Journal of Architectural Engineering

To improve system efficiency under part-load conditions, the supply air temperature set point for a single-duct constant air volume air handling unit (AHU) system is often reset based on either return air temperature or outside air temperature. Both reset strategies make engineering sense as long as the reset schedules are reasonable. Quite often the decision to use one over the other is made with the assumption that they will both achieve some energy savings. However, the impact of these two strategies on AHU energy consumption could be very different. An in-depth analysis and comparison of these two commonly used supply air temperature reset strategies for a single-duct constant air volume system is presented in this paper. It is shown that the reset strategy based on outside air temperature is inherently better than that based on return air temperature, with lower energy consumption and improved building comfort level.

This study is divided into two parts. The first study determines window size and size reductions for different wall and ceiling reflectance combinations that are needed in a classroom to achieve one leadership in energy and environmental design (LEED) daylight factor credit. The second study determines the power consumption of indirect luminaires with a target illuminance of $538\text{lux}$ for different wall and ceiling reflectance combinations. LEED credits for the optimizing energy performance are determined. It is found that ceiling reflectance has a higher impact on light levels and energy performance than wall reflectance. A ceiling reflectance of 90% and wall reflectance of 75% allows a minimum window-to-wall ratio of 0.444 to achieve one LEED daylight factor credit. The same room decreases lighting power density for an indirect fluorescent lighting system by one-third below the maximum permissible lighting power density specified in American Society of Heating, Refrigerating and Air-Conditioning Engineers/Illuminating Engineering Society of North America (ASHRAE/IESNA) Standard 90.1-2001. If lighting constitutes 50% of the total ASHRAE/IESNA 90.1 load, 0.92 LEED credits for the optimization of energy performance can be obtained for new construction and 2.92 credits can be obtained for existing buildings.

To design an efficient and effective inventory control system for the manufactured housing (MH) industry, it is necessary to accelerate the flow of information and products across the supply chain. To achieve this goal, the system needs three ingredients: generators of quick information flow, generators of quick material flow, and facilitators of both information flow and material flow. This paper proposes a material requirements planning (MRP) system that uses a database approach to manage the large amount of information involved in the material-requirements estimation process for the MH industry. A prototype MRP database and a Visual Basic interface have been developed by using information collected through the research. The proposed MRP system was tested using data provided by a manufactured housing facility to demonstrate its functionality and application to any MH facility. This proposed MRP system can be used to develop better planning strategies and to respond quickly to unexpected changes in demand for the MH industry.

Life-cycle assessment (LCA) and life-cycle cost analysis (LCC) techniques are used to study a 25-year operational life cycle for plumbing fixtures and water-consuming appliances for four different multioccupant building scenarios: an apartment, a college dormitory, a motel, and an office building. Both analysis methodologies suggest that the specification of higher-efficiency fixtures and appliances is environmentally and economically justified for the scenarios considered. Additionally, both the LCA and LCC results suggest that natural gas should be used insted of electricity for water heating when both energy sources are practical options. The study found the dominant environmental impacts of domestic water consumption to be attributable to water intake, global warming potential, and fossil-fuel depletion. The dominant life-cycle cost component is for maintenance, repair, and replacement. The results of this study can be especially beneficial to long-term building owners, such as universities, because operational costs savings can be realized.

There are different ventilation control methods for outdoor air quantity in air-conditioned spaces to reduce the energy consumed in cooling the outdoor air. Demand controlled ventilation (DCV) is an important strategy to control the outdoor air quantity. However, the current practice in DCV systems creates several problems for air-conditioned office buildings. Although metabolic carbon dioxide $\left(\mathrm{C}{\mathrm{O}}_2\right)$ concentration is mainly used as a surrogate indicator for ventilation adequacy, the conventional DCV system does not seriously consider the placement location of the $\mathrm{C}{\mathrm{O}}_2$ sensor, and it does not take into account the adverse effects of the consequential increase in pollutant concentrations in the indoor space when the fresh airflow rate is reduced. In this study, a long period of subjective and objective measurements were conducted in an occupied office to examine its suitability for conversion to a new demand controlled ventilation system (nDCV). After the feasibility investigation, an nDCV system was developed to optimize the energy consumed for outdoor air ventilation while providing the desirable thermal comfort and indoor air quality. The true optimization of this nDCV is achieved by a new concept of the optimized indoor air quality window which determines the most representative locations for the indicator sensors. A minimum ventilation rate is determined by a calibration procedure for the pollutant inventory of a building, taking into account the infiltration characteristics. Radon gas, which is a notorious carcinogenic indoor pollutant, is used as a reference to determine the minimum fresh airflow rate. The findings show that this nDCV system reduced 16% of fresh air cooling energy consumption without jeopardizing the thermal comfort and indoor air quality.