Busting Top Aircuity Myths

BUSTED: Calibrating sensors every six months will help with sensor accuracy but will not solve offset drift. Aircuity’s differential measurement approach uses one sensor to measure the reference and the room air to eliminate offset drift, which is the largest component of drift. Even with 6-month calibration, the offset drift can be very large after only a few weeks. Field calibration addresses the gain and linearity drift, which occur at a slower rate.

Furthermore, to address and deliver optimal sensor accuracy, Aircuity directly compensates for barometric pressure and is not susceptible to impact of humidity. Commercial CO2 sensors do not, and both of these effects can vary the output of the sensor by as much as 100 PPM. Finally, Aircuity filters the air going to the sensors to again limit the gain and linearity drifts.

So, calibrating discrete CO2 sensors every 6 months will not solve these accuracy and drift issues and, thus greatly have far less accuracy compared to Aircuity. For acceptable performance at minimum, there must be differential measurement, barometric compensation, no humidity influence, and filtering of the sensed air with a HEPA grade filter.

BUSTED: Aircuity does not have any control or over a fume hood’s operation.  In critical environments, Aircuity’s only interaction with fume hoods is monitoring the fume hood’s volumetric flowrate, sash position, and (if applicable) occupancy sensor data feedback points in order to populate Aircuity’s Fume Hood Performance Analytic. A customer may then choose to use the data provided in the Fume Hood Performance Analytic to make informed decisions regarding how fume hoods are used throughout their facility.

BUSTED: Aircuity provides all clients with an Assurance Services Commitment (ASC). This is NOT a maintenance cost and was actually born from clients requesting a solution to their overwhelming deferred maintenance issues. Because clients need their systems to work over their full usual lifetime, they requested to be “assured” there would be NO hidden costs and NO surprise costly fixes; this was of particular interest for their critical environments.

ASC is a guarantee and warranty for the entire system and also includes freshly NIST traceable calibrated sensors that are installed once a year or bi-annually depending on the application and system configuration. In addition, the ASC includes all data analytics via the web services and mobile applications. This solution alleviates implementing more systems that likely won’t get properly maintained and which will cause energy penalties or more critically impact safety.

The ASC pricing is provided to clients for full transparency. Aircuity will agree to pricing for as long as a client desires, without obvious value add or new product offering.

Lastly, Aircuity is a life cycle solution. ASC is far lower in total cost when compared to ‘do it yourself calibration and replacement approaches. ASHRAE and many self-sufficient clients who know and are responsible for smooth building operation understand the need for regular calibration. Without such an approach, system will not perform as intended and should not be relied upon for control or accurate data interpretation.

HYBRID: Aircuity is a sensing platform which provides a ‘smart signal’ for Demand Control Ventilation but it does not directly control. This is the responsibility of the Lab or Building control system. With Aircuity’s reliable and smart DCV control signal, the BMS or LCS can implement the correct sequence of operations. Aircuity’s analytics can also help clients validate performance and/or quickly assess when things aren’t working as intended. So, one might say, providing control is the ultimate responsibility of the lab control or BMS company.

It’s important to also note, that Aircuity and its partners take serious responsibility to assist in design and implementation of the proper sequences. Our platform makes DCV easier and more reliable for all control systems and by virtue of our smart signal (high selecting of all measured parameters) this greatly reduces costs and errors associated with field programming required from these other entities.

HYBRID: This is somewhat complicated.  First, Aircuity is NOT a replacement for safe lab practices and protocols. The platform helps save energy when the room air meets set thresholds and provides control signals to indicate when more air is needed for increased safety. To many, this is a data driven approach preferred over a ‘static’ or fixed control operation; which can be seen as always providing the wrong amount – either too much and wasting energy or not enough and jeopardizing safety and with no insight into lab operation. Lab DCV however, is NOT a candidate for every room in every project and it must be assessed for both mechanical ability to control over the desired ACH range and for the type of experiments and chemicals that are being utilized currently in that space. A good reference is UCI’s Smart Lab Program Decision Tree, which examined 1,300 labs and found DCV to be applicable to close to 90% while the rest may qualify for “monitoring only”, where clients have access to data through Aircuity on the space but Aircuity is not sending a DCV command signal.

Aircuity uses two types of TVOC sensors – an MOS and a PID (10.6 ev lamp which is industry standard), and also monitors particles, CO2, CO and dewpoint if desired. The system then provides a high select smart signal to the lab control or BMS company, so they can simply receive the command for more or less air. This approach to sensing accounts for a wide array of contaminants, but Aircuity always works closely with EH&S or animal care professionals to ensure certain rooms deemed extremely hazardous are not implementing DCV.

Best practice is to monitor spaces when not implementing DCV if system test areas exist and consultation with our partners should easily guide to optimal final engineered solution.

