Brent Stephens, Ph.D. – The Intersection of Building Science, Energy efficiency & IAQ

Air Date: 3-13-2015 | Episode: 360


This week on IAQ Radio we welcome Dr. Brent Stephens to discuss how building science is used to ensure energy efficiency and IAQ can co-exist…

Full Description: 

This week on IAQ Radio we welcome Dr. Brent Stephens to discuss how building science is used to ensure energy efficiency and IAQ can co-exist. Dr. Stephens is an assistant professor in the Department of Civil, Architectural and Environmental Engineering at Illinois Institute of Technology (IIT) where he teaches courses in

Dr. Brent Stephens

Dr. Brent Stephens

Building Science, Building Enclosure Design, and Indoor Air Pollution. He has a Ph.D. in Civil Engineering and an M.S.E. in Environmental and Water Resources Engineering, both from the University of Texas at Austin. Dr. Stephens and members of his Built Environment Research Group (BERG) at IIT conduct research on energy and air quality in the built environment, primarily with field measurements in and around buildings. Their work continues to advance methods for assessing energy efficiency, indoor air quality, and environmental exposures within buildings. They are on the leading edge of the segment of academia intent on ensuring energy efficiency and good indoor environmental quality can co-exist. LEARN MORE about the Built Environment Research Group (BERG) here http://built-envi.com/ and on IAQ Radio today!Illinois Institute of TEch

Z-Man’s Blog:

The more we can measure, the more we can learn.

As a high school student Brent Stephens was interested in computers. His interest in energy efficiency was piqued by a friend’s father who was in the business of performing energy retrofits and revenue sharing in the savings. In college he enrolled in electrical engineering and had difficulty relating to and understanding it. He liked environmental engineering related to air and water and gained an interest in green buildings and energy efficiency. He then worked with Southface Energy Institute in GA. Southface was good at working with builders and home owners, (earthcraft.org) but a lot of their technical information came from DOE, EPA, ASHRAE, Oakridge Lab, etc. Brent sought to work in a research based group. Studied under Jeff Siegel and earned a PhD at University of Texas. Dr. Stephens is an assistant Professor at Illinois Institute of Technology where he teaches courses in Building Science, Building Enclosure Design and Indoor Air Pollution.

Gold NuggetsNuggets mined from today’s episode:

  • IAQ and energy efficiency are intricately linked.
  • Built Environment Research Group (BERG) http://built-envi.com investigates problems and solutions related to energy and air quality within built environments. Projects range from measuring human exposures to indoor pollutants to dynamic energy modeling. Operating within the architectural engineering department the group blends disciplines and uses engineering principles to address problems and solutions. Practicality drives BERG’s research, using the lab to study data gathered from “real environments”. A current “real research” project studies the effects of energy efficiency retrofits in a wide range of Chicago housing stock combining: energy consequences, building envelope leakage, filtration efficiency reduction, filter related pressure drops, etc. Brent’s team also studies vacant buildings on the Illinois Institute of Technology (IIT) campus: combining energy consequences, building envelope leakage, filtration efficiency, filter related pressure drops, etc. Brent’s team also studies unoccupied buildings on the Illinois Institute of Technology (IIT) campus.
  • On filtration. The vast majority of airborne particles are smaller than 0.2 microns (200 nanometers). Knowing MERV # doesn’t necessarily predict performance outside of the MERV range. Filter efficiency is size-resolved, but it’s hard to translate aerosol science into filtration standards. Filters that perform well in the MERV range of 0.3-10 microns often perform poorly against smaller particles capturing only 10%-20% of smaller particles. Most filtration test labs don’t measure below 0.3 micron particles.
  • Building envelope as particulate barrier. The building envelope functions as a filter for airborne particulate. Tighter buildings are more resistant to particulate penetration than older leaky ones. Comparing indoor particle levels to outdoor levels doesn’t define how much is removed by: building envelope, filtration, or deposition. Total indoor exposure, how particles enter structures, how particles are controlled, how to measure them are among issues of research interest. When there are no particle sources indoors, sample readings will be lower indoors. During studies particulate can be artificially manipulated to do necessary math and understand how much is removed at the envelope, how much at the filter, and how much through deposition indoors. Tracer gas is one of the building science research tools. The HVAC system design and type & location of filter effects migration of outdoor pollutants indoors. When possible testing is done pre and post energy efficiency retrofitting.
  • Building envelope as a barrier to gases. The building envelope doesn’t stop carbon dioxide. Some building envelopes are known to reduce ozone 40%-45%, presumably by ozone depleting chemical reactions.
  • The Alfred P. Sloan foundation has funded a $35 million study of the built environment.
  • Indoor microbiome. The Alfred P. Sloan foundation has provided about $35 million in funding to study microbes in the built environment over the last 10 years.
  • Our bodies and our buildings are colonized by a wide range of microorganisms – our microbiome. Nature dominates which microorganisms predominate outdoors, human microorganisms dominate indoors. Petri dish sampling underestimates by >99%. Microbiome studies need to be focused beyond general characterization.
  • Advice to practitioners: control systems are improving, consider both indoor and outdoor pollutants, balance between ventilation and filtration, and think about CO2.
  • Bringing down the costs of measurement.com, theOpen Source Building Science Sensors (OSBSS) project demonstrates how to build inexpensive building environmental and operational sensors for long-term studies of the indoor environment using open source hardware and software. The more we can measure the more we can learn.

Today’s Music: This is Illinois Tech, IIT Today YouTube

 Z-Man signing off

Trivia:

Name the IIT graduate who while working at Motorola in the 1970s conceived the mobile phone and led the team that developed it and brought it to market.

Answer: Martin Cooper

Martin Cooper, Inventor of the Cellular Telephone

Martin Cooper, Inventor of the Cellular Telephone

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