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Title
Nighttime Radiative Cooling of Low-slope Roof Systems
Nighttime Radiative Cooling of Low-slope Roof Systems
Date
9/2011
9/2011
Author(s)
Matthew Dupuis
Matthew Dupuis
Page(s)
Keyword(s)
temperature; cooling; night; surface
temperature; cooling; night; surface
Abstract
Nighttime radiative cooling of roof systems is a phenomenon that occurs every night. The net effect of this process is that roof membranes cool below the ambient air temperature. The amount of cooling and temperature differential that develops depends on multiple factors. This paper uses field data collected from the Midwest Roofing Contractors Association (MRCA) test bed project in Manhattan, Kansas, which has TPO, EPDM, PVC and polymer-modified bitumen membranes present. The membranes have had thin-film photovoltaic (PV) panels adhered to them; each of these membranes and PV panels has been instrumented for temperature with ermocouples placed directly below the membrane. In addition, the MRCA site has a suite of weather and radiometric sensors to record the net energy exchange taking place every day. Discussion within the paper includes details of the sensor system, history of research in the area of radiative cooling, theory of the energy exchange taking place, charts of field data, maximum observed temperature differentials, frost and dew formation, and the observed membrane temperature convergence every night. In addition to the present Nighttime radiative cooling of roof systems is a phenomenon that occurs every night. The net effect of this process is that roof membranes cool below the ambient air temperature. The amount of cooling and temperature differential that develops depends on multiple factors. This paper uses field data collected from the Midwest Roofing Contractors Association (MRCA) test bed project in Manhattan, Kansas, which has TPO, EPDM, PVC and polymer-modified bitumen membranes present. The membranes have had thin-film photovoltaic (PV) panels adhered to them; each of these membranes and PV panels has been instrumented for temperature with thermocouples placed directly below the membrane. In addition, the MRCA site has a suite of weather and radiometric sensors to record the net energy exchange taking place every day. Discussion within the paper includes details of the sensor system, history of research in the area of radiative cooling, theory of the energy exchange taking place, charts of field data, maximum observed temperature differentials, frost and dew formation, and the observed membrane temperature convergence every night. In addition to the present data and discussion, there is a brief description of the future work currently being done with the data and validating a temperature model.
Nighttime radiative cooling of roof systems is a phenomenon that occurs every night. The net effect of this process is that roof membranes cool below the ambient air temperature. The amount of cooling and temperature differential that develops depends on multiple factors. This paper uses field data collected from the Midwest Roofing Contractors Association (MRCA) test bed project in Manhattan, Kansas, which has TPO, EPDM, PVC and polymer-modified bitumen membranes present. The membranes have had thin-film photovoltaic (PV) panels adhered to them; each of these membranes and PV panels has been instrumented for temperature with ermocouples placed directly below the membrane. In addition, the MRCA site has a suite of weather and radiometric sensors to record the net energy exchange taking place every day. Discussion within the paper includes details of the sensor system, history of research in the area of radiative cooling, theory of the energy exchange taking place, charts of field data, maximum observed temperature differentials, frost and dew formation, and the observed membrane temperature convergence every night. In addition to the present Nighttime radiative cooling of roof systems is a phenomenon that occurs every night. The net effect of this process is that roof membranes cool below the ambient air temperature. The amount of cooling and temperature differential that develops depends on multiple factors. This paper uses field data collected from the Midwest Roofing Contractors Association (MRCA) test bed project in Manhattan, Kansas, which has TPO, EPDM, PVC and polymer-modified bitumen membranes present. The membranes have had thin-film photovoltaic (PV) panels adhered to them; each of these membranes and PV panels has been instrumented for temperature with thermocouples placed directly below the membrane. In addition, the MRCA site has a suite of weather and radiometric sensors to record the net energy exchange taking place every day. Discussion within the paper includes details of the sensor system, history of research in the area of radiative cooling, theory of the energy exchange taking place, charts of field data, maximum observed temperature differentials, frost and dew formation, and the observed membrane temperature convergence every night. In addition to the present data and discussion, there is a brief description of the future work currently being done with the data and validating a temperature model.