Design for the Environment/Residential Insulation

This page is part of the Design for the Environment course

Residential wall insulation is a fundamental component of the modern house. Layered between the exterior bricks and the drywall inside, insulation forms the major barrier against thermal conductivity through the exterior of a house.

Currently the most commonly used insulation in Canada is mineral wool insulation, however this insulation has associated environmental concerns, and therefore warrants an analysis of more environmentally friendly alternatives. Using Rockwool as our baseline alternative, two other forms of insulation were analysed in order to evaluate the best material for this application. The two other materials chosen were flax as alternative one, and Cotton Denim insulation as alternative two. The goal of this report is to provide future home owners a basis to compare available forms of residential wall insulation, and make an informed decision when choosing the type of insulation for their home.

Project Information
Section1 Group 9A  Brandon McLean (Brandon McLean) Janice Luu (J.Luu) Patricia Sheridan (pksheridan) Catharine Darling (Catie)

Highlights and Recommendation
A functional analysis was initially performed to ensure that all materials met the requirements of the Ontario Building Codes, and were suitable for use in the Greater Toronto Area. An R-value of 17 for basement walls, 20 for the upper walls and 32 for the ceiling was used as the basis of comparison for each insulation. Since all the insulation materials were available in either the exact desired R-value or greater, each achieved the desired insulating capacity required. Also, since all insulation materials met the building code standards for moisture, fire and mould resistance, and all could last a minimum of fifty years without degradation there was no clear distinction between the different materials. However, when evaluated on the health risks that needed to be taken during installation, Rockwool required significant protection to the installer, and thus was a less likely candidate for recommendation based on this evaluation.

To determine the environmental impact of each insulation two forms of lifecycle assessments were completed. A Streamlined Life Cycle Assessment was used as a qualitative measure to determine the apparent environmental impact, and an Economic Input-Output Life Cycle Assessment was used as a quantitative measure to determine the amount of environmental impact created from the amount of insulation used. Since the environmental impact of the use stage of our material is negligible as the material simply sits within the walls, the use stage was analysed in terms of the functional performance of the material.

Combining the results from both analyses it was determined that the cotton denim alternative was the most environmentally friendly alternative. This was largely due to 85% of the material used to make this insulation being post-industrial denim waste. As a result, since the material would have been disposed of anyway, there is no impact in the pre-manufacturing stage. As well, since the material is almost completely biodegradable, it has minimal impact at its end of life. The flax alternative was eliminated as a potential candidate for recommendation during this stage due to the environmental impact of shipping the insulation over from Europe. Until there is a manufacturing plant located in North America, this is not a viable alternative as the impact of shipping insulation across the world is much more significant than the benefits of being a biodegradable alternative. Since rockwool is made of non-renewable resources, and has a large environmental impact during its pre-manufacturing and manufacturing stage, it is clear that this alternative has a large environmental impact and is not a good choice.

A cost analysis was performed to ensure that the alternatives were within a feasible price range for the average home owner. The cost to insulate a house with rockwool was determined to be approximately $4000, while the cost to insulate with flax was approximately $6800. The cost to insulate with the most environmentally friendly alternative, cotton denim, was $5300. Since the difference between rockwool and cotton denim was less than 25% of the cost of rockwool, it was decided that the price difference was not significant enough to warrant reversing the projected recommendation from the environmental analysis.

A societal analysis was completed to determine if there were any major reasons why a future home owner would not wish to purchase a specific insulation alternative. Rockwool was decided to have the greatest impact as the fibres caused detrimental health effects to the workers with long term exposure. For flax, concerns were raised that if the insulation was used on a large scale, as mineral wool currently is, there would be issues with producing enough crops for both food and insulation and that there could be a disruption in the crop rotations. For cotton denim, no major negative societal impacts were proven which thus continued our recommendation of this as our best alternative.

As a result, it is recommended that a future home owner use recycled cotton denim to insulate their home as it has great environmental benefits without a significant economic cost.

Overview

 * Rock wool insulation has been in world wise use for over 70 years . In the present day version of rock wool insulation compose of 95% natural Basalt rock though the US-EPA Comprehensive Procurement Guidelines (CPG) recommends that there is 75% of recycled steel slag, 0.08% to 3% binders (Phenol formaldehyde resin) and 0.01% to 0.5% de-dusting agent (mineral oil) . Series of research studies are still being conducted on the human health effects when humans are exposed to the fibers of rock wool particularly members of the North American Insulation Manufacturing Association (NAIMA) whom have invested tens of millions of dollars on these researches.

Environmental Analysis

 * The most environmental impact of rock wool insulation occurs during pre-manufacturing, manufacturing and disposal as shown in the Streamlined Lifecycle Assessment (SLCA) below.

