What Kind of Insulation Should I Use In My Project?
Insulation is one of the most important aspects of building construction. It helps to keep buildings warm in the winter and cool in the summer, which can save you money on your energy bills. There are many different types of insulation available, each with its own advantages and disadvantages.
In Passiv Haus construction, we aim for a wall with a U-value (the amount of heat lost over time) of less than 0.15 W/m²K. Each type of insulation has a Thermal Conductivity value (also known as a K-value), if the Thermal Conductivity is low, we need less insulation thickness to reach our target U-value, while higher Thermal Conductivity numbers means thicker insulation layers to reach the same value.
When choosing building insulation, there are a few factors you need to consider, such as the climate you live in, the type of building you have, and your budget. You also need to make sure that the insulation you choose is compatible with the other materials used in your building. Additionally, we want to be conscious of the up-front carbon emissions involved in the creation of our insulation, measured in kgCO2e/m2, where a lower number is better, and a negative number shows a product that sequesters carbon.
In this article, we will discuss the different types of building insulation available and help you choose the right type for your needs. We will also discuss the factors you need to consider when choosing building insulation.
Mineral Wool
“Mineral wool” insulation is a type of insulation made from molten rock or slag that is spun into fibres. Mineral wool insulation is also fire-resistant and can help to reduce noise levels.
There are two main types of mineral wool insulation: stone wool and slag wool. Stone wool is made from molten rock, while slag wool is made from molten slag, which is a byproduct of the steelmaking process. On average, it contains 70% post-industrial recycled material and needs no chemical flame-retardants. Both types of mineral wool insulation are available in various forms, including batts, rolls, and loose fill.
Mineral wool insulation is a relatively affordable and easy-to-install type of insulation. It is also a sustainable material, as it is made from recycled materials.
Here are some of the benefits of mineral wool insulation:
Good insulator
Fire-resistant
Noise-reducing
Affordable
Easy to install
If you are looking for a type of insulation that is effective, fire-resistant, easily installed, then mineral wool insulation is a good option.
Thermal Conductivity (λ) | 0.032 - 0.040 W/m.K |
Cost | Moderate |
Net Carbon Emissions | 4.7 - 5.1 kgCO2e/m2 (moderate) |
Toxicity | Low |
Installation | Similar to fibreglass. Care should be taken not to compress the insulation when applying materials on top |
Vapour Permeability | 10-30 - permeable |
Suitability | Walls (Cavity, Internal, External), Roofs |
Fire Classification | A1 Non-combustible materials with no contribution to fire, no flaming droplets/particles |
Image: Achim Hering, CC BY 3.0, via Wikimedia Commons
Fibreglass
Fibreglass insulation is a type of insulation made from very fine glass fibres. It is also fire-resistant and can help to reduce noise levels.
Fibreglass insulation is available in various forms, including batts, rolls, and loose fill. It is relatively easy to install, and it is a cost-effective way to improve the energy efficiency of a building.
Here are some of the benefits of fibreglass insulation:
Good insulator
Fire-resistant
Noise-reducing
Cost-effective
Easy to install
However, fibreglass insulation can also be irritating to the skin and lungs. It is essential to wear protective gear when handling fibreglass insulation.
If you are looking for a type of insulation that is effective, fire-resistant, and cost-effective, then fibreglass insulation is a good option. However, it is important to be aware of the potential health risks associated with fibreglass insulation.
Here are some additional details about fibreglass insulation:
It is made from recycled glass, so has a low carbon footprint compared to other insulations made from virgin materials.
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It is easy to cut and install so you can do it yourself.
It is backed by a variety of warranties, so you can be sure that it will perform as advertised.
Thermal Conductivity (λ) | 0.040 - 0.044 W/m.K |
Cost | Low |
Net Carbon Emissions | 1.2 - 1.8 kgCO2e/m2 (low) |
Toxicity | Low, but PPE and long sleeves should be worn to reduce skin and respiratory irritation |
Installation | Installation of batts and rolls in the roof is a low-skilled task, but dense-pack fibreglass requires professional installation |
Vapour Permeability | 1-2 perms - slightly permeable |
Suitability | Walls (Cavity, Internal), Roofs |
Fire Classification | A1 Non-combustible materials with no contribution to fire, no flaming droplets/particles |
Cellulose
Cellulose insulation is a type of insulation made from recycled paper. It is made by breaking down paper into small fibres, which are then blown into or sprayed into wall cavities or other spaces.
