Recent cedr_cbe_other items

Envelope-driven comfort risk in residential demand response

Fri, 12 Jun 2026 00:00:00 +0000

Residential demand response (DR) is a valuable resource for grid reliability, but remains challenging because the highly heterogeneous residential building stock leads to widely varying and hard-to-predict load and comfort responses during DR events. Although prior research has estimated the technical potential of DR-capable technologies for achieving energy demand savings, little is known about how they affect thermal comfort. In particular, it remains unclear how indoor thermal conditions due to DR depend on the thermal envelope characteristics of the housing stock. To address this gap, this study provides a systematic, location-specific assessment of indoor thermal performance during DR-events across the US housing stock using both typical DR weather data and detailed building metadata. We evaluate how envelope characteristics influence indoor temperatures during realistic simulated summer and winter DR events across 37 US locations, applying both temperature threshold and...

Temporal resolution matters: Evaluating carbon emission factors for accurate accounting in commercial buildings

Fri, 3 Apr 2026 00:00:00 +0000

Accurately quantifying operational carbon emissions from buildings is essential to verify that decarbonization targets are met. Yet many current practices rely on overly simplified yearly average emission factors that overlook the temporal variability of the electrical grid generation. This issue becomes increasingly critical with the rising penetration of renewable energy and the adoption of demand-side strategies in buildings, such as load shifting. Existing literature on net-zero carbon buildings rarely examines how the temporal resolution of emission factors affects accounting accuracy. In this study, we evaluated a range of grid emission factors (annual, seasonal, time-of-day, season-hour, and month-hour) and quantified their impact on carbon emissions accounting accuracy for commercial buildings across 18 U.S. grid regions. These emission factors, derived from publicly available datasets, are applied to measured hourly electricity consumption profiles from over 600 real...

Teaching Life Cycle Assessment: An Accessible Approach for Future Architects and Building Professionals

Wed, 17 Sep 2025 00:00:00 +0000

Architects play a vital role in decarbonization efforts. Architects need the skills to assess the environmental impacts of their designs while understanding how early-stage design decisions shape the environmental impacts of their final designs. However, most academic structures do not provide future architects with the skills and knowledge needed to perform life cycle assessment (LCA) nor understand the linkages between design decisions and environmental impacts. Based on experiences from teaching LCA and life cycle thinking to architecture students in Brazil and the United Kingdom, we outline our vision for providing architecture students with the skills needed by industry to navigate the ever-changing climate crisis. We highlight that not everyone needs to do a full-scale assessment, but everyone should be able to engage in conversations related to sustainability and impact reduction.

Assessment of Embodied Water Impacts for Landscape Architecture Strategies: A Life Cycle Assessment Approach

Thu, 24 Jul 2025 00:00:00 +0000

Addressing the pressing issue of water scarcity and environmental impact, this research investigates the embodied water impacts of landscape architecture strategies. Employing life cycle assessment (LCA) and water footprint methodologies, the study explores hardscape, vegetation, and building elements within urban landscapes. Through a case study of the Bauer Wurster Hall East Courtyard at UC Berkeley, various landscape design scenarios are analyzed for their embodied water impacts. The findings reveal large differentials in embodied water between scenarios. The original site design showcases a total of 1440 kL embodied water, while the remodeled version amplifies to 5820 kL. Notably, concrete and steel emerge as primary contributors to embodied water, despite their relatively low mass proportions on-site. Concrete paving, in particular, demonstrates a significant impact, outweighing other paving materials like asphalt and brick. The findings emphasize the need for informed decision-making...

Integrating symbolic neural networks with building physics: A study and proposal

Thu, 19 Jun 2025 00:00:00 +0000

Symbolic neural networks, such as Kolmogorov–Arnold Networks (KAN), offer a promising approach for integrating prior knowledge with data-driven methods, making them valuable for addressing inverse problems in scientific and engineering domains. This study explores the application of KAN in building physics, focusing on predictive modeling, knowledge discovery, and continuous learning. Through four case studies, we demonstrate KAN’s ability to rediscover fundamental equations, approximate complex formulas, and capture time-dependent dynamics in heat transfer. While there are challenges in extrapolation and interpretability, we highlight KAN’s potential to combine advanced modeling methods for knowledge augmentation, which benefits energy efficiency, system optimization, and sustainability assessments beyond the personal knowledge constraints of the modelers. Additionally, we propose a model selection decision tree to guide practitioners in appropriate applications for building physics.

