Design of a Low-Cost Wireless Data Logger for Monitoring the Occupant's Thermal Perception

Abstract

Achieving thermal comfort for the building occupant often means increasing energy
consumption. This work aims to develop an affordable, reliable and easy to use data logger to
track occupant's thermal perception. It would allow the development of new approaches to
achieve comfort by energy sobriety. This article presents the fabrication of a data logger device
that allows to periodically and simultaneously measure an individual's physiological and
physical parameters with a microcontroller-based system. The overall device is tested by
comparing each sensor’s mean output between them to assure that the physical measures have
small discrepancies. Also, the comparison was made to ensure that the two ways of data saving
were reliable. The results showed that the data-logger showed no issues and is functioning well.
The thermocouples had a reading difference of 0.05°C and constantly sent data. The oximeter
needs to be closest to the wrist to return stable reading. The spectral decomposition sensors
returned the same value but need to be placed perpendicular to the light source. Data was well
transmitted to an online database and was well registered on the SD card. This is consistent
with discoveries already made on those sensors. For the preliminary test, the measure confirms
the efficiency of the design as it matches expectation and admits relatively low deviation for
all units. Our finding showed that it is possible to secure the input in both ways: online and
offline solutions. Also, it permits the possibility of an easier protocol which uses more than
two data loggers for online data record through Google API. Identifying individual parameters
and not solely global parameters will permit further development toward the fulfillment of
optimal thermal comfort. Despite the work done, design amelioration is needed to optimize the
portability of the devices.