2024-03-28T14:15:38Zhttps://escholarship.org/oaioai:escholarship.org:ark:/13030/qt8ms2x24r2021-12-01T21:16:49Zqt8ms2x24rQuantification on Fuel Cell Degradation and Techno-Economic Analysis of a Hydrogen-Based Grid-Interactive Residential Energy Sharing Network with Fuel-Cell-Powered VehiclesHe, YingdongZhou, YuekuanWang, ZheLiu, JiaLiu, ZhengxuanZhang, Guoqiang2021-08-23Hydrogen-based (H2-based) interactive energy networks for buildings and transportations provide novel solutions for carbon-neutrality transition, regional energy flexibility and independence on fossil fuel consumption, where vehicle fuel cells are key components for H2-electricity conversion and clean power supply. However, due to the complexity in thermodynamic working environments and frequent on/off operations, the proton exchange membrane fuel cells (PEMFCs) suffer from performance degradation, depending on cabin heat balance and power requirements, and the ignorance of the degradation may lead to the performance overestimation. In order to quantify fuel cell degradation in both daily cruise and vehicle-to-grid (V2G) interactions, this study firstly proposes a two-space cabin thermal model to quantify the ambient temperature of vehicle PEMFCs and the power supply from PEMFCs to vehicle HVAC systems. Afterwards, a stack voltage model is proposed to quantify the fuel cell degradation for multiple purposes, such as daily transportation and V2G interactions. Afterwards, the two models are coupled in a community-level based building-vehicle energy network, consisting of twenty single residential buildings, rooftop PV systems, four hydrogen vehicles (HVs), a H2 station, community-served micro power grid, local main power grid, and local H2 pipelines, located in California, U.S.A. Comparative analysis with and without fuel cell degradation is conducted to study the impact of dynamic fuel cell degradation on the energy flexibility and operating cost. Furthermore, a parametrical analysis is conducted on the integrated HV quantity and the grid feed-in tariff to reach trade-off strategies between associated fuel cell degradation costs and grid import cost savings. The results indicate that, in the proposed hydrogen-based building-vehicle energy network, the total fuel cell degradation is 3.16% per vehicle within one year, where 2.50% and 0.66% are caused by daily transportation and V2G interactions, respectively. Furthermore, in the H2-based residential community, the total fuel cell degradation cost is US$6945.2, accounting for 33.4% of the total operating cost at $20770.61. The sensitivity analysis results showed that, when the HV quantity increases to twenty, the fuel cell degradation of each HV decreases to 2.50%, whereas the total fuel cell degradation cost increases to 42.8% of the total operating cost. Last but not the least, the cost saving by V2G interactions can compensate the fuel cell degradation cost when the grid feed-in tariff is reduced by 40%. Research results can provide basic modelling tools on dynamic fuel cell degradation, in respect to vehicle power supply, vehicle HVAC and V2G interactions, together with techno-economic feasibility analysis, paving path for the development of hydrogen energy for the carbon-neutrality transition.Solar energyWind turbineFuel cell degradationCabin thermal modelHydrogen energy storage and economyDistributed hydrogen infrastructureapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/8ms2x24rpublicationoai:escholarship.org:ark:/13030/qt61g3g2672021-12-01T21:15:49Zqt61g3g267Transformation Towards a Carbon-Neutral Residential Community with Hydrogen Economy and Advanced Energy Management StrategiesHe, YingdongZhou, YuekuanYuan, JingLiu, ZhengxuanWang, ZheZhang, Guoqiang2021-10-09Cleaner power production, distributed renewable generation, building-vehicle integration, hydrogen storage and associated infrastructures are promising for transformation towards a carbon-neutral community, whereas the academia provides limited information through integrated solutions, like intermittent renewable integration, hydrogen sharing network, smart operation on electrolyzer and fuel cell, seasonal hydrogen storage and advanced heat recovery. This study proposes a hybrid electricity-hydrogen sharing system in California, United States, with synergistic electric, thermal and hydrogen interactions, including low-rise houses, rooftop photovoltaic panels, hydrogen vehicles, a hydrogen station, micro and utility power grid and hydrogen pipelines. Advanced energy management strategies were proposed to enhance energy flexibility and grid stability. Besides, simulation-based optimizations on smart power flows of vehicle-to-grid interaction and electrolyzer are conducted for further seasonal grid stability and annual cost saving. The obtained results indicate that, the green renewable-to-hydrogen can effectively reduce reliance on pipelines delivered hydrogen, and the hydrogen station is effective to address security concerns of high-pressure hydrogen and improve participators’ acceptance. Microgrid peer-to-peer sharing can improve hydrogen system efficiency under idling modes. Furthermore, the integrated system can reduce the annual net hydrogen consumption in transportation from 127.0 to 1.2 kg/vehicle. The smart operation (minimum input power of electrolyzer and fuel cell at 65 and 80 kW) can reduce the maximum mean hourly grid power to 78.2 kW by 24.2% and the annual energy cost to 1228.5 $/household by 38.9%. The proposed district hydrogen-based community framework can provide cutting-edge techno-economic guidelines for carbon-neutral transition with district peer-to-peer energy sharing, zero-energy buildings, hydrogen-based transportations together with smart strategies for high energy flexibility.Solar energyDistributed renewable energy sharingFlexible energy management strategyHydrogen energy storage and economyDistributed hydrogen infrastructureapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/61g3g267publicationoai:escholarship.org:ark:/13030/qt5th5s8qb2021-11-15T19:42:30Zqt5th5s8qbApplication of Gagge’s Energy Balance Model to Determine Humidity-Dependent Temperature Thresholds for Healthy Adults Using Electric Fans During HeatwavesTartarini, FedericoSchiavon, StefanoJay, OllieArens, EdwardHuizenga, Charlie2021-10-16Heatwaves are one of the most dangerous natural hazards causing more than 166,000 deaths from 1998–2017. Their frequency is increasing, and they are becoming more intense. Electric fans are an efficient, and sustainable solution to cool people. They are, for most applications, the cheapest cooling technology available. However, many national and international health guidelines actively advise people not to use them when indoor air temperatures exceed the skin temperature, approximately 35°C. We used a human energy balance model, to verify the validity of those recommendations and to determine under which environmental (air temperature, relative humidity, air speed and mean radiant temperature) and personal (metabolic rate, clothing) conditions the use of fans would be beneficial. We found that current guidelines are too restrictive. Electric fans can be used safely even if the indoor dry-bulb temperature exceeds 35°C since they significantly increase the amount of sweat that evaporates from the skin. The use of elevated air speeds (0.8m/s) increases the critical operative temperature at which heat strain is expected to occur by an average of 1.4°C for relative humidity values above 22%. We also analysed the most extreme weather events from 1990 to 2014 recorded in the 115 most populous cities worldwide, and we determined that in 103 of them the use of fans would have been beneficial. We developed a free, open-source, and easy-to-use online tool to help researchers, building practitioners, and policymakers better understand under which conditions electric fans can be safely used to cool people.ResilienceHeat stressCoolingAir movementHeat StrainOpen-source toolapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/5th5s8qbpublicationoai:escholarship.org:ark:/13030/qt8fs0k03g2020-07-14T23:20:13Zqt8fs0k03gPlug Load Energy Analysis: The Role of Plug Loads in LEED CertificationFuertes, GwenSchiavon, Stefano2013-01-07Plug loads use 12% of site energy in U.S. office buildings. The relative importance of plug loads is rising and it is projected to increase more in years to come. We studied the predicted and simulated plug load energy consumption using data submitted to the U.S. Green Building Council for LEED certification. The study included 660 LEED for Commercial Interiors projects and 429 LEED for New Construction projects. This is the first study to analyze LEED submittal data related to plug load energy use. The submittal data from these projects was mined and statistically analyzed. The results show that 73% of the projects under LEED-CI that attempted the credit dedicated to plug loads earned 2 of 2 points available (90% or more of eligible equipment is ENERGY STAR rate). Additionally, we found that projects most frequently specify ENERGY STAR rated laptops, monitors, desktops and printers, whereas televisions, fax machines, refrigerators and dishwashers were less frequently specified. Under LEED-NC, the median peak plug load power intensity reported among the projects was 10.8 W/m2. Most of the projects complied with the LEED requirement of 25% process load energy use, with the median percentage being 25% and the 1st and 3rd quartiles ranging from 18% to 31%. 