Modeling and Test-and-Rate Methods for Innovative Thermosiphon Solar Water Heaters: Preprint

Conference paper regarding research in modeling and test-and-rate methods for thermosiphon solar domestic water heaters

Enhanced Sequential Search Methodology for Identifying Cost-Optimal Building Pathways

The BEopt software is a building energy optimization tool that generates a cost-optimal path of building designs from a reference building up to zero-net energy. It employs a sequential search methodology to account for complex energy interactions between building efficiency measures. Enhancement strategies to this search methodology are developed to increase accuracy (ability to identify the true cost-optimal curve) and speed (number of required energy simulations). A test suite of optimizations is used to gauge the effectiveness of each strategy. Combinations of strategies are assembled into packages, ranging from conservative to aggressive, with so up to 71% fewer required simulations are required

Analysis Model for Domestic Hot Water Distribution Systems: Preprint

A thermal model was developed to estimate the energy losses from prototypical domestic hot water (DHW) distribution systems for homes. The developed model, using the TRNSYS simulation software, allows researchers and designers to better evaluate the performance of hot water distribution systems in homes. Modeling results were compared with past experimental study results and showed good agreement

Pipe Freeze Prevention for Passive Solar Water Heaters Using a Room-Air Natural Convection Loop: Preprint

Conference paper regarding research in the use of freeze prevention for passive solar domestic water heating systems

Northward Market Extension for Passive Solar Water Heaters by Using Pipe Freeze Protection with Freeze-Tolerant Piping: Preprint

Conference paper regarding research in freeze-protection methods that could extend market acceptance for passive solar domestic water heating systems in more northern climates if the U.S

Identifying Inefficient Single-Family Homes With Utility Bill Analysis: Preprint

Differentiating between energy-efficient and inefficient single-family homes on a community scale helps identify and prioritize candidates for energy-efficiency upgrades. Prescreening diagnostic procedures can further retrofit efforts by providing efficiency information before a site-visit is conducted. We applied the prescreening diagnostic to a simulated community of homes in Boulder, Colorado and analyzed energy consumption data to identify energy-inefficient homes

Preliminary Measurements of the Energy Impact of Infiltration in a Test Cell

All existing computer models for calculating energy consumption of buildings assume that infiltration increases the heating and cooling load on a building by an amount equal to the mass flow rate of the infiltration times the enthalpy difference between the inside and outside air - with the latent portion of the enthalpy difference sometimes neglected. Recent theoretical and empirical evidence suggests that this approach sometimes, and perhaps often, overstates the energy cost of infiltration. Calorimetric measurements have been conducted on a small test cell with measured amounts of infiltration introduced under conditions: a) where the existing model is expected to give correct results; and b) where the existing model is expected to overstate the energy cost of infiltration significantly. The preliminary data obtained convincingly show that infiltration can lead to a much smaller change in the energy load than is customarily calculated; changes as small as 10 per cent of the calculated value have been measured in a test call. The data also suggest that the phenomenon occurs in full-sized houses as well. This leads us to introduce the infiltration Heat Exchange Effectiveness (IHEE) as a measure of the effectiveness of a building in 'recovering' heat otherwise lost (or gained) due to infiltration. Preliminary investigation of possible correlations between the pressure coefficient determined from fan pressurization data and the infiltration heat exchange effectiveness factor suggest that the fan pressurization results may be useful in predicting the infiltration heat exchange effectiveness factor for buildings

Redesign of Lighting Fixtures for the Texas Department of Corrections

Implementation of these recommendations will result in reduced construction cost of $91,418 and annual operating savings of$88,910 if recommendations 1-5 and 6a are implemented at Amarillo and Gatesville. Use of recommendations 1-5 and 6b will increase first cost by $22,592, but annual operating savings also increase to$98,928 while 6c would provide first cost savings of $67,606 and operating savings of$73,882 annually. Additional maintenance savings will be realized in each case since the fixtures recommended above use tubes with 20,000 - 24,000 hour operating lifetimes instead of the 12,000 hours of the base case tubes.Over 100 tests of potential design modifications for the cell light fixtures used by the Texas Department of Corrections have been conducted. As a result of these tests, the following recommendations are made: 1. Turn diffuser material so prisms face cell. 2. Enlarge diffuser opening to 16 by 46 inches. 3. Replace 1/2-inch hardware cloth by #3 stainless cane weave with 2-inch mesh, painted white. 4. Replace ballasts with Advance R-2S40-TP Mark III or equivalent. 5. Replace blankets with light colored blankets. 6a. Use fixture with four 34 watt tubes if no allowance for fixture degradation is deemed acceptable; 6b. Use fixture with three 40 watt high efficiency tubes and reflector if 10%-15% margin above 20 fc is needed; 6c. Use fixture with four high efficiency tubes if 20% margin above 20 fc is considered necessary

Potencial de economia de energia elétrica através do uso da luz natural e da ventilação híbrida em edifícios comerciais em Florianópolis

O objetivo deste estudo é estimar o potencial de economia de energia elétrica com o uso da luz natural integrada ao sistema de iluminação artificial e a utilização da ventilação híbrida em edifícios comerciais localizados em Florianópolis, SC. O trabalho foi baseado em simulações computacionais nos programas EnergyPlus e Daysim. Foram simulados modelos de ambientes de edificações comerciais, com três geometrias, três dimensões de sala por geometria, dez áreas de janela por modelo e quatro orientações. Os modelos foram examinados por meio de quatro estudos de caso. No Caso 1 (referência), a edificação opera com sistemas de iluminação e de condicionamento artificiais; no Caso 2, ocorre a integração da iluminação natural com a artificial, com condicionamento artificial; já no Caso 3, utilizam-se a ventilação híbrida e a iluminação artificial; no Caso 4, adotam-se a iluminação natural integrada com a artificial e a ventilação híbrida. Os consumos de eletricidade do Caso 1 foram comparados com os demais casos. Assim, foi estimado o potencial de economia de energia elétrica gerado pelo uso da luz natural e ventilação híbrida. Conclui-se que a utilização da iluminação natural e da ventilação híbrida em edificações comerciais localizadas em Florianópolis apresenta potencial de economia de energia elétrica de até 64,9% e que essas estratégias podem ser utilizadas para aumentar a eficiência energética desse tipo de edificação

Performance evaluation of damper control settings for operation of multiple-zone variable air volume reheat system in different building applications and climate types

Choosing the right control strategies is an important task for effective operation of variable air volume reheat (VAVR) system in commercial buildings. In this design, dampers’ position inside air terminal units (ATUs) are modulated to adjust the amount of air supply volume based on thermal zones’ cooling or heating demand. A minimum air flow fraction (MAFF) is set for damper settings of ATUs to avoid under-ventilation problem in thermal zones. This study investigated the impact of MAFF value on various performance aspects of multiple-zone VAVR design in different building applications and climate types. A five-storey commercial building for three applications of school, office and retail in four climate types of tropical monsoon, hot desert, Mediterranean and humid continental have been simulated in EnergyPlus building simulation software. The results of simulations have shown that lowering MAFF value in ATUs would reduce the required reheat coil energy to maintain precise air supply temperature at part load cooling scenarios. Nonetheless, this reduction could have some implications on thermal comfort and indoor air quality level of thermal zones in a multiple-zone arrangement. It was concluded that in general it is an energy efficient control strategy to keep MAFF value to as low as 0.1 for high ventilation rate spaces like classrooms in school buildings (except for hot desert climate). On the other hand, it is advisable to not reduce MAFF value below 0.3 for low ventilation rate spaces like office areas to avoid any air quality issues in thermal zones