Honors College Theses

Date

2021

Major

Mechanical Engineering (B.S.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Marcel Maghiar

Abstract

The present study evaluates the thermal comfort in the east bedroom of the Net-Zero Energy Residential Test Facility (NZERTF) in a mixed-humid climate. This unit was constructed by the National Institute of Standards and Technology for scholars to analyze its energy performance and indoor environmental quality. The thermal comfort is investigated in a designated bedroom space by analyzing 27 dry-bulb temperature, 4 airspeed, 6 globe temperature, and 6 relative humidity sensors in a 3x3x3 array and a center sensor stand during two opposite seasonal months (July and December). The conventionally ducted heat pump, small duct high velocity, and heat recovery ventilation systems are operated intermittently based on a temperature set point interval. A laptop and "Child B" are simulated with 1.2 and 1.7 metabolic rates (met) and seasonally different clothing ranges (clo). Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) are calculated based on the ASHRAE standard 55-2017. PMV with higher clo and 1.2 met resulted within the ± 0.5 thermal comfort zone during both months. Simulations with the higher clo (0.57 and 1.14 clo) and higher met expectedly provided slightly higher PPD than 10% limit, which corresponds to the thermal comfort zone. However, for the simulated occupant with 1.7 met, 84.1% and 92.9% of the daily time on July and respectively December is within the limit of 20%, known as local thermal comfort limit. Based on the prediction calculations, the thermal comfort in the respective NZERTF space during these months is determined to be habitually satisfying.

Thesis Summary

This study presents the analysis and prediction on thermal comfort in the east bedroom of the Net Zero Energy Residential Test Facility during July and December 2017. This dwelling was constructed by the National Institute of Standards and Technology for scholars to analyze its energy performance and indoor environmental quality. The conventionally deducted heat pump, small duct high velocity, and heat recovery ventilation systems were operated intermittently to provide a high quality of the indoor environment. The indoor environmental parameters were measured in various locations of the room by installing the 3x3x3 array of sensors and the center sensor stand. These environmental parameters and personal factors of the simulated occupant were used to determine the Predicted Mean Vote and Predicted Percentage of Dissatisfied in the east bedroom. Based on the prediction and calculation of PMV and PPD, the simulated occupant will generally express thermal satisfaction inside of the NZERTF, if proper clothing rate and metabolic rate are considered based on the indoor environment.

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