Forrest wins Friend of Facilities Award

Forrest was the first Princeton faculty to be awarded the Friend of Facilities award for his efforts helping make the campus more efficient and sustainable.


Forrest giving WeLL seminar at Berkeley CBE – Rethinking Radiant

Rethinking Radiant with CHAOS: Reflecting thoughts for Transparent research Emitting new ideas

Talk Abstract (12:15-1:30 2/6):  As the director of CHAOS (Cooling and Heating for Architecturally Optimized Systems) Lab at Princeton who is starting a short sabbatical until April at CBE I will try to give an overview of research and then drill into topics of common interest and debate.  I will present a brief overview of the work we have been doing the past 5 year (including some discoveries of Harrison Fraker’s past) and then zoom in on our current work on radiant systems. CHAOS originated as fun acronym, but also refers a consideration of system entropy to generate novel thermal systems and architectures. Through that thrust we are researching three primary areas: 1. Deeper geothermal 2. Liquid desiccants, and 3. Radiant systems and sensors. I will attempt to magically weave the relationships of those topics together and then focus on radiant systems.

Workshop (2pm-4pm 2/6): Between 3 and 5 CHAOS researchers will be in town next week returning from Singapore and visiting from Princeton with SMART sensor in tow. After the talk we plan to have an informal workshop. We will plan to start around 2pm for those that might be busy for the talk but interested in the workshop. Meet in the large conference room. The workshop will include a detailed overview of MRT calculations and measurement systems, and also the thermal comfort history and models we have reviewed. We will also discuss IoT hardware we have used for sensor backbone and prototyping infrastructure we have leveraged. Data management practices the database and REST-API systems we have setup on various platforms will be reviewed

CHAOS Participants include:
Eric Teitelbaum: Princeton PhD candidate (defending winter 2019), leader and constructor of Cold Tube in Singapore, SMART co-inventor and CSO of Hearth Labs spinoff
Nicholas Houchois: Researcher, co-inventor and leader of SMART development, CEO of Hearth Labs spinoff
Dr. Kianwee Chen: ETH Phd previously with MIT SMART, now Andlinger Center postdoctoral fellow with CHAOS lab.
Hongshan Guo (remote): Princeton PhD candidate (defending spring 2019), human body exergy modeling and research, coaxial geothermal borehole modeling, and urban radiant heat exchange and sensing.
Mauricio Lloyola Vergara (remote): Princeton PhD candidate (defending spring 2020), Post occupancy evaluation of IEQ and architectural spatial quality compared to proposed use and informed by IoT sensing techniques
Dorit Aviv (Remote): Asst Prof. U-Penn, Princeton PhD candidate (defending spring 2020): Surface geometry and form relating to radiant and evaporative surface heat and mass transport for experimental pavilions and architectures.

Summary with links to papers and references
The CHAOS lab has been working on a series of project exploring radiant heat transfer leveraging unconventional methods of reflection, transparency and emissivity of materials. These include architectural pavilions like the Thermoheliodome (EnB paper) and review of measurement methods like the black globe (EnB paper). This also includes the development of a 3D radiant heat exchange “SMART” Sensor (Princeton news). In parallel to the SMART sensor development we have built up significant expertise in IoT sensor design and construction. We have used those expertise to build deployable air quality sensors motivated by our bias toward radiant systems that air should be for breathing, not heating and cooling. Last year we published a paper on the potential of these inexpensive distributed sensors to spatially define the sources of pollutants throughout all aspects of a building’s ventilation systems and spaces.

Most recently on January 18th we launched the ColdTube in Singapore, an outdoor radiant cooling pavilion in Singapore as reported by Today. It is a collaboration between Berkeley (Jovan Pantelic), ETH (Arno Schlueter), UBC (Adam Rysanek), and Princeton (CHAOS lab). I will present the most recent findings including new questions they present regarding the ability to mitigate condensation with transparent membranes and also decouple convection from radiant exchanges. Our ASR paper just came out last week in the journal where the original concept was published in 1963. In this context there are also new questions about the validity of black globe measurements, which initial results show are incapable of measuring MRT more than 2.5K below the ambient temperature. This relates to many assumptions that have been made about radiant heat transfer and thermal comfort, and to what I believe is a commonly held false assumption that MRT cannot be significantly shifted from air temperature. In addition, as shown in our Singapore prototype, we can create environments with nearly zero convective heat exchange with the body while maintaining >100W/m2 of heat dissipation. We are interested in expanding building environmental analysis beyond empirical comfort boxes on psychrometric charts to realtime management of Watts of heat exchange with occupants by all means of conditioning. As the SMART sensor has the capability of also sensing occupancy and skin temperature of occupants, one of the future goals is to try to understand if and how indirect feedback on metabolic rate and thermal state might be generated and used to directly manage the Watts exchanged with occupants for a truly human-centric control. Ideally these last provocations will provide for plenty of discussion and lead into the workshop in the afternoon for those who are interested with the SMART sensor and my researchers who are visiting.


