In recent years a war has been waged in China – one for clean air. With arguably the world’s highest levels of public awareness of environmental health as well as an explosion of construction, an emerging trend has been the use of continuous monitoring to track and validate indoor environmental quality. Much of the best practices can be applied to India, which is challenged with even more polluted outdoor and indoor environments, and whose populace is similarly waking up to the health risks.
Practitioner’s Perspective
This article is from the perspective of a consulting and engineering firm providing indoor air quality (IAQ) assessments, ventilation system design, and implementation of systems in both China and India.
Five years ago, a client of Sanghaibased firm PureLiving requested the ability to continuously monitor their air quality after an office-wide filtration system was installed. After a market search failed to yield suitable systems that could measure PM2.5 levels and report over the Internet, the firm had no choice but to create its own monitor. Less than a month after the monitors got installed, Shanghai experienced some of the highest levels of pollution ever recorded locally (over 1,800 per cent higher than the WHO 24-hour health standard). The monitoring system showed that despite the high outdoor levels, the filtration system achieved 93 per cent average reduction. Instead of having to respond to employee panic, the client won staff trust and scored a PR coup for employee care. Since then, PureLiving have sought to integrate monitoring into schools, offices, and buildings, and currently oversee more than 3,000 monitors streaming live data over a Cloud monitoring network.
Why Monitor?
A very fast growth in the adoption of monitors is being witnessed for a number of reasons.
Monitors are critical for developing recognition of an IAQ problem, which then drives improvement. Traditionally, costly and time-consuming manual audits were necessary to diagnose baseline conditions. However, today, continuous monitors make it possible to quickly, inexpensively, and meaningfully depict the health performance of a space.
Moore’s Law – sensors have come way down in price while increasing in performance.
There is growing recognition that monitoring is critical to validate performance. With the easy availability of inexpensive consumer grade monitors (as low as around US$ 40), it is easy and natural for employees and tenants to test out their homes and offices. This can either be a PR nightmare or, as a marketing, selling or recruiting point.
Monitoring data enables self-auditing and green building certification performance validation. Building owners want to keep their spaces performing at a high level over time. The addition of furnishings, increase of headcount density, maintenance, and outdoor air infiltration, are all factors that impact air quality after commissioning. Increasingly, there are operations teams reviewing air quality data over time and across properties to optimise. Companies also want ROI and Green Building certification systems like LEED, WELL, and RESET, are all granting points for monitoring. In fact, the LEED standard for Existing Buildings (EBOM) now grants up to 9 points for an IAQ pilot credit that largely relies on monitoring.
Monitoring enables automation. Traditionally, performance of air quality improvement systems degrade quickly after commissioning due to:
– Improper system operations
– speed, on/off, filter maintenance
– Failure to control infiltration of outdoor air, or;
– Negative pressurisation bringing in unfiltered outdoor makeup air.
Training helps, but overcoming ingrained habits, staff turnover, is a challenge. The answer is to take the operator out of the equation, using automation software powered with live readings to govern filtration and ventilation system operation “on-demand” only when needed.
Today, one of the most frequent questions asked is “How do I select a monitor?” After all, monitors today may cost between $35 to more than $5,000. Typically, a monitor should be selected with a few considerations:
1. Pick a monitor based on the sensors needed, the criticality of performance, and how challenging the environment is. The parameters presented in Table 1 are the most important in IAQ monitoring.
2. “Paper specs” are not a good indicator of performance. Often, sensor capabilities listed in technical or marketing data sheets are used to compare and select sensors. However, sensors are impacted by design (ie. sensor proximity on a PCB may lead to elevated temperature readings and premature failure.) Sensors often also vary widely in terms of longterm stability.
3. Realistic expectations of accuracy. Instead of looking for accuracy that is close to the reference source, evaluators should test by batches of at least 4 units and look for repeatability of readings and fit to the reference monitor’s response curve. This indicates manufacturing and sensor quality
4. RESET monitoring standards are key to identifying the difference between
good and poor sensors. Created in China in 2011 and adopted by companies across the world, RESET is a healthy building standard for IAQ built around continuous monitoring data. RESET also certifies monitoring hardware with a set of requirements that categorize monitor quality into three groups: A for calibration-grade, B for commercial-grade, and C for consumer-grade. RESET includes requirements that one would not normally consider such as a data buffer so that in case communications fails, data will still be stored.
