families reduced
basic expenses for household necessities in order to afford their energy bill.
Outdoor Environment and Health:
A 2002 life cycle assessment study by Nishioka et al. (2002) found that overall,
insulation improvements in the US would decrease energy use and energy production
plants PM2.5 emissions over a 10-year-period such that it would lead to 60 fewer
fatalities, 2000 fewer asthma attacks, and 30,000 fewer restricted activity days.
While overall insulation is beneficial, various negative health effects are associated with
exposure to each type of insulation. Some health effects occur immediately after
exposure (in the short term), while others the long term; some on an individual scale of in
home inhabitants or insulation-installing contractors, and some on a broader societal scale,
such as global warming and environmental impacts.
Health effects of Cellulose Insulation:
Cellulose insulation poses minimal health risks to those who protect themselves
properly by hiring a contractor to install it properly. Cellulose’s high dust content allows
it to easily become an airborne respiratory irritant if it’s not properly installed. It’s ability
to absorb and retain moisture make cellulose insulation a prime location for mold and
pathogen growth so ensuring that water damage does not occur is essential (Godish,
2006). One case study showed respiratory alveolar structural changes as a result of high
exposure to fibrous insulation made in part by cellulose insulation (McDonald, 2000).
Perhaps most concerning though is that cellulose insulation is 15% flame retardant by
mass, including reproductive toxin, borate (associated with poor sperm quality and
tumors of the testes) (Bouissou, 1965a & b; Dixon, 1979; Ghosh, 1998; Konstantinova,
1992; Weir, 1972), or ammonium sulfate (Morgan, 2004).
Health Effects of Spray Foam Insulation :
If properly and safely installed by a contractor, spray foam does not pose any
known health risks to a home’s inhabitants. It is a reproductive toxin associated with
kidney tumors in rats and testicular tumors in mice (Turnbull, 1994), made of ether, polyl,
flame retardants, and isocyanates, the latter of which is associated with decreased
immune response and dermatitis (Baur, 2009). The real looming risk of spray foam
insulation is that it can release fluorocarbons (CFCs) upon disposal into landfills
(Kjeldsen, 2003). CFCs have a contribution to global warming that is 950 times the
impact of carbon dioxide, the primary carbon pollutant that is regulated.
Health Effects of Fiberglass Insulation:
If protective safety gear isn’t worn during application, fiberglass induces
dermatitis (Farkas, 1983; Lee, 1992; Verbeck, 1991), characteristic of red rash and itchy,

irritated skin but otherwise the long term effects of fiberglass insulation in the
environment are not well known.
Environmental Health Comparative Assessment:
Given that the short term effects of fiberglass are well documented, in the short
term we ranked fiberglass as the most severely harmful to health, but in the long run it is
the least harmful. Taking the reproductive toxicity and global warming effects of spray
foam insulation and cellulose into consideration, we ranked spray foam as the least
environmental-health-friendly in the long term, followed by cellulose and then by
fiberglass. Our analysis would have been enriched by more complete data on the
production and disposal practices of each type of insulation. Fibreglass is usually thrown
out with regular solid waste or contractors pay a fee to dispose of it in landfills.
How do the insulation types rank overall?
A star ranking system is created based on qualitative judgments and findings. In
the below chart, the scores ranged from 1 star, meaning poor performance, to 3 stars
meaning good performance. The scores were designated based on the comparative
criteria performance qualities that were identified as holding primary importance. The
details of these were discussed previously in this report. For example, for an
environmental score, spray foam received the worst ranking because of its potential
contributions to global warming upon disposal.

Overall, if pricing is ignored, the star rankings equalize or become 13, 14, and 15, with
fiberglass retaining its highest score among the three. The results incorporate
performance quality factors in order of priority for consumer purchasing decision factors.
Weights of performance qualities were not allocated because the overall star scores
matched up pretty well with the most important qualities, except for thermal.
Conclusions:
1. Insulations are fairly equal in performance when pricing is ignored.
2. Focus on installing it properly and selecting the right type for the job to ensure
effective performance.
3. More Life Cycle Assessments to assess environmental impacts.
4. The health benefits that warmth brings to low income families outweigh the underlying
health risks.

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