32% of the projects reported using eQUEST as an energy simulation tool. Only 5 of 429 LEED-NC projects reviewed attempted and were approved exceptional calculations for claiming energy savings on efficient plug loads or office equipment.plug loadsLEED certificationenergy simulationENERGY STARapplication/pdfCC-BYeScholarship, University of Californiahttps://escholarship.org/uc/item/8fs0k03gpublicationoai:escholarship.org:ark:/13030/qt2j83q6pb2020-07-13T16:41:27Zqt2j83q6pbOptimizing energy conservation measures in a grocery store using present and future weather filesAijazi, Arfa NBest, RobSchiavon, Stefano2019-09-01Grocery stores are one of the most energy intensive building types, which makes targets for zero net energy (ZNE) particularly challenging. This study builds on a prior computational optimization study to identify combinations of energy conservation measures (ECMs) for an existing grocery store in San Francisco. As the climate changes, also the retrofit recommendations based on simulation results from historical-based weather files may vary. In this paper, we looked at how the optimization results change when accounting for climatechanges over the building’s service life by using future weather files. We found that the expected changes in future weather are sufficient to alter retrofit recommendations. This type of analysis is thus important to ensure that buildings designed now can continue to meet performance objectives into the future.climate change adaptationwhole building energyretrofitzero net energybuilding energy simulationapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/2j83q6pbpublicationoai:escholarship.org:ark:/13030/qt5c3460r12020-02-12T22:11:47Zqt5c3460r1Urban form and climate: case study, TorontoBosselmann, PeterArens, EdwardDunker, KlausWright, Robert1995-04-01This article describes a joint urban design study by the Berkeley Environmental Stimulation Laboratory and the Centre for Landscape Research at the University of Toronto. The study analyzed the effect of future development in Toronto's Central Area on streetlevel conditions of sun, wind, and thermal comfort. The study originated in response to public concern about the quality of the downtown environment and to implementation measures adopted by the Toronto city council in May 1993. The research presented in this article examines the shadowing produced by downtown buildings and recommends procedures and standards for preserving sunlight on Toronto's downtown sidewalks and open spaces. Second, this study considers the effects of buildings on wind conditions at street level. Third, the study evaluates the combined effects of sun and wind conditions on pedestrian comfort. Rather than focusing on just the effects of individual buildings, this research evaluates the cumulative effects of area-wide development.application/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/5c3460r1articleJournal of the American Planning Associationvol 61, iss 2oai:escholarship.org:ark:/13030/qt6tj0s2bm2019-12-02T16:35:45Zqt6tj0s2bmLessons learned from field monitoring of two radiant slab office buildings in CaliforniaBauman, FredRaftery, PaulKarmann, Caroline2015-01-01In this paper we present the results from field studies of two low-energy office buildings in California, both using radiant slab ceiling systems (thermally activated building systems, TABS) for primary cooling and heating in the buildings. Both buildings are certified LEED Platinum and incorporate a wide range of energy efficient technologies and design strategies, including TABS, advanced shading systems, underfloor air distribution, chilled beams, ceiling fans, natural ventilation, and photovoltaic panels. Findings and analysis from the following building performance assessment techniques will be discussed. - Occupant satisfaction survey. Occupant surveys are an invaluable source of information for describing how well the building is providing a high quality indoor environment for the occupants. In addition, the survey results are also compared against a large benchmark survey database of over 50,000 occupants. - Wireless measurement system. A network of wireless sensors was installed in selected zones of the buildings to provide additional more detailed information about the operation and control of the radiant slab system. This data was combined with trend data from the building management system (BMS) to examine the performance of the buildings during both winter and summer conditions. Some control issues were identified and corrected based on these measurements.- Energy performance analysis. We collected utility data for 2014 in one of the buildings and used this information to determine the building’s Energy Star rating.Thermally activated building systemsradiant slab systemswhole-building technologiesenergy efficiencyoccupant surveyfield monitoringcontrolsapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/6tj0s2bmpublicationoai:escholarship.org:ark:/13030/qt1885072n2019-05-06T20:26:03Zqt1885072nDesigning for the future: Are today’s building codes locking in the wrong strategies by using past climate data?Waltner, MegAijazi, Arfa2018-01-01California has set goals for zero net energy buildings and greenhouse gas emissions reductions that will be achieved in part through the state’s building energy codes. Decisions about what measures to include in code are informed by building energy models that rely on historical climate data. However, even under moderate emissions scenarios, by 2050 mean temperatures in California are projected to increase by almost 4 degrees Fahrenheit compared to pre-1990 levels and there is evidence that current day temperatures are already shifted from the historical record. Not only do these energy models underlie cost-effectiveness analyses which influence the prescriptive code, they inform building system selection and sizing, and they are the basis for program incentive awards. While the general trends are predictable – as temperatures increase, average cooling energy increases and heating decreases – the effects of future climate on the state’s building policies have not been thoroughly analyzed. To what extent will lower winter heating loads increase the business case for buildings to electrify? Under future climate, are increased cooling efficiency measures cost-effective that aren’t today? How will future climate affect the energy and emissions performance of California’s buildings and what policies can be adopted today to future-proof them? This paper starts to address these questions by examining the performance of prototype buildings within a subset of California’s climate zones under past and future climate scenarios. It models energy efficiency measure variants to these prototypes and compares the energy, emission, cost, and thermal load outcomes under future climate scenarios compared to historical design weather and makes policy recommendations based on the results.application/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/1885072npublicationoai:escholarship.org:ark:/13030/qt0s43g0822019-04-16T05:27:45Zqt0s43g082Sensitivity of passive design strategies to climate changeAijazi, ArfaBrager, Gail2018-12-10Observed global warming trends undermine the conventional practice of using historic weather files, such as Typical Meteorological Year (TMY), to predict building performance during the design process. In order to limit adverse impacts such as improperly sized mechanical equipment or thermal discomfort, it is important to consider how the building will perform in the future. Like all passive design strategies, natural ventilation, relies on local climate to be effective in improving building performance. This paper combines future weather files with whole building energy simulations to assess the sensitivity and feasibility of natural ventilation in providing thermal comfort in three locations, representing different climate types. The results show how building performance, as measured by thermal comfort metrics, changes over time. Natural ventilation can provide a buffer against warming climate, but only to a certain extent. Future weather files are useful for identifying where and when there is a risk that an exclusively passive design is no longer possible.Natural VentilationClimate ChangeThermal ComfortSimulationapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/0s43g082publicationoai:escholarship.org:ark:/13030/qt0pc847pb2018-10-30T16:50:05Zqt0pc847pbUnderstanding Climate Change Impacts on Building Energy UseAijazi, ArfaBrager, Gail2018-10-01Climate changeadaptationresilienceapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/0pc847pbarticleASHRAE Journalvol 60, iss 10oai:escholarship.org:ark:/13030/qt70w098tb2018-10-30T16:49:34Zqt70w098tbA Conversation on Adaptation in the Built EnvironmentAijazi, ArfaBrager, Gail2018-10-01Climate changeadaptationresilienceapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/70w098tbarticleASHRAE Journalvol 60, iss 10oai:escholarship.org:ark:/13030/qt7qg1945w2018-05-16T21:09:48Zqt7qg1945wEffective Daylighting: Evaluating Daylighting Performance in the San Francisco Federal Building from the Perspective of Building OccupantsKonis, Kyle Stas2012-01-30Commercial office buildings promoted as “sustainable,” “energy efficient,” “green,” or“high performance” often reference use of daylight as a key strategy for reducing energyconsumption and enhancing indoor environmental quality. However, buildings are rarelystudied in use to examine if the design intent of a sufficiently daylit and a visuallycomfortable work environment is achieved from the perspective of building occupants orhow occupant use of shading devices may affect electrical lighting energy reduction fromphotocontrols. This dissertation develops a field-based approach to daylightingperformance assessment that pairs repeated measures of occupant subjective responseusing a novel desktop polling station device with measurements of the physicalenvironment acquired using High Dynamic Range (HDR) imaging and otherenvironmental sensors with the objective of understanding the physical environmentalconditions acceptable to occupants. The approach is demonstrated with a 6-month fieldstudy involving (N=44) occupants located in perimeter and core open-plan office spacesin the San Francisco Federal Building1 (SFFB). Over 23,100 subjective assessmentspaired with physical measures were analyzed to develop models of visual