New approach to estimate sensible heat flux through optical triangulation

•Introduction of a new optical device based on optical power triangulation technique (OPTT) for measuring sensible heat flux.•The device consists of a transmitter (LED) and a receiver (photodetectors and processing unit) to measure beam wander due to refractive index fluctuations caused by temperature variations.•Experimental validation of the device in a controlled indoor environment, achieving a measurement accuracy of up to 60 W/m2 with a coefficient of determination of 0.95.•Comparison of the device’s performance with traditional methods like Eddy Covariance and Bowen ratio energy balance, highlighting its lower cost and ease of installation.•Potential for the device’s application in both indoor and outdoor environments, including greenhouses, with future work aimed at field testing. In this work, a new optical device capable to measure sensible heat flux (H) through optical power triangulation technique (OPTT) is proposal. The measuring from device is based on the beam wander effect, which is due to refractive index fluctuations caused by temperature variation. The device was assessed in an indoor environment considering as a reference H determined from temperature gradient and the aerodynamic resistance to heat transfer (rHa). The rHa was quantified by two approaches based on the flow (free or forced convention) and the surface properties. The device can measure heat flux up to 60 W/m2 with a standard estimate error less than 2.55 W/m2 and coefficient of determination of 0.95. Future works will focus on field testing and comparison with traditional field methods of H estimates applied to agricultural, hydrology and atmosphere.