Strengths:
Cellulose insulation has a relatively low thermal conductivity, meaning that it is a good insulator.
It has a similar conductivity to mineral wool, but sequesters carbon, unlike mineral wool.
Cellulose insulation is also fire-resistant due to a borate treatment. This means that it will not catch fire easily, even if it is exposed to high temperatures.
Cellulose insulation is moisture-resistant. This means that it will not absorb moisture, which can help to prevent mould and mildew growth.
Cellulose insulation is sustainable. It is made from recycled paper, which is a renewable resource.
Cellulose insulation is eco-friendly. It does not off-gas harmful chemicals, making it a safe and healthy choice for your home.
Cellulose insulation is sound-absorbing. This can help to reduce noise levels in your home, making it more peaceful and comfortable.
Cellulose insulation is affordable. It is a relatively inexpensive insulation material.
Cellulose insulation is easy to install. It can be blown in or sprayed in, making it a relatively quick and easy installation process.
Weaknesses:
Cellulose insulation can be dusty during installation. This is because it is made from recycled paper, which contains small particles of paper. However, this dust can be easily controlled by using a dust mask and by taking other precautions.
Cellulose insulation can settle over time. This means that it may need to be topped off or replaced after a few years. However, this is not a major issue, and it is usually a relatively easy and inexpensive fix.
Cellulose insulation is not as versatile as some other types of insulation. For example, it is not as good at resisting moisture as some other types of insulation. However, cellulose insulation is still a good choice for most applications.
Thermal Conductivity (λ) | 0.035 - 0.040 W/m.K |
Cost | Low |
Net Carbon Emissions | -1.8 kgCO2e/m2 (sequesters carbon) |
Toxicity | Low |
Installation | Similar to fibreglass in that loose-fill in attics is low-skilled, but installation elsewhere should be done by a professional. PPE should be worn. |
Vapour Permeability | 10-50 perms - high permeability |
Suitability | Walls (Internal), Roofs |
Fire Classification | B-s2, d0 |
Image: メルビル, CC BY 3.0, via Wikimedia Commons
Closed-Cell Spray Foam
Closed-cell spray foam is a type of insulation that is sprayed into place. It is made up of small cells that are filled with gas, such as air or nitrogen. This makes closed-cell spray foam a very effective insulator, as it does not conduct heat well.
Closed-cell spray foam is also very dense, which makes it a good choice for applications where strength and durability are important. For example, closed-cell spray foam is often used in commercial buildings and in areas that are exposed to the elements.
Here are some of the benefits of closed-cell spray foam:
Excellent insulator
Very dense
Strong and durable
Water-resistant
Fire-resistant
Can be used as an air-barrier
However, closed-cell spray foam is also more expensive than other types of insulation. It is also important to note that closed-cell spray foam can be difficult to install, so it is best to hire a qualified contractor.
In some cases, it may be possible to use a ‘flash and batt’ insulation approach to create an air barrier and also keep insulation costs low. This involves installing a 50-100mm lift of closed-cell insulation into a cavity, then topping it up with batt insulation such as mineral wool. However, this does mean multiple installation steps, and may not be suitable in all cases.
If you are looking for a type of insulation that is very effective, strong, and durable, then closed-cell spray foam is a good option. However, it is important to be aware of the potential drawbacks of closed-cell spray foam, such as the higher cost and the difficulty of installation.
Older versions of closed-cell foam used HFC (hydrofluorocarbon) blowing agents, which had a high global warming potential. Newer formulations used HFO (hydrofluoroolefin) which has a relatively low global warming potential. There are some manufacturers who have developed water based blowing agents.
There have been some recent news articles about incorrectly installed spray foam insulation. Your installer should take into account the moisture levels of the surrounding materials, humidity of the air and temperature, adjusting the chemical mixture accordingly. A professional installer should provide this information as part of your warranty documentation.
Here are some additional details about closed-cell spray foam:
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It can be sprayed into hard-to-reach areas, such as attics and crawl spaces.
It is backed by a variety of warranties, so you can be sure that it will perform as advertised.
