Thermal insulation is a critical component of passive houses, and it plays a key role in ensuring their energy efficiency and comfort. In this blog post, we will explore what thermal insulation is, how it is measured, what methods are used for testing it, and what benefits it offers. We will also discuss the various materials used with thermal insulation and the cost considerations involved.
What is Thermal Insulation?
Thermal insulation refers to the materials or systems used to reduce heat transfer between the inside and outside of a building. The primary goal of thermal insulation in passive houses is to minimise heat loss in winter and heat gain in summer, which reduces the energy required to maintain a comfortable indoor temperature.
How is Thermal Insulation Measured?
Thermal insulation is typically measured by its thermal resistance, which is expressed in units of m²K/W (square metres Kelvin per Watt). Thermal resistance is a measure of a material’s ability to resist heat flow, and it is calculated as the thickness of the material divided by its thermal conductivity. The higher the thermal resistance of a material, the more effective it is at insulating.
What Methods are Used for Testing Thermal Insulation?
There are several methods used for testing thermal insulation in passive houses, including: Blower Door Test: This test measures the airtightness of a building’s envelope by measuring the air pressure difference between the inside and outside of the building. The blower door test provides information about the amount of air that is leaking into or out of the building, which can be used to identify areas where insulation is insufficient or missing.
Infrared Thermography: This method involves using a thermal imaging camera to visualise the temperature distribution on the surface of the building envelope. Infrared thermography can be used to identify areas of the building where heat is being lost due to insufficient insulation, air leaks, or thermal bridges.
Calculation Models: This method involves using computer simulation software to model the heat flow through the building envelope. Calculation models take into account the properties of the building materials and the weather conditions, and they can be used to predict the energy consumption and indoor temperature of the building.
These methods are used to verify that a passive house meets the high standards for thermal insulation and airtightness required by the passive house standard. By measuring the performance of the insulation and the building envelope, it is possible to identify areas for improvement and to ensure that the building meets the high standards required for passive houses.
What are the Benefits of Thermal Insulation?
The benefits of thermal insulation in passive houses include: Energy Efficiency: High levels of thermal insulation minimise heat loss in winter and heat gain in summer, reducing the energy required to maintain a comfortable indoor temperature. This leads to lower energy bills and a reduced carbon footprint.
Comfort: Thermal insulation helps to maintain a comfortable indoor temperature by minimising temperature fluctuations and reducing drafts. This improves the overall comfort of the building and makes it more livable.
Durability: Thermal insulation helps to protect a building from moisture damage, mould, and rot. This extends the lifespan of the building and improves its overall durability.
What Materials are Used with Thermal Insulation?
There are many different materials that can be used with thermal insulation, including:
Fibreglass: Fibreglass is a common type of insulation that is made from fine glass fibres. It is commonly used in walls, attics, and crawl spaces.
Cellulose: Cellulose is a type of insulation that is made from recycled paper products. It is a natural, environmentally friendly option that is often used in walls and attics
Rockwool: Rockwool is a type of insulation made from natural volcanic rock that has been melted and spun into fibres. It is fire-resistant, durable, and has a high R-value, making it a popular choice for passive houses.
Polystyrene: Polystyrene is a type of insulation made from expanded polystyrene beads. It is lightweight, easy to install, and has a high R-value, making it a popular choice for passive houses.
Sheep’s wool: Sheep’s wool is a natural type of insulation that is made from the fleece of sheep. It is a renewable resource that is both eco-friendly and biodegradable. It is a great choice for passive houses because it is a good insulator, has good air-sealing properties, and is also fire-resistant.
Wood Fibre: Wood fibre insulation is made from the waste soft wood material (think sawdust, chips and other waste pieces) from the wood processing industry most often located in Eastern Europe. It’s available in different densities and thicknesses depending on whether you want to use it internally or externally, on walls, floors lofts or roofs. It’s a popular method of insulation for people who are looking for a product that’s environmentally friendly as it would otherwise be a waste material.
What are the Cost Considerations?
The cost of thermal insulation can vary widely depending on the type of insulation used and the complexity of the installation. However, the cost of insulation is typically offset by the energy savings it provides over the long term.
In addition to the cost of the insulation itself, there are also labour costs associated with installation, which can be significant for more complex installations. However, the investment in thermal insulation is typically recouped within a few years through the energy savings it provides, making it a cost-effective investment over the long term.
Thermal insulation is a critical component of passive houses, and it plays a key role in ensuring their energy efficiency and comfort. The benefits of thermal insulation include lower energy bills, improved comfort, and a longer lifespan for the building.
