This research introduces a thermal transition 2D map and a 3D volume visualization of a 3 × 3 × 3 array of temperature data in a second-floor east bedroom of the Net-Zero Energy Residential Test Facility (NZERTF) located in Maryland, USA. The NZERTF is an airtight and highly efficient house constructed by the National Institute of Standards and Technology in 2015 for a scholar’s research activity. The designated bedroom indoor condition was measured with 27 dry-bulb temperatures in a 3 × 3 × 3 sensor array during the peak summer (July) and peak winter months (December), 2017. Both “Child B” and “Laptop” thermal loads were simulated using a heating box in the east bedroom and an ultrasonic humidifier in the kitchen. Moreover, the conventionally ducted heat pump and small duct high-velocity systems were operated intermittently based on a temperature set point interval, and the heat recovery ventilation system was operated every 45 min. Based on the collected data, researchers observed a total of 76 small (1.11–1.38  \(^\circ{\rm C} \) raise) and 35 big (1.38–1.94 \(^\circ{\rm C} \) raise) irregular temperature spikes at various locations and heights of the 3 × 3 × 3 sensor array during both July and December. 24 big temperature spikes occurred at the low level of stands 1, 2, and 3 between 9:30 AM and 2 PM in December, while 7 cases were recorded at Low and Middle levels of stands 8 and 9 from 7 AM to 8 AM in July. Among them, the notable 35 temperature spikes with temperature increase of 1.38–1.94  \(^\circ{\rm C} \) were investigated and visualized into the thermal map and thermal volume through an interpolation function in MATLAB software. Utilization of this thermal technique presentation enables researchers and engineers to discern critical data point relationships and characteristics with ease and effectively initiate further investigation of the causes of temperature irregularities.