Why Indoor Air Quality Matters
Indoor Air Quality (IAQ) refers to the air quality in a building or structure, breathed in every day by the building’s occupants.
When planning new residential buildings, schools, offices or light commercial buildings, many things must be considered. Besides structural factors, there are also the topics of heating, cooling and something often neglected: indoor air quality.
Did you know that the indoor air we breathe, whether at home, at the office, or in a hotel room could in fact be much more polluted than the air outside?
- 90% of our lives is spent indoors
- Indoor air quality can be 2 to 5x worse than outdoor air quality
Indoor Air Pollutants
With the right system (air conditioning, ventilation, air purification equipment) air pollutants such as
- pollen
- spores
- cement dust
- bacteria
- viruses or
- germs
can be filtered out of the air.
Indoor Air Quality Components
Ventilation: Ensures the provision of fresh and clean air
Energy recovery: Delivers energy savings by transferring heat and moisture between airflows
Air processing: Delivers the required conditioned air to optimize the energy efficiency of indoor HVAC equipment
Humidification: Ensures the desired moisture level in the conditioned space
Filtration: Ensures clean and healthy air by filtering out pollen, dust and odors that are harmful to our health
Particles
The particles in the air can vary from simple pollen grains to germs, bacteria and viruses
Particulate matter are categorized based on their size
The smaller the particle, the more dangerous for our health
Particles & Areas of Deposit
The lighter and smaller a particle is, the longer it stays in the air.
• PM10, all particles up to 10 µm (0.01 mm)
Deposit in the nose and pharynx of the human respiratory system
• PM2.5, all particles up to 2.5 µm (0.0025 mm)
Are small enough to reach the human lung
• PM1, all particles up to 1 µm (0.001 mm = 1 micron)
Are small enough to find their way through the cell membranes of the alveoli into the human bloodstream and cause life-threatening diseases
Due to their harmfulness (high risk for cardio vascular diseases), permanence and frequency, particles smaller than 2.5 μm (i.e. PM2.5 and PM1) need the most attention.
Ventilation
Venitlation systems ensure optimal climate conditions by providing a fresh, healthy and comfortable environment for buildings of all sizes and different applications.
Ventilation dilutes and eliminates pollutants in indoor air.
In a completely closed room in a building, air cannot easily enter/leave the room, causing air pollutants to remain and accumulate in the room. This could impact the health of people in the room. Ventilation is essential for diluting and removing these air pollutants.
Ventilation System Importance
- The goal of ventilation units is to bring fresh air into closed spaces and exchange it with stale air.
- Ventilation and the use of highly efficient particle filtration provided by HVAC systems can reduce the airborne concentration of bacteria and viruses and thus the risk of transmission through the air.
- Ventilation systems and adequate air-exchange rate have been demonstrated to be an effective solution to protect people from contaminants, including viruses.
- Ventilation systems need to be used and maintained correctly in order to be effective.
What to consider when choosing a ventilation system?
Filtration
After the intake of fresh outdoor air a filtration stage is needed, to clean the air. Also the return air filtration is important. Particles from the room moving towards the return air grills have to be filtered out to prevent contamination of the whole ventilation system.
Noise level
Having a ventilation system able to provide fresh air and air-exchange with the lowest possible noise emission is key to not bother occupants in the building.
Hygiene
Ventilation units need to be designed in a way to avoid any kind of contamination to prevent the proliferation of molds and bacteria.
Energy efficiency
When air is exchanged, thermal energy in the exhaust air needs to be recovered and transferred to the fresh air in the most efficient way.
Compactness
A compact ventilation unit makes installation easier and allows saving space. It is important to optimize the use of building space and be cost efficient.
Filtration
Virus particles can piggyback on larger dust particles or droplets and travel through a building. Infectious diseases can be controlled by interrupting the transmission routes used by a pathogen. Using high efficiency air filters in air conditioning and ventilation systems can help to capture the majority of airborne particles.
Mechanical Air Filters
Mechanical filter consist of media with porous structures of fibers or stretched membrane material to remove particles from airstreams.
Some filters have a static electrical charge applied to the media to increase particle removal.
The fraction of particles removed from air passing through a filter is called “filter efficiency”.
Filter Classification
With the introduction of the new ISO 16890 standard, filter classification is made based on the capability to filter out certain particles according to the particle size (i.e. particle size range ≤ 1 μm, ≤ 2.5 μm or ≤ 10 μm). ISO 16890 Classifications are based on where particles are deposited in the human lung.
Filter Groups (ISO 16890) | Required minimum filtration | Particulate Matter filtered out: | ||
ePM1, min | ePM2.5, min | ePM10 | ||
| ISO ePM1 | ≥ 50% | Nanoparticles, exhaust gases, viruses | ||
| ISO ePM2.5 | ≥ 50 % | Bacteria, fungal and mold spores, pollen, toner dust | ||
| ISO ePM10 | ≥ 50 % | Pollen, desert dust | ||
| ISO Coarse | < 50% | Sand, hair | ||
Filter Efficiency
Filter efficiency is the fraction of particles removed from air passing through a filter.
The effectiveness of reducing particle concentrations depends on several factors:
Filter efficiency
Size of the particles
Airflow rate through the filter
Location of the filter in the HVAC system or room air cleaner
High efficiency particulate air (HEPA) filters are at least 99.97% efficient at filtering 0.3 μm particles and in general more efficient than ePM1 filters.
Higher filter efficiency generally results in increased pressure drop through the filter. It is therefore important to ensure HVAC systems can handle filter upgrades without negative impacts to pressure differentials and/or air flow rates prior to changing filters.
Air disinfection through UV-C light
Did you know that ultraviolet energy inactivates viral, bacterial, and fungal organisms so they are unable to replicate and potentially cause disease?
The entire UV spectrum is capable of inactivating microorganisms, but UV-C energy (wavelengths of 200 – 280 nm) provides the most germicidal effect.
Disinfection and sanitization through UV-C light is widely used in hospitals.
UV-C light however is a health hazard to the human body.
By treating recirculated & fresh air with UV-C light directly within the Air Handling Units, clean and microbe free air can be achieved without exposing the human body to harmful UV light.