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A carbon dioxide sensor is a fundamental element in any indoor air quality system for its ability to store, analyze, and act upon captured data with guidance from a building management system.

Indoor air quality remains a top priority for building owners

March 17, 2022
A longtime benchmark for occupant well-being, IAQ has entered the mainstream lexicon due to the COVID-19 pandemic.

Indoor air quality (IAQ) has been a longstanding benchmark for building owners to provide a safe and healthy space for occupants. For years, ASHRAE has published recommendations for ventilation and IAQ in residential buildings. According to ASHRAE Standard 62.2 “Ventilation and Acceptable Indoor Air Quality in Residential Buildings,” houses should receive 0.35 air changes per hour, but not less than 15 cubic feet of air per minute, per person.

For commercial office space and other large buildings, ASHRAE collaborated with the American Institute of Architects, the U.S. Green Building Council, the Building Owners and Managers Association International, the Sheet Metal and Air Conditioning Contractors’ National Association, and the U.S. Environmental Protection Agency to develop Indoor Air Quality Guide: Best Practices for Design, Construction and Commissioning.

Inside the 2010 700-plus page book, the section Apply More Advanced Ventilation Approaches recommends to “use demand-controlled ventilation where appropriate.” It goes on to explain that demand-controlled ventilation (DCV) is “a control strategy that varies the amount of ventilation by resetting the outdoor air intake flow setpoints to an occupied space based on the changing number of occupants. The goal is to avoid underventilation as well as overventilation … . The simplest approach to DCV is control of the outdoor air rate in an on–off manner based on signals from a room occupancy sensor, time clock, or light switch. A more sophisticated approach uses a signal that is proportional to the number of persons in a space to automatically modulate the amount of outdoor air.”

ASHRAE acknowledges that the energy-conservation benefits of DCV may be modest in typical office buildings, meaning its cost-effectiveness is tenuous. But the document then immediately notes that certain aspects of DCV controls “may be beneficial to such a building in ensuring that the design ventilation rates are supplied under all operating conditions. For example, continuous measurement of outdoor airflow rates and indoor CO2 levels can help building personnel find ventilation system faults or make adjustments to the HVAC system setpoints, thus avoiding overventilation or underventilation relative to the design or code requirements.”

A rising priority

The airborne nature of the COVID-19 virus made IAQ a top priority for building owners and facilities managers worldwide. In the United States, many corporations are still formulating return-to-office plans while employees continue to work from home. But this past fall, schools have largely opened to students returning to campus—and some never stopped in-class instruction throughout the pandemic. The improvements to HVAC systems and to monitoring IAQ in schools can serve as a model for commercial building owners who have not yet modified their ventilation systems.

When Congress passed the Coronavirus Aid Relief and Economic Security (CARES) Act in March 2020, $13.2 billion of the budgeted $30.75 billion was allotted to the Elementary and Secondary School Emergency Relief (ESSER) Fund. The Coronavirus Response and Relief Supplemental Appropriations Act 2021, signed into law later that year, provided an additional $54.3 billion for the ESSER II Fund. And the American Rescue Plan (ARP) Act, signed in March 2021, included $122 billion for the ARP ESSER Fund.        

“ESSER funding can be put toward permanent facility upgrades that improve indoor air quality,” Schneider Electric notes in documentation available on its website. “These upgrades include: filtration, ventilation, air purification, and other systems that improve indoor air quality; inspections, testing, maintenance, repair, and replacement of aging building controls and HVAC systems; technologies related to temperature scanning, occupancy counting, access control, and security systems; outdoor learning infrastructure; energy performance contracting and modernization services that increase financial flexibility for upgrades; and any other improvements that enable operations of schools to reduce risk of virus transmission and exposure to environmental health hazards, and to support student health needs.”

The CARES Act also created a tax incentive for commercial properties to make upgrades to their facilities. Schneider Electric states the incentive offers a full deduction of certain project costs in a single year, as opposed to having to spread the deduction over decades. Improvements that qualify for this incentive include upgrades to building management systems, sensors, valves, actuators, uninterruptible power supplies, switchgear, and other electrical distribution equipment. The incentive does not apply to new construction, expansions, remodels, the building envelope, or residential structures.

Sense of urgency

“Perhaps for the first time ever, indoor air quality sensing is on the front pages of national newspapers,“ says Justin Lavoie, who leads Schneider Electric’s digital building channel development team. “Schools, offices, and buildings are racing to implement healthy building strategies with IAQ sensors.