Pre-manufacturing
 * Mining of basalt rock releases the most greenhouse gases (GHG) and air pollutants out of all the other sectors within pre-manufacturing. The result of mining could lead to unnaturally high concentrations of GHGs and air pollutants especially SO2.  Also basalt rocks are hard and heavy which would require more fossils fuels to transport to the manufacturer therefore in this stage the emissions of the hydrocarbons (CO and CO2) would be high.  On the positive side of rock wool insulation, the main component of the insulation basalt rock is readily available for extraction as they make most of the world’s oceanic crust .  In terms of the recycled steel slag, in the European countries over 90% of the steel slags are recycled and reused for other application, therefore this by-product is readily available too.

Manufacturing
 * Rock wool is formed by melting the basalt rocks and recycled steel slag in two separate furnaces till they have become molten material. They are then mixed and transferred into a rotating spinner and spun into fibers by a centrifugal force extruding the material through small holes at the side of the spinning device.  The surface is coated with binder phenol formaldehyde to maintain its shape and de-dusting agent mineral oil to suppress dust.  Once this is done, the fibers are collected and formed into blankets or batts .  In this stage, majority of the rock wool manufacturing plants that are part of North American Insulation Manufacturing Association (NAIMA) operates in a close-loop system meaning that there are no wastewater discharges.  Also they would operate under a Maximum Achievable Control Technology (MACT) standard in order to reduce and limit the air emissions.

Disposal
 * Rock wool insulation is not biodegradable; therefore all of the insulation must be land filled at the end of its life cycle . According to a scope of a two-storey house with an approximate square footage of 1500 ft2 and a basement area of 750 ft2, approximately 6000 ft2 of insulation must be land filled.

Cost Analysis

 * The cost analysis was based on a two-storey house with an approximate square footage of 1500 ft2 and a basement area of 750 ft2. The type of rock wool insulation used was Flexibatt from the distributor Home Depot and their supplier was manufacturer Roxul.

Electrical Energy during manufacturing
 * Total electrical energy used is 3570 kWh (from EIOLCA)
 * Hourly price for electrical energy is $0.0535/kWh
 * 3570 kWh × $0.0535/kWh = $191

Insulation Cost
 * Total R14 needed(1750’ ft2)
 * Covers 59.7 ft2, $29.67 per package
 * 1750’ ÷ 59.7’ = 29.3 ≈ 30 packages
 * 30 packages × $29.67 per package = $890.10
 * Total R22 (needed 4179’2’’ ft2)
 * Covers 39.8 ft2, $28.67 per package
 * 4179’2’’÷39.8=105.004≈106 packages
 * 106 packages×$29.67 per package = $3039.02
 * Total per house
 * 3039.02 + 890.10 = $3929.12

Disposal
 * Weight of Insulation:
 * R14 = 15.672kg per package × 30packages = 471.16kg
 * R22 = 13.6kg per package × 106packages = 1441.6kg
 * 71.16 + 1441.6 = 1911.76kg = 1.912 mt
 * Disposal cost for solid waste $71/mt :
 * 1.912 × $71 = $135.75

Therefore total Direct cost: 191 + 3929.12 + 135.75 = $4255.87

Societal Analysis

 * The major issue with rock wool insulation is the health issue during manufacturing and installation stage. Over $100 million for the past 25 years has been spent on numerous research and studies on the long term health risk for workers in manufacturing plants exposed this fiber .  As rock wool is a type of synthetic vitreous fibers (SVF) which can cause reversible skin, eye, and lung irritation if expose to it for a short duration of time which is why much pre-caution must be taken during the installation stage such as wear loose-fitting, long-sleeved and long-legged clothing to prevent irritation and make sure there is good ventilation like open a window or a door .  These fibers are easily inhaled since they are so small but too large to exhale therefore getting stuck in the lungs which would damage the cells in the lungs. These damage cells would reproduce eventually creating a tumour hence lung cancer .  Therefore the fibers produced during the manufacturing stage must have a diameter greater than 1μm; else the substance would be considered a hazardous substance, meaning that it would be subjected to CERCLA (Comprehensive Environmental Response Compensation, and Liability Act) requirements.

Overview
Flax fiber insulation is a new form of insulation that started in the 1990’s The type analyzed is composed of 80% Flax fiber, 10% Potato Starch which acts as the binder for the insulation and 10% borax which acts as the fire retardant and provides resistance against pests and mold. The main advantage of these three materials is that they are all natural materials that are easily disposed of through composting or recycling. Flax Fiber Insulation is manufactured in Europe, with the majority in Finland, France and Germany. Flax Fiber insulation is an infeasible option for any non-local distributor, due to the cost and environmental impact of shipping. The suppliers Flauchshaus (Germany) and Flax 100 in the UK both state the impossibility of supplying to Canada.

Environmental Analysis

 * The streamline life cycle analysis can be seen below. From this analysis it is clear that the life cycle stages which produce the largest environmental impact are the pre-manufacturing, manufacturing and transport stages.