discomfort andshade control and to examine the assumptions of existing daylighting performanceindicators. The analysis found that existing daylight performance indicatorsoverestimated the levels of daylight illuminance required by occupants to workcomfortably without overhead ambient electrical lighting. Time-lapse observation ofinterior roller shades showed that existing shade control models overestimated thefrequency of shade operation and underestimated the level of facade occlusion due tointerior shades. Comparison of measured results to the daylighting objectives of theSFFB showed that available daylight enabled electrical lighting energy reduction in theperimeter zones but not in the open-plan core zones. The results extend existingknowledge regarding the amount of daylight illuminance acceptable for occupants towork comfortably without overhead electrical lighting and for the physical variables (andstimulus intensities) associated with visual discomfort and the operation of interiorshading devices.daylightingdaylighting assessmentSan Francisco Federal Buildingapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/7qg1945wmonographoai:escholarship.org:ark:/13030/qt748006tf2017-11-28T18:55:58Zqt748006tfMeasuring the effectiveness of San Francisco's planning standard for pedestrian wind comfortKim, HyungkyooMacdonald, Elizabeth2016-09-26In 1985, San Francisco adopted a wind comfort standard in its Downtown Area Plan in response to increasing concerns about the city’s downtown public open spaces becoming excessively windy. After 30 years of implementation, this study revisits the standard and examines its effectiveness in promoting pedestrian comfort. 701 valid samples were collected from 6 months of field study, which combined surveying pedestrians and on-site collection of microclimate data. Statistical analysis and an assessment using the physiological equivalent temperature (PET) show that 11 mph (4.92 m/s), the comfort criterion in places for walking, performs as an effective determinant of outdoor comfort in San Francisco. This study sheds light on climate-resilience of cities as they have become key urban challenges today.WindOutdoor thermal comfortUrban planningField studyPhysiological equivalent temperatureSan Franciscoapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/748006tfpublicationoai:escholarship.org:ark:/13030/qt2z5974682017-07-26T20:52:52Zqt2z597468PMV-based event-triggered mechanism for building energy management under uncertaintiesXu, ZhanboHu, GuoqiangSpanos, Costas JSchiavon, Stefano2017-10-01This paper provides a study of the optimal scheduling of building operation to minimize its energy cost under building operation uncertainties. Opposed to the usual way that describes thermal comfort using a static range of air temperature, the optimization of a tradeoff between energy cost and thermal comfort predicted mean vote (PMV) index is addressed in this paper. In order to integrate the calculation of the PMV index with the optimization procedure, we develop a sufficiently accurate approximation of the original PMV model which is computationally efficient. We develop a model-based periodic event-triggered mechanism (ETM) to handle the uncertainties in the building operation. Upon the triggering of predefined events, the ETM determines whether the optimal strategy should be recalculated. In this way, the communication and computational resources required can be significantly reduced. Numerical results show that the ETM method is robust with respect to the uncertainties in prediction errors and results in a reduction of more than 60% in computation without perceivable degradation in system performance as compared to a typical closed-loop model predictive control.Building energy managementevent-triggered mechanismoperational optimizationpredicted mean vote (PMV) indexuncertainties in building operationapplication/pdfCC-BY-NC-SAeScholarship, University of Californiahttps://escholarship.org/uc/item/2z597468publicationoai:escholarship.org:ark:/13030/qt6gz6t90p2016-08-09T19:25:21Zqt6gz6t90pDoes Wind Discourage Sustainable Transportation Mode Choice? Findings from San Francisco, California, USAKim, HyungkyooMacdonald, Elizabeth2016-03-10This paper explores whether and to what extent wind discourages sustainable transportation mode choice, which includes riding public transportation, bicycling, and walking. A six month-long field study was carried out at four locations in San Francisco, a city that has been promoting sustainable transportation mode choice but that experiences high wind levels. It involved surveying pedestrians and on-site recording of microclimate data using various instruments. The survey adopted a mixed-method approach to collect both quantitative and qualitative data. Statistical analyses using Kruskal Wallis tests and ordinal logistic regression models identified the significant effect of wind speed on San Francisco’s residents in estimating their discouragement for waiting at transit stop without shelter, bicycling, and walking. Qualitative data revealed a deeper understanding of how wind influences their sustainable transportation mode choice. This research argues for the need to adopt climate-based efforts in urban planning and policy and sheds light on the climate resilience of citieswindsustainable transportation modemixed-methodSan Franciscoapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/6gz6t90particleSustainabilityvol 8, iss 3, 2572071-1050oai:escholarship.org:ark:/13030/qt0h50x0h82016-08-09T19:10:27Zqt0h50x0h8Urban Form, Wind, Comfort, and Sustainability: The San Francisco ExperienceKim, Hyungkyoo2014-04-01In 1985, spurred by the residents’ strong interest in the quality of the built environment and in securing comfort in public open spaces, San Francisco became the first city in North America to adopt a downtown plan, supplemented by a planning code, on ground-level wind currents to mitigate the effects of adverse wind. Since then, the plan has mandated that new developments in the downtown and four additional areas in the Rincon Hill, South of Market, Van Ness, and South Beach neighborhoods, all associated with high density or development potential and substantial outdoor activities, be designed or adopt wind-baffling measures so as to not cause ground-level wind current in excess of 7 mph in places for seating and 11 mph in those for walking for no more than ten percent of the time year round, between 7 am and 6 pm, to minimize potential discomfort generated by excessive ground-level wind currents; and 26 mph for no more than one hour per year to secure pedestrian safety.This research examines whether San Francisco’s plan on ground-level wind currents made the city’s public open spaces more comfortable and what is the impact on use of sustainable transportation modes. More specifically, it studies (1) whether the plan changed San Francisco’s urban form so as to provide a more wind-comfortable environment; (2) whether the wind speed criteria stipulated in the plan effective determinants of outdoor comfort in San Francisco; and (3) whether the plan achieves a wind comfort level that would increase the residents’ willingness to use sustainable transportation modes.Two types of methods were adopted in this research: wind tunnel tests and field studies. The wind tunnel tests, carried out in 2013 at the Center for Environmental Design Research (CEDR), use a boundary layer wind tunnel in which the wind movement in a selected urban area is simulated through use of a scale model of the area’s built form. The field study, carried out from July 2012 to December 2012, consisted of pedestrian survey combined with on-site collection of microclimate data, such as wind speed, temperature, relative humidity, and solar radiation. The two methods are effective in addressing the relationships that the sub-research questions seek to examine and the nature of the variables that need to be measured. They also successfully1incorporate a mixed-method approach that amalgamates qualitative methods such as observation, interview, and mapping with quantitative statistical analyses.This research presents the following findings. First, San Francisco’s wind planning has changed the city’s urban form so as to provide a more wind comfortable environment. Through a series of simulations using the boundary layer wind tunnel and comparing the wind speed ratios at 318 locations in the selected sites of Yerba Buena, Van Ness, Civic Center, and Mission Bay North in the 1985 and 2013 urban form conditions, it was discovered that the overall mean wind speed ratio dropped by 22 percent from 0.279 in 1985 to 0.218 in 2013. It means that the urban forms of the four sites have been changed so that the expected actual ground-level wind speeds have decreased by the same rate. However, there still exist a number of excessively windy places in San Francisco that are associated with specific urban form conditions, including direct exposure of street orientation to the west wind, high-rise building façades that directly meet the ground, and continuous street walls.Second, through on-site surveys and microclimate measurements, it was discovered that wind speed significantly affects people’s perceived outdoor comfort and that 11 mph is an effective criterion that determines outdoor thermal comfort in San Francisco. Significant differences are found in the frequency distributions of people’s responses to all of the four comfort measures, which are thermal sensation, wind sensation, wind preference, and overall comfort. Also, the net effects of equivalent wind speed on the comfort measures are strong when the speed is less than 11 mph but become weaker when the speed is 11 mph or higher, meaning that there exists a difference in how much wind determines comfort between the two wind conditions. However, a wide range of dimensions on how people perceive wind and comfort exists, including adaptation, surrender, and avoid, which makes