February 2014


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David BeargEMAIL INTERVIEWDavid W. Bearg and Ken Sinclair

David W. Bearg, P.E. Environmental Health & Building Science Life Energy Associates

With a combination of an educational background in Chemical Engineering (a B.S. from Northeastern University) and Environmental Health (an M.S. from the Harvard School of Public Health), and over thirty years of experience in understanding and resolving indoor air quality issues, Mr. Bearg has an in depth understanding of what it takes to achieve a healthy indoor environment.  His definitive book, Indoor Air Quality and HVAC Systems, was published in 1993.  His current efforts focus on Integrated Performance Assessments to determine whether the various components of a building and its HVAC systems are achieving, or not achieving, a healthy indoor environment.  Key components of these investigations involve assessments of ventilation and moisture management performance.


A building can be considered “Smart” or “Intelligent” if it can be self aware in the areas of ventilation and moisture management performance such that it both provides diagnostic information on performance in these areas and even implement changes.

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SinclairWhat areas of Automated Buildings are you involved with?

Bearg:  I am involved with what I call “Autonomics” where a building can be considered “Smart” or “intelligent” if it can be self aware in the areas of ventilation and moisture management performance such that it both provides diagnostic information on performance in these areas and even implement changes in HVAC operation.  This “intelligence” can then complete the feedback loop in making sure that the operational performance is actually achieved in these areas that are critical for the achievement of healthy indoor environments.

Sinclair What do you see as the biggest challenges for achieving this goal?

Bearg:  One challenge is the need to have accurate enough data in the areas of ventilation and moisture management performance so that the sophisticated software analytics can provide meaningful operational instructions for the automatic control of the HVAC system.  The quality of the action taken here can be no more accurate than the quality of the data being input into the software.  The term, “Garbage In, Garbage Out” (GIGO) comes to mind.  If accurate data in these areas becomes available, a better job of optimizing building performance can be achieved, not only for energy use, but for healthfulness as well. 

Another challenge is that too many people seem to think that designing a building to comply with ASHRAE 62.1 minimum ventilation rates is sufficient to achieve good IAQ.  The reality, however, is that the goal of this Standard is to have no more than 20% of those exposed dissatisfied.  Providing greater amounts of ventilation have been shown to reduce short term absentee rates due to more rapid dilution and removal of cold and flu viruses. 

Another challenge is that too many myths and misunderstandings exist about how to achieve good indoor air quality and so decisions that impact ventilation effectiveness, such as the geometry of the airflow through the occupied spaces, the amount of ventilation to be provided, and how this ventilation will be controlled fall short of achieving this goal.

SinclairCan you give an example of a typical control-based ventilation shortcoming?

Bearg:  Yes, the use of VAV boxes controlled by thermostats in conference rooms.  In this situation the occupied space becomes overcooled during unoccupied intervals when the VAV box is at its minimum and then after occupancy there is a time lag until the thermostat experiences the needed “rise in temperature” to increase the amount of supply air and ventilation.  The result here is the early part of the meeting is severely under-ventilated.  I’m finding this under-ventilation to be occurring almost everywhere I look for it, so there needs to be a better way of providing ventilation in variable occupancy locations.   

contemporary Sinclair:  What techniques have you seen working to achieve this goal?

Bearg:  One approach to provide accurate and reliable data on both ventilation and moisture management performance is the use of a shared-sensor monitoring systems.  In this approach, a network of sampling lines are installed and the monitoring system automatically and sequentially draws air from key locations and brings this sampled air to a central location where both carbon dioxide and absolute humidity are measured using laboratory grade equipment.

SinclairWhat developments do you see in the future evolution of Autonomics?

Bearg:  One possibility is that a major player decides to move into this area of accurate monitoring and creates the next generation of shared sensor monitoring systems bringing about a reduction in costs as well as increase in software analytics to be the brain behind a more intelligent building.  When this happens, risk and uncertainty in building operations can be reduced and building occupants will get the benefits from healthier and more productive indoor environments.


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