Thermal Conductivity (λ) | 0.025 - 0.027 W/m.K |
Cost | High |
Net Carbon Emissions | 23.2 kgCO2e/m2 (very high) |
Toxicity | Stay out of the building during spraying. There are reports of lingering odours and/or off-gassing that affect chemically sensitive people |
Installation | Building should be vacated by everyone but the installed during spraying. Foam may have to be installed in layers (known as ‘lifts’) to allow for proper curing. Odours may linger, but if properly mixed, the foam is inert once cured. |
Vapour Permeability | <1 perms - impermeable |
Suitability | Walls (Internal), Roofs |
Fire Classification | - |
Image: Cdpweb161, CC BY-SA 3.0, via Wikimedia Commons
Open-Cell Spray Foam
Open-cell spray foam is a type of insulation that is sprayed into place. It is made up of larger cells that are filled with air. This makes open-cell spray foam a less effective insulator than closed-cell spray foam, but it is also more flexible and less expensive.
Open-cell spray foam is often used in residential applications, such as attics and walls. It is also a good choice for soundproofing applications.
Here are some of the benefits of open-cell spray foam:
Less expensive than closed-cell spray foam
More flexible than closed-cell spray foam
Good soundproofing properties
Easy to install
However, open-cell spray foam is not as effective an insulator as closed-cell spray foam. It is also not as water-resistant, so it is not a good choice for applications where moisture is a concern.
If you are looking for a type of insulation that is less expensive, flexible, and easy to install, then open-cell spray foam is a good option. However, it is important to be aware of the potential drawbacks of open-cell spray foam, such as the less beneficial U-value and the lower water resistance.
There have been some recent news articles about incorrectly installed spray foam insulation. Your installer should take into account the moisture levels of the surrounding materials, humidity of the air and temperature, adjusting the chemical mixture accordingly. A professional installer should provide this information as part of your warranty documentation.
Here are some additional details about open-cell spray foam:
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It can be sprayed into hard-to-reach areas, such as attics and crawl spaces.
It is backed by a variety of warranties, so you can be sure that it will perform as advertised.
Thermal Conductivity (λ) | 0.038 - 0.045 W/m.K |
Cost | High |
Net Carbon Emissions | 2.9 kgCO2e/m2 (moderate) |
Toxicity | Stay out of the building during spraying. There are reports of lingering odours and/or off-gassing that affect chemically sensitive people |
Installation | Building should be vacated by everyone but the installed during spraying. Foam may have to be installed in layers (known as ‘lifts’) to allow for proper curing. |
Vapour Permeability | 5-10 perms (low permeability) |
Suitability | Walls (Internal), Roofs |
Fire Classification | - |
Image: Andrealopezb, CC BY-SA 4.0 , via Wikimedia Commons
Expanded Polystyrene (EPS)
Expanded polystyrene insulation (EPS) is a type of foam insulation made from polystyrene beads that have been expanded with heat or steam. It is a lightweight, rigid material that is a good insulator. EPS is available in a variety of forms, including boards, sheets, and blocks. It is also available in a variety of compressive strengths.
EPS is often used in construction applications, such as walls, roofs, and foundations.
Here are some of the benefits of EPS insulation:
Lightweight and easy to handle
Good insulator
Water-resistant
Durable
Cost-effective
However, EPS insulation is also not as fire-resistant as some other types of insulation. It is also important to note that EPS insulation is not a good choice for applications where moisture is a concern.
If you are looking for a type of insulation that is lightweight, easy to handle, and a good insulator, then EPS insulation is a good option. However, it is important to be aware of the potential drawbacks of EPS insulation, such as the lower fire resistance and the potential for moisture damage.
There is a graphite-infused version of EPS available called GPS (graphite polystyrene), which has a lower thermal conductivity than regular EPS.
Here are some additional details about EPS insulation:
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It can be cut to size, so it is easy to install.
It is backed by a variety of warranties, so you can be sure that it will perform as advertised.
Thermal Conductivity (λ) | 0.030 - 0.045 W/m.K |
Cost | Moderate |
Net Carbon Emissions | 4.9 - 6.6 kgCO2e/m2 (moderate) |
Toxicity | Low |
Installation | Lightweight and easy to handle. Can be cut with normal woodworking tools, but specialist blades can produce much cleaner cuts |
Vapour Permeability | 2.5 - 5.0 perms (slightly permeable) |
Suitability | Walls (External, Cavity, Internal), Roofs, Floor (Sub-slab) |
Fire Classification | C - Moderate contribution to fire spread, moderate fire growth rate, moderate smoke production |
Image: Cjp24, CC BY-SA 4.0, via Wikimedia Commons
Extruded Polystyrene (XPS)
Extruded polystyrene insulation (XPS) is a type of foam insulation that is made by extruding polystyrene beads through a die. This creates a closed-cell foam with a smooth surface. XPS is a rigid material that is a good insulator. It is available in a variety of forms, including boards, sheets, and blocks.
