What is thermal insulation and how is it used?
Thermal insulation is the inhibition of heat transfer from one object to another differing in temperature and which is in thermal contact with it.
There are many situations in which it is desirable to reduce heat transfer in a certain direction, the most common case being the insulation of buildings with the aim of minimizing heat losses in winter and gains in summer.
However, other industrial products in which it is necessary to improve the efficiency in its consumption and security should not be overlooked.
Some examples are distribution pipes for hot or cold liquids, heat exchangers or boilers where the efficiency in its consumption is a must. Also, thermal insulation is crucial for specific packaging in the food-industry and food delivery.
With the environmental pressures that blight the world nowadays, insulation is becoming more and more important as it is a linchpin of the reduction of the energy obtained from fossil fuels and, consequently, a downsizing of CO2 emissions to the atmosphere.
How insulation works
Insulation works by providing a region of insulation in which thermal conduction is reduced either by creating a thermal barrier or by being thermal radiation reflected rather than absorbed by the lower-temperature body.
The insulation materials’ natural capacity to inhibit the transmission of heat
The use of pockets of trapped gasses which are natural insulants
Even if gasses may have in abstract poorer thermal conduction properties compared to liquids and solids, they have another key property that makes them one of the preferred thermal insulators in the industrial sector: lightweight.
This is explicitly shown with the extended use of EPP and EPS in industry. Consisting of 98% air and just 2% matter, the small cells or bubbles within the structure of these materials make them great thermal insulators. In turn, its low weight enables forgetting traditional heavier structures, which is extremely useful for systems such as HVAC. Not to mention that this lightness offers higher sustainability and implies less assembly and maintenance costs. As a consequence, it is no wonder that EPP and EPS are held as two of the most prominent materials when dealing with thermal insulation in the industrial sector.
How is thermal insulation performance graded
The insulating capability of a material is measured as the inverse of thermal conductivity (k). A low thermal conductivity is synonymous with a high insulating capability.
Let’s do a quick overview of the most important concepts in the graduation of thermal insulation:
Thermal conductivity (λ):
it measures the ease with which heat can travel through a material by conduction.
Thermal Resistance (R):
It relates the thermal conductivity of a material to its width. A greater thickness means less heat flow and, consequently, lower conductivity.
Specific Heat Capacity (SHC)
Is the amount of heat needed to raise the temperature of 1kg of the material by 1 degree. The higher the SHC, the better insulator a material will be.
It refers to the mass per unit volume of a material. A high density material maximizes the overall weight and is an aspect of low thermal diffusivity.
It measures the ability of a material to conduct thermal energy relative to its ability to store thermal energy. Insulators should have low thermal diffusivity.
It is the extent to which a material permits the passage of water through it and is intimately tight with the risk of condensation.
EPP for thermal insulation
Expanded Polypropylene (EPP) is a 95% air closed-cell material that features air pockets within the hollow cylinder-shaped particle structure. Its thermal insulation properties, in combination with others such as lightness, structural resistance, energy absorption, acoustic insulation and design flexibility, guarantee its suitability for a large number of applications.
If we assign values to the main conditionings of thermal insulation performance, EPP performs in the following way:
- Thermal conductivity (λ) = 0.036 – 0.040
- Thermal resistance = 4.2 (at 100mm K⋅m2/W)
- Specific Heat Capacity (J) = 1100 kg.K
- Density = 20 – 200 kg / m3
- Embodied energy = 95.40 MJ/kg
- Vapor permeable: No
Guaranteeing thermal insulation in heating, ventilation, and air-conditioning (HVAC) systems is essential for ensuring they are efficient and sustainable structures that prevent energy losses and leakings. The best way to achieve this efficiency is incorporating customized HVAC technical parts made of EPP. Theyensure a long-lasting performance, minimize heat loss, provide optimal acoustic insulation and eliminate having heavy structures due to their lightness. What’s more, EPP HVAC components resist moisture and are completely inert, meaning they do not release unwanted fibers or compounds into the outdoor air
Duct systems and fittings:
EPP, as a foam, is highly valued for its ergonomy, which makes the assembly and installation of the duct systems and fittings very fast and simple. Its features avoid the unwanted leakings that cause energy waste.
Due to the limelight of air in its composition (95%), this material allows both cold and heat to be preserved. This makes it the perfect candidate for transporting, for example, thermolabile medicines, without the need for extra elements to the packaging. It is also very useful for the agro-food industry, where temperature can spoil the perishable products, particularly in last mile transportation.
EPP’s outstanding characteristics, such as high resistance to impact and compression, lightweight and temperature, low water absorption capacity and, particularly, thermal insulation properties make it the perfect choice to protect delicate electronic components that are no good friends with water or sudden temperature changes. Besides, EPP can also be made of antistatic (static dissipative -ESDP) raw materials. This enables the use of EPP packaging for the transport of electronic systems, e.g. for companies offering contract electronics assembly.
EPS for thermal insulation
Expanded polystyrene (EPS) is a rigid and tough, closed-cell foam consisting in 98% air and just 2% of matter. It is usually made of pre-expanded polystyrene beads, using blowing agents that form bubbles and expand the foam.
When translating thermal insulation properties into numbers, EPS performs in avarage in the following way:
- Thermal conductivity (λ) = 0.034 – 0.038
- Thermal resistance = 3.52 (at 100mm K⋅m2/W)
- Specific Heat Capacity (J) = 1300 kg.K
- Density = 15 – 30 kg / m3
- Embodied energy = 88.60 MJ/kg
- Vapor permeable: No
EPS performs better than EPP in terms of the insulation of buildings. Namely, EPS is the most widely used insulating material for ETIX systems (Exterior Thermal Insulation System) , since it is a solution that provides a very good quality-to-price ratio, responding to the technical requirements of these systems in all types of weather.
similarly to EPP, EPS is also a great candidate to transport temperature sensitive loads, which is especially useful in the pharma and agro-food industry. Due to its lightness and sustainability, it is one of the best materials for thermal insulation in the industrial sector.
This is explicitly shown with the extended use of EPP and EPS in industry. Consisting respectively in 95% and 98% air and just 5% and 2% matter, the small cells or bubbles within the structure of these materials make them great thermal insulators. In turn, its low weight enables forgetting traditional heavier structures, which is extremely useful for systems such as HVAC. Not to mention that this lightness offers higher sustainability and implies less assembly and maintenance costs. As a consequence, it is no wonder that EPP and EPS are held as two of the most prominent materials when dealing with thermal insulation in the industrial sector.
At Knauf Industries we have a broad variety of EPP and EPS solutions aimed at guaranteeing thermal insulation in all the above mentioned sectors. Not only that, but we are also worldwide recognised for developing customized, turnkey projects for our clients, from the design of a part or packaging to the construction of a production plant dedicated to them.