it difficult to judge the effectiveness easily.Third, the research findings suggest that San Francisco’s wind planning does not achieve a wind comfort level that would increase people’s willingness to use sustainable transportation modes. It was found that higher wind levels discourage people to wait at transit stop with no shelter, to bike, to walk outside, or to sit outside. Also, significant differences with regard to people’s willingness to use sustainable transportation modes exist between when the equivalent wind speed is less than 11 mph and when it is 11 mph or higher. However, the net effects of equivalent wind speed in both wind conditions were not statistically significant, indicating that the criterion does not successfully determine whether people are comfortable enough to be willing to use sustainable transportation modes. Although the criterion was not originally developed to consider the use of sustainable transportation modes, it can be suggested that the criterion can be revised.A wide range of solutions must be studies for cities in varied climate regions. Cities and regions should not only study and develop their own climate-based ways to make a more climate- responsive city but also vigorously evaluate their effectiveness. Collaboration and cooperation between urban design, urban climatology, and many other relevant fields of expertise is crucial in future research and practice.City PlanningSustainabilityArchitectureapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/0h50x0h8publicationoai:escholarship.org:ark:/13030/qt2dm1k82k2016-08-08T23:35:34Zqt2dm1k82kWind and the city: An evaluation of San Francisco's planning approach since 1985Kim, HyungkyooMacdonald, Elizabeth2015-09-24In 1985, San Francisco adopted a downtown plan on ground-level wind currents intended to mitigate the negative effects of wind on pedestrians’ perceived comfort in public open spaces. The plan mandates that new buildings in designated parts of the city associated with high density or development potential be designed or adopt measures to not cause wind in excess of accepted comfort levels. This study examines whether and to what degree the plan has successfully shaped an urban form that mitigates wind by comparing the ground-level wind environment in 1985 and 2013. A series of wind tunnel tests found that during San Francisco’s windiest season when the westerly winds are prevalent, the overall mean wind speed ratio measured at 318 locations in four areas of the city dropped by 22 percent. However, there still exist many excessively windy places that are associated with specific urban form conditions, including streets oriented to have direct exposure to westerly winds, flat façades on high-rise buildings, and horizontal street walls where building façades align. Recommendations based on the findings include incorporating more tangible guidance on the built form conditions, expanding the plan’s reach to cover more parts of the city, and learning from strategies used elsewhere. By evaluating the urban form impacts of a wind mitigation policy that has been in place for 30 years, the research offers insights for other cities that have implemented or plan to adopt similar approach and sheds light on issues related to wind comfort in high-density urban areas.urban formwindoutdoor comfortSan Franciscowind tunnel simulationapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/2dm1k82kpublicationoai:escholarship.org:ark:/13030/qt6n99w3bx2016-05-13T15:46:30Zqt6n99w3bxPerformance, Prediction and Optimization of Night Ventilation across Different ClimatesLandsman, Jared2016-04-01Night ventilation, or night flushing, is a passive cooling technique that utilizes the outdoor diurnal temperature swing and the building’s thermal mass to pre-cool a building through increased outdoor airflow at night, allowing radiant cooling to take place during the day when the building is occupied. Previous studies have demonstrated a potential reduction in cooling load and improvement in comfort from the implementation of night ventilation. However, very few field studies have been done looking at the impact of location and climate on night ventilation performance. This thesis describes the performance, in terms of indoor environmental conditions, of three buildings from both the U.S. and India that use night ventilation as their primary cooling method. The analysis is based on monitored data collected from each building (ranging in duration from two months to one year), including indoor and outdoor air temperature, mass temperature, supply temperature, and airflow rate. The first building, located in Oakland, California, uses forced ventilation at night to increase the airflow. The second building, located in Sunnyvale, California, uses natural ventilation by means of automated windows. The third building, in Auroville, India, uses natural ventilation by means of occupant-controlled windows. The research methods used the following approach: 1) Assess the cooling strategy by comparing indoor conditions from days that did and did not use night ventilation, specifically in relation to the adaptive comfort model; 2) Develop a hybrid model, using both first principle equations and the collected data, to predict the instantaneous air and mass temperatures within each building; 3) Determine an optimized ventilation control strategy for each building to minimize energy and maintain comfortable temperatures. The study yielded the following results: 1) The buildings in the mild climate are successfully keeping the indoor temperature low, but also tend to be overcooling; 2) The night ventilation strategy has very little impact on the indoor conditions of the buildings in the mild climate; 3) The impact of night ventilation is less significant when there is low internal loads and heavy mass; 4) The building in the hot and humid climate is keeping the indoor temperature within the comfort bounds for 88% of the year; 5) The night ventilation strategy has advantageous impact on indoor conditons of the building in the hot and humid climate, but not enough to cool the space on its own; 6) Model predictive control has the potential to further improve the performance of night ventilation.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/6n99w3bxpublicationoai:escholarship.org:ark:/13030/qt2c76d4nw2015-09-21T22:08:29Zqt2c76d4nwCommercial Office Plug Load Energy Consumption Trends and the Role of Occupant BehaviorGandhi, Priya2015-09-21Plug loads are an increasingly important end-use in commercial office buildings. They currently account for 12-50% of total commercial building energy consumption, and as the efficiencies ofregulated major end-uses, such as space conditioning and lighting systems, continue to increase, plugload energy use is expected to rise. This study evaluates patterns in collected plug load data and the effect of a behavior-based intervention to reduce plug load energy consumption.This project leverages a data collection effort originally funded for a study by the California AirResources Board, where 100 plug load monitoring power strips were installed at individualworkstations in the Franklin Building, an office building in Oakland owned by the UC Office of thePresident (UCOP). Each occupant received one power strip and connected up to four devices to beindividually monitored. For this project, only the labeled devices (desktop, laptop, monitor, task light)are included. An analysis of the collected data reveals a clear distinction between work days and non-work days(weekends and holidays). Overall, the monitored occupants have regular work schedules, turn off theirequipment at the end of the work day, and do not often stay late or come in on the weekends. Desktops consume the most power per person, followed by monitors and then task lights. Laptop power trendswere more difficult to discern because users often disconnect them to work in other locations (that werenot monitored). Desktops demonstrate the widest range of power consumption among the devicesmonitored. During unoccupied periods (overnight and on non-work days), desktops draw the mostpower, followed by laptops. All devices draw more power overnight on work days than over weekendsand holidays, indicating that users are more likely to turn equipment off before a longer break from theoffice. Much of the literature on reducing plug load energy consumption in commercial buildings is focusedon technology-based solutions, such as purchasing new equipment or installing sophisticated controlsto turn off equipment when not in use. The literature on changing occupant behavior to reduce energyuse is focused on residential occupants, however multiple studies show that even when occupants donot pay their own bills and have no financial incentive to save energy, other factors can encouragebehavior change. One such motivating method is by using gamification, or turning an everyday activity into a game to encourage behavior change by making it more fun and interesting.With the help of leadership at UCOP, an online sustainability game, Cool Choices, was initiated in theFall of 2014 and 30 employees signed up to play. Cool Choices encourages occupant behavior changesto save water, energy, and reduce waste; players earn points for each action they complete at work or athome and compete with each other on teams. Survey responses from game participants showed thatplayers were motivated to play because the game looked fun, and because the actions suggested wereeasy to perform. An analysis of the energy impact revealed that because occupants were alreadyengaging in relevant energy saving behaviors (e.g. turning equipment off at the end of the day), therewas limited opportunity for further behavior-based reductions. Using trends identified in the baseline analysis, a simplified plug load model was developed to predictpower consumption based on device type, day type (work day or non-work day), and time step, using aMonte Carlo