Thermal comfort is the human satisfaction with the thermal environment1. The occupant’s perceived level of thermal comfort influences their productivity and even their health and well-being.
Building materials influence the heat transfer and thermal performance of buildings. They also play a critical role in reducing the energy consumption in buildings.
Thermal Conductivity
The thermal conductivity of a material is how much heat is transferred across it. It depends on the material, wall thickness and the difference in temperature on both sides of the wall. The more conductive the material, the faster the heat moves through it. The thermal conductivity of a building material is usually measured in watts per metre Kelvin (W/mK).
It’s important to choose materials with low thermal conductivity, as they are good insulators and reduce the flow of heat from one side of a room to the other. This is because when heat flows from one side of a room to the next, it causes the indoor air temperature to rise and can lead to discomfort for occupants.
Having the right materials in your home will also help you save energy costs. This is because your home will be less reliant on artificial heating and cooling, which uses more energy over time and can put a strain on the national power grid.
Using high-quality insulation and building materials with a lower thermal conductivity will also ensure that your home stays comfortable for longer, meaning you’ll be able to stay off the hot and cold cycle and avoid fluctuations in temperature. This will result in greater productivity, as people won’t need to keep getting up to adjust their air conditioners and will be able to concentrate on their work without feeling uncomfortable.
Thermal Insulation
The insulating properties of a material reduce the transfer of heat from hot surfaces to cooler ones, reducing energy consumption. Thermal insulation can be found in everything from insulating the concrete floor of an industrial processing plant to lining domestic cavity walls. Despite the wide range of contexts, all functionalised insulating materials abide by the same fundamental principles: lower energy losses equals greater efficiency and improved returns on investment.
Besides being cost competitive, many of these insulation products are made from renewable resources and are highly durable. This contributes to the sustainability of a building’s environmental footprint, and minimises waste production and maintenance requirements over its lifetime.
In addition to reducing energy consumption, thermal insulation can provide a number of other benefits. For example, it can reduce noise levels by absorbing and blocking sound waves. It can also improve comfort levels by keeping a building warm in winter and cool in summer.
In terms of thermal mass, some construction materials such as brick veneer offer good thermal storage. However, it is important to ensure that they are adequately insulated. The best practice is to have bricks insulated and finished with plasterboard. Masonry walls should also be shaded on the north side to allow them to absorb heat during the day. This helps to avoid overheating and high energy use during the summer.
Fire Retardancy
It takes a lot of heat to cause a building material to ignite, and many of the most popular and common materials used in buildings offer some degree of fire resistance. While no practical material is completely fireproof, the majority of residential fires are caused by faulty fireplaces or smokers falling asleep while smoking and being awoken by the fire [source: FEMA]. Fire resistant materials help prevent these types of residential fires.
The most common fire-resistant construction materials include glass for windows, gypsum board (or drywall), concrete and brick. Glass has a low heat conduction rating that makes it hard to ignite, and a variety of glass compositions exist that offer different levels of fire resistance. For example, float glass and wire glass have lower temperature limits than soda-lime glass.
Gypsum board is made from a non-combustible gypsum core and a layer of paper on each side, making it very fire-resistant. The gypsum resists high temperatures and releases water vapor, helping to extinguish the fire. Concrete is another common and extremely durable fire-resistant material, with a high thermal resistance that helps it hold up against extreme heat.
Bricks are also naturally resistant to fire, with different bricks offering different levels of resistance. Some of the most fire-resistant bricks are known as refractory bricks, and they’re often used to reinforce steel frames in construction projects.
Noise Reduction
The thermal performance of a building is determined by the materials used. The higher the thermal conductivity of the material, the faster heat can travel through the material and the warmer the indoor air will be. The use of passive cooling techniques helps reduce the impact of thermal conductivity on the internal temperature of buildings.
Energy-efficient building materials are also designed to minimize a building’s thermal fluctuations, reducing the amount of energy needed for heating or cooling. This results in lower energy bills and potential tax incentives. These materials also help improve indoor air quality by filtering contaminants and reducing the release of harmful VOCs.
In terms of thermal comfort, the ideal environment is a room with an average air temperature between 22degC and 27degC with a relative humidity of 40%-60%. The human body creates more heat when performing physical activities, so it is important to provide a comfortable space to allow the body to lose excess heat.
The optimum construction material for thermal comfort is one with low thermal conductivity and high thermal mass, which allows the material to absorb and store heat and then release it slowly. This process is known as the thermal lag and can significantly influence the comfort level of a room. Thermal lag is best achieved with heavy construction materials such as brick and concrete.