With COVID-19 cases now on a rapid decline and public health restrictions loosening, there are new opportunities and expectations for in-person activities. For example, at my workplace, indoor mask-wearing will soon no longer be required. This change will be dramatic. After all, we have been required to wear protective face coverings and follow many other disease-prevention and control guidelines for two years. Being unmasked will be both liberating and unnerving. The ability to interact with others indoors without face coverings, plexiglass barriers, social distancing, and reduced occupancy requirements will be refreshing. However, the return to such "normal" behavior is a formidable prospect for those representing more vulnerable and susceptible populations.

For all of us, the pandemic has shaped our expectations about buildings’ roles in facilitating or discouraging disease transmission. The coronavirus’ aerosol-based propagation has brought increased scrutiny to building mechanical systems and windows. The development of building sensor networks, a growing trend before the pandemic, is now accelerating. Such networks enable the monitoring of various factors related to building resource use and, increasingly, occupant health. With the rapid introduction of pathogen-killing Far-UV-C lighting, sensors are even being used to monitor healthy levels of UV light in occupied spaces.

Courtesy Biology and the Built Environment Center at the University of Oregon

John Waszak is the co-founder of L&M Instruments, which develops wireless building sensors with a broad spectrum of capabilities. The company’s Apollo sensor, for example, is used to monitor the safe elimination of infectious diseases in spaces via UV-C light. In the following interview, Waszak discusses the development of building sensors and their utilization in a post-pandemic world.

Blaine Brownell: Before the pandemic, how was building sensor technology advancing?

John Waszak: Before the pandemic, the biggest movement we saw was sensor scale-out. Whether it was IoT or some sort of local mesh network, there was activity around significantly increasing the spatial resolution of sensory feedback. It felt like the activity was driven equally by occupant-centric building initiatives and energy efficiency efforts. Building management system folks were exploring IoT technology and getting familiar with cloud technologies like AWS and Azure. The sensor scale-out was enabled, in more than a small part, by the wearable movement. This movement produced the low-power network connectivity and inexpensive solid-state sensors that would advance prototyping and proof-of-concepts.

How has the pandemic affected the growth, capabilities, economics, or other aspects of building sensor technology?

Early in the pandemic, it became obvious that low-occupancy buildings are as expensive to run as fully occupied buildings. While many buildings had transitioned to lower-cost LED lighting and smart sensors to control lighting, the HVAC system, by and large, had to continue to operate at full-occupancy energy levels. With a complete return to the office uncertain for the foreseeable future, there is an opportunity for sensor technology to both enable that return and help buildings to manage through a range of occupancy levels. Given all that, I see two primary areas where the pandemic will significantly impact building sensor technology: pathogen risk mitigation and occupant-centric key performance indicators (KPIs).

Pathogen risk mitigation includes everything in the pre-pandemic sensor toolbox—such as sensors for VOC, CO2, particulate, air pressure, and relative humidity—but is vastly distributed throughout the building. It is not enough to know the airflow and exchanges through the primary HVAC return. One needs to understand the number of air exchanges through OR7, the Grand Canyon Conference Room, or Classroom 106. Of course, this scale-out ties nicely into the pre-pandemic efforts around networked sensors and analytics. Pathogen risk mitigation has also brought UV-C to the forefront of disinfection initiatives. UV-C has long been known to deactivate nasty pathogens, with a few strong companies in the UV-C disinfection business long before the pandemic. And now it is well known, and not surprising, that UV-C deactivates SARS-CoV-2. As a result, many companies are making a go of it in the UV-C disinfection business while regulatory bodies are trying to determine safety guidelines for new UV-C varieties such as Far UV-C. This safety concern, along with the need to measure UV-C “fluence” to ensure proper pathogen deactivation, has created a market for UV-C sensing devices in labs around the world, as well as an opportunity for sensor deployment anywhere UV-C is used in building environments.

Occupant-centric KPIs will move us away from tracking how much energy is required to run a building (i.e., kWh/m2-yr) to how much energy is needed to run a building on an occupancy basis (perhaps kWh/occupant-yr). This will create a need for sensors to not only detect occupancy but also optimize occupancy. HVAC, in particular, will need to move in the direction of motion-controlled lighting. Due to the longer time constants involved in heating and cooling, sensors and analytics will need to sense and predict occupancy such that smart HVAC environments can be set in motion ahead of likely occupancy. These interconnected HVAC environments will also need more sensors to manage spaces better. Passive heating and cooling techniques may also come into play, integrating additional sensors and intelligence to feed into the smart HVAC management logic. For instance, sunlight sensors and weather forecasts can feed into heating and cooling logic, reducing unnecessary setpoint overshoot and undershoot. There is also the synergistic occupant-centric effect that building design will want to create spaces that are more comfortable to encourage employees to frequent the office, which will, in turn, improve the per-occupancy KPIs.