simulation. The model used day type and time step as proxies for occupancy, so when occupancy was not well predicted by the work day/non-work day dichotomy, the model becameincreasingly unreliable. Even after adding an additional variable (month), the model was still not ableto predict power consumption to an acceptable degree of accuracy per industry standards. The model demonstrated a need for a new, more accurate proxy for occupancy, perhaps based on individualoccupants, rather than devices. application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/2c76d4nwpublicationoai:escholarship.org:ark:/13030/qt935461rm2015-02-10T18:12:02Zqt935461rmQuantifying the Comprehensive Greenhouse Gas Co-Benefits of Green BuildingsMozingo, LouiseArens, Ed2014-10-24This report quantifies, for the first time, the greenhouse gas (GHG) emissions co-‐benefits associated with water, waste and transportation usage in certified green commercial office buildings in California. The study compares the measured values of water, waste and transportation usage self-‐reported by a set of office buildings certified under the Leadership in Energy and Environmental Design rating system for Existing Building Operations and Maintenance (LEED-‐EBOM) to both baseline values of conventional California office buildings and predicted values based upon state standards for green buildings and GHG impact prediction methods. The green buildings in the LEED-‐EBOM dataset produced 50% less GHGs due to water consumption than baseline buildings, 48% less due to solid waste management, and 5% less due to transportation. If applied to the entire California office building stock, performance typical of the certified green buildings would save 0.703 MMTCO2e/yr from transportation, 0.084 MMTCO2e/yr from water, and 0.044 MMTCO2e/yr from waste, for a total potential savings of about 0.831 MMTCO2e/yr relative to conventional construction. In addition, buildings earning additional credits for specified performance thresholds for water and waste in the LEED-‐EBOM code attained performance levels even higher than required by the code provisions, suggesting that such code provisions in other contexts may help incentivize larger GHG emissions reductions than anticipated.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/935461rmpublicationoai:escholarship.org:ark:/13030/qt1g55n6352014-12-04T18:00:48Zqt1g55n635Designing for an acceptable wind environmentArens, Edward A1981-03-01Tall or exposed buildings adjacent to public open spaces may cause local winds at ground level that are much more intense than winds found elsewhere at ground level. These winds may affect the comfort and safety of pedestrians and thus reduce the usefulness of the outdoor open spaces. In recent years, wind problems have become more common, as more tall buildings are built and as cities and building owners place increasing emphasis on public plazas and open space. Since both the cost and economic benefits of such plazas and open space may be very high, significant financial losses may occur when such spaces re rendered unusable due to wind.The designers of buildings and their sites would benefit from being able to anticipate, in the planning stage, the possibility of local wind flow zones that cause unacceptable discomfort to users of outdoor space. If such zones are found, appropriate design decisions can eliminate them or direct pedestrians away from them.This paper reviews present knowledge of pedestrian comfort in the wind and outlines how to design projects that avoid unacceptable wind environment.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/1g55n635publicationoai:escholarship.org:ark:/13030/qt2rx7w3942014-02-27T20:30:47Zqt2rx7w394Office tenant needs studyMurray, S.Powell, K.1999-10-01CBE and the Fisher Center for Real Estate and Urban Economics were approached by Spieker properties in June of 1999 to help them better understand the emerging needs of leading-edge office tenants. Spieker Properties is one of the nation’s largest publicly traded real estate companies, with over 40 million square feet of commercial properties located in California and the PacificNorthwest.Spieker was specifically interested in ensuring the long-term value of their existing portfolio of space, and making sure that they were looking at the correct mix of services and infrastructure to appeal to a new profile of client in high technology, bio-technology and service sector industries. Specifically, would these leading-edge industries be interested in leading-edge building and office technologies?CBE was interested in the study because it gave our Center an opportunity to talk with end-users about the kinds of new technologies and building management practices they have been considering for their buildings, and to put into context the desirability and marketability of these technologies and practices.The Office Tenant Needs Study was organized around focus groups of 8 to 15 people. Participants were selected jointly by CBE staff and Spieker Properties based on business sector (high-tech, bio-tech or services) and company profile (size, geographic scope, revenues and space use).Focus groups are rarely a definitive sample of user attitudes and needs. What they offer instead is a reality check on assumptions we may be working under in our research, and (if they work well) a vibrant "brainstorming" approach to issue identification and clarification.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/2rx7w394publicationoai:escholarship.org:ark:/13030/qt1b4358202014-02-20T21:23:52Zqt1b435820Case study of CalSTRS headquartersGoins, JohnMoezzi, Mithra2011-08-01It is a widely accepted fact that buildings must use less energy and reduce greenhouse gas (GHG) emissions to help mitigate global climate change. At the same time, buildings are for people: to succeed they must also provide environments that suit their intended occupants. Researchers usually consider these two criteria – reducing GHG emissions and providing good environments for their occupants -- separately despite their close relationship; buildings generally require energy and emit GHGs to produce suitable environments. This building performance case study presents findings about energy use and occupant sentiment together, seeking to uncover new relationships between the two concerns. It considers the designers, owners, operators and occupants’ contributions and relationship to energy use in the California State Teachers Retirement System(CalSTRS) Headquarters building in West Sacramento, California. More specifically, the study investigates how the design and operations processes contribute to the building’s low source energy use intensity, as indicated by its ENERGY STAR rating of 95, while maintaining high occupant satisfaction ratings for building features and indoor environmental quality (IEQ.) The study reviews these satisfaction ratings in light of the low measured energy intensity.This report addresses issues commonly observed in green building design and operations; and the recommendations it includes suggest ways to enhance the design process, improve operations efficiency and increase occupant satisfaction. For these reasons, this report is particularly useful to designers of green office buildings and members of organizations that own and/or operate office buildings.Findings were developed from surveys and interviews of building occupants, building operators, owners’ representatives and facilities staff. These surveys and interviews were performed during spring 2011 and were conducted in close collaboration with Hellmuth, Obata and Kassabaum (HOK) staff. The project was a collaboration between Center for the Built Environment at the University of California, Berkeley, and PortlandState University.The report proceeds as follows. We begin with a description of the building and its physical context, followed by a discussion of the data and methods used. A discussion of findings is next. Findings related to building performance are presented first, followed by findings related to operations. A summary completes the reportapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/1b435820publicationoai:escholarship.org:ark:/13030/qt8v13t41t2014-02-04T19:26:45Zqt8v13t41tLaboratory field studies/performance feedbackFederspiel, Clifford CZhang, QiangArens, Edward1999-12-01This report describes the development and testing of a new method of benchmarking whole-building energy use in laboratory buildings. The energy intensity of laboratory buildings is four to five times higher than that of other kinds of commercial buildings such as office buildings. This fact coupled with the importance of high-tech industries in California makes energy-efficiency of laboratory buildings an important issue in California.The most common method of benchmarking energy use in buildings is to compare the energy use of the building under consideration with the energy use of a population of like buildings. Usually there is some empirical compensation for features and factors that affect energy use such as the size of the building and the weather conditions. Two fundamental limitations of this approach are: 1) only similar kinds of buildings can be compared, and 2) the entire population may be inefficient, which would cause many inefficient buildings to be rated as efficient. The first limitation is important when benchmarking laboratory buildings because there is no public database of energy use and building features that can be used to construct empirical benchmarks for laboratories. The second limitation is also important because there is evidence that energy-consuming processes in laboratory buildings, especially HVAC systems, are inefficient because of highly conservative design practices and the need for risk avoidance.The benchmarking method described in this report is fundamentally different than the method described above. The principle is to construct a benchmark that represents the minimum