Architectural Engineering Commons^™

Implications Of Human Performance And Perception Under Tonal Noise Conditions On Indoor Noise Criteria, Lily M. Wang, Erica E. Ryherd

Durham School of Architectural Engineering and Construction: Faculty Publications

This research investigated differences in task performance and perception under six non-time-varying ventilation-type background noise spectra with differing tonality. The results were related to five indoor noise criteria systems: Noise Criteria (NC), Balanced Noise Criteria (NCB), Room Criteria (RC), Room Criteria Mark II (RC-Mark II), and the A-weighted equivalent sound pressure level (L_Aeq). These criteria systems are commonly used in the U.S. building industry, but concerns exist over whether they are appropriate for all noise situations. Thirty test subjects completed three types of performance tasks (typing, reasoning, and math) and answered questions about their perception of the indoor …

Demand-Based Optimal Control To Save Energy: A Case-Study In A Medical Center, Ik-Seong Joo, Li Song, Mingsheng Liu, Mike Carico

Durham School of Architectural Engineering and Construction: Faculty Publications

Continuous Commissioning^® (CC^®) strategies include reducing simultaneous heating and cooling, scheduling the facility’s occupancy needs, utilizing free cooling, and minimizing excessive supply air and outside air. Most significantly, this demandbased control energy conservation strategy can facilitate mechanical system performance at near optimal conditions through the gradual advancement of control systems and the ability of upstream systems reading the status of downstream systems.

This paper demonstrates demand-based temperature, pressure and economizer control by the mathematical optimization methodology illustrated by a case-study, implemented with actual systems in a 1.2 million square foot medical center. Based on the optimization results, …

Optimal Control In Three-Deck Multi-Zone Air-Handling Units: A Case-Study, Ik-Seong Joo, Li Song, Mingsheng Liu, Barry Douglas

Durham School of Architectural Engineering and Construction: Faculty Publications

A multi-zone air-handling unit was popular several decades ago due to the convenience of small sized modular units, which were inexpensive to install and easily maintained in a mechanical room. The cost and convenience proved to be of little benefit as the units perform poorly from an energy usage perspective. A “three-deck” multi-zone unit is a hybrid of its kind, and it can be very efficient when controlled properly. In theory, there will not be simultaneous heating and cooling if its heating damper is controlled separately from the control of the cooling damper. When the zone load is neutral (not …

Evaluation Of A Virtual Refrigerant Charge Sensor, Woohyun Kim, James E. Braun, Haorong Li

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper presents a thorough evaluation of a method for determining refrigerant charge that employs low-cost, non-invasive measurements (i.e., surface mounted temperature measurements). The method could be used as part of a protocol for verified service providers (VSPs) in AC diagnostic tune-up or refrigerant charge, air flow (RCA) verification programs. Ultimately, the method could be embedded within a portable virtual refrigerant charge gauge for a technician’s use or permanently installed on the AC unit. The accuracy of the virtual refrigerant charge sensor method is evaluated in this paper using laboratory data for a number of different systems and over a …