XPS is often used in construction applications, such as walls, roofs, and foundations. It is also used in marine applications and in the packaging industry.
Here are some of the benefits of XPS insulation:
Rigid and durable
Good insulator
Water-resistant
Chemical-resistant
Cost-effective
However, XPS insulation is also not as fire-resistant as some other types of insulation. It is also important to note that XPS insulation is not a good choice for applications where moisture is a concern. Additionally, XPS uses a blowing agent in it’s manufacture with a global warming potential 1400 times that of CO2. The blowing agent will escape over time (a process also known as off-gassing) and be replaced by air, which can lead to a decline in thermal resistance of around 10% over the lifetime of the product.
If you are looking for a type of insulation that is rigid, durable, and a good insulator, then XPS insulation is a good option. However, it is important to be aware of the potential drawbacks of XPS insulation, such as the lower fire resistance and the potential for moisture damage.
Here are some additional details about XPS insulation:
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It can be cut to size, so it is easy to install.
Thermal Conductivity (λ) | 0.033 - 0.036 W/m.K |
Cost | Moderate |
Net Carbon Emissions | 14.3 - 98.7 kgCO2e/m2 (high to extremely high) |
Toxicity | Low |
Installation | Similar to EPS |
Vapour Permeability | 1-2 perms - slightly permeable |
Suitability | Walls (External, Internal), Roofs, Floors (Floating Floor) |
Fire Classification | D - high contribution to fire spread, high fire growth rate, significant smoke production |
Image: Mongarort2, CC BY-SA 4.0, via Wikimedia Commons
Polyisocyanurate (PIR)
Polyisocyanurate insulation (also known as PIR or polyiso) is a rigid, closed-cell foam insulation that is made from isocyanate and polyol. It is a very good insulator, with an R-value that is typically higher than other types of insulation. Polyisocyanurate insulation is also fire-resistant and moisture-resistant. The insulation is typically covered with a foil face, but other facing materials are also used, depending on the application of the insulation. For example, tissue-faced boards are commonly used in flat roofing applications.
Polyisocyanurate insulation is available in a variety of forms, including boards, sheets, and blocks. It is often used in construction applications, such as walls, roofs, and foundations. It is also used in industrial applications, such as refrigerated containers and cold storage facilities.
Here are some of the benefits of polyisocyanurate insulation:
Excellent insulator
Fire-resistant
Moisture-resistant
Durable
Cost-effective
However, polyisocyanurate insulation is also more expensive than other types of insulation. It is also important to note that polyisocyanurate insulation can be difficult to install, so it is best to hire a qualified contractor.
If you are looking for a type of insulation that is very effective, fire-resistant, and moisture-resistant, then polyisocyanurate insulation is a good option. However, it is important to be aware of the potential drawbacks of polyisocyanurate insulation, such as the higher cost and the difficulty of installation.
Polyiso is blown with similar blowing-agents as EPS, so has a similar global warming potential. The boards are non-recycleable at the time of writing, but they can be removed and re-used in other projects, leading to a small reclamation market.
Here are some additional details about polyisocyanurate insulation:
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It can be cut to size, so it is easy to install.
It is backed by a variety of warranties, so you can be sure that it will perform as advertised.
Thermal Conductivity (λ) | 0.022 - 0.035 W/m.K |
Cost | Moderate |
Net Carbon Emissions | 5 kgCO2e/m2 (moderate) |
Toxicity | Low |
Installation | Similar to other foam board materials |
Vapour Permeability | 0.01 - 0.2 perms - impermeable |
Suitability | Walls (External, Cavity, Internal), Roofs, Floors (Sub-slab, Floating floor) |
Fire Classification | B - Limited contribution to fire spread, low fire growth rate, limited smoke production |
Sealle, CC BY-SA 4.0, via Wikimedia Commons
Wood Fibre
Wood fibre insulation is a type of insulation made from recycled wood fibres. Wood fibre insulation is also fire-resistant and can help to reduce noise levels.
Wood fibre insulation is available in various forms, including boards, and loose fill. It is relatively easy to install, and it is a cost-effective way to improve the energy efficiency of a building. Panels can be installed easily using a tongue-and-groove system, but are non-structural.