Building and occupant characteristics as predictors of temperature-related health hazards in American homes

Fri, 4 Apr 2025 00:00:00 +0000

Many cities and regions are making significant investments towards planning for extreme temperature and in particular extreme heat. A heat vulnerability index (HVI) is a metric to track spatial variation in extreme temperature risk to target mitigation interventions. Most HVIs focus on demographic characteristics, which generally relate to vulnerability, and lack information about the building stock, which mediate the occupant’s exposure to extreme temperatures. In this study, we use the Energy Information Administration’s (EIA) Residential Energy Consumption Survey (RECS) to estimate prevalence of temperature-related illness in the United States and develop machine learning models using climate, demographic, and building characteristics to predict them. Temperature-related illness affects approximately 2 million households annually, around 1% of the total population. The models we developed predict temperature-related illness with up to 85% accuracy. The most important feature...

The Villages at 995 East Santa Clara St, San Jose: Energy & Emission Report

Tue, 18 Feb 2025 00:00:00 +0000

Our study uses EnergyPlus simulations to examine whole-building demand and energy end-use profiles for different design options and then uses these outputs to evaluate cost and carbon impacts of each scenario in Xendee, a modeling platform designed to “right size” and balance investments in distributed energy resources (DER).

Our results show that efficiency measures are key to meet the ambitious performance metrics for this project; however, most of the technology potential occurs for heating, ventilation and air conditioning (HVAC) or domestic hot water (DHW) loads which are a relatively small portion of a mid-rise multifamily building’s overall energy use. The most meaningful strategies to reduce or shift loads for this building include DHW load shifting, energy recovery ventilation, dynamic ventilation, and ceiling fans. Envelope strategies improve overall annual building performance but become an issue when lower heat loss increases cooling during the...

Assessing thermal comfort and participation in residential demand flexibility programs

Tue, 14 Jan 2025 00:00:00 +0000

Residential space-conditioning-based demand flexibility (DF) has become an increasingly sought-after method for demand-side load management to enhance grid reliability and facilitate integration of renewable energy generation. However, predicting the effectiveness and flexibility of residential DF resources is challenging. Current estimates show that only 50% of projected savings from DF resources are actualized. Currently, there is a very limited understanding of how thermal comfort during space-conditioning-based DF events in real-world settings impacts household energy use behaviors and, consequently, the success of DF programs in achieving targeted savings. This paper proposes a method to comprehensively assess the thermal comfort implications of DF strategies and presents results of their impacts on DF event participation decisions and demand savings. The study's key findings are: 1) DF event setpoint offsets that maintain indoor operative temperatures between 18 to 22°C...

Assessing Overheating Risk and Energy Impacts in California's Residential Buildings

Sun, 24 Nov 2024 00:00:00 +0000

Extreme heat causes more weather-related deaths in the United States than any other natural hazard, and these events are projected to increase in frequency, intensity, and duration. As a result, it is critical to ensure safe thermal conditions in homes while minimizing excessive cooling energy use. In California, where the median age of homes is 45 years and nearly 40% lack mechanical cooling, this deficiency undermines one of the most essential goals of housing: to shelter people from outdoor weather of a warming planet. We aim to quantify the overheating risk in the housing sector to support the development of public policies related to maximum safe indoor thermal limits and building energy use. Using the ResStock modeling framework, we created over 52,000 building models to represent California's residential housing stock and assessed overheating risks by simulating indoor temperatures and analyzing the energy impacts of adding cooling systems.Our findings reveal significant...

Passive and low-energy strategies to improve sleep thermal comfort and energy resilience during heat waves and cold snaps

Mon, 4 Nov 2024 00:00:00 +0000

In high- and middle-income countries, there is a great reliance on heating, ventilation, and air conditioning systems (HVAC) to control the interior thermal environment. However, these systems are expensive to buy, maintain, and operate while being energy and environmentally intensive. Easily-accessible passive and low-energy strategies, such as fans and electrical heated blankets, address these challenges but their comparative effectiveness for providing comfort in sleep environments has not been studied. Using passive strategies in combination with low-energy strategies that elevate air movement like ceiling or pedestal fans enhances the cooling effect by three times compared to using fans alone. We extrapolated our experimental findings to estimate heating and cooling effects in two historical case studies: the 2015 Pakistan heat wave and the 2021 Texas power crisis. Passive and low-energy strategies reduced sleep-time heat or cold exposure by 69-91%. The low-energy strategies...

