INDOOR AIR QUALITY & FACTORS IN DESIGNING A HEALTHY BUILDING
Air quality in interiors is known as IAQ which provides an indication of the pollution or level of cleanliness in the air indoors affecting the health and comfort of building occupants.
There are numerous sources of air pollution that can be categorized as coming from outdoor sources that make their way indoors, from occupant related activities such as smoking and cooking and from certain chemicals in products such as cleaning products, certain construction material and from paints.
IAQ can be measured through a few different factors; the air velocity, air temperature, humidity and the prevalence of particles/pollutants or VOCs (Volatile Organic Compounds) in the air. Other factors such as how “stuffy” a space feels; because of a lack of ventilation are also taken into consideration. Usually, when a space feels stuffy, it is because there is an excess of CO2 in the air. A healthy level of CO2 in an indoor environment is 250-350 parts per million. If this is exceeded, the occupants may start to feel drowsy, nauseous and experience poor concentration. The amount of CO2 in the air is measured by a CO2 sensor. As CO2 is colorless, odorless and tasteless, it is hard to detect it without a technological device such as A CO2 sensor. The prevalence of particles in the air must also be measured to determine how clean and healthy the air is. Particles are categorized based on their size. Larger particles are hazardous at the level of 20 micrometers per cubic meter and finer, smaller particles should not exceed 10 micrometers per cubic meter. This is true for both indoor and outdoor spaces. Exposure to VOCs can cause burning eyes, headaches, nausea and asthma attacks and long-term exposure can lead to a host of diseases involving kidney and lung damage. Usually, haze and smog is made up of a density of these tiny micro particles. It is possible to measure air particles by forcing air through a funnel into a particle counter which uses laser to count and measure particles through a process called light scattering.
It’s important to keep in mind that VOC’s include a range of various chemicals all of which have their own toxicity levels that are found in building and textile materials, home cleaning products, paint and furniture polish, glue, carpeting and even certain wallpapers. To minimize the prevalence of VOCs in the air indoors, there are a few things we can keep in mind for example:
- Airing out your building during and after construction or renovation works or when you’ve just had some areas painted
- By only purchasing and using products with low or no VOCs which is usually mentioned in the product specifications.
Air quality in building architecture can be managed through both natural and mechanical means or through a hybrid ventilation system that utilizes both natural and mechanical ventilation. In a mechanical ventilation system, automatic or manual detection systems can be used to determine which spaces require more ventilation. In mechanical ventilation systems such as HVAC, it is essential to keep the system regularly maintained by changing filters and checking for exhaust efficiency etc. When mechanical ventilation systems are not regularly maintained, it can be quite hazardous to the occupants of the building and they can do more than good. Natural ventilation is another means for ventilating a building and getting rid of CO2, VOCs and bringing in fresh air into a space. In addition to windows, vents and doors, natural systems can also include the use of plants to clean the indoor air. Green buildings that utilize green walls or indoor planting areas are efficiently able to manage CO2 and VOC levels through the air-purifying qualities of plants.
It is not always possible to rely on natural ventilation due to the presence of noise pollution from outdoors or because of strong sunlight and in these circumstances, a hybrid solution can be considered. Most sustainability certification programs today take into consideration the importance of IAQ and fresh air. There are many different certification programs and sustainability bodies internationally like BREEAM, based in the UK and LEED based in the US which award points for designing for good IAQ which incorporates use of fresh air as well as innovative mechanical systems.
HOW TO REDUCE AIR POLLUTION IN CONSTRUCTION:
Construction and the built environment are responsible for 4% of particle emissions caused by site machinery, demolitions and chemicals used in construction and finishing works. Big quantities of construction dust from concrete/cement, silica and wood as well as particles released from machinery engines and exhausts are known as PM10. PM10 is not visible to the naked eye and it is made up of sulphates that contribute to outdoor air pollution. It is vital to manage these chemicals and particulates on site through responsible building practices. There are a number of ways we can do this:
- Avoid the burning of waste materials that cause smoke and the release of carbon dioxide and carbon monoxide into the air. A lot of air pollutants are released primarily through combustion processes. We must fight this harmful practice common in Pakistan as an integral part of initiating sustainability within the construction industry. Many countries have made it illegal now for example it is illegal to burn materials on site in the UK and you can be fined under the Clean Air Act 1993.
- Use technology and equipment which does not cause emissions or produces lower levels of emissions. There are many new construction companies manufacturing construction equipment that have lower fuel consumption and use low-Sulphur diesel.
- Use sprinklers and water sprays to control PM10 or dust produced on site.
- Avoid the use of hazardous construction materials that emit VOCs and make sure to keep a check on which material is being used and what chemicals it is composed of. Hazardous building material is usually categorized into the following:
- Asbestos (friable and non-friable)
- Polychlorinated Biphenyls (PCB)
- Synthetic Mineral Fibres (SMFs)
- Lead based paint
- Copper Chromium Arsenate (CCA) –treated timber
Photo by Aleksandar Pasaric: https://www.pexels.com/photo/photo-of-skyscrapers-surrounded-with-clouds-1437493/