New article on non-condensing radiant panel experiments in Architectural Science Review

Revisiting radiant cooling: condensation-free heat rejection using infrared-transparent enclosures of chilled panels

Eric Teitelbaum, Adam Rysanek, Jovan Pantelic, Dorit Aviv, Simon Obelz, Alexander Buff, Yongqiang Luo, Denon Sheppard & Forrest Meggers
Accepted 09 Dec 2018,  Published online: 31 Jan 2019

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In this study, we enhance the understanding and design of a radiant cooling technology for outdoor comfort in tropical climates, originally proposed by R.N. Morse in 1963, in this journal. We investigate a type of radiant cooling methodology whereby the cold temperature source is physically separated from the outdoor environment by an insulated enclosure using a membrane transparent to infrared radiation. The enclosure isolates the radiant cooling surface from ambient conditions, allowing the radiant surface to be cooled significantly below ambient dew point temperatures without incurring condensation. For this new study, a Fourier Transform Infrared (FTIR) Spectroscopy analysis on three candidate membrane materials is undertaken and a prototype experimental test panel is fabricated. Our study shows that for a 5°C chilled panel temperature, the exterior membrane surface temperature reaches 26°C in a 32°C / 70% RH environment resulting in an effective mean radiant temperature of 15.8°C. These results provide new evidence in support of Morse’s original proposal, that such panels could provide significant radiant cooling without condensation in humid environments. Radiant cooling products based on the studied technology may offer an ability to provide thermally comfortable conditions in hot environments without the energy required for dehumidification.

Do black globes work? New replication paper published in Energy and Buildings!

Our paper led by Hongshan Guo with co-authoers Eric Teitelbaum, Nicholas Houchois, Michael Bozlar, and Forrest Meggers is out this month:

We present a critical look at the advent of the black globe thermometer in the 1930’s by Bedford and Warner in the context of biophysiological research at the time by them and others. In addition we present new results analyzing the validity of the technique that remains common practice today. We show that it is limited spatially, temporally and materially in ways not appreciated fully by many researchers.

CHAOS presents papers at International Building Physics Conference in Syracuse

Hongshan Guo, Eric Teitelbaum, Yongqiang Luo, Theo Keeley-Leclaire, and Michael Bozlar all presented papers at the conference.

Papers can be found here by author:

Here are the PDFs

Condensation free radiant cooling panel

Click to access FinalPaperFileUpload_463_0722085741.pdf

Coaxial Geothermal Borehole

Click to access FinalPaperFileUpload_281_0630092607.pdf

Dew point evaporative cooling

Click to access FinalPaperFileUpload_276_0701104855.pdf

Liquid Desiccant system

Click to access FinalPaperFileUpload_454_0704020220.pdf

Vizualizing exergy flows

Click to access FinalPaperFileUpload_198_0630092639.pdf

Evolution of air quality paper published!

In the open source journal Frontiers in Built Environment


Sensing of Indoor Air Quality—Characterization of Spatial and Temporal Pollutant Evolution Through Distributed Sensing

  • 1School of Architecture, University of Waterloo, Waterloo, ON, Canada
  • 2CHAOS Lab, School of Architecture & Andlinger Center for Energy and Environment, Princeton University, Princeton, NJ, United States

Discouraged by the high-cost and lack of connectivity of indoor air quality (iAQ) measurement equipment, we built a platform that would allow us to investigate what kinds of iAQ evolution information could be collected by a low-cost, distributed sensor network. Our platform measures a variety of iAQ metrics (CO2, HCHO, volatile organic compounds, NO2, O3, temperature, and relative humidity), can be flexibly powered by batteries or standard 5 W power supplies, and is connected to an infrastructure that supports an arbitrary number of nodes that push data to the cloud and record it in real-time. Some of the sensors used in our nodes generate data in standard units (like ppm or °C), and others provide an analog signal that cannot be directly converted into standard units. To increase the relative precision of measurements taken by different nodes, we placed all 6 pairs of the nodes used in our deployments in the same environment, recorded how they reacted to changing iAQ, and developed calibration functions to synchronize their signals. We deployed the comparatively cross-calibrated nodes to two different buildings on Princeton University’s campus; a fabrication shop and an office building. In both buildings, we placed nodes at key positions in the ventilation supply chain, providing us with the ability to monitor where indoor air pollutants were being introduced, and when they tended to be introduced—enabling us to monitor the evolution of pollutants temporally and spatially. We find that the occupied space of the first building’s fabrication shop and the second building’s open-plan office have higher levels of volatile organic compounds (VOCs) than outside air. This indicates that both buildings’ ventilation systems are unable to supply enough fresh air to dilute VOCs generated inside those spaces. In the second building, we also find indications that other parameters are being driven by set-backs and occupancy. These first deployments demonstrate the ability of low-cost distributed iAQ sensor networks to help researchers identify where and when indoor air pollutants are introduced in buildings.

Forrest presenting at Department of Energy Better Building Summit

Indoor Environmental Quality for Energy and Productivity

Advances in building sensors, HVAC and lighting allow us to create highlyefficient, modern spaces for federal employees. Do these technologies also improve indoor air quality and productivity? Learn how 3 research teams are using a distributed sensor network to create an accurate picture of building performance and its effect on employees while reducing cost.

Brian Gilligan, U.S. General Services Administration

Chris Pyke, U.S. Green Building Council

Forrest Meggers, Princeton University

Research team led by Prof Forrest Meggers, faculty jointly appointed in the School of Architecture and the Andlinger Center for Energy and the Environment.