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  • Kennedy Campbell

What's an IEQ Sensor? IEQ 101

Sensors are taking over indoor spaces. Traditionally, we only install a few sensors in our living and working spaces: temperature (in your thermostat), carbon monoxide (hopefully!), smoke, and maybe humidity. Moving into the future, one of the most diverse and beneficial sensors for any space is an IEQ (Indoor environment quality) sensor. These sensors measure various parameters, and in this article we'll discuss eight of the most important ones. Ultimately, these sensors can give a near perfect snapshot of the current health of your building environment, and how that relates to tenant comfort and energy performance.


Indoor environment quality (IEQ) is a term that encompasses all of the parameters that impact the quality of a building’s environment, and how those factors can impact the tenants occupying that building.


Treat this post like an interactive learning guide. Use this table of contents to navigate and learn what an IEQ sensor can do:


All of these data points, can be tuned (with the help of a good building automation system) to positively impact the health, satisfaction, and productivity of the people occupying the space. On top of that, monitoring these elements and making necessary adjustments can save time and money, in energy costs and maintenance. Many of these factors also appear in green building standard requirements and other building codes, therefore by monitoring IEQ using sensors the necessary targets can be met to achieve standards such as those set in the Canadian Green Building Council's LEED rating system, or the US Green Building Council’s LEED rating system.


The importance of IEQ on our health is nicely put by the CDC in their IEQ guide:

Understanding the sources of indoor environmental contaminants and controlling them can often help prevent or resolve building-related worker symptoms. National Institute for Occupational Safety & Health

Now lets get into it!


VOC's


VOC's or Volatile Organic Compounds are gaseous chemicals or pollutants that are emitted from certain solids or liquids in the building's interior. VOC's can come from cleaning supplies, building materials off-gassing, various office supplies like ink and toner, and several other sources.

VOC's (especially those that emit odours, like cleaning supplies) can affect employee or tenant comfort and potentially trigger allergies, cause headaches, nausea, dizziness and even liver, kidney or CNS damage. Some VOCs are even classified as carcinogens that can lead to Cancer after long term exposure.

Details on specific health effects of each specific VOC can be found in the Agency for Toxic Substances and Disease Registry of Toxic Substances Portal.



Monitoring the total VOC's in your building environment can help serve as an early marker for maintenance teams. For example, by monitoring trends in VOC content of the indoor air you could discover a problem like a sewage leak much sooner than relying on tenant complaints. It can also help identify pollutant causing items you were unaware of previously, such as open cans of paint or vehicle emissions from an on-site garage. When pollutants can’t be removed from the site, the IEQ sensor will identify areas where you need to add ventilation and improve HVAC to keep the space clean and maintain tenant health.


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CO2 Levels & Air Quality


Why you would want to measure CO2 levels probably seems fairly obvious, we know that too much carbon dioxide can be harmful to human health. A study conducted by the National Institute of Environmental Health Sciences determined that complex cognitive skills can decrease significantly in office settings when compared to working in normal CO2 levels, as can be found outside of the building.

Impact of changes in CO2 levels on employees' cognitive abilities - Vaisala 2017


A lesser known benefit of tracking CO2 is that it can actually be used to estimate occupancy levels. We emit carbon dioxide when we exhale, so through simple calculation we can estimate how many people are in a given space with an IEQ sensor. Ultimately, measuring CO2 and occupancy ratios in a space allows for a building to implement DCV, or demand controlled ventilation, the most energy efficient form of ventilation control according to a study by the US Department of Energy (DOE).


An Air Quality Index (AQI) is a simple rating system that can be used to asses indoor air quality, by consolidating several factors like CO2 and VOC concentrations in the indoor air. Here is one good example of a rating system from an algorithm developed by Bosch Sensortec in Germany.

Other factors that affect indoor air quality are particulate matter such as PM2.5 and PM10.


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Ambient Temperature & Relative Humidity



It’s easy to understand how temperature and humidity, and whether they’re too high or too low, can impact our comfort level. Living in Canada we know how uncomfortably hot, humid days are in the summer and how painfully dry, cold temperatures can be in the winter. The human zone of comfort for ambient temperature is somewhere between 20 and 26 degrees C, and relative humidity should remain ideally between 40% and 50%. That being said, both ambient temperature and relative humidity can have impacts beyond just employee or tenant comfort.


A study conducted in 2019 concluded that as office temperature increased so did women’s productivity, with each degree of temperature increase the subjects’ correct answers went up by about 2%.


Monitoring the temperature and humidity throughout the building’s spaces can also help cut HVAC operating costs. Monitoring these data points in several different areas (not just one!) will ensure that all areas of the building are at the desired temperature. This means that building energy consumption can be reduced, by limiting the use of air conditioning or heating where it isn't needed (zone based controls). It also eliminates the need for tenants to bring in personal heating and cooling devices (such as space heaters) which require more electricity to power than the buildings own HVAC system.

