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Thirty low-income housing units located in the high altitude San Luis Valley of Colorado received various energy conservation measures (ECM) in the summer of 2007. Measures included new furnaces, new tankless water heaters, programmable thermostats, addition/repair of roof insulation, existing furnace tune-up (where applicable), CFL bulbs and minor air sealing. Measurement and verification of the energy savings consisted of pre- and post-retrofit walk-through audits, blower door testing and temperature monitoring of select units. Verification methods consist of two whole building approach methods in addition to the calibrated simulation approach, following the ASHRAE Guideline 14-2002 protocols. All three methods are shown to produce remarkably similar savings estimates, with whole building approach methods being the simplest and least costly (time-intensive) to utilize for savings verification. The analysis provides insight into the effectiveness of the various methods as well as the impacts of the ECMs on residential energy consumption [ABSTRACT FROM AUTHOR]

This paper summarizes the results of field testing to evaluate the performance of simplified and optimal control strategies for shifting peak cooling loads and reducing building energy costs through the utilization of both the passive and active thermal energy storage systems for an elementary school in Colorado. In particular, the performance of precooling of building thermal mass as well as real-time model-based predictive optimal controls is evaluated. The results indicate that the school is saving roughly 47% on its annual electricity costs by utilizing the TES operated using their optimal control strategy. [ABSTRACT FROM AUTHOR]

A simulation/optimization tool has been developed to design building shell that minimizes energy use costs associated with heating and cooling systems. The tool couples an optimization algorithm to a building energy simulation engine to select optimal values of a comprehensive list of parameters associated with the envelope of residential buildings including the building shape. Three optimization methods are utilized including genetic algorithm (GA) approach, sequential search technique, and particle swarm technique. In this paper, the performance in terms of accuracy and efficiency of the three optimization approaches was compared for various sets of building envelope parameters. For relatively large search spaces, it was found that the GA could identify the minimum cost point to with an accuracy of 0.4% using 60% of the simulations required by sequential search technique and only 40% of the simulations needed by the particle swarm optimization method. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of an investigation to assess the impact of solar models used to estimate hourly global, diffuse, and direct solar radiation on annual building energy use. The building energy analysis is carried out by detailed whole-building simulation tools that used hourly Typical Meteorological Year (TMY) weather files. Annual energy use for prototypical office buildings with various geometric aspect ratios and window-to-wall ratios was obtained for several tropical sites. Nonsolar weather data for the same sites were obtained from the National Climatic Data Center (NCDC). Moreover, one-year TMY-formatted weather files developed from predictions of solar radiation from four models and from measured data are used in the analysis to determine the effect of the solar model on the annual energy use of prototypical office buildings. The four models include the Kasten model, Muneer model, Zhang and Huang model, and neural network-based model. The results of the analysis indicate that the Zhang and Huang model, when used with site-fitted coefficients, outperforms the neural network model and the Kasten model for accurately predicting annual building energy use. [ABSTRACT FROM AUTHOR]

This paper summarizes the results ofa comparative analysis of four models (the Kasten, Muneer, Zhang and Huang, and neural network-based models) used to predict hourly solar radiation for six tropical sites. All four models require cloud cover and nonsolar weather data to predict global, diffuse, and direct solar radiation. Predictions from the models are compared against measured solar data obtained for meteorological stations in the six tropical sites. Nonsolar weather data for the same sites were obtained from the National Climatic Data Center (NCDC). Results of the validation analysis indicate that the Zhang and Huang model is suitable for predicting hourly solar radiation in tropical climates. [ABSTRACT FROM AUTHOR]

This paper presents a connectionist approach using a neural network (NN) and genetic algorithm (GA) to optimize the selection of office building shape. The optimization takes into account both energy and construction costs. In the analysis, the footprint dimensions of the office building are optimized while its volume and height are assumed to be predefined. Various input parameters are considered in the optimization analysis, including climate, window-to-wall ratio, type of glazing, and wall or roof insulation. Results from a whole-building simulation tool are utilized to train and test the NN-GA-based optimization approach. The analysis indicates that the hybrid NN-GA approach offers a robust and efficient method of optimizing the shape selection for office buildings when Bayesian neural networks are utilized instead of conventional neural networks. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of a comparative analysis for three models utilized to predict solar radiation in Tunisia. The three models include the Kasten model, the Zhang and Huang model, and a neural network-based model. The analysis was based on measured solar data for Sidi Bou Saîd (close to Tunis, Tunisia). The measured hourly solar radiation data were obtained from the Tunisian Institut National de la Meterologie (INM) for the year 1997 and include global, direct, and diffuse solar radiation. Non-solar weather data for the same site were obtained from the US National Climatic Data Center (NCDC). The results of the validation analysis indicate that the Zhang and Huang model is suitable for predicting solar radiation in Tunisia. [ABSTRACT FROM AUTHOR]