Pre-manufacturing
 * The main advantage of flax fiber insulation is that flax fiber and potato starch are completely renewable materials, since it can be grown to meet the demand. All three of the materials have energy intensive pre-manufacturing stages. Before the flax fiber can be combined to form insulation, the flax plant must first be grown, harvested and then the fibers must be separated form the rest of the plant.   New methods, which are much less energy intensive have been created to improve the processing of the flax plant directly related to the separation of the fibers. This technology is only improving, thereby reducing the energy required in the pre-manufacturing stage.  Most of the direct energy comes from the sun, but there is a lot of indirect energy present in the equipment and process required to plant, fertilize, de-weed and harvest the flax plant.  The potato starch has a similarly energy intensive process except the starch must be separated from the potatoes.  Borax has an energy intensive process as the boron must first be mined, and then combined with other chemicals to create borax.

Manufacturing


 * The manufacturing of the product is solely related to combining the three materials into the final insulation product. This is done on a textile non-woven line, and is not a very energy intensive process, with minimal environmental impacts. A comparison of the energy usage shows that the pre-manufacturing stage requires more overall energy by a difference of 142.14 GJ of energy.

Transportation


 * Due to the fact that this product can only be purchased in Europe, for this design to be implemented in Canada would require shipping, primarily by airplane. This presents a large problem due to the low density to volume ratio of the insulation. For one house, at a transport cost of $115 000, (assuming a profit margin of 20% on $147 444.423150 000 dollars) the following emissions were obtained from the EIOLCA:

If the environmental effect of the airplane is taken into account then it that would skew all the other data, making it negligible. The total global warming potential to fly over enough insulation for one house is approximately 174 times greater than the total. The This proves that a non-local distribution of insulation is infeasible, and negates all the positive environmental impacts of the insulation.

Disposal


 * Flax Fiber Insulation is 100% natural and can be disposed of through composting, burning or recycling [18]. This implies that the environmental effect during the disposal stage is negligible. In addition, flax fiber insulation is a carbon neutral alternative, so the amount of C02 in the air that is consumed during growth is equal to the amount released at the end of the lifecycle.

Cost Analysis
The cost of insulation is based upon March 2008 quotes received from Construction Resources based in the UK. For 1 pack, containing three batts of the appropriate size of insulation (120x100x625 mm), the cost is 16.00 pounds, which is equivalent to 32.00 USD. For one house regular two-story house approximately 634 sheets of insulation are required. That is a total cost of $ 6 762.33 per house. The cost of transportation has a huge impact, and influences the feasibility of the design. A quote for one house, as found on a Canadian Shipping company estimated the cost to be approximately $147 444.423. The only cost to the consumer is the cost of the insulation. The insulation can be installed by hand, and would be done by the subdivision contractors. If their salary is considered, it will take an estimate of 1 eight hour day for one worker per house multiplied by an approximate salary of 22.96$/hr. This is a total of $183.68 per house. There is no disposal cost on the insulation, as it can simply be thrown in the compost, or burnt. It does not require any special handling, and will not end up in a landfill if it is assumed it will be properly disposed of.
 * Cost to purchase Insulation:
 * Cost of Transportation:
 * Installation Cost
 * Disposal Cost

Societal Analysis
A major societal concern arises in producing potatoes and flax. The potato crop could be used to as food as opposed starch. An increaded demand for insulation, creates an increase in the demand for potatoes thereby raising the price of potatoes and limiting the quantity available as food. In addition, were the demand for flax fiber insulation to increase dramatically flax would be used more frequently in crop rotation. This would impact the surrounding environment and soil, in removing essential nutrients from the soil. In addition, if both more potato crops and flax crops are required then more farms/crops will be devoted to the flax plant and potatoes, and less will be used to grow food crops such as corn and cereal. An additional societal concern arises due to the limited history of flax fiber use as insulation, since the 1990s. This leaves the consumer and community with a doubt as to the efficiency and resistance to degradation of the insulation, as well as a doubt as to its long-term environmental impact. This is prominent in the minimal usage of flax fiber insulation. The majority of the insulation is chosen by the construction industry. This industry is skeptical of using new materials for insulation that does not have an extensive performance history due to previous disasters.

Overview

 * Recycled denim insulation is a new type of cotton insulation (only 15 to 20 years old) which uses post-industrial denim scraps left over from the manufacturing of jeans and other denim cloths as their primary ingredient. The insulation is made primarily from post-industrial denim waste from large jean manufacturers, however 5% of the material is binder fibre composed of bicomponent plastic and 10% is most likely a cellulose based lofting fibre.

Environmental Analysis

 * As with the other two alternatives, both an EIOLCA as well as a more qualitative streamlined LCA were preformed on denim insulation to determine its environmental impact. As an EIOLCA sector for denim insulation does not exist the following product was created using a scope of 50 average homes and information given in the patent in and pricing obtained from

The major result from the EIOLCA from the above product can be seen below in graphical form.