Here are some of the benefits of wood fibre insulation:
Good insulator
Fire-resistant
Noise-reducing
Easy to install
Sustainable
Recyclable
However, wood fibre insulation can also be irritating to the skin and lungs. It is essential to wear protective gear when handling wood fibre insulation. Additionally, wood fibre is one of the most expensive insulation types in relation to its thermal resistance at the time of writing.
If you are looking for a type of insulation that is effective, fire-resistant, and cost-effective, then wood fibre insulation is a good option. However, it is important to be aware of the potential health risks associated with wood fibre insulation.
Here are some additional details about wood fibre insulation:
It is made from recycled wood, so it is a sustainable material.
It is available in a variety of thicknesses, so you can choose the right insulation for your needs.
It is easy to cut and install so you can do it yourself.
Thermal Conductivity (λ) | 0.038 - 0.060 W/m.K |
Cost | High |
Net Carbon Emissions | -1.9 kgCO2e/m2 (sequesters carbon) |
Toxicity | Very low |
Installation | Loose-fill products can be installed similar to cellulose, and boards are handled like rigid foam. |
Vapour Permeability | 50 to 150 perms - very permeable |
Suitability | Walls (External, Internal), Roofs |
Fire Classification | E - Very high contribution to fire spread, very high fire growth rate, substantial smoke production |
Image: Jamesh251 James Henderson, CC BY-SA 3.0, via Wikimedia Commons
Sheep Wool
Sheep's wool insulation is a natural insulator that performs similarly to wood fibre insulation. Sheep's wool insulation is also fire-resistant and can help to reduce noise levels.
Sheep's wool insulation is available in various forms, including batts, rolls, and loose fill. It is relatively easy to install, and it is a cost-effective way to improve the energy efficiency of a building.
Here are some of the benefits of sheep's wool insulation:
Good insulator
Fire-resistant
Noise-reducing
Easy to install
Sustainable
Hypoallergenic
Moisture-wicking
However, sheep's wool insulation can also be more expensive than other types of insulation. It is also important to note that sheep's wool insulation can be susceptible to mould and mildew if it is not properly installed.
If you are looking for a type of insulation that is effective, fire-resistant, and sustainable, then sheep's wool insulation is a good option. However, it is important to be aware of the potential drawbacks of sheep's wool insulation, such as the higher cost and the susceptibility to mould and mildew.
The net carbon emissions of sheep's wool insulation are even lower when the wool is sourced from sheep that are raised on sustainable farms.
Here are some additional details about sheep's wool insulation:
It is made from a renewable resource, so it is environmentally friendly.
It is non-toxic and does not off-gas harmful chemicals.
It is a good sound absorber, so it can help to reduce noise levels in your home.
If you are looking for an eco-friendly and effective insulation option, then sheep's wool insulation is a good choice.
Thermal Conductivity (λ) | 0.035 - 0.042 W/m.K |
Cost | Moderate |
Net Carbon Emissions | 1 kgCO2e/m2 (very low) |
Toxicity | Low |
Installation | Similar to mineral wool and other friction-fit batts |
Vapour Permeability | 10-20 perms (vapour open) |
Suitability | Walls (Internal), Roofs |
Fire Classification | E - Very high contribution to fire spread, very high fire growth rate, substantial smoke production |
Image: Shadokat at English Wikipedia, CC BY-SA 3.0, via Wikimedia Commons
Hemp
Hemp insulation is a type of insulation that is made from hemp fibres. Hemp is a strong and durable material that is also naturally fire-resistant. Hemp insulation is made by chopping up the hemp fibres and then blending them with a binder. The binder can be a natural material, such as lime, or a synthetic material, such as cement.
Overall, hemp insulation is a good option for those looking for an effective, sustainable, and eco-friendly insulation material. However, it is important to be aware of the potential drawbacks of hemp insulation, such as the higher cost and the susceptibility to pests.
Here are some additional details about the strengths and weaknesses of hemp insulation:
Strengths:
Hemp insulation has a low thermal conductivity, meaning that it is a good insulator. This can help to keep your home warm in winter and cool in summer, saving you money on your energy bills.
Hemp insulation is also fire-resistant. This means that it will not catch fire easily, even if it is exposed to high temperatures.
Hemp insulation is a good sound absorber. This can help to reduce noise levels in your home, making it more peaceful and comfortable.
Hemp insulation is sustainable. It is made from the fibres of the hemp plant, which is a renewable resource.
Hemp insulation is eco-friendly. It does not off-gas harmful chemicals, making it a safe and healthy choice for your home.
