The extraction and processing of non-renewable insulation materials creates greenhouse gas emissions and increases demand on natural resources. Using recycled and recyclable insulation reduces these impacts.
LANCA studies were performed on insulation made from pasture grass, seaweed, reed and recycled jute. They have low impacts overall due to credits for biotic production and photosynthesis.
Inorganic Insulators
Insulation materials can be classified according to their state of aggregation, chemical composition and production method. They may be solid, liquid or gaseous. Solid insulators have high dielectric strength and low specific heat capacity. They have a large volume resistivity and a low surface conductivity. Liquid insulators have a small volume resistivity and a high specific heat capacity, but they lose heat by convection and evaporation. Gaseous insulators are a combination of gases, such as air, elegaz and Freon-21 (dichlorofluoromethane).
Inorganic porous insulating materials include sand, cellulose fibres, shattered glass, vermiculite and perlite. They have a high porosity, low density and a large hygroscopicity. They also have a low thermal conductivity.
Foam insulators are made from polymer materials such as expanded polystyrene (EPS) and extruded polyurethane foam (XPS). EPS is produced by vaporizing pentane into a mixture of polystyrene particles. This produces a white, closed-cell foam. XPS is manufactured by melting polystyrene particles with key additives in an extruder. The resulting mixture is a white, rigid, closed-cell foam. The foam has a low thermal conductivity, and its density varies depending on moisture content.
Insulation materials are a vital part of achieving energy efficiency in buildings. However, many insulation materials have significant environmental impacts. This is because they use up to 40% of the world’s natural resources and produce over 45% of waste disposal [42]. Therefore, it is important to choose insulating materials that are non-toxic, have a high specific heat capacity and low thermal conductivity. In addition, the insulation material should have a fire-retardant rating.
Cellulose Insulation
Cellulose insulation is made from recycled paper products, typically post-consumer waste newsprint. It has a high recycled content (75-85%) and fewer emissions during manufacturing than other types of insulation. It is often cheaper than fiberglass insulation and may qualify for energy rebates or incentives.
The insulation can be blown in, loose-fill or dense packed using a machine and can be used throughout a home in attics, walls, and floors. It can also be tucked between studs and joists to help with air sealing and sound reduction.
There are four major types of cellulose insulation on the market – dry cellulose, spray-applied cellulose, stabilized cellulose and low-dust cellulose. Low-dust cellulose contains small amounts of oil or other products to reduce nuisance levels of dust during installation. It is suitable for homes with people who are sensitive to paper dust and can be particularly beneficial in a house with old, dry insulation where moisture issues are prevalent.
Moisture is a key issue in most insulation problems and can lead to mold growth and structural damage. Cellulose insulation impedes moisture movement by capillary action and vapor diffusion and helps keep moisture at manageable levels within buildings. It can also trap carbon, thereby reducing greenhouse gasses and other harmful chemicals from entering the atmosphere, a process known as carbon sequestration. However, if not installed properly, cellulose can absorb moisture that could cause mold growth and insect infestation.
Mineral Wool Insulation
Unlike fiberglass insulation, mineral wool is not made with binders, which means that it does not release volatile organic compounds (VOCs) into the air during its manufacturing process. It also does not use chlorofluorocarbons, which are a type of greenhouse gas and destroy the earth’s protective ozone layer. This type of insulation can be a good choice for people who want to avoid VOCs, but still want a product that has good energy efficiency and fire resistance.
This type of insulation is made from inorganic fibers derived from basalt, a volcanic rock. It is noncombustible and does not support fungi, mildew or rot. It resists moisture and vapor better than fiberglass insulation. It is a good choice for moisture-prone areas, such as bathrooms, and also has good acoustical properties.
It can be used sheathed around building supports and girders and it is an ideal material for fire-resistant walls. It has a very high melting point and low thermal conductivity, so it slows the spread of fire. It can also be used to insulate air-handling ducts and pipes.
It is stiffer than fiberglass, making it easier to cut and install precisely. It also has a higher R-value of about R-15 at 3.5 inches, which is more than enough for most residential applications. This is due to its tighter construction, which reduces air movement.
Foam Plastic Insulation
Foam plastic insulation materials, such as expanded polystyrene (EPS), extruded polystyrene (XPS) and polyisocyanurate (polyiso), are good insulators and help designers meet today’s stringent energy codes for new construction and renovation projects. They also provide other benefits such as moisture barriers, which reduce mold and mildew growth, and sound attenuation.
Most foam insulation products use 10-40% recycled material, which is a great environmental benefit since it reduces the amount of waste that ends up in landfills. However, many of the raw materials for these products are limited and must be obtained from petrochemical sources such as natural gas or petroleum. Additionally, fossil fuels are needed for mining and transportation of these materials.
These petrochemicals are not renewable and their reserves will be depleted over time. Furthermore, the binders used for some fibreglass batt insulation and cellulose insulation offgas formaldehyde over time which can impact indoor air quality. Choosing rigid and spray foam options that do not require binders helps avoid this offgassing issue.
Until recently, these materials used CFCs as blowing agents, which are strong greenhouse gases and contribute to ozone depletion. The CFCs have been replaced with hydrochlorofluorocarbons, which still deplete the ozone layer but are less damaging than the CFCs they replace. It is important for the environmentally concerned builder to consider avoiding all forms of foam insulation that contain HFCs.