Spatial Thermal Autonomy (sTA): A New Metric for Enhancing Building Design Towards Comfort, Heat Resilience and Energy Autonomy

Mon, 4 Nov 2024 00:00:00 +0000

Achieving thermal comfort in buildings while maintaining energy efficiency is a critical challenge in architecture and engineering design and operation. Traditional thermal comfort metrics used in the early stages of design tend to neglect two key aspects: spatial variability of thermal conditions within buildings and the promotion of passive design strategies over active conditioning systems. This oversight leads to localized discomfort, excessive energy use, and increased vulnerability to overheating. To address these issues, we propose a novel metric called spatial Thermal Autonomy (sTA). The primary advantage of sTA is its ability to capture spatial variability in thermal conditions, offering a more comprehensive view of comfort across different building zones. Additionally, sTA supports passive design by quantifying a building's capacity to maintain comfort without active energy use. We performed a simulation case study evaluating sTA for different thermal zone sizes, passive...

Harmonized Resilience at Roosevelt Village: How Futuristic Grid-Interactivity and Resilience Come Together in Senior Affordable Housing

Fri, 11 Oct 2024 00:00:00 +0000

To decarbonize the buildings and electricity sectors at a pace consistent with state and national climate goals, buildings must become grid resources, capable of morphing load profiles to accommodate variable renewable generation, facilitate cost-effective grid decarbonization, and help ensure reliable power system operation. Simultaneously, the changing climate poses increasing risks of extreme weather events and resulting power outages that developers, designers, and building operators must plan for. This yield s new questions around the best approaches to achieve these outcomes, what it costs, who benefits, and what barriers there are to widespread adoption.We seek to answer these questions by adopting a futuristic set of grid-interactive design requirements for a mid-rise affordable housing, mixed-use development: to sustain critical loads during an outage and to consume no grid electricity for residential end-uses between 4-9pm every day. We present an approach that achieves...

Impact of Window vs Windowless Exam Rooms on Cognitive Performance: A Field Study During a University Exam

Thu, 11 Apr 2024 00:00:00 +0000

This study aims to measure the impact of having visual connections to nature through windows on the cognitive performance of university students, as assessed by their final exam scores. To build upon prior research conducted in controlled laboratory and climate chamber settings, which may have a gap between findings and real-world contexts, demonstrating the positive effects of window views on occupants, this study addressed the limitations of lab-based experiments by conducting a field test in university lecture rooms with 121 students enrolled in STEM classes, taking their actual final exam. In the field test, we randomly assigned the students to either of two conditions: one with windows and one without, while monitoring indoor environmental factors. The results revealed no significant difference in cognitive performance—whether measured by scores or cognitive efficiency gauged by the time taken to complete the exam—between students in conditions with and without window views....

Quantification on Fuel Cell Degradation and Techno-Economic Analysis of a Hydrogen-Based Grid-Interactive Residential Energy Sharing Network with Fuel-Cell-Powered Vehicles

Wed, 1 Dec 2021 00:00:00 +0000

Hydrogen-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...

Transformation Towards a Carbon-Neutral Residential Community with Hydrogen Economy and Advanced Energy Management Strategies

Wed, 1 Dec 2021 00:00:00 +0000

Cleaner 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...

Application of Gagge’s Energy Balance Model to Determine Humidity-Dependent Temperature Thresholds for Healthy Adults Using Electric Fans During Heatwaves

Mon, 1 Nov 2021 00:00:00 +0000

Heatwaves 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...

Optimizing energy conservation measures in a grocery store using present and future weather files

Mon, 13 Jul 2020 00:00:00 +0000

Grocery 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.

Designing for the future: Are today’s building codes locking in the wrong strategies by using past climate data?

Mon, 6 May 2019 00:00:00 +0000

California 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...

Sensitivity of passive design strategies to climate change

Mon, 15 Apr 2019 00:00:00 +0000

Observed 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...

A Conversation on Adaptation in the Built Environment

Fri, 12 Oct 2018 00:00:00 +0000

A Conversation on Adaptation in the Built Environment

Understanding Climate Change Impacts on Building Energy Use

Fri, 12 Oct 2018 00:00:00 +0000

Understanding Climate Change Impacts on Building Energy Use

PMV-based event-triggered mechanism for building energy management under uncertainties

Wed, 26 Jul 2017 00:00:00 +0000

This 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...