amount of energy required to meet a set of basic functional requirements of the building. These requirements include codecompliant environmental controls, adequate lighting, etc. The benchmark is computed based on idealized models of equipment and system performance. Using idealized models produces a benchmark that is independent of design and easy to compute.Once the benchmark has been computed for a single building, an effectiveness metric is computed by dividing the model-based benchmark by the actual consumption. This metric, or its inverse, can be compared with the metrics of other buildings. Since functional requirements have been incorporated into the benchmark, it is possible to compare the performance of dissimilar buildings, or buildings that have rare or unique functional requirements.A benchmarking tool was developed that implements the benchmarking method described above. The tool is an MS Access database with calculation methods for implementing the model-based calculations.The database produces reports that allow a user to view historical performance trends as well as relative performance compared to other buildings in the database.The performance of the model-based benchmarking method was compared with two alternative methods based on the ability to predict actual energy use. Using building energy data from the UC Berkeley campus, it was shown that the model-based benchmarking method was more accurate when a combination of laboratory and non-laboratory buildings were analyzed.In addition to demonstrating the efficacy of model-based benchmarking, several other lessons were learned about building energy analysis. By constructing a model that represents the best possible performance, errors in the input data regarding schedule of operation and recorded energy use were detected because of effectiveness metrics that were significantly greater than unity. This demonstrates that recorded energy-related data may be unreliable and that the model-based benchmarking method may be able to detect errors of this kind in addition to detecting unsatisfactory energy-use performance. From analyzing building data that included a class 100 cleanroom it was clear that improvements in the fan power model could yield further improvements in the benchmarking accuracy.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/8v13t41tpublicationoai:escholarship.org:ark:/13030/qt2hw1t5zf2014-01-30T21:02:53Zqt2hw1t5zfLaboratory field studies performance feedbackFederspiel, Clifford CZhang, QiangArens, Edward1999-12-01This report describes the development and testing of a new method of benchmarking whole-building energy use in laboratory buildings. The energy intensity of laboratory buildings is four to five times higher than that of other kinds of commercial buildings such as office buildings. This fact coupled with the importance of high-tech industries in California makes energy-efficiency of laboratory buildings an important issue in California.The most common method of benchmarking energy use in buildings is to compare the energy use of the building under consideration with the energy use of a population of like buildings. Usually there is some empirical compensation for features and factors that affect energy use such as the size of the building and the weather conditions. Two fundamental limitations of this approach are: 1) only similar kinds of buildings can be compared, and 2) the entire population may be inefficient, which would cause many inefficient buildings to be rated as efficient. The first limitation is important when benchmarking laboratory buildings because there is no public database of energy use and building features that can be used to construct empirical benchmarks for laboratories. The second limitation is also important because there is evidence that energy-consuming processes in laboratory buildings, especially HVAC systems, are inefficient because of highly conservative design practices and the need for risk avoidance.The benchmarking method described in this report is fundamentally different than the method described above. The principle is to construct a benchmark that represents the minimum amount of energy required to meet a set of basic functional requirements of the building. These requirements include code-compliant environmental controls, adequate lighting, etc. The benchmark is computed based on idealized models of equipment and system performance. Using idealized models produces a benchmark that is independent of design and easy to compute.Once the benchmark has been computed for a single building, an effectiveness metric is computed by dividing the model-based benchmark by the actual consumption. This metric, or its inverse, can be compared with the metrics of other buildings. Since functional requirements have been incorporated into the benchmark, it is possible to compare the performance of dissimilar buildings, or buildings that have rare or unique functional requirements.A benchmarking tool was developed that implements the benchmarking method described above. The tool is an MS Access database with calculation methods for implementing the model-based calculations. The database produces reports that allow a user to view historical performance trends as well as relative performance compared to other buildings in the database.The performance of the model-based benchmarking method was compared with two alternative methods based on the ability to predict actual energy use. Using building energy data from the UC Berkeley campus, it was shown that the model-based benchmarking method was more accurate when a combination of laboratory and non-laboratory buildings were analyzed.In addition to demonstrating the efficacy of model-based benchmarking, several other lessons were learned about building energy analysis. By constructing a model that represents the best possible performance, errors in the input data regarding schedule of operation and recorded energy use were detected because of effectiveness metrics that were significantly greater than unity. This demonstrates that recorded energy-related data may be unreliable and that the model-based benchmarking method may be able to detect errors of this kind in addition to detecting unsatisfactory energy-use performance. From analyzing building data that included a class 100 cleanroom it was clear that improvements in the fan power model could yield further improvements in the benchmarking accuracy.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/2hw1t5zfpublicationoai:escholarship.org:ark:/13030/qt51q6c2sf2014-01-30T19:33:22Zqt51q6c2sfBuilding a case for building performanceLehrer, David2001-08-01You have seen the facts before. Americans make up less than 5% of the world’s population, yet consume 25% of the earth’s resources and create 25% of the world’s greenhouse gases. We are also told that the construction and operation of buildings are major contributors to this problem, and that as building industry professionals we have a major responsibility to improve the performance of the buildings and environments that we create.Although a growing number of states and municipalities have adopted energy efficiency and green building initiatives, the private sector has been very slow to accept this responsibility. Obviously there are several reasons for this. One factor may be the generally conservative, risk-averse nature of the building industry. As service providers we must strive to achieve the goals of our clients, many of them developers and building owners primarily concerned about controlling first costs, and less concerned about a building’s future operating cost and performance. For this section of the building industry to adopt a progressive approach to sustainable design, we will need to make a persuasive business case for sustainable design.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/51q6c2sfpublicationoai:escholarship.org:ark:/13030/qt0dg7j6232014-01-28T19:14:41Zqt0dg7j623A tenant interface for energy and maintenance systemsFederspiel, Clifford CVillafana, Luis2003-04-01We describe the design of a user interface for energy and maintenance systems in commercial buildings. The user interface is for use by occupants (tenants) of commercial buildings. Our hypothesis is that by allowing tenants access to information from the energy and maintenance systems and by giving them some control over these systems, energy and maintenance performance can be improved. We used interviews with potential users and existing energy and maintenance databases to guide the design.We describe the design of a user interface for energy and maintenance systems in commercial buildings. The user interface is for use by occupants (tenants) of commercial buildings. Our hypothesis is that by allowing tenants access to information from the energy and maintenance systems and by giving them some control over these systems, energy and maintenance performance can be improved. We used interviews with potential users and existing energy and maintenance databases to guide the design.User interfaceenergy managementmaintenancebuildingsapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/0dg7j623publicationoai:escholarship.org:ark:/13030/qt4b65c4xw2014-01-23T19:54:29Zqt4b65c4xwModel-based benchmarking with application to laboratory buildingsFederspiel, Clifford, Ph.D.Zhang, QiangArens, Edward, Ph.D2002-01-01The most common method of benchmarking energy use in buildings is to compare the energy use of the building under consideration with the energy use of a population of like buildings. Usually there is some empirical compensation for features and factors that affect energy use such as the size of the building and the weather conditions. Two fundamental limitations of this approach are: 1) only similar kinds of buildings can be compared, and 2) the entire population may be inefficient, which would cause many inefficient buildings to be rated as efficient. The first limitation is important