BUSTED: Many Aircuity clients have experienced that this couldn’t be farther from the truth. Aircuity strongly believes in a layered approach to safety and lab banding, in addition to other ongoing EH&S programs that are necessary to ensure safe lab practices. Aircuity seeks to provide EH&S and many other owner constituent groups with a data driven approach to safety, including an additional layer of safety by increasing air when needed. Aircuity has improved clients’ safety and even indirectly lowered workers’ comp claims. Along with savings, Aircuity aims to directly support EH&S clients with analytics and insights that they didn’t previously have access to, while providing a more proactive approach to implementing safety across their building portfolio.

BUSTED: First, it is critically important to note that ASHRAE currently guides clients to maintain one set Minimum in absence of monitoring. The reasoning is basically so that ‘occupancy’ isn’t the trigger for increasing ACH and thus exposing occupants to lower levels for prolonged periods until room reaches ‘occupied’ ACH. That said, we can’t don’t dictate to clients what ACH they can or can’t program their system to however there are studies such as Yale’s in 2008that found 8 ACH is far more effective than 6 for maintaining safe purge effectiveness.

However, for both new construction and retrofits, many energy analysis are done comparing going from 6/4 to 4/2 and this still delivers meaningful energy reduction; better than most other conservation measures when looking at total impact. Going to 4/2 with some additional control strategies will result in additional savings of 30-40%!  Also, what should also never be forgotten is that Aircuity delivers more air when needed (typically 12 – 16 ACH) and provides an information layer for increased insight to safety protocols.  These three benefits can then be fully analyzed for their total merit to an owner, and a full business decision can be made. When looking at total impact, including safety, operational, energy static approaches will never beat a dynamic application.

BUSTED: Aircuity has hard data that demonstrates this is not the case. Even though safety is a relative situation, a typical example shows:

During a 60-day study of a university client’s two lab buildings, it was found to have over 17,000 events where an increase to ACH was implemented. Events driving ACH happen often and typically randomly across many spaces in a building.

A 60- day analysis of each building identified the number of “events” (defined as high TVOC or Particle readings) in each building.

1. 1. Building A had 157 lab rooms and averaged 7.6 events per room/month: 14,318 events annually
   2. Building B had 70 lab rooms and averaged 3.6 events per room/month: 3,024 events annually

HYBRID: Aircuity is a life cycle cost solution with benefits well beyond just accurate sensing. However, depending on the vertical market and application, first cost can be higher or lower.

For no lab C02 only systems, Aircuity first costs will be the highest when compared to discrete sensors. The system is still life cycle cost better for applications involving more than 15 – 20 discrete sensors if accurate measurement and control is desired.

As the market moves to WELL/RESET requirements, Aircuity will be less first cost expensive, especially when including particulate measurement and if one was to actually try and include PID TVOC sensors. So, this would be much closer, or Aircuity may be first cost more competitive.

For lab systems, which look similar to above, it will be difficult to install and implement the required system for much less than Aircuity.

Note: Because of Aircuity’s unique platform architecture, we can measure up to 7 parameters per location and with the very efficient calibration program this is impossible to beat if done in the field in a similar fashion.

BUSTED: Aircuity has been in business for 20 years, has ~ 1,000 installations and is installed in over 100 million sq. ft. (across 17 different countries and 43 states). The sensing platform works and works well over time, as there are several clients that have dozens of installations working for over a decade. With the Assurance program these systems will work well for many more. Aircuity also runs system diagnostics, remotely monitors systems and provides transparent performance analytics.

This said, Aircuity often refers to a client’s first system as their phase I project, and this should be utilized to optimize the sequences, implementation and project management strategies and Aircuity will happily share best practices on all Phase I projects.

BUSTED: About half of Aircuity’s overall business is in labs (critical environments). The other half is in variable occupancy spaces and standard commercial DCV applications. Aircuity has reliably executed these projects for nearly two decades.

TOTALLY BUSTED: This is far from true and many studies have proven this – this is not an Aircuity finding. There are CO2 sensors that are marketed as “self-calibrating” but as discussed in the FAQs, these don’t work and are inaccurate, typically initially and definitely over time. Aircuity’s sensors drift as well – all sensors do.  However, as discussed Aircuity is NIST traceably recalibrating these on a scientific time requirement and/or full replacing at no additional costs (above ASC), so the client is actually getting the most accurate sensing for life of their building.

WELL????: Yes, there is one more thing to ‘maintain’ but hopefully by now you can see the Assurance Services Commitment addresses this and it is up to the client if they or Aircuity’s local partner does the sensor swaps. So, most maintenance personal are actually relieved to know they will not have another deferred maintenance item in their facility.

BUSTED: Metal Oxide sensors are a very high level and broad range of only a small portion of TVOC’s.  Aircuity implements both MOS and PID sensors for all lab DCV projects and for most WELL/RESET projects as it provides a far more accurate representation of TVOC’s.  Metal Oxide sensors typically have more drift and inaccuracies than calibrated PID’s and will miss a large percentage of TVOC’s when utilized in a lab DCV application.  This is a critical point for lab DCV applications.