The U.S. buildings sector accounted for approximately 41% of United States primary energy consumption in 2010. Of this energy used by U.S. residential and commercial buildings, approximately 10% can be attributed to losses through the building envelope due to air infiltration. The purpose of this RFI is to collect information that will be used by BTO for strategic planning of the broader windows and opaque envelope technologies R&D portfolio. Specifically, BTO is seeking information from the public on diagnostic technologies that can be used to identify infiltration through the envelope, including in and around fenestration, of residential and commercial buildings. In particular, BTO is interested in the current state-of-the-art in infiltration diagnostic technologies, forthcoming research and development (R&D) advances that could reduce cost or improve performance, and the potential market implications of improved infiltration diagnostics. Responses to this RFI will impact the development of the BENEFIT 2016 FOA. This is solely a Request for Information and not a Funding Opportunity Announcement (FOA). EERE is not accepting applications and will not respond to questions.