Roof Color-Based Warm Roof Evaluation in Cold Regions Using a UAV Mounted Thermal Infrared Imaging Camera

Existing studies on reducing urban heat island phenomenon and building temperature have been actively conducted; however, studies on investigating the warm roof phenomenon to in-crease the temperature of buildings are insufficient. A cool roof is required in a high-temperature region, while a warm roof is needed in a low-temperature or cold region. Therefore, a warm roof evaluation was conducted in this study using the roof color (black, blue, green, gray, and white), which is relatively easier to install and maintain compared to conventional insulation materials and double walls. A remote sensing method via an unmanned aerial vehicle (UAV)-mounted thermal infrared (TIR) camera was employed. For warm roof evaluation, the accuracy of the TIR camera was verified by comparing it with a laser thermometer, and the correlation between the surface temperature and the room temperature was also confirmed using Pearson correlation. The results showed significant surface temperature differences ranging from 8 °C to 28 °C between the black-colored roof and the other colored roofs and indoor temperature differences from 1 °C to 7 °C. Through this study, it was possible to know the most effective color for a warm roof according to the color differences. This study gave us an idea of which color would work best for a warm roof, as well as the temperature differences from other colors. We believe that the results of this study will be helpful in heating load research, providing an objective basis for determining whether a warm roof is applied.

Thermal infrared imaging experiment of S-type binary asteroids in the Hera mission

<p>The thermal infrared imager TIRI onboard the ESA Hera spacecraft is being developed to investigate thermophysical properties of the S-type asteroid 65803 Didymos and its moon Dimorphos by mapping thermal inertia and compositional variations of them. TIRI is based on an uncooled micro-bolometer array of 1024 x 768 effective pixels and covers the field of view of 13.3° x 10.0°, with the resolution of 0.23 mrad per pixel. TIRI has an eight-position filter wheel to be used as one wide bandpath at 8-14 µm for thermal imaging, six narrow bands peaked at 7.8, 8.6, 9.6, 10.6, 11.65, and 13.1 µm for compositional information, and one closed plate both for a shutter and a temperature reference.</p> <p>TIRI will be mounted on the top panel of the Hera spacecraft to point the target asteroids in the same direction with other instruments AFC, PALT, and Hyperscout-H, for the simultaneous observations. The asteroid surface temperature will change day and night according to thermal inertia and roughness of the surface layer, which will be consequently derived from the diurnal temperature profile. The maximum temperature in a day will also change according to the solar distance of the asteroid from ~1 to ~2 au at the beginning to the end of the nominal mission. During the early characterization phase (ECP) at 20 to 30 km from the asteroid, TIRI will take images from large solar phase angles from 50° to 70° with the spatial resolution of ~4.6 to 6.9 m per pixel to construct the asteroid shape model even in the night side and map the thermal inertia and composition. During the detailed characterization phase (DCP) at 10 to 20 km from the asteroid, TIRI will take images from the noon with the spatial resolution of ~2.3 m per pixel for more detailed thermal properties and compositional mapping. During the close-up operation phase (COP) at < 5 km from the asteroid, TIRI will take images from the noon with the spatial resolution of ~1 m per pixel. Higher spatial resolution will be achieved during the further close observations.</p> <p>In the Hayabusa2 mission, thermal imaging has revealed the highly porous nature of C-type asteroid from global to local scales (Okada et al, 2020; Shimaki et al, 2020), but nobody knows the surface properties of S-type asteroids so that this is a unique opportunity to investigate the S-type asteroid Didymos in comparison with the C-type asteroid Ryugu. For the moon Dimorphos, it will be the smallest asteroid ever explored so that it is also a unique opportunity to investigate the small-sized asteroid, especially for the strength and porosity. TIRI will contribute to verifying Yarkovsky and YORP (B-YORP) effects, orbital and rotational evolution in relation to thermophysical modeling. The temperature profile and compositional difference between the inside and outside of the artificial crater formed by the kinetic impact of the NASA DART spacecraft will be the important target both for the purpose of planetary defense and science.</p>