The solution to pollution is dilution

Solving buildings' exterior airflow measurement problem

Open Window In Office with Woman with Brown Hair Breathing Fresh AirBy: Jesse Shoemaker, KMC Controls Director of OEM Sales

When I first started in the building automation manufacture, I had a mentor that would ofttimes say, "The solution to pollution is dilution." Seventeen years, and many roles, afterward, it's a mantra that I've often repeated, but since COVID came into the moving picture, it'south been something that I've been thinking well-nigh much more than often.

In my industry we mostly deal with monitoring and controlling heating, ventilation, and air workout (HVAC). Have you ever wondered if the air you lot're breathing is clean, or if enough fresh air is coming into your space, or whether you take too much CO2 in your infinite? We engineer and manufacture the sensors that answer those questions and the controllers that make necessary adjustments when something is out of spec.

Fresh air has e'er been important.

Fresh air has always been of import, but information technology's rarely been taken seriously and incorporating the necessary tools to monitor and control our built spaces accept historically been among the first things to be discarded to cutting costs. For example, after the energy crisis in the mid-1970'south, national conservation measures were put into identify, which chosen for a reduction in ventilation to five cubic anxiety of air per minute (CFM) per person – a reduction of 66 percentage from previous standards. Unfortunately, many buildings are all the same fix at that level due to cost. However, the American Gild of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommends a "minimum ventilation rate of 15 CFM per person in residential buildings in social club to provide indoor air quality (IAQ) that is acceptable to homo occupants and that minimizes agin health effects."

Ventilation (divers as the rate of indoor air exchanges with fresh, conditioned outside air) has been recognized as the kickoff line of defence for good for you buildings. Further, smart infrastructure and loftier-performing buildings guidelines stipulate that the accurate measurement of outdoor airflow rates are a central component of building blueprint.

Why does this matter?

Why does this thing? The brusk answer is obviously COVID. However, COVID is non the only affliction that impacts health, nor is it the only danger that buildings and their occupants face up. For a population that spends most of its fourth dimension in buildings, brining fresh (outside) air inside is the most efficient and systematic manner to improve the quality of the air we exhale. According to the EPA, Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often two to 5 times higher than typical outdoor concentrations. Pollutants tin be combustion byproducts, allergens, biological agents (mold), pesticides, atomic number 82, asbestos, ozone, or other volatile organic compounds that derive from a multifariousness of sources. However, it is important to annotation that virtually pollutants affecting IAQ come from sources inside buildings.

Is that air you lot're breathing?

Is the building you lot're sitting in right now getting the proper amount of outside air? How would you know if information technology wasn't? What does a building with insufficient levels of airflow look like? Occupants might complain of frequent headaches, frequent fatigue, or they may feel more irritated than normal. These are all symptoms of sick building syndrome (BRI) or ill building syndrome (SBS).

In the The states, it is estimated that poor air quality results in $150 billion of illness-related costs per year, and $93 billion, or 62 pct of those costs, represent lost productivity from symptoms associated with SBS. It's important to note that those numbers are all pre-COVID. The cost of poor ventilation is skyrocketing and that will not slowdown someday before long.

In fact, considering fresh air has such significant wellness benefits, ASHRAE, CDC, EPA, WHO, and others have identified ventilation as a cornerstone in any IAQ monitoring and control strategy. That's considering it has been demonstrated that occupant productivity and cognitive part can meliorate eight to xi percent past improving IAQ.

Aren't nosotros already doing this?

Maybe. Drawing and conditioning outside air for heating, cooling and ventilation is mutual for whatsoever building and the need for proper ventilation of buildings is not new. Notwithstanding, over the last two years, nosotros have heard of many instances where outside air dampers were either disconnected or boarded over, which may not have come to light without the recent focus on IAQ. See, the COVID pandemic has shone a spotlight on the implications of poor IAQ.

And until al fresco (outside) schools, offices, and storefronts become a widespread movement, it's condom to expect that the amount of fourth dimension spent indoors is non likely to modify anytime shortly. So, outside airflow (ventilation) volition remain critical to providing a safety, productive, and free energy efficient indoor environment.

What's stopping us?

