People spend most of their time indoors, which increases exposure to harmful pollutants. Indoor air contaminants come from different sources, such as tobacco smoke and combustion processes, cleaning products, paints and pesticides.
Building materials used for new construction or renovation need to be low-emitting and have a capacity to buffer moisture and anthropogenic (human-generated) indoor pollutants. Natural building materials made from renewable raw materials satisfy these criteria and offer additional advantages.
Insulation
Insulation helps to maintain a constant temperature, which saves energy and reduces operating costs. It also contributes to indoor air quality by helping to control the humidity levels and ventilation rates within a building. This can help to limit the growth of mold and other harmful microorganisms that can trigger health concerns in occupants.
Moldy insulation – such as fiberglass insulation that contains organic materials like cellulose, wood fibers or animal hair – is an issue for many homeowners and can cause irritation, coughing, wheezing, asthma symptoms and even more serious respiratory diseases. For this reason, it is important to use low-emitting insulation materials that are also moisture resistant and odorless.
Another concern is that some types of insulation, particularly fiberglass insulation, may break down over time and become airborne. This can occur in ductwork that is not properly sealed or in areas where water leaks have occurred. It can also happen in older buildings where fiberglass insulation was used to line ducts and is still in place.
The good news is that many newer insulation products such as polyiso continuous insulation are based on natural and renewable raw materials and are considered to have very low emission properties. In fact, a recent study compared the emission rates of a variety of natural and synthetic insulation materials under standard testing conditions. The results of this study confirmed that natural insulation materials have significantly lower emissions than conventional synthetic and mineral based insulation.
Walls
The walls of a building are one of the primary sources of air pollutants, releasing formaldehyde, VOCs and other toxic fumes from paints, glues, adhesives and furnishings. Additionally, combustion sources such as wood, coal and oil heating and cooking equipment release harmful combustion byproducts into the indoor environment.
In recent years, increasing energy efficiency has pushed builders to limit air infiltration and tighten the insulation envelope. Unfortunately, the result is reduced ventilation rates which exacerbates the impact of building materials on indoor air quality.
For this reason, wall systems should be low-emitting, durable and able to buffer moisture and anthropogenic indoor pollutants in order to improve IAQ. Luckily, several eco-friendly options for the wall assembly are available. In addition to incorporating best-in-class insulating products, such as polyiso continuous insulation, architects can also consider earth plasters with a green finish, which reduce the amount of VOCs emitted into the air during construction and maintenance.
Furthermore, living walls are natural air-filters that significantly improve indoor air quality, metabolising harmful toxins and releasing fresh oxygen. They also help to lower noise levels in the workspace, creating a more relaxing environment which will boost concentration and productivity.
Floors
Many building materials emit (semi-)volatile organic compounds that can have a negative impact on indoor air quality. Common pollutants include carbon monoxide, particulate matter and combustion byproducts. Others include household cleaners, pesticides and personal care products. Biological contaminants like pet dander and mold are also problematic. These contaminants are typically emitted from building materials, furnishings and interior finishes, although some originate outdoors. The concentration of these pollutants is influenced by the amount of time that indoor spaces are used and the rate at which they exchange air with the outdoors through infiltration, natural ventilation and mechanical ventilation.
In recent decades, a number of eco-friendly and sustainable building materials have become more popular with architects and builders. These building materials tend to have lower embodied energy than traditional building materials and are manufactured using less toxic chemicals. They can also contribute to healthy indoor air. However, these materials may be prone to emissions of harmful chemicals such as VOCs, formaldehyde and radon.
Most new flooring materials off-gas VOCs during the off-gassing process, which can lead to poor indoor air quality. This is because VOCs, like formaldehyde, can cause short-term and long-term health problems including nose, throat and skin irritation; allergic reactions; and respiratory problems. For this reason, it is important to ask for low-VOC or no-VOC adhesives and maintenance materials when installing new resilient floors.
Ceilings
Since people spend more than 80% of their time indoors, ensuring optimal IEQ is crucial for the health and productivity of occupants. This includes controlling the quality of outdoor air entering buildings, and the quality of building materials used for walls and ceilings.
Airborne pollutants can cause eye, throat and nose irritation, asthma and allergies, nausea or even damage to the central nervous system. The most common pollutants are volatile organic compounds (VOCs) that off-gas from construction and furnishing materials and combustion byproducts. Others include radon that can form in soil and rock, environmental tobacco smoke, and harmful bacteria and viruses.
Although designers pay close attention to the materials they choose for walls and floors, too often the same care is not given to ceilings. It is important to consider that dropped ceilings are usually return air plenums through which conditioned, recirculated indoor air is drawn by HVAC systems. Unless they are extremely well sealed, these plenums can allow a large amount of outside air to pollute indoor space as it is heated or cooled.
In addition, many modern ceilings use paper-backed drywall in the form of acoustic ceiling tiles and vapor barriers, which can encourage mold growth. Additionally, paints and stains that are applied wet release VOCs, which can off-gas for long periods of time. Choosing low-VOC products helps to keep these contaminant levels as low as possible, and supports sustainability by reducing energy consumption.