Weaknesses:
Hemp insulation is more expensive than some other types of insulation. However, the cost of hemp insulation has been declining in recent years, and it is becoming more affordable.
Hemp insulation can be susceptible to pests if it is not properly installed. This is because pests are attracted to the moisture in hemp insulation. However, there are ways to protect hemp insulation from pests, such as using a pest-resistant barrier.
Hemp insulation can be heavy and difficult to handle. This is because it is made from the fibres of the hemp plant, which are very strong. However, there are now lighter-weight forms of hemp insulation available, making it easier to install.
Hemp insulation is not as versatile as some other types of insulation. For example, it is not as good at resisting moisture as some other types of insulation. However, hemp insulation is still a good choice for most applications.
Thermal Conductivity (λ) | 0.039 - 0.070 W/m.K |
Cost | Moderate |
Net Carbon Emissions | -3.1 kgCO2e/m2 (sequesters carbon) |
Toxicity | Very low |
Installation | Panels are installed between studs and rafters. Hempcrete blocks and wall sections can be assembled in site and require relatively little skill, similar to that of straw bale construction |
Vapour Permeability | 10-20 perms (vapour open) |
Suitability | Walls, Roofs |
Fire Classification | E - Very high contribution to fire spread, very high fire growth rate, substantial smoke production |
Image: Christian Gahle, nova-Institut GmbH, CC BY-SA 3.0, via Wikimedia Commons
Straw
Traditionally, straw construction involves stacking bales which are later covered in render or plaster, however, there are now load-bearing panels also available on the market. Straw is a renewable material that is a good insulator because it has a lot of air pockets. These air pockets trap heat, which helps to keep buildings warm in the winter and cool in the summer.
Strengths:
Straw insulation is sustainable. It is made from the stalks of wheat, barley, or rye, which are renewable resources.
Straw insulation is eco-friendly. It does not off-gas harmful chemicals, making it a safe and healthy choice for your home.
Straw insulation is sound-absorbing. This can help to reduce noise levels in your home, making it more peaceful and comfortable.
Offers a high DIY potential.
Weaknesses:
Straw insulation can be difficult to install. This is because it is a bulky material that can be difficult to handle. It is also important to seal straw insulation properly to prevent pests from getting inside.
Straw insulation has a poor thermal conductivity as an insulation, but it is low as a structural material. Insulation will have to be relatively thick to reach U-values similar to that of other assemblies.
Straw insulation can be susceptible to pests if it is not properly sealed. This is because pests are attracted to the moisture in straw insulation. However, there are ways to protect straw insulation from pests, such as using a pest-resistant barrier.
Straw insulation can be heavy and bulky. This can make it difficult to transport and install. However, there are now lighter-weight forms of straw insulation available, making it easier to work with.
Straw insulation is not as versatile as some other types of insulation. For example, it is not as good at resisting moisture as some other types of insulation, requiring large roof overhangs to protect walls. However, straw insulation is still a good choice for most applications.
Thermal Conductivity (λ) | 0.106- 0.09 W/m.K |
Cost | Low (bales) to high (prefabricated panels) |
Net Carbon Emissions | -14.5 kgCO2e/m2 (sequesters carbon) |
Toxicity | Very low |
Installation | Straw bales can be incorporrated into the building as infill or structural components. Straw panels are comparable to other types of structural insulated panels (SIPS) |
Vapour Permeability | 1 to 10 perms (low permeability) |
Suitability | Walls |
Fire Classification | E - Very high contribution to fire spread, very high fire growth rate, substantial smoke production |
Image: Colin Rose, CC BY 2.0, via Wikimedia Commons
Cotton
Cotton batt insulation is a type of insulation made from recycled cotton fibres. It is a sustainable and environmentally friendly option for insulating homes and buildings. Cotton batt insulation is also non-toxic and non-irritating, making it a safe choice for people with allergies or sensitivities.
Cotton batt insulation is made from recycled cotton fibres that are bound together with a natural resin. The fibres are typically sourced from denim scraps, which are a byproduct of the textile industry. Cotton batt insulation is available in a variety of thicknesses and thermal conductivities, making it a versatile option for a variety of applications.
Strengths:
Cotton batt insulation has a low thermal conductivity, meaning that it is a good insulator. This can help to keep your home warm in winter and cool in summer, saving you money on your energy bills.
Cotton batt insulation is also fire-resistant due to borate treatment. This means that it will not catch fire easily, even if it is exposed to high temperatures.