Typical office energy costs - Vaisala 2017


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Atmospheric Air Pressure


Having lower or higher internal air pressure, versus the outdoor air pressure of your building can cause a number of problems that can be costly and potentially dangerous if not properly tuned. If you’ve ever experienced doors slamming or swinging open with no explanation or had trouble opening windows and doors there’s a chance that the incorrectly tuned air pressure is the cause.


Negative air pressure (when the pressure inside is lower than outside) causes outdoor air to be drawn into the building through the envelope, and positive air pressure creates the opposite effect. In both scenarios your heating and cooling systems have to work harder to either heat up or cool down the indoor air that’s coming in, or makeup for the air that is being lost. There is also risk of property damage or harm to tenants when doors swing open and slam on their own or are too heavy to push open, especially in the case of a fire or evacuation.


In commercial buildings it's extremely beneficial to control the building pressurization by calculating differential air pressure (indoor vs outdoor). During hotter months, differential pressure should be slightly positive so that cool, dehumidified indoor air can keep the building envelope dry. During colder months, differential pressure should be slightly negative so that a small amount of dry outdoor air leaking into the building discourages moisture from condensing in the building envelope.


Typically the solution can be found in the HVAC system controls. Air pressure issues can be caused by leaky ducts or improper air balancing. Being able to monitor and detect issues with the indoor air pressure, using an IEQ sensor, means getting to the root of the costly problem and getting things resolved faster.


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Light Intensity and Colour Temperature


We use a standard of measurement called the Kruithof curve to determine the ideal range of illuminance and light colour temperature. The curve is displayed with the colour temperature along the x-axis with the illuminance levels along the y-axis and the ideal crossover between the two components is highlighted as the most pleasing and comfortable for humans. Go too far either way in the curve, and lighting appears too red or blue and typically come across as unnatural and uncomfortable. Luckily, getting the perfect lighting in your space doesn’t require complicated math or graphs, if your IEQ sensor can report data to the building's lighting automation system.

Kruithof Curve - Wikipedia


Other than it needing to be bright enough to see inside your building, lighting has a major impact on people. In humans, our circadian rhythm - or what you might call your internal clock - regulates our sleeping and waking hours and there are external factors that throw that internal rhythm off. Light can have a major impact on sleep patterns and in turn, hormones. Exposure to blue light, especially late at night has the highest impact on the circadian rhythm and can also lead to melatonin suppression. Melatonin has protective properties and has shown to lessen damage to organs and tissue, such as in our retinas and our brains. In an office or workspace lighting can severely impact employee satisfaction and productivity, lighting that is too dim can cause eye strain and headaches and ultimately cause vision to deteriorate, especially when paired with the bright light of a computer screen. Harsh lighting however, can also cause eyestrain, headaches and has been linked with migraines. Finding a balance between artificial and natural light is a great way to counteract these ailments, utilizing an IEQ sensor to read light levels in your space can help you indicate when artificial lighting can be dimmed to allow the natural light from outside to brighten your space.


Similarly, cool and warm toned light can have differing effects on employees. While warm light (red and yellow tones) can provide a comforting feeling, it also makes people tired. Similarly, cool light tends to focus people and increase productivity but can be harsh and uninviting. By detecting light tones with an IEQ sensor you can maintain that sweet spot between too warm and too cool throughout the building. Alternatively, you can allocate different light tones and in various spaces, you might find warm and comforting light is ideal for the lobby or employee break rooms, while a more cool toned light inspires productivity and new ideas in a breakout or conference room.



Saving money by detecting light levels is fairly straightforward, when the light isn't needed dim it or shut it off completely! When paired with occupancy detecting technology, lights can be shut off when spaces aren't in use. And, when paired with light intensity sensing, lights can be automatically dimmed when there is sufficient natural light (this is called Daylight Harvesting). Practices like these won't just save money on the electricity bill, but also reduce the amount spent on long-term maintenance, because you're only using your lighting when it's needed.


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Connectivity and Automation


Our own in-house developed IEQ solution comes in a small, sleek, battery operated IEQ sensor and works with our cloud digital twin platform, SpacrApp. All of the eight key features discussed in this post can be detected using the SpacrSense IEQ device and monitored through the app's dashboard. SpacrApp takes the work out of trying to understand if your space is comfortable and safe, it will immediately notify you if any of the levels are outside of the ideal range.

SpacrApp IEQ dashboard



SpacrApp can also be used to automate HVAC or lighting systems based on the SpacrSense readings. For example, lights can be set to dim when there is enough natural light in the space.

SpacrApp IEQ sensor notification indicating humidity is below the comfortable range



The SpacrApp also works from any device with an internet connection meaning you can check on a notification from the IEQ sensor at any time, and from anywhere to determine if the situation requires immediate attention. This also gives you the power to control any device remotely; lighting and HVAC systems can be turned securely controlled from anywhere with an internet connection.


Get in touch with us today if you want to learn more about how our IEQ sensors and Digital Twin software can keep your building safe and comfortable while reducing your emissions and maintenance costs!


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