In this paper, a transient numerical model for a radiant floor panel is integrated into a whole-building simulation program and utilized to evaluate various control strategies. Both conventional and optimal control strategies for hot-water radiant floor systems applied to residential buildings are considered in this paper The optimal controls are developed to maintain an acceptable thermal comfort level for occupants and to reduce heating energy cost. It is found that the optimal controls have the potential to save up to 30% of heating energy use compared to conventional controls. However, the performance of optimal control strategies depends on several design and operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents an integrated IAQ/HVAC simulation environment that can model the impact of contaminant-based demand-controlled ventilation (DCV) strategies on both indoor air quality and HVAC system energy use for multizone buildings. The predictions of the integrated IAQ/HVAC simulation environment are first validated against experimental data obtained from laboratory testing. Then the simulation environment is used to investigate the performance of three ventilation control strategies, namely: one conventional control using fixed-position for outside air damper and two DCV strategies, including on/off control and proportional- integral-derivative (PID) control. In particular a series of parametric analyses is conducted to determine the impact of selected design and operational features of DCV strategies on both indoor air quality and HVAC system energy use. The sensitivity analysis revealed that leakage from outside air dampers, use of a temperature economizers, selection of CO2 sensors, tuning of PID controllers, and selection of CO2 set points can have a significant impaction both indoor air quality and energy consumption of HVAC systems. [ABSTRACT FROM AUTHOR]

The paper summarizes the results of a series of analyses to assess the impact of the selection procedure used to generate of typical year weather on annual building energy use. The building energy analysis is carried out using detailed whole building simulation tool that utilizes hourly typical year weather files. Annual energy use for prototypical office buildings are obtained for 10 sites representing a wide range of climatic conditions in the U.S. In particular, the analyses presented in this paper evaluate the impacts of weighting factors for various weather variables and of the length of historical data used on predicting the energy use of building systems. The results of the analysis indicated that a maximum of 5% difference in annual office building energy use can result from the selection procedure used to generate typical weather year for the 10 US climates considered in this study. [ABSTRACT FROM AUTHOR]

In this paper, the results a series of sensitivity analyses are presented and discussed to assess the impact of the selection methodology to generate a typical weather year suitable for energy analysis of building systems. In particular, the impact of weighting factors associated with various weather variables was investigated. Moreover, the effect of the length of recorded data used to generate the typical year was evaluated. The analysis is carried out for 10 US sites for which measured weather data are reported for at least 30 years. The results indicate that using the TMY2 selection approach it was better to assign more weight to global solar radiation than to direct normal radiation and that 15 years of recorded data would be sufficient to generate a typical weather year. [ABSTRACT FROM AUTHOR]

In this paper, several solar models based on Zhang et al., Zhang and Huang, and Watanabe models are developed and tested against measured solar data obtained for several locations throughout the world. The solar models can predict hourly global, direct normal, and diffuse solar radiation from cloud cover information and non-solar data including dry-bulb temperature, wind speed, and relative humidity. Refinement of the Zhang and Huang model is also carried out to improve its prediction accuracy for tropical climates. Specifically, new coefficients of the model were determined based on regression analysis using measured hourly solar data from various tropical sites. Variations of the Zhang and Huang models requiring fewer input variables were also developed. These model variations were tested for both tropical and non-tropical climates. The analysis results indicated that while only two variables (solar angle and cloud cover) are required to predict hourly global solar radiation for high latitude locations, dry-bulb temperature is required to accurately predict solar radiation for the tropical locations. [ABSTRACT FROM AUTHOR]

This paper evaluates the cooling performance of a personalized partition air supply system, a ceiling air supply system, and an underfloor air supply system using results obtained from full-scale chamber experiments and computational fluid dynamics simulations. The experimental and the simulation results indicate that the partition supply system provides better indoor thermal comfort levels than the ceiling supply system and the underfloor supply system. The partition supply system can reach the desired thermal comfort levels around the occupant faster than the other two systems. It can also reduce the cold draft affecting the occupant by adjusting the operable outlet grilles on the partition. The simulation results agree with the testing data for similar airflow and temperature distributions. [ABSTRACT FROM AUTHOR]

This paper announces the completion of a large new data set of International Weather for Energy Calculations 2 (IWEC2), i.e., typical year, weather files for 3012 locations outside of the U.S. and Canada and describes the procedures used to produce these weather files, including how the raw weather data from the Integrated Surface Hourly (ISH) database were processed and how missing records and unrecorded climate parameters have been derived. Particular attention was paid to the derivation of global horizontal and direct normal solar radiation using a combination of empirical and analytical solar models. The procedure used to select the typical months making up the IWEC2 files from the historical weather record. is also explained. These IWEC2 weather files are then compared to other sources of international weather data and to an earlier, smaller set of IWEC weather files developed in 2001. The IWEC2 weather files are found to have very similar heating degree days, and slightly more cooling degree-days than the IWEC. There is substantially more variation in the solar radiation, with the IWEC2 weather files having somewhat less total and somewhat more direct normal solar radiation than the earlier IWEC weather files. [ABSTRACT FROM AUTHOR]