Buildings' energy consumption has a great energetic and environmental impact worldwide. The architectural design has great potential to solve this problem because the building envelope exerts influence on the overall system performance, but this is a task that involves many objectives and constraints. In the last two decades, optimization studies applied to energy efficiency of buildings have helped specialists to choose the best design options. However, there is still a lack of optimization approaches applied to the design stage, which is the most influential stage for building energy efficiency over its entire life cycle. Therefore, this article presents a multi-objective optimization model to assist designers in the schematic building design, by means of the Pareto archived evolutionary strategies (PAES) algorithm with the EnergyPlus simulator coupled to evaluate the solutions. The search process is executed by a binary array where the array components evolve over the generations, together with the other building components. The methodology aims to find optimal solutions (OSs) with the lowest constructive cost associated with greater energy efficiency. In the case study, it was possible to simulate the process of using the optimization model and analyze the results in relation to: a standard building; energy consumption classification levels; passive design guidelines; usability and accuracy, proving that the tool serves as support in building design. The OSs reached an average of 50% energy savings over typical consumption, 50% reduction in CO operating emissions, and investment return less than 3 years in the four different weathers.

The increase of operating temperature on a photovoltaic (PV) cell degrades its electrical efficiency. This paper is organized to describe our latest design of an aluminum substrate-based photovoltaic/thermal (PV/T) system. The electrical efficiency of the proposed PV/T can be increased by ∼ 20% in comparison with a conventional glass substrate-based PV. The work will benefit hybrid utilization of solar energy in development of building integrated photovoltaic systems.

Three grid-connected monocrystalline silicon arrays on the National Institute of Standards and Technology (NIST) campus in Gaithersburg, MD have been instrumented and monitored for 1 yr, with only minimal gaps in the data sets. These arrays range from 73 kW to 271 kW, and all use the same module, but have different tilts, orientations, and configurations. One array is installed facing east and west over a parking lot, one in an open field, and one on a flat roof. Various measured relationships and calculated standard metrics have been used to compare the relative performance of these arrays in their different configurations. Comprehensive performance models have also been created in the modeling software pvsyst for each array, and its predictions using measured on-site weather data are compared to the arrays' measured outputs. The comparisons show that all three arrays typically have monthly performance ratios (PRs) above 0.75, but differ significantly in their relative output, strongly correlating to their operating temperature and to a lesser extent their orientation. The model predictions are within 5% of the monthly delivered energy values except during the winter months, when there was intermittent snow on the arrays, and during maintenance and other outages.

The Net-Zero Energy Residential Test Facility (NZERTF) was designed to be approximately 60 % more energy efficient than homes meeting the 2012 International Energy Conservation Code (IECC) requirements. The thermal envelope minimizes heat loss/gain through the use of advanced framing and enhanced insulation. A continuous air/moisture barrier resulted in an air exchange rate of 0.6 air changes per hour at 50 Pa. The home incorporates a vast array of extensively monitored renewable and energy efficient technologies including an air-to-air heat pump system with a dedicated dehumidification cycle; a ducted heat-recovery ventilation system; a whole house dehumidifier; a photovoltaic system; and a solar domestic hot water system. During its first year of operation the NZERTF produced an energy surplus of 1023 kWh. Based on observations during the first year, changes were made to determine if further improvements in energy performance could be obtained. The changes consisted of installing a thermostat that incorporated control logic to minimize the use of auxiliary heat, using a whole house dehumidifier in lieu of the heat pump's dedicated dehumidification cycle, and reducing the ventilation rate to a value that met but did not exceed code requirements. During the second year of operation the NZERTF produced an energy surplus of 2241 kWh. This paper describes the facility, compares the performance data for the two years, and quantifies the energy impact of the weather conditions and operational changes.

