What is IEQ?
Indoor environmental quality (IEQ) refers to the environmental conditions inside regularly occupied space and it is determined by many factors, including indoor air quality (IAQ), indoor thermal quality (ITQ – also known as thermal comfort), indoor lighting quality (ILQ – also known as visual comfort) and indoor sound quality (ISQ – also known as acoustic comfort). IEQ has an impact on occupant´s health and comfort, which in turn affects the productivity of occupants.
What is IAQ?
Indoor quality (IAQ) is a constantly changing interaction of complex factors that affect the types, levels and importance of pollutants in indoor environments. These factors include: 1. sources of pollutants or odours (from outdoors and indoors), 2. moisture and humidity, 3. design, maintenance and operation of building´s ventilation systems, 4. other factors affecting comfort or perception of indoor air quality, 5. and occupant´s perceptions and susceptibilities.
EPA Guide states: “Controlling IAQ involves integrating three main strategies. One: Manage the sources of pollutants either by removing them from the building or isolating them from people through physical barriers, air pressure relationships, or by controlling the timing of their use. Two: Dilute pollutants and remove them from the building through ventilation. And three: Use filtration to clean the air of pollutants.”
Outdoor air pollutant sources are from the environment around a building (appearing in a natural way), combustion sources (automobiles, equipment) and odours. And indoor air pollutant sources are coming from finishes and furnishing (building materials), building equipment (HVAC, etc.), and from the building´s occupants.
What are the IAQ parameters?
In general, IAQ parameters are basically airborne particles/contaminants coming from various sources: biological (excessive concentrations of bacteria, viruses, fungi or moulds, dust mites, pollen), chemical (tobacco smoke, emissions from products used in a building such as office equipment, furniture/wall/floor coverings, carbon monoxide, nitrogen dioxide) and physical (occupant satisfaction).
1.basic IAQ parameters: carbon dioxide (CO2), particulate matter (PM2.5), carbon monoxide (CO) and volatile/total organic compounds (VOCs and TVOCs),
2.and complementary IAQ parameters: particulate matter (PM10), formaldehyde (CH2O), sulphur dioxide (SO2), nitrogen oxides (NO2), ozone (O3) and total microbial count.
How do we measure IAQ parameters?
The IAQ parameters can be measured in an occupied space and there are threshold values for indoor air quality parameters stated for example in ISHRAE IEQ Standard and the ISO 16000 Standards. (Note that there could be additional VOCs/TVOCs to be measured for detailed analysis, up to 20 parameters.)
The measurement duration shall depend on the parameter and type of space. IAQ measurements need to be planned and executed based on the ISO 16000 Standards, as appropriate. There are two possible ways when to measure.
A.The measurements of all basic IAQ parameters could be done two times in each season (and three times a day) and complementary IAQ parameters to be measured twice a year three times a day.
B.Continous monitoring of basic IAQ parameters (recorded once per hour for all year) and these results could be confirmed by measurements once a year. And complementary IAQ parameters measured twice a year three times a day.
Note that when IAQ measurements are carried out, the ventilation system shall operate in a ‘normal’ operation mode for at least the previous 48 hours and during the measurement.