To reply that question, you first must empathize the root issue. To bring in the correct volume of outside air, you must first know how much air is going inside. As it turns out, it's hard to measure out exactly how much exterior air goes within a building's HVAC system.

There are numerous challenges to measuring ventilation rates (frequently chosen airflow measurement). What are some of those challenges? Y'all mean beside blocking a fresh-air intake? Outset, nigh buildings are not designed with outdoor airflow measurement in-listen, making it difficult to accurately make up one's mind the amount of air inbound a building.

Further, traditional technology is heavily affected by the weather. Wind gusts, low air velocities, temperature and humidity variations, airborne particulate matter (dust, clay, pollen, waste product), and dampers, bends, or restrictions (that touch airflow) – all mutual occurrences – will negatively touch on airflow measurement in traditional technology (more on that later).

Energy efficiency schemes, such as what nosotros saw in the 70'south, can likewise affect ventilation rates. Demand command ventilation (DCV) schemes seek to regulate airflow every bit a function of occupants in a given infinite, often using indoor CO2 levels as a proxy for head counts, which will obviously touch on ventilation rate.

So, what'southward stopping u.s.? Inaccurate airflow measurement.

Delivering accurate, repeatable measurements in any ecology condition is disquisitional to establishing a proper ventilation strategy, whether that includes DCV, minimum airflow or damper position, or optimizing conditions for occupant condolement.

A summary of traditional technologies.

There are numerous airflow measurement technologies available, merely few that can produce repeatable, accurate measurements for all types of equipment. Nearly all measurement devices accept extremely restrictive installation parameters, which can limit the equipment that traditional devices may exist practical to.

  • Differential pressure (which uses pitot tube) is an accepted standard for measuring airflow, only it is not recommended for ducted systems that accept bends or restrictions, or for measuring low velocities.
  • Thermal dispersion sensors have proven to be accurate in measuring low velocity airflow, but airstream pollutants like dirt, dust, feathers, cobwebs, or animal waste significantly touch on performance.
    • Thermal dispersion sensors are also afflicted past bends and restrictions in ductwork.
    • Additionally, thermal dispersion sensors crave regular maintenance and factory calibration for any repair.
  • Conditioned orifice plates are effective but may require significant modification to mechanical systems, resulting in the highest installed toll, and they are not guaranteed to be a fit for all equipment.
    • Additionally, when measuring low velocities, a conditioned orifice must artificially amplify the differential force per unit area across the orifice, which compromises resolution and accuracy.

What'south the solution?

The most contempo innovation for measuring outside airflow is a patented applied science, which uses a characterized damper method. This method is non impacted by the weather, low air velocities, temperature, ductwork bends, turbulent airflow, or any of the other traditional pitfalls in the airflow measurement space.

Given that measurements are based on measured damper functioning, this approach can also be applied to nearly any type of equipment or mechanical system – ducted or not! This new method uses a high precision inclinometer mounted on an exterior damper bract to establish a damper label bend, also as several probes to accurately mensurate outside air (OA), render air (RA), and supply air (SA) temperatures.

Nosotros created this technology to solve a problem, non price gouge.

The cost to install a characterized damper airflow measurement organization tin be dramatically less than traditional technologies.

More buildings, specially schools, demand to measure their exterior airflow, which means a for a solution to truly address to this problem, information technology must exist affordable and reliable. Today'south applied science, coupled with the characterized damper method of outside airflow measurement allows applied science like ours to provide real-fourth dimension performance metrics, which can be monitored with a building automation organisation or a local brandish for building occupants.

Ongoing maintenance costs are minimal since there are no probes in the unfiltered airstream to be cleaned or recalibrated, and the supply airflow measurements are taken in filtered air.

To ensure long-term accuracy, system diagnostics are regularly performed using automated air-measurement methods (ASHRAE standards 62.1, 111, and 189.1). If the arrangement is found to exist out of tolerance, the calibration routine can be reinitiated to establish an updated label curve to reverberate the current mechanical system.

Considering the advantages of utilizing a characterized damper airflow measurement organisation, information technology could make proper ventilation achievable for nearly whatsoever building.

And remember, the solution to pollution is dilution.