Commercial-scale solar photovoltaic (PV) arrays were designed, constructed, and are now operational on the Gaithersburg, Maryland campus of the National Institute of Standards and Technology (NIST). A design-bid-build process was followed where the contractors used photovoltaic system modeling tools both during the initial design phase and during the postbid, prebuild phase. To help investigate the specific aspects of the contractors' evolving designs, the authors conducted their own independent photovoltaic system modeling. This independent modeling helped identify design elements that could be improved and so aided efforts to maximize the annual renewable energy generation. An estimated 2.5% gain in annual energy generation is being realized as a result of this independent modeling effort. To provide context for the modeling work and the lessons learned, key events impacting the design-bid-build process are described. The installed systems are summarized and also contrasted with the proposed designs. The power generation at three sites are compared over two different 12-month intervals.

Three grid-connected monocrystalline silicon photovoltaic arrays have been instrumented with research-grade sensors on the Gaithersburg, MD campus of the National Institute of Standards and Technology (NIST). These arrays range from 73 kW to 271 kW and have different tilts, orientations, and configurations. Irradiance, temperature, wind, and electrical measurements at the arrays are recorded, and images are taken of the arrays to monitor shading and capture any anomalies. A weather station has also been constructed that includes research-grade instrumentation to measure all standard meteorological quantities plus additional solar irradiance spectral bands, full spectrum curves, and directional components using multiple irradiance sensor technologies. Reference photovoltaic (PV) modules are also monitored to provide comprehensive baseline measurements for the PV arrays. Images of the whole sky are captured, along with images of the instrumentation and reference modules to document any obstructions or anomalies. Nearly, all measurements at the arrays and weather station are sampled and saved every 1s, with monitoring having started on Aug. 1, 2014. This report describes the instrumentation approach used to monitor the performance of these photovoltaic systems, measure the meteorological quantities, and acquire the images for use in PV performance and weather monitoring and computer model validation.

The heating process of melting margarine requires a vast amount of thermal energy due to its high melting point and the size of the reservoir it is contained in. Existing methods to heat margarine have a high hourly cost of production and use fossil fuels which have been shown to have a negative impact on the environment. Thus, we perform an analytical feasibility study of using solar thermal power as an alternative energy source for the margarine melting process. In this study, the efficiency and cost effectiveness of a parabolic trough collector (PTC) solar field are compared with that of a steam boiler. Different working fluids (water vapor and Therminol-VP1 heat transfer oil (HTO)) through the solar field are also investigated. The results reveal the total hourly cost ($/h) by the conventional configuration is much greater than the solar applications regardless of the type of working fluid. Moreover, the conventional configuration causes a negative impact to the environment by increasing the amount of CO, CO, and NO by 117.4 kg/day, 184 kg/day, and 74.7 kg/day, respectively. Optimized period of melt and tank volume parameters at temperature differences not exceeding 25 °C are found to be 8-10 h and 100 m, respectively. The solar PTC operated with water and steam as the working fluid is recommended as a vital alternative for the margarine melting heating process.

Vibration is one of the most common loading modes during handling and transport of solar silicon wafers and has a great influence on the breakage rate. In order to control the breakage rate during handling and facilitate the optimization of the processing steps, it is important to understand the factors which influence the natural frequency of thin silicon wafers. In this study, we applied nonlinear finite element method to investigate the correlation of natural frequency of thin solar silicon wafer with material microstructures (grain size and grain orientation), thickness variation and crack geometry (position and size). It has been found that the natural frequency for anisotropic single crystal silicon wafer is a strong function of material orientation. Less than 10% thickness variation will have a negligible effect on natural frequency. It is also found out that cracks smaller than 20 mm have no dominant effect on the first five natural frequency modes anywhere in the silicon wafer.

The health and wellbeing of building occupants should be a key priority in the design, building, and operation of new and existing buildings. Buildings can be designed, renovated, and constructed to promote healthy environments and behaviors and mitigate adverse health outcomes. This paper highlights health in terms of the relationship between occupants and buildings, as well as the relationship of buildings to the community. In the context of larger systems, smart buildings and green infrastructure strategies serve to support public health goals. At the level of the individual building, interventions that promote health can also enhance indoor environmental quality and provide opportunities for physical activity. Navigating the various programs that use metrics to measure a building's health impacts reveals that there are multiple co-benefits of a "healthy building," including those related to the economy, environment, society, transportation, planning, and energy efficiency.