“The first step toward improving IAQ is to measure it. Fortunately, there are all kinds of sensors. Three foundational [types] are carbon dioxide sensors, temperature sensors, and humidity sensors. [But] you can only go so far with simply installing more IAQ sensors. Where you can amplify impact is by integrating IAQ sensors with intelligent building management systems. Intelligent BMSs don’t just use IAQ sensor data; they use data from occupancy sensors, room controllers, and even meeting-room booking platforms. Equipped with this data, you can direct attention where people are congregating. If one meeting room is occupied all day, your BMS can detect that and increase air exchanges there, but not in the meeting room down the hall that’s sitting empty.”

Jon Schoenfeld, director of energy and analytics for Buildings IOT, a Concord, Calif.–based master systems integrator, software designer, and building asset manager, offers several suggestions for facility managers to improve IAQ and thermal comfort in their buildings:

  • Install IAQ sensors to gain visibility into contaminants that may be present, and bring that data into a central analytics platform to provide actionable insights or facilitate demand-based controls.
  • Measure and analyze IAQ and ventilation to detect high concentrations of specific contaminants like CO2, total volatile organic compounds (TVOC), relative humidity, smoke, and other toxins. Use the best data available in the commissioning of building systems to calculate and regulate temperatures, HVAC controls, and ventilation according to industry standards and organizational thermal/IAQ goals.
  • Adhere to WELL Building and ASHRAE standards by integrating expert support to regulate indoor air quality concerns and manage key IAQ offenders. Work with a provider that will calculate metrics and make changes to efficiently meet industry standards. Prevent health issues caused by exposure to pollutants with intelligent dashboard monitoring, reporting, and controls.
  • Measure and set preferred thermal quality and building health key performance indicators. Work with a partner that can ensure proper digital cleaning practices are in place and track sterilization processes.

Schoenfeld also advises building owners and managers to install IAQ sensors. “CO2, TVOC, particulates and other contaminants all have different sources and different impacts on our health,” he says. “Continuously monitoring for these contaminants is the only way to know if you have a problem and how you might fix it. You can’t fix things you can’t see, and you can’t monitor everything in real time. Ensure full visibility into all your equipment and spaces by integrating all your systems into a common platform. A smart monitoring system should include comprehensive, connected sensors for everything from equipment operation to temperature and IAQ that report to a central repository and present data visually and with mobile compatibility.”

Finally, he recommends building owners to “implement automated and demand-based controls for IAQ, thermal comfort, and digital cleaning processes, and improve overall operational efficiency, via an enterprise-level intelligent building analytics, monitoring, and controls strategy.”        

Innovation at the hardware level

The increased importance of IAQ has driven the development of new products and technologies not just in the software realm, but in hardware as well. One recent example is Senseware’s Air Duct IAQ system, which is designed to monitor the air moving through HVAC ductwork. The system “allows for the highest accuracy measurements of your CO2, VOC, and particulate levels,” the company explained when introducing the Air Duct Mounting System late last year. “Air is captured from the entire space as it is pulled through the return ducts. It is also possible to monitor the filtered air provided to the spaces through the supply ducts.”

The company custom-designs the system’s mounts to fit the width of a property owner’s air duct, which it says ensures maximum monitoring potential. “As we have come to see via research and testing, data from a standard IAQ device can be limited by the location it is installed in,” the company added. “Naturally occurring air currents in the space define what a sensor can detect. As air moves in dynamic patterns that are dictated by the layout of the space and the location of the HVAC vents, there are oftentimes imbalances in the overall distribution of air from ventilation systems. Some areas may have fast-moving and frequently changed air, while other areas may have stale, stagnant air. Certain pockets of air may therefore have higher levels of irritants, while others will measure as clean air.”

These less-than-perfect conditions led the company to develop the Air Duct IAQ system, which can be mounted in a return duct that contains air gathered from an entire space. In this scenario, the system measures overall levels of pollutants and irritants rather than just taking data from pockets of air. Alternatively, it can be mounted on a supply duct, which enables the building owner to analyze the quality of the air being delivered in the space before it encounters any pollution sources.

In its document “15 ways to reduce energy bills while optimizing for indoor air quality,” Schneider Electric notes that individual measures are helpful, but having a state-of-the-art means of monitoring and analyzing the data is essential. “Today’s advanced BMSs give you much more visibility and control over your building’s conditions than legacy systems,” explains the company (which offers BMS solutions on the commercial market). “Not only are these modern BMSs likely to have more rigorous cybersecurity protection, they also enable sophisticated capabilities when it comes to IAQ monitoring and energy efficiency.”

Whether the facility is a commercial office building preparing for employees to return, a school full of students and staff, or a cultural institution or hotel appealing to potential visitors, IAQ will likely remain a high priority for everyone.

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