Alternate Thermal Management

Building Wall Technologies Challenge

Innovations in Building Wall Technologies Using Anisotropic Composites to Reduce Building Energy Consumption

Background

In 2010, the primary energy consumption attributed to building envelope (roofs and walls) was 5.8 quadrillion BTUs (almost 6% of entire US energy consumption) 1 .  In new construction, highly insulated building envelopes can partially address this opportunity; however in existing buildings, adding the appropriate amount of insulation material is often impractical due to high cost and/or space limitations. ORNL is exploring alternate thermal management technologies, beyond insulation, for reducing the energy consumption attributed to building envelopes. Specifically, ORNL is investigating the efficacy of adding anisotropic composites to external walls coupled with a heat sink or source (such as the ground) in reducing wall-generated heating and cooling loads. This concept entails actively diverting heat to a sink or from a source via anisotropic composites.

Figure 1. Schematic representation of heat re-direction using the anisotropic concept. Left – heat flow in summer through a regular wall; Right – majority of the heat flow is redirected to the heat sink via the anisotropic composite.

During FY17, numerical simulations were performed that included two-dimensional finite element analysis (FEA) models of wall assemblies and whole-building modeling to estimate the annual reductions in wall-generated heating and cooling loads, and associated energy consumption. The baseline wall consisted of 2x4 wood frame with cavity insulation. The anisotropic composite consisted of three layers of aluminum (Al) foil-faced polyisocyanurate (PIR) foam boards. It is noted that the Al-PIR composite is only one example of an anisotropic composite; many other configurations are possible.

The FEA models indicated reduction in heat gains of up to 80% with the anisotropic composite under Phoenix-like weather conditions. The whole-building modeling study showed that annual energy cost savings of up to $270 are possible under Phoenix and Baltimore weather conditions, by retrofitting a baseline wall with an anisotropic composite. Figure 1 shows the wall geometry utilized in the FEA model.

Figure 2. Model used in FEA; the heat sink temperature is assumed to be 10 K below the ambient temperature

In FY18, ORNL will explore the technical details and optimization of the system(s) combining the anisotropic composites and heat sink/source for laboratory testing to experimentally validate the findings of FY17. If the potential of anisotropic composites reduce unintended heat transfer can be established, further investigation of experimental system design(s) and development of innovative methods of implementing them in real buildings are needed.

The Challenge

JUMP into STEM invites University of Tennessee (UT) students to contribute to early stage R&D by utilizing the experimental design(s) of ORNL to propose methods of implementing anisotropic thermal management in existing buildings.

The challenge is to design a bench-top, i.e. at a smaller but a realistic scale, anisotropic composite and a heat sink system than can be incorporated in a typical residential wall. The anisotropic composites need to be designed to have very high thermal conductivity in the direction parallel to the wall and low thermal conductivity in the direction along the thickness of the wall.

Following are the suggested attributes of pilot-scale prototypes:

  • Baseline wall – typical 2 x 4 construction with cavity insulation
  • Anisotropic composite containing alternate layers of foam and Al-foil (or another composite design) for an exterior application
  • Connection between the anisotropic composite and the heat sink or source (such as ground)

While applicants are allowed to propose alternate anisotropic composite designs, it should be noted that the evaluation will be more heavily-weighted towards designs of how to integrate the anisotropic composite to a wall and the heat sink/source.

This JUMP into STEM Challenge requires the design of how the system of anisotropic composite and heat sink/source will be attached to a real building. The system will be developed and implemented for testing in one of the flexible research platform or natural exposure test facilities of ORNL. As an example, ORNL has a 1-storey test building called the Envelope Systems Research Apparatus (ESRA) that has a south-facing exterior wall, which could a potential test site.

The Award

An ORNL Summer Internship will be awarded to the top selected idea submission. The winning UT student or team of students submitters will be invited to work with ORNL research staff for a 10-week summer internship* with the HERE Program.  Potential work focus during the summer internship may include:

  • Collaboration in updating and optimizing the students' proposed designs of the anisotropic composite and integration of the composite to a wall and heat sink.
  • Perform field-tests of the integrated anisotropic composite wall system in one of the test facilities of ORNL.
  • Work with ORNL's Building Technologies Research & Integration Center (BTRIC) user facility on investigation of technologies to improve energy efficiency and environmental capability of residential and commercial buildings.

*Internship Awards are subject to ORNL site access requirements and availability of funding.

About the Internship: Oak Ridge Institute of Science and Education (ORISE) administers an array of programs for ORNL that meet the Laboratory's strategic goals for science education and workforce development, and serve the entire academic continuum for k-12 students and teaches to university students, postgraduates and faculty. Most of the programs can be categorized as research participation. This type of program uses the strengths of the Laboratory to provide mentored research experiences that complement the academic program or provide work-based experience and training. ORISE also works with the Laboratory to administer events or short-term programs that are designed to inform, reach out to specific populations, or offer opportunities for competition.

Idea Submission Deadline

Idea Submission Period Ends: March 1, 2018 at 11:59 PM EST

MORE DETAILS

About this Pilot: Recognizing the value of connecting with early stage innovators, ORNL is launching a 2018 pilot: JUMP into STEM. Leveraging the success of the online JUMP community, ORNL will partner with the University of Tennessee (UT) to advance student skills in the STEM field and encourage early stage research in building energy efficiency. During the JUMP into STEM pilot, UT students will have an opportunity to compete for Awards, including the potential for 2018 summer internships with ORNL.  And in the spirit of crowdsourcing innovation, the JUMP community will still be open to others to comment and vote on the posted ideas. This community discussion helps DOE, ORNL, and industry partners gauge the market's interest in the topic and potential solutions.  Students must complete an online application and meet the criteria for the internship program to be eligible to receive the internship.

1: https://energy.gov/sites/prod/files/2014/02/f8/BTO_windows_and_envelope_report_3.pdf

JUMP into STEM Walls Challenge

Alternate Thermal Management

Submitted by (@cfoisyga)

Geo-Thermal Heat Sink for Anisotropic Material

My idea is to minimize the thickness of the unit added to the exterior of residential homes. I believe I can accomplish this by using already known technology that geothermal heating and air uses. By using the earth to warm or cool the air inside the wall I believe I can minimize the layers of the anisotropic material. My proposed idea uses the anisotropic material to transfer the spread the heat through the material ...more »

Voting

1 vote
1 up votes
0 down votes