Targeted Retrofit Demonstrations using Simplified Screening for Envelope and Duct Leakage
Dr. Mark Modera | University of California, Davis
This work is intended to advance the state of the art associated with envelope and duct leakage sealing by using a recently developed diagnostic screening technology/methodology to identify buildings with leakage problems. This new technology/methodology takes advantage of advances in IoT (Internet of Things) technologies that have made sensors and remote communication quite inexpensive. In this project, inexpensive high-accuracy pressure sensors, combined with a methodology developed in a National Institute for Standards and Technology (NIST)-funded Small Business Innovation Research project, will be used as a screening tool in multiple buildings to quantify envelope and duct leakage. After the initial screening, one building will be chosen for retrofit duct sealing and/or envelope sealing. Finally, the Heating, Ventilation, and Air Conditioning(HVAC) energy use of the chosen building will be measured before and after the retrofit to determine the overall energy savings due to air sealing. In addition, if applicable, this project will utilize a new technology for sealing building envelopes that has demonstrated excellent results within an existing Environmental Security Technology Certification Program (ESTCP) project ( EW-201511).
A project recently completed for the NIST developed a methodology for assessing envelope leakage and duct leakage using small, inexpensive sensors to measure pressures at various points within and around a building. The pressure data, combined with a one-time measurement of the outdoor air intake to the building, allows determination of building envelope leakage and duct leakage to/from outdoors by monitoring the pressure responses associated with various modes of operation.
The sensor package was originally developed for fault detection and diagnostics (FDD) in HVAC equipment and has the ability to upload data remotely (via cell-phone data packets) to a secure file transfer protocol server for analysis. The instruments are not connected to the building network or energy management system, which ensures the security of the operations in the building.
Research conducted by NIST showed that reducing envelope air leakage of apartments and office buildings to levels similar to those required by United States Army Corps of Engineers can save 30% of the energy required for heating and cooling of those buildings. It is expected that the screening tool will provide a more cost effective method for identifying buildings on military bases that would benefit from sealing, allowing Utility Energy Service Contracts to target buildings with the highest return on investment. Assuming a 10% adoption rate for retrofit envelope sealing, and use patterns similar to U.S. commercial buildings, envelope leak sealing could save Department of Defense (DoD) 2,200 billion British Thermal Unit (BTU) per year.
Research investigating the impact of sealing duct leakage has also demonstrated significant energy savings. A Navy Techval project estimated a range of energy savings from 10%-30% of energy used for cooling and fan operation for multiple retrofit duct sealing projects. One of the objectives of this study will be to use the screening tool to determine where duct sealing will be most effective. Again, assuming a 10% adoption rate for retrofit duct sealing and similar end-use patterns, reducing duct air leakage could save the DoD 800 billion BTU per year. The Techval project did not measure heating savings from duct sealing; however, in colder climates heating savings should be expected in DoD facilities.