Cotton batt insulation is moisture-resistant. This means that it will not absorb moisture, which can help to prevent mould and mildew growth.
Cotton batt insulation is sustainable. It is made from recycled cotton fibres, which are a renewable resource.
Cotton batt insulation is eco-friendly. It does not off-gas harmful chemicals, making it a safe and healthy choice for your home.
Cotton batt insulation is sound-absorbing. This can help to reduce noise levels in your home, making it more peaceful and comfortable.
Cotton batt insulation is hypoallergenic. This means that it is less likely to trigger allergies in people with sensitive skin.
Weaknesses:
Cotton batt insulation is more expensive than some other types of insulation. However, the cost of cotton batt insulation has been declining in recent years, and it is becoming more affordable.
Cotton batt insulation can be difficult to install. This is because it is a bulky material that can be difficult to handle. It is also important to seal cotton batt insulation properly to prevent pests from getting inside. It can be difficult to cut around obstacles such as plumbing penetrations.
Cotton batt insulation is not as versatile as some other types of insulation. For example, it is not as good at resisting moisture as some other types of insulation. However, cotton batt insulation is still a good choice for most applications.
Thermal Conductivity (λ) | 0.035 W/m.K |
Cost | Moderate |
Net Carbon Emissions | 2.3 - 3.4 kgCO2e/m2 (moderate) |
Toxicity | Low |
Installation | Similar to other friction-fit batts. |
Vapour Permeability | 1 perm - moderate permeability |
Suitability | Walls (Internal), Roofs |
Fire Classification | A - Limited combustibility, limited contribution to fire, no significant smoke emission or droplets/particles |
Image: U.S. Department of Agriculture, Public domain, via Wikimedia Commons
Cork
Cork insulation is a type of insulation that is made from the bark of the cork oak tree. Cork is a natural, renewable material that is very good at insulating against heat and sound. It is also fire-resistant, moisture-resistant, and mould-resistant.
Cork insulation is available in a variety of forms, including boards, granules, and sheets. It can be used to insulate walls, roofs, floors, and other areas of a building.
Strengths:
Cork insulation has a thermal conductivity similar to wood-fibre insulation
Cork insulation is also fire-resistant. This means that it will not catch fire easily, even if it is exposed to high temperatures.
Cork insulation is moisture-resistant. This means that it will not absorb moisture, which can help to prevent mould and mildew growth.
Cork insulation is sustainable. It is made from the bark of the cork oak tree, which is a renewable resource.
Cork insulation is eco-friendly. It does not off-gas harmful chemicals, making it a safe and healthy choice for your home.
Cork insulation is sound-absorbing. This can help to reduce noise levels in your home, making it more peaceful and comfortable.
Cork insulation is hypoallergenic. This means that it is less likely to trigger allergies in people with sensitive skin.
Cork insulation is breathable. This means that it allows moisture to escape, which can help to prevent mould and mildew growth.
It can be left exposed, and will naturally turn grey when exposed to the elements.
Weaknesses:
Cork insulation is more expensive than some other types of insulation. However, the cost of cork insulation has been declining in recent years, and it is becoming more affordable.
Cork insulation can be difficult to install. This is because it is a brittle material that can be difficult to cut and work with. It is also important to seal cork insulation properly to prevent pests from getting inside.
Cork insulation is not as versatile as some other types of insulation. For example, it is not as good at resisting moisture as some other types of insulation. However, cork insulation is still a good choice for most applications.
Thermal Conductivity (λ) | 0.036 - 0.043 W/m.K |
Cost | High |
Net Carbon Emissions | Not available |
Toxicity | Very low |
Installation | Installed like other board insulation. Some versions can be used externally |
Vapour Permeability | 0.05 perms - very low permeability |
Suitability | Walls (Internal, External), Floors (Under flooring) |
Fire Classification | E - Very high contribution to fire spread, very high fire growth rate, substantial smoke production |
Image: Zemin0419, CC BY-SA 4.0, via Wikimedia Commons
Calcium Silicate
Calcium silicate insulation is made from natural materials, such as sand and lime. These materials are relatively abundant and do not require a lot of energy to extract or process.
Calcium silicate insulation is also a fire-resistant material, which makes it a safe choice for insulation in high-risk areas. It is also relatively lightweight and easy to install, making it a good choice for a variety of applications.
Strengths:
Excellent insulator: Calcium silicate insulation has a high R-value, meaning that it is a good insulator. This can help to keep your home warm in winter and cool in summer, saving you money on your energy bills.