when benchmarking laboratory buildings because there is no public database of energy use and building features that can be used to construct empirical benchmarks for laboratories. The second limitation is also important because there is evidence that energyconsuming processes in laboratory buildings, especially HVAC systems, are inefficient because of highly conservative design practices.This paper describes a benchmarking method that is fundamentally different than the method described above. The principle of the new method is to construct a benchmark that represents the minimum amount of energy required to meet a set of basic functional requirements of the building. These requirements include code-compliant environmental controls, adequate lighting, etc. The benchmark is computed based on idealized models of equipment and system performance. Using idealized models produces a benchmark that is independent of design and easy to compute. Once the benchmark has been computed for a single building, an effectiveness metric is computed by dividing the model-based benchmark by the actual consumption. This metric, or its inverse, can be compared with the metrics of other buildings. Since functional requirements have been incorporated into the benchmark, it is possible to compare the performance of dissimilar buildings, or buildings that have rare or unique functional requirements.The performance of the model-based benchmarking method was compared with two alternative methods based on the ability to predict actual energy use. Using building energy data from the UC Berkeley campus, it was shown that the model-based benchmarking method was more accurate when a combination of laboratory and non-laboratory buildings was analyzed.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/4b65c4xwpublicationoai:escholarship.org:ark:/13030/qt1pz2528w2012-01-30T19:59:28Zqt1pz2528wCollecting Occupant Presence Data for Use in Energy Management of Commercial BuildingsRosenblum, Benjamin Tarr2012-01-30Occupant presence data, a record of where, when and by whom a building is occupied, can be anasset in managing energy consumption in commercial buildings. This thesis develops aframework for evaluating sources of occupant presence data for use in energy management. Theproject starts with a classification of potential occupant data sources using characteristicsrelevant to energy management, such as spatial and temporal granularity. This inventory alsoaddresses the degree to which data sources might characterize occupant groups from the lowgranularity of trend and binary occupied status, to occupant count, to high granularity occupantidentity, preference, and activity information. Potential occupant data sources are then correlatedto particular energy management strategies. As a practical assessment of this correlationframework several occupant data sources were evaluated in field studies at two office sites inNorthern California. At one site purpose-built data sources were installed at workstations whilethe other relied on existing, found, network-based data sources. This project’s survey andclassification of occupant data sources, along with evaluation in the field of installed and existingnetwork-based data sources, can serve as a reference for building energy managers and serviceproviders on collecting occupant data for use in energy management of commercial buildings.Occupant presenceenergy managementcommercial buildingsoccupant datatemporal granularityspatial granularityapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/1pz2528wmonographoai:escholarship.org:ark:/13030/qt2pd6f6kb2011-08-12T18:55:29Zqt2pd6f6kbDeveloping the San Francisco wind ordinance and its guidelines for complianceArens, Edward ABallanti, D.Bennett, C.Guldman, S.White, B.1989-01-01In 1985 San Francisco adopted a wind ordinance as part of its Downtown Plan. To our knowledge, it is the first U.S. wind code containing specific legal and technical requirements for compliance. It addresses both comfort and safety criteria. The comfort criteria tend to be the critical ones in San Francisco's unusual climate, where uncomfortable sea breezes are pervasive but dangerously strong winds relatively rare. Compared to the criteria used in other codes worldwide, this ordinance uses relatively low thresholds windspeeds that may be exceeded relatively large amount of the time.This paper discusses the development of the ordinance and its compliance guidelines by which wind testing procedures and reporting are standardized. A critical part of the effort was obtaining and generalizing an appropriate wind record for the downtown area. This is discussed, together with considerations for achieving uniformity among consultant's reports.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/2pd6f6kbpublicationoai:escholarship.org:ark:/13030/qt7pc2q3vx2011-08-12T18:55:23Zqt7pc2q3vxGeographical extrapolation of typical hourly weather data for energy calculation in buildingsArens, Edward AFlynn, Larry ENall, Daniel NRuberg, Kalev1980-08-01Two techniques are developed and tested for creating composite and synthetic hourly weather data for a wide range of sites. The first technique selects real weather data segments from a source multiyear weather record, and links them into a composite synthetic year, in which the hourly values are unchanged from the source. The second technique adjusts the real hourly data values of the source to create a more completely synthetic year. The techniques may be applied individually or in combination. The resulting synthetic year or years can be used to provide data that is representative of long-term climate for building energy prediction either at the first-order station where the source hourly weather data were recorded, or at a nearby second-order station for which only summarized climate averages are available. Additionally, the adjustment technique can generate synthetic data to represent specific time periods at second-order stations for use in energy audits and experiments. The effectiveness of extrapolating weather data from one location to another is assessed, and the uses of the two techniques are described. Two user-interactive Fortran programs, SELECT and ADJUST, are appended.Building energycomputerized climate dataapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/7pc2q3vxpublicationoai:escholarship.org:ark:/13030/qt3j62w3nm2011-08-12T18:55:19Zqt3j62w3nmSiteclimate: a program to create hourly site-specific weather dataArens, E.Lee, E.Bauman, F.Flynn, L.1985-12-01Building loads are calculated using hourly weather tapes from the nearest available first-order weather station, or from data summarized from such tapes. These weather stations are ofter remote from the building site, and in different terrain. The climate experienced on site may be significantly different from that on the weather tape, and as such a result the energy use simulated for envelope-dominated buildings can contain substantial error.A program is described that modifies hourly weather tape data to make them more closely approximate the climate found on building sites. The program is eventually intended to be used by designers, engineers and researchers, who will input both local climate data and a description of the building site's physical surrounding in order to make the data transformations. The method is only partially tested and is still under development.In this paper, the approach used to modify hourly weather data is discussed, the method of user input is presented, and the individual algorithms are summarized. Future refinements to the program and validation studies are outlined.Building energycomputerized climate datasite-specific weather datamicroclimateweather tapessolar radiationtemperaturewind.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/3j62w3nmpublicationoai:escholarship.org:ark:/13030/qt0165c77h2011-08-12T18:55:11Zqt0165c77hSun, wind, and pedestrian comfort: a study of Toronto's Central AreaBosselmann, P.Arens, Edward ADunker, K.Wright, R.1990-12-01application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/0165c77hpublicationoai:escholarship.org:ark:/13030/qt0gn8f4hq2011-08-12T18:55:08Zqt0gn8f4hqWind and building energy consumption: an overviewArens, Edward AWilliams, P.1981-05-15The environment around a building affects its energy consumption primarily by influencing its requirement for space heating and cooling. The environmental variables influencing the amount of energy needed for heating and cooling are outside temperature, humidity, solar radiation, and wind.Wind influences building energy consumption by affecting the following:1. Air infiltration and exfiltration from conditioned spaces, resulting from pressure gradients and the resulting mass transfer through surface.2. The rate of heat transmission to or from external surfaces, partially determined by the turbulent mixing of air close to the building surface.3. Mechanical systems efficiency. Air circulation around buildings affects the thermal efficiency of air-conditioning cooling towers, and can increase fan power requirements when ventilation inlets and exhausts are poorly located.4. The necessity for enclosing and conditioning outdoor space. Buildings commonly have uncomfortable surroundings, and architects have responded to this by enclosing the surrounding in atria or malls which need to be heated or cooled. Such enclosures might not be necessary if the site and building were designed to control air movement to an acceptable level.application/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/0gn8f4hqpublicationoai:escholarship.org:ark:/13030/qt2533v2d22011-08-08T19:46:39Zqt2533v2d2California department of education HQ block 225: California's valedictorianBauman, FredWebster, TomDickerhoff, Darryl JFentress, CurtisPopowski, Matt2009-01-01The bar was raised high for the building, also known as Block 225, before construction began. The California Department of General Services wanted a green building, and