5. Costs
Initial. Monitors meeting RESET standards typically cost about $100-300 for Grade C (Consumergrade) monitors, about $600-1,200 for Grade B (Commercial-grade) monitors, and upwards of $3,000 for Grade A (Calibration-grade).
Maintenance. Annual or semiannual calibration is critical for maintaining accuracy, particularly in polluted environments and is generally mandatory for recertification. Generally, annual calibration and maintenance costs are typically 10-20 per cent of initial cost.
Software. Most professional software is on a subscription basis and can be paired with different hardware. Annual costs may be free for limited basic versions or Table $100-300 per monitor per year depending on total number of monitors and the sophistication of the software.
Hosting and connectivity. If privacy is a concern, local hosts and networking may be required, but in most cases, monitors simply need to connect to the Internet.
Deployment Tips
Deployment location, choice of communications protocols, power supplies, should be carefully planned to ensure representative data – or data at all – is received for analysis.
1. Connectivity. WiFi, while ubiquitous, is least stable, due to the tendency for IT staff to change settings on the network.
GPRS or SIM-card may meet the requirements of security policies that disallow outside devices onto their network, but are similarly volatile if coverage is unstable or phone credits are not regularly recharged. LAN cable is generally preferred for stability.
2. How many monitors are needed?
Monitors read only the nearby air quality. Therefore, the appropriate number of monitors depends on how many representative environments are in a space. In a mixed use office environment, the general rule of thumb is about one per 500 sq.m. Building standards and certification programs such as RESET may have their own requirements. Also, sensitive populations may expect monitoring around them. Generally, focus on staff areas.
3. Location and placement
Height. Generally in the breathing zone – 1-2 m high above the floor is ideal.
• What to avoid. Monitors should not be located near windows or areas of outdoor air intrusion, near HVAC supply ducts, or any sources of unusual IAQ pollutants. If possible, a site survey taking handheld readings to check the representativeness of planned monitoring locations should be done ahead of time.
Tables vs wall mounted. If possible, wall mounted is preferable, as occupants are major sources of IAQ pollution and can particularly impact CO2 and VOC readings. Wall mounts do require some installation (see photos) but also are less likely to be disrupted, unplugged, or moved. For new construction, be aware that newly painted walls can impact TVOC readings.
Ducts. Generally, we are most interested in measuring the actual ambient air that occupants are breathing. However, if our purpose is to certify the building’s own ventilation system, we want to measure the air being supplied by the ducts. The use of a duct box that penetrates the duct as well as secures the monitor, can achieve this.
Documentation. It is very important to create – and maintain – the location of monitors on a floorplan or BIM (building information management) system plan. Monitors have a way of moving and accountability can be a problem over time, especially with staff turnover.
4. Validation. Monitors must be checked against reference machines, preferably before deployment and then once again on-site. Documentation should be kept in case of challenge. Outdoor air may be used as a field expedient check for CO2 and TVOC.
5. Signage. As previously mentioned, occupants may often impact monitoring, either by moving the monitors, unplugging them, breathing on them, doing construction work near them, or even stealing them. Secure them with a Kensington loop-lock or install directy on a wall if possible.
Cloudware and analysis
Sensor data is of little value, especially to non-experts. Today, software is built on the cloud to provide remote access, be interoperable, create easier interoperability, allow benchmarking and trend analysis, and enable automation. However, privacy issues may impact this decision. Although the focus is currently on air, software platforms are enabling us to increasingly include other environmental parameters, such as light and sound. For instance, real estate servce firm JLL is already monitoring indoor air quality and sound in its offices in Mumbai and Bangalore.
Conclusions and takeaways
Continuous air quality monitoring is a critical component of effective IAQ systems, from assessing the baseline condition to optimising settings to maintenance. Much of the lessons, technology, and software that is coming out of China are applicable to India at an even lower price.
