Studying thermal characteristics of seating materials by recording temperature from 3 positions at the seat-subject interface.

AIM OF THE STUDY: To determine whether 3 fixed positions of seat-subject interface temperature measurement offer more information than a single point of measurement. MATERIALS AND METHODS: Temperature data was simultaneously acquired (sampling frequency 1 Hz/sensor) from each of three sensor positions (right & left mid-thigh and coccyx), from the subject-seat interface. The data was acquired whilst subjects (6 males, 5 females: 21-40 yrs: BMI 19.3-26.4) sat for 20 min on each of three types of seat material (foam, gel mould and solid wood). Data collection was performed at the same time of day for each subject: ambient temperature between 21.1 and 21.2 °C, ambient relative humidity 50.9%. RESULTS: Analysis of data from the sensors, post mathematical smoothing, for each subject (n = 11; ANOVA, followed by post-hoc t-tests) revealed each of the measurement positions to have a significantly different recorded temperature (p < 0.01). However, profile of temperature change at the same measurement position using the same seating material during the 20 min sitting period, was highly correlated (r > 0.99) between subjects, a consistent finding across all 11 subjects regardless of seat material selected. CONCLUSION: Use of 3 positions of measurement (3 sensors) appears necessary when performing detailed studies of temperature change at the seat-subject interface. The high level of comparability of results between subjects supports potential of this method to resolve quantitative components of qualitative measurements, e.g., thermal comfort.