Sound and thermal insulation

In the past, houses were built with thick walls, high ceilings, and generally large and spacious courtyards, so there was little need for sound and thermal insulation. However, over time, with population growth and advances in technology, multi-storey buildings without courtyards, featuring thin walls, low ceilings, and very limited spacing between structures, have become common. As a result, traditional-style houses are gradually disappearing, while the number of multi-storey buildings and skyscrapers continues to increase. On the other hand, noise generated by vehicle traffic, industrial machinery, and other sources has led to significant noise pollution, especially in large cities.

The changes in building design have made it much easier for heat and sound to transfer between the interior and exterior of buildings. The human hearing range is between 20 and 20,000 Hz, with the highest sensitivity to sounds around 1,000 Hz, and most environmental sounds fall within this audible range. Therefore, the need for sound and thermal insulation in buildings has become an important issue in construction.
By using acoustic and thermal insulation materials, not only is human comfort improved, but energy consumption is also reduced. These materials help prevent heat loss from inside during cold seasons and reduce heat entry into buildings during warm seasons. However, this is not merely a choice; according to Chapter 19 of building regulations, the external parts of buildings must be sufficiently thermally insulated to ensure energy efficiency.

This regulation was approved in Iran in 2002. Exterior building components refer to roofs and walls that are in contact with outdoor air and the external environment, and do not include interior walls of buildings. The required level of sound and thermal insulation depends on various factors, such as the building’s function, its geographical location, the built-up area, and the size of the city where it is constructed. Compliance with these regulations is particularly mandatory in urban areas, and a completion certificate is issued to builders only when appropriate sound and thermal insulation measures have been implemented in the building.

What is sound and thermal insulation and what are its applications?

Thermal insulation is designed to reduce or eliminate the amount of heat transferred between objects at different temperatures. Heat always flows from a hotter object to colder ones. However, not all materials transfer heat at the same rate. By using thermal insulation materials with low thermal conductivity, heat transfer is significantly slowed down.
Sound insulation works by blocking, absorbing, or reducing the transmission of sound waves. These waves are generated by vibrations that travel through air at specific frequencies.
When selecting appropriate thermal and sound insulation, several factors can influence the choice of material.
Heat is transferred in three ways:

• Conduction: heat transfer through direct contact.
• Convection: heat transfer through air (fluid movement).

• Radiation: heat transfer through infrared radiation.

Some thermal insulation materials behave differently depending on the type of heat transfer. For example, aluminum foil is more effective in insulating against radiant heat, while fiberglass is a better option for reducing heat transfer through convection and conduction. Therefore, depending on the building’s application and other requirements, the most suitable thermal insulation material can be selected.
For sound insulation as well, the appropriate type of material can be chosen based on whether the goal is to reduce internal noise within a building or to block external noise. For exterior environments, an insulating material is needed that can reflect or reduce airborne vibrations. For interior sound insulation, materials that absorb sound are more effective.
The cellular structure of insulation materials plays a key role in this performance. In other words, the porosity of the material, as well as cell size, density, and thickness, all determine the level of sound reduction.
There are also insulation materials that serve both thermal and acoustic purposes simultaneously, and some of them also have fireproof properties.

Types of sound and thermal insulation

Mineral wool

Mineral wool is a collection of mineral fibers made from molten igneous rock or slag. It does not absorb water, is non-combustible, and is considered a type of fireproof material. This material is dense and porous and slows the transfer of heat and cold through walls, floors, and ceilings. In addition, it can absorb airborne sound and impact vibrations, making it a type of thermal and sound insulation.

Fiberglass

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Fiberglass is a combination of polymer materials and glass fibers, in which glass wool is used as the reinforcing insulating material. This porous material traps air inside enclosed spaces in both hot and cold seasons and absorbs airborne sound similarly to mineral wool.

Cellulose insulation

Cellulose insulation is made of 75–85% recycled paper fibers and 15–25% fire-retardant materials, and it also has fireproofing capability. Covering walls and ceilings with fiber is simple and inexpensive, and it is environmentally friendly as well.

Spray foam insulation

Spray foam floor insulation is a polyurethane foam spray that prevents heat transfer and minimizes air movement. It is excellent for keeping cold or heat inside or outside the insulated space, but it is not a sound absorber. However, a sound-control spray foam can be applied to walls after construction. Foam insulation is inexpensive, environmentally friendly, and also provides fire-resistant protection.

Foam board insulation

Foam boards are made from polystyrene. These boards have an insulation rating of R5 per inch of thickness. Polystyrene boards can help reduce sound transmission by separating layers, limiting noise to either inside or outside a room.
Thermal and sound insulation materials can be used not only in the walls and ceilings of residential, commercial, educational buildings, etc., but also in various industrial and commercial applications to reduce noise and heat. These applications are as follows:

• Pipe and valve enclosures
• Machinery enclosures
• Floor coverings
• Doors
  
• Vehicle panels and equipment
• Engine enclosures

If you are also looking for the best way to protect your building against fire, as well as improve sound and thermal insulation, visit the Kalar Machinery Manufacturing website and learn more about the company’s services.