The L&M Instruments Apollo sensors monitor UV-C power and energy levels. Can you talk about how these sensors will enable safe human inhabitation of interior spaces?

The Apollo sensors are the only low-cost devices on the market that can measure for low energy safety applications, such as UV-C “hazard” levels, and high energy disinfection levels. They leverage the same mixed-signal processing technology and miniaturization that has enabled wearable sensors to produce a low-cost sensor that works just as well as research-grade systems that sell for up to ten times the price. Apollo was also designed to measure low-pressure mercury, discharge (pulsed Xenon), excimer, and LED source technologies. This simplifies the deployment process for buildings that might employ multiple technologies over time.

There are two important factors when applying UV-C disinfection solutions: one is the need to apply enough energy or fluence to deactivate the pathogen. The other is not to apply too much energy in the presence of occupants to risk UV-C exposure to those occupants. The Apollo dose indicators and the Apollo technology applied to building automation systems enable the management of both ends of this energy spectrum.

How do Apollo sensors function for both UV and Far-UV-C capabilities? For example, how might sampling be utilized in occupied zones as well as empty room disinfection?

The Apollo series of sensors have detection capability throughout the UV-C spectrum, including Far-UV-C. Apollo models can detect the entire spectrum or be tuned for a particular region, including narrow-band options to pick out a specific spectral line, such as 254nm.

In empty-room disinfection applications, short disinfection cycles are achieved with high-energy sources such as low-pressure mercury or pulsed Xenon. In these scenarios, Apollo is used for initial configuration and ongoing validation. For initial setup, multiple Apollo units are placed around the volume of the room to ensure that the stationary or mobile UV-C sources deliver enough dose to the areas of interest in the room. The same devices can then be used periodically to validate that the system is operating properly over time.

Occupied-room disinfection includes upper room disinfection and, for lack of a better term, lower-room disinfection. Upper-room disinfection has been deployed for decades and includes disinfecting air in an area above the occupants, using baffling techniques to help ensure UV-C light does not cause a hazardous situation for the occupants. Lower-room disinfection is an emerging technique where UV-C energy levels below what would be considered dangerous to humans are incident at the occupant level in the room. In the case of Far UV-C, higher energy levels are being proposed to increase the effectiveness of the disinfection process. The proposed higher energy levels are based on empirical evidence indicating that the Far UV-C energy cannot penetrate the skin or cornea. That said, Far UV-C systems can also run below the currently documented hazard levels until regulatory bodies clear the way for higher energy levels. In all these occupied room cases, Apollo is used to measure both efficacy (disinfection energy) and safety (occupant exposure) levels of UV-C energy. The Apollo technology can also be integrated into a building management system, akin to a UV-C thermostat, for real-time monitoring and alerting.

In a post-pandemic world, how do you imagine the future of building sensors, including UV-sampling devices, will look?

Buildings will incorporate many more networked sensors, improving coverage and spatial resolution in efforts to improve comfort and productivity while reducing overall energy consumption. New solutions will require analytics, honed over time, to move from simply knowing the environmental variables at the higher spatial resolution to meeting the occupant-centric and energy reduction goals. Building management system providers will move to the cloud to manage the scale-out and effectively evolve the analytics. Despite exceptional availability from the major cloud providers, building management system architecture will need to anticipate occasional cloud outages and provide systems that can run in “legacy” mode until availability is restored. As building system control migrates to the cloud, network security will become its own pillar of the building management system solution. The big challenge will be to provide real ROI given all the added complexities and costs, both capital and operational.

The proliferation of UV-C technologies will include disinfection of recirculated air and individual room disinfection. A new emphasis on ventilation calls for added air quality measures, including particulate filtering and UV-C disinfection. UV-C sensors will be required to monitor both the UV-C sources doing the contamination and the adjacent service areas to ensure no UV-C is escaping the disinfection enclosure. The use of individual room disinfection for rooms that either cannot achieve robust ventilation or require surface disinfection (operating rooms, locker rooms) requires dose monitoring for initial configuration and ongoing operations.

The views and conclusions from this author are not necessarily those of ARCHITECT magazine or of The American Institute of Architects.