Additionally the results of the streamlined LCA can be see in the following table:

Pre-Manufacturing


 * The SLCA analysis preformed revealed that the major environmental benefits result from the fact that denim insulation consists principally (85% by mass) of post-industrial denim waste which it successfully diverts from being landfill waste . That being said, relatively minor negative effects do result from its use of non-renewable petrochemical derived plastics and manufacturing intensive cellulose pulp which make up the majority of the other 15% of the product.


 * This result is easily seen in the EIOLCA as well where the majority of greenhouse gas emissions as well as total air, water and gas release, all result from the cellulose and organic fibre manufacturing sector. It should be noted a sensitivity analysis was performed where the cellulose was replaced with polyester type fibre material (also a potental although slighly more unlikly lofting fibre acording to the products patent information ) which decreased the total greenhouse gas emissions by almost two times and the total air residuals by over ten times.

Manufacturing


 * The manufacturing process is fairly simple consisting mainly of three stages :
 * Moulding and distribution of binding and lofting fibre by suction
 * Heat treatment to 150°C
 * Cutting and packing


 * These processes involved in the manufacturing of denim insulation are extremely environmentally friendly. Any waste products are shredded and incorporated back into the manufacturing process; also the process itself produces no gaseous residuals which results in a zero waste manufacturing process . Additionally, the energy requirements needed to manufacture the product is far lower than that of fibreglass or Rockwool insulation, which require temperatures of well over 1000°C to form and bind the insulation fibres in comparison to this product’s 150°C manufacturing temperature.

Transportation/Shipping


 * Some of the largest negative environmental effects come from the product’s delivery phase which both employs a large amount of truck transportation over long distances and utilizes common plastic based packaging. As the majority of denim manufacturing in North America is done in Mexico large amounts of truck transportation are required to deliver this product to a Canadian home. Although the EIOLCA analysis shows transportation to be a large contributor to greenhouse gas emissions this is most likely understated in comparison to the SLCA analysis as it only considers insulation industry norms which involve far less transportation on average. The insulation is also all packaged in large plastic wrapping which will most likely be disposed of afterwards and end up as landfill waste.

Disposal


 * The product is primarily biodegradable cotton, which would be in the landfill regardless of its use as insulation. Additionally, most of the other components used are natural or non toxic materials such as paper based cellulose or naturally occurring borax and therefore should not adversely affect the ecosystem. As such, denim insulation also performs extremely well in its disposal phase. It is important to note that EIOLCA does not consider the disposal phase of a product so only SLCA results are discussed in this section.

Cost Analysis

 * Using the products information obtained from, price quote obtained from distributors located in the GTA and the Canadian R value recommendations , the total cost of denim insulation required to insulate a two-storey house with an approximate square footage of 1500 ft2 and a basement area of 750 ft2.is calculated as follows:

R-Value/Insulation Choice
 * R-20 for walls- therefore chose Bonded Logic R-21 (product code 10000-02124)
 * R-17 for basement walls – therefore chose Bonded Logic R-19 (product code 10000-02124)
 * R-32 for ceiling – therefore chose Bonded Logic R-19 (product code 10000-02124)layered over R -13 (product code 10000-01324)

Area Calculations (accounting for 2.5% safety factor):
 * 1669’* 1.025 = 1711 square feet of Bonded Logic R-21
 * (761’*1.025) + (750*1.025) = 1549 square feet of Bonded Logic R-19
 * 761*1.025 = 780 square feet of Bonded Logic R-13

Costs Calculations:
 * R-21 (@$1.47/ft2) –1711ft2*$1.47/ft2 = $2515.17
 * R-19 (@$1.36/ft2) – 1549ft2*$1.36/ft2 = $2106.64
 * R-13 (@$0.88/ft2) – 780ft2*$0.88/ft2 =  $686.40
 * Total = $5308.21
 * Including tax = $6051.36

It should also be considered that installation of this material will probably be somewhat less expensive as it is easier to handle and requires no additional safety equipment. This means that the cost of direct labor would possibly be less than normal; however, due to the fact that this is a new product and no studies have been conducted on how much labor it would save it is impossible at present to determine exact numbers for this statement.

Societal Analysis
A number of positive societal effects were identified with the use of denim insulation. Public preference for this product is extremely positive as it can be handled without the use of any protective equipment. Furthermore, it is extremely easy to install and far less hazardous than most types of insulation not have any of the negative stigmas which have been created about the possible carcinogenic effects of many other types of insulation. Another benefit of Denim is that the material has excellent sound absorbent properties, better than those of regular fibreglass or Rockwool insulation making it an ideal alternative for closely packed neighbourhoods where sound is an issue.