Office of Energy Efficiency & Renewable Energy

U.S.-Brazil Collaboration Leads to Innovative Device That Reduces Energy Use in Buildings

December 2, 2016

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The Portable Window Energy Meter — jointly developed by researchers from Brazil and the United States — can reduce energy losses in buildings by measuring and assessing the energy performance of windows without removing them from their site.

The Portable Window Energy Meter — jointly developed by researchers from Brazil and the United States — can reduce energy losses in buildings by measuring and assessing the energy performance of windows without removing them from their site.

Researchers from the United States and Brazil have developed a new device that can reduce energy losses in buildings by measuring and assessing the energy performance of windows without removing them from their site. The Portable Window Energy Meter, still in prototype stage, was developed by researchers from Lawrence Berkeley National Laboratory (LBNL) and from Brazil’s Federal University of Santa Catarina, and is part of a large effort funded by EERE’s International Program. The collaboration aims to accelerate deployment of clean energy technologies under the U.S.-Brazil Strategic Energy Dialogue.

The reduction of energy use in buildings is a key part of the Energy Department’s strategy to achieve several goals, including doubling energy productivity by 2030. The Energy Department estimates that the amount of energy lost annually through windows in the United States corresponds to approximately $40 billion. Increasing the use of energy efficient windows and adding measurement and verification of installed windows’ thermal and optical properties can mitigate this energy loss. The new Portable Window Energy Meter developed by U.S. and Brazilian researchers addresses this problem by facilitating the measurement and assessment of energy performance of windows without removing them from their building site.

The Portable Window Energy Meter helps determine the energy efficiency performance of a window by measuring the thermal and optical properties of windows in the field. When deployed commercially, this instrument will help rating agencies, code officials, energy auditors, and forensic experts with verifying energy indices of fenestration products. It will also help consumers to make informed decisions about window replacement and retrofits by facilitating energy audits and assessment of energy performance of installed windows during their lifespan.

The principle of the Portable Window Energy Meter is the measurement of heat flow through the window glazing using a set of strategically placed surface heat flux meters, while maintaining uniform temperature condition of the interior of the measurement apparatus. Professor Saulo Güths, of the Department of Mechanical Engineering at the University Federal of Santa Catarina in Brazil, is the principal developer of this instrument. In collaboration with researchers from the Lawrence Berkeley National Lab, he tested and measured the performance of the Portable Window Energy Meter following procedures established by international standards widely adopted by the industry.

Dr. Charles Curcija from LBNL showcased the Portable Energy Meter for the first time at the National Fenestration Rating Council Fall Membership Meeting in early October. Meeting participants from different segments see a potential market among energy auditors. The project team is looking for commercial partners to assist with demonstration and commercialization of the new device. 

EERE's International Program accelerates the speed and scale of clean energy deployment through international collaboration with strategic partners.