the design-build team set a goal of achieving LEED Gold certification — a relatively new green standard in 1999.Block 225 is the first California state office building to use an underfloor air-distribution system and is the first design-build office building in the state’s history. The integrated approach to design and construction resulted in the building’s completion 10 months ahead of schedule. The design-build team and Department of General Services blazed a trail for all future statedeveloped projects.Other ArchitectureCalifornia Department of Education Headquarterssustainabilityhigh performance buildingUFADLEED Platinumapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/2533v2d2publicationoai:escholarship.org:ark:/13030/qt71m638802011-08-08T18:16:28Zqt71m63880Advanced benchmarking for complex building types: laboratories as an exemplar.Mathew, PaulClear, RobertKircher, KevinWebster, TomLee, Kwang HoHoyt, Tyler2010-01-01Complex buildings such as laboratories, data centers and cleanrooms present particular challenges for energy benchmarking because it is difficult to normalize special requirements such as health and safety in laboratories and reliability (i.e. system redundancy to maintain uptime) in data centers which significantly impact energy use. For example, air change requirements vary widely based on the type of work being performed in each laboratory space.We present methods and tools for energy benchmarking in laboratories, as an exemplar of a complex building type. First, we address whole building energy metrics and normalization parameters. We present empirical methods based on simple data filtering as well as multivariate regression analysis on the Labs21 database. The regression analysis showed lab type, lab-area ratio and occupancy hours to be significant variables. Yet the dataset did not allow analysis of factors such as plug loads and air change rates, both of which are critical to lab energy use. The simulation-based method uses an EnergyPlus model to generate a benchmark energy intensity normalized for a wider range of parameters. We suggest that both these methods have complementary strengths and limitations.Second, we present “action-oriented” benchmarking, which extends whole-building benchmarking by utilizing system-level features and metrics such as airflow W/cfm to quickly identify a list of potential efficiency actions which can then be used as the basis for a more detailed audit. While action-oriented benchmarking is not an “audit in a box” and is not intended to provide the same degree of accuracy afforded by an energy audit, we demonstrate how it can be used to focus and prioritize audit activity and track performance at the system level. We conclude with key principles that are more broadly applicable to other complex building types.Other Engineeringenergy benchmarkinglaboratory energywhole building energyEnergyPlusaction-oriented benchmarkingapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/71m63880publicationoai:escholarship.org:ark:/13030/qt4bw8g4xn2011-08-08T18:16:25Zqt4bw8g4xnResPoNSe: modeling the wide variability of residential energy consumption.Peffer, ThereseBurke, WilliamAuslander, David2010-01-01People living in houses consume a substantial portion of total electricity consumption— 37% of U.S. electricity end use (Energy Information Administration (EIA) 2008)—which produces greenhouse gases. U.S. households exhibit extreme variability in energy consumption from one house to another. The variation in energy consumption from differences in climate and building characteristics is well-studied; however, the effect of various appliance end use and especially the variation in the behaviors of the people that use them is less understood. Yet, this variability is critical to the effective design of technology, efficiency, and/or demand response programs in order to reduce this consumption, especially during periods of peak electricity consumption. While many techniques have been used to simulate actual residential energy consumption using models, most fail to take into account the behavioral component that contributes to the wide spectrum of residential energy consumption.Towards this end, we have developed the Residential Power Network Simulation (ResPoNSe) to capture the spectrum—not average—of the electrical consumption of California households over the course of a hot summer day. ResPoNSe models the electricity consumption of a thousand households in order to test different demand response scenarios. Distributions of household characteristics, numbers and types of appliances per house, power consumption of the appliances, and the duration these appliances are used provide a more realistic variation of energy consumption. In turn, this simulation tool can provide a model of the spectrum of consumer response to different efficiency, marketing, or demand response programs.Other Engineeringdemand responseResidential Power Network Simulationelectrical consumptionapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/4bw8g4xnpublicationoai:escholarship.org:ark:/13030/qt30h937bh2011-08-08T18:16:06Zqt30h937bhCase study of Kresge Foundation office complex.Goins, John2011-01-01Most building performance evaluations only describe whether a building meets certain criteria. In contrast, this report describes the performance of the Kresge Foundation Complex (Complex) in relation to industry‐standard design and operations performance criteria while examining the appropriateness of these criteria for the Complex and similar high‐performance buildings. More specifically, this study examines the Complex's performance in 20 areas. It also highlights potential flaws in human factors, energy use, landscape water use, and acoustics criteria and suggests improvements in biodiversity and stormwater criteria.The Center for the Built Environment (CBE) and associates analyzed the performance of the Complex, a highperformance green project built in 2004 with a Platinum rating in the Leadership in Energy and Environmental Design rating system for New Construction (LEED‐NC). The CBE team analyzed the following aspects of the Complex: human factors; indoor water use; stormwater management; landscape performance (water use and biodiversity); acoustics; lighting; indoor air quality (IAQ); thermal comfort; energy performance; and first, life‐cycle, and operational costs (Table 1.) CBE used evaluation criteria drawn from industry standards, guidelines, best practices when available, and professional judgment where standards were not definitive or required interpretation.The results were derived from CBE's occupant satisfaction database; the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Performance Measurement Protocols (PMP); LEED‐NC Version 2.1 design criteria; and other relevant criteria for biodiversity,1 operations, and life‐cycle costs. Appendix A contains a complete description of the basis for the scoring for each of the 20 evaluations.Table 1 shows a summary scorecard of the Complex’s performance, for all 20 evaluations. The (+) sign indicates conformity with these criteria and performance consistent with what the authors consider appropriate for high‐performance buildings. The (‐) sign indicates nonconformity with relevant criteria or other causes for concern. The building meets or exceeds performance criteria in 14 of the 20 areas evaluated.The occupant survey results in Table 1 were obtained from the CBE Occupant Satisfaction Survey, which is cited in several guidelines and green building rating systems, including LEED‐NC. PMP results in Table 1 are based on ASHRAE’s PMP. Although the United States Green Building Council, which developed the LEED‐NC rating system (USGBC 2002), is a coauthor of PMP, PMP differs from the LEED‐NC Version 2.1 rating system under which the building was certified. It describes performance measurement techniques for buildings in operation and is based on industry standards where applicable. It does not cover buildings in design, does not specify performance hurdles, and is not a rating system. Neither does PMP cover site issues. Instead, PMP and other criteria represent a way to evaluate how well the performance objectives of LEED‐NC were achieved.Other Architectureapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/30h937bhpublicationoai:escholarship.org:ark:/13030/qt0s5159kp2011-08-08T18:01:05Zqt0s5159kpTeaching students about two-dimensional heat transfer effects in buildings, building components, equipment, and appliances using Therm 2.0.Huizenga, CharlieArasteh, DariushFinalyson, ElizabethMitchell, RobinGriffith, BrentCurcija, Dragan1999-01-01THERM 2.0 is a software program, available for free, that uses the finite-element method to model steady-state, two dimensional heat-transfer effects. It is being used internationally in graduate and undergraduate laboratories and classes as an interactive educational tool to help students gain a better understanding of heat transfer. THERM offers students a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed to model thermal properties of building components such as windows, walls, doors, roofs, and foundations, it can be used to model thermal bridges in many other contexts, such as the design of equipment. These capabilities make it a useful teaching tool in classes on heating, ventilation, and air conditioning (HVAC); energy conservation; building design; and other subjects where heat-transfer theory and applications are important. The program’s interface and graphic presentation allow students to see heat-transfer paths and to learn how changes in materials affect heat transfer. It is an excellent tool for helping students understand the practical application of heat-transfer theory.Other ArchitectureTHERM 2.0finite element methodheat transferheat transfer modeltwo dimensional heat transferteaching studentsapplication/pdfpubliceScholarship, University of Californiahttps://escholarship.org/uc/item/0s5159kppublication