Measuring the effectiveness of San Francisco's planning standard for pedestrian wind comfort

Wed, 7 Dec 2016 00:00:00 +0000

In 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.

Does Wind Discourage Sustainable Transportation Mode Choice? Findings from San Francisco, California, USA

Tue, 9 Aug 2016 00:00:00 +0000

This 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...

Urban Form, Wind, Comfort, and Sustainability: The San Francisco Experience

Tue, 9 Aug 2016 00:00:00 +0000

In 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...

Wind and the city: An evaluation of San Francisco's planning approach since 1985

Mon, 8 Aug 2016 00:00:00 +0000

In 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...

Performance, Prediction and Optimization of Night Ventilation across Different Climates

Fri, 13 May 2016 00:00:00 +0000

Night 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,...

Lessons learned from field monitoring of two radiant slab office buildings in California

Mon, 7 Mar 2016 00:00:00 +0000

In 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...

Urban form and climate: case study, Toronto

Wed, 27 Jan 2016 00:00:00 +0000

This 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...

Plug Load Energy Analysis: The Role of Plug Loads in LEED Certification

Mon, 2 Nov 2015 00:00:00 +0000

Plug 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....

Commercial Office Plug Load Energy Consumption Trends and the Role of Occupant Behavior

Mon, 21 Sep 2015 00:00:00 +0000

Plug 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...

Quantifying the Comprehensive Greenhouse Gas Co-Benefits of Green Buildings

Tue, 10 Feb 2015 00:00:00 +0000

This 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,...

Office tenant needs study

Thu, 27 Feb 2014 00:00:00 +0000

CBE 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 Pacific

Northwest.

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...

Case study of CalSTRS headquarters

Thu, 20 Feb 2014 00:00:00 +0000

It 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...

Laboratory field studies/performance feedback

Tue, 4 Feb 2014 00:00:00 +0000

This 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.

Building a case for building performance

Thu, 30 Jan 2014 00:00:00 +0000

You 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...

Laboratory field studies performance feedback

Thu, 30 Jan 2014 00:00:00 +0000

A tenant interface for energy and maintenance systems

Tue, 28 Jan 2014 00:00:00 +0000

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.

Model-based benchmarking with application to laboratory buildings

Thu, 23 Jan 2014 00:00:00 +0000

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 energyconsuming processes in laboratory buildings, especially HVAC systems, are inefficient because of highly conservative design practices.

This...

Effective Daylighting: Evaluating Daylighting Performance in the San Francisco Federal Building from the Perspective of Building Occupants

Wed, 1 Feb 2012 00:00:00 +0000

Commercial 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...

Collecting Occupant Presence Data for Use in Energy Management of Commercial Buildings

Mon, 30 Jan 2012 00:00:00 +0000

Occupant 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...

Advanced benchmarking for complex building types: laboratories as an exemplar.

Fri, 5 Aug 2011 00:00:00 +0000

Complex 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...

ResPoNSe: modeling the wide variability of residential energy consumption.

Fri, 5 Aug 2011 00:00:00 +0000

People 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...

Case study of Kresge Foundation office complex.

Fri, 5 Aug 2011 00:00:00 +0000

Most 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...

Teaching students about two-dimensional heat transfer effects in buildings, building components, equipment, and appliances using Therm 2.0.

Fri, 5 Aug 2011 00:00:00 +0000

THERM 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...

California department of education HQ block 225: California's valedictorian

Tue, 26 Jul 2011 00:00:00 +0000

The 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.

Geographical extrapolation of typical hourly weather data for energy calculation in buildings

Thu, 23 Oct 2008 00:00:00 +0000

Two 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....

Wind and building energy consumption: an overview

Tue, 13 Mar 2007 00:00:00 +0000

The 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...

Designing for an acceptable wind environment

Mon, 12 Mar 2007 00:00:00 +0000

Tall 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...

Developing the San Francisco wind ordinance and its guidelines for compliance

Wed, 13 Sep 2006 00:00:00 +0000

In 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.

Sun, wind, and pedestrian comfort: a study of Toronto's Central Area

Wed, 13 Sep 2006 00:00:00 +0000

Sun, wind, and pedestrian comfort: a study of Toronto's Central Area

Siteclimate: a program to create hourly site-specific weather data

Fri, 27 Jan 2006 00:00:00 +0000

Building 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...