Fire-resistant: Calcium silicate insulation is fire-resistant. This means that it will not catch fire easily, even if it is exposed to high temperatures.
Moisture-resistant: Calcium silicate insulation is moisture-resistant. This means that it will not absorb moisture, which can help to prevent mould and mildew growth.
Durable: Calcium silicate insulation is durable. It can withstand a lot of wear and tear, making it a good choice for applications where durability is important.
Environmentally friendly: Calcium silicate insulation is made from natural materials, such as sand and lime. This means that it is a sustainable and environmentally friendly choice.
Weaknesses:
Cost: Calcium silicate insulation is more expensive than some other types of insulation. However, the cost of calcium silicate insulation has been declining in recent years, and it is becoming more affordable.
Installation: Calcium silicate insulation can be difficult to install. This is because it is a brittle material that can be difficult to cut and work with.
Not as versatile as some other types of insulation: Calcium silicate insulation is not as versatile as some other types of insulation. For example, it is not as good at resisting moisture as some other types of insulation. However, calcium silicate insulation is still a good choice for most applications.
Can be cut with woodworking power tools, but will cause excessive wear to blades and considerable dust. PPE must be worn to protect lungs.
Thermal Conductivity (λ) | 0.059 - 0.12 W/m.K |
Cost | High |
Net Carbon Emissions | -10 to -20 kgCO2e/m2 (sequesters carbon) |
Toxicity | Very low |
Installation | Attached to substrate with adhesive similar to tiling. PPE must be worn when cutting |
Vapour Permeability | 0.1 - 0.2 perms - low permeability |
Suitability | Walls |
Fire Classification | A1 |
Image: Achim Hering, CC BY 3.0, via Wikimedia Commons
Aerogel
Aerogel insulation is a type of insulation that is made from a gel that has been dried out using supercritical drying or freeze-drying. This process leaves behind a highly porous material with a very low density. Aerogel insulation has some of the lowest thermal conductivity values of any known material, making it an incredibly efficient insulator. It is also very lightweight and water-repellent, making it a versatile material with a wide range of potential uses.
Strengths:
Low thermal conductivity: Aerogel has one of the lowest thermal conductivities of any known material, making it an incredibly efficient insulator. This means that it can help to keep buildings warm in the winter and cool in the summer, saving energy and money.
Lightweight: Aerogel is also very lightweight, making it easy to transport and install. This is a major advantage over other types of insulation, which can be bulky and difficult to handle.
Water-repellent: Aerogel is water-repellent, which means that it is resistant to moisture damage. This is a major advantage in applications where moisture can be a problem, such as in building insulation or solar panels.
Fire-resistant: Aerogel is also fire-resistant, making it a safe choice for insulation in high-risk areas. This is because aerogel does not burn and does not release any harmful fumes when it does catch fire.
Versatile: Aerogel can be used in a variety of applications, including building insulation, solar panels, and electronics. This makes it a very versatile material with a wide range of potential uses.
Weaknesses:
Expensive: Aerogel is currently very expensive, which limits its widespread adoption. However, as the technology improves, the cost of aerogel is expected to come down.
Brittle: Aerogel is also very brittle, making it difficult to handle and install. This is a major challenge that needs to be addressed before aerogel can be widely used in construction applications.
Not as strong as other types of insulation: Aerogel is not as strong as other types of insulation, so it may not be suitable for all applications. For example, aerogel would not be a good choice for insulation in areas where there is a risk of impact damage.
Sensitive to UV rays: Aerogel is sensitive to UV rays, so it must be protected from sunlight. This can be a challenge in outdoor applications.
Overall, aerogel insulation is a very promising material with a number of potential benefits. However, it is important to be aware of its weaknesses before making a decision about whether or not to use it.
Thermal Conductivity (λ) | 0.015 W/m.K |
Cost | Very high |
Net Carbon Emissions | 2.5 kgCO2e/m2 (moderate) |
Toxicity | Low |
Installation | Available as strips for reducing thermal bridging, or as sheets for direct application. Also available as laminates with other boards such as magnesium oxide board, ready for plastering |
Vapour Permeability | 5 perms - permeable |
Suitability | Walls, Floors, Thermal Bridges |
Fire Classification | C - Moderate contribution to fire spread, moderate fire growth rate, moderate smoke production |
Image: Courtesy NASA/JPL-Caltech, Public domain, via Wikimedia Commons
