Buildings being made for people to live in, must take into account human comfort, while being designed. As a matter of fact, comfortable indoor environments increase occupants’ productivity, health and overall well-being.
Here is the third article of our serie on performance indicators : visual comfort, acoustic comfort, air quality and thermal comfort. Take a look at our previous article on acoustic comfort here.
Have you ever heard about the “sick building syndrome” ?
Sumedha M. Joshi, doctor in Preventive and Social Medicine in India, has described the sick building syndrome as “a situation in which the occupants of a building experience acute health or discomfort related effects that seem to be linked directly to the time spent in the building.” No specific illness or cause can be identified although the complainants are localized in a same room or zone. This feeling of illness increases sickness symptoms, absenteeism and reduces productivity indoor.
In 1970, oil embargo led building designers to make buildings more airtight, with less outdoor air ventilation, in order to improve energy efficiency. The ventilation was reduced to 5 cfm/person. This reduced ventilation rate was found to be inadequate to maintain the health and comfort of building occupants. In order to have an acceptable indoor air quality (IAQ) with a minimum energy consumption,
“The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) revised ventilation standards to a minimum outdoor air flow rate of 15 cfm/person to avoid the problems related to inadequate ventilation.”
In an office, although the standards are 20 cfm/person, many have been constructed with a poor design to increase the number of offices and saleable area that contributes to inadequate ventilation.
So how can green design and smart technology improve air quality ?
According to The Environmental Protection Agency (EPA), Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, that relates to the health and comfort of building occupants. The IAQ is deteriorated by the concentration of pollutants within the air.
Gases or particles released into the air are the primary cause of indoor air quality depreciation. We can consider different sources such as the fuel-burning combustion appliances, tobacco product, building materials and furnishings, household cleaning and maintenance products, excess moisture or outdoor air pollution. An efficient ventilation is essential to dilute these emissions within the air while an inadequate ventilation will increase indoor pollutant levels. Couple with high temperature and humidity levels, concentrations of pollutants in the air can only increase.
In order to have a sense of the IAQ, some signs may appear within the rooms or building. For instance, you may see moisture condensation on windows or walls, find smelly or stuffy air, dirty central heating and air cooling equipment or simply areas where books, shoes, or other items become moldy.
Green design strategies improve air quality
High humidity will cause fungus and molds which is hazardous for human health. HVAC helps reducing humidity levels by drying the air. However moisture related contaminants can arise from HVAC system itself. To prevent this from happening, HVAC filters need to be regularly maintained and cleaned and coils need to be designed and protected against bacteria from condensate water.
HVAC systems are not the only source that can decrease IAQ; materials and furnitures inside a space can also reject dangerous particles as Volatile Organic Chemicals (VOCs). According to the EPA, these chemicals can cause eye, nose and throat irritations, coughing, fatigue, skin rashes, and allergic reactions. It is important to identify the kind of furniture brought in the room. Chemicals can also come from insulation, newly installed flooring, carpet or furniture made of certain pressed wood products.
Therefore, it is essential when purchasing wood furniture to invest in solid wood furniture that is made with sustainable materials and with no toxic finishes. As Lynn Hoffman Design explain, when considering purchasing a new piece of furniture, check carefully to make sure it is actually solid wood, Forest Stewardship Council (FSC) certified from well-managed forests. The finish on solid wood furniture also must be taken into account by looking to low-VOCor waxed finishes. Other excellent options for healthy and sustainable wood furniture are second hand furnitures as the dangerous particles emitted decrease as furniture pieces age.
Smart technologies monitor air quality
By bringing new technologies into consideration, IAQ can be controlled and adapted to the need of the occupants.
Demand Controlled Ventilation (DCV) is a control method that modulates the volume exchange of fresh or outside air into an enclosed space by mechanical air conditioning equipment according to the choice, number or activity of the occupants. With sensors, you can control CO2 level in order to increase oxygen and thus, improving indoor air quality.
The Federation of European Heating, Ventilation and Air Conditioning Associations explain how it works with an office example. “A DCV system based on air-quality control adapts the airflow rate to the actual pollution load, which often is proportional to the occupancy. All the rooms in an office building are almost never occupied at the same time. Furthermore, it is most unlikely that the peak level of occupancy occurs simultaneously in all occupied rooms. For instance, quite a few studies show that in cellular offices usually less than about 50% of the office rooms are occupied at the same time. The bigger the variation between the minimum and peak loads, the more energy savings can be expected with a DCV system based on air-quality control.”
Connected objects such as Foobot, can easily monitor your indoor air quality. It takes just a few minutes to install and then, you can start receiving data with an app on your phone. As the web site Make Of Use explains, “the monitor tracks VOCs, particulate matter, relative humidity, and temperature. You can view an indoor air quality score that combines all of the metrics into a simple and comprehensive score. The app also provides real-time details for each data point. You can even tag a specific event to recall what is causing pollutants and receive tips on how to breathe better air.”
In our next article, we will focus on the last performance indicator, thermal comfort.