Buildings Research

Energy Efficient Buildings

Barriers to the Design and Construction of Energy Efficient Buildings

Residential and commercial buildings account for nearly half of all energy used in the United States, and commercial buildings account for the largest portion of peak demand in most regions. Energy intensity (Btu/sf) and electric intensity (KWh/sf) in commercial buildings during the years 1990 – 1999 increased by 12% and 18% respectively over previous thirty-year averages, and residential energy use is predicted to increase another 27% by the year 2025. Yet technologies and knowledge exist that could be used to create better, high-performance buildings. In fact, combined with better systems integration, they could cost-effectively achieve savings as high as 50% in new buildings, as compared to minimally code compliant structures. Existing retrofit technologies and retro-commissioning practices could provide economically efficient additional energy savings in the range of 5 – 20% in existing buildings.

Advancements in energy efficiency in the residential and commercial building sectors in California and the United States are currently falling short of potential. While increasing plug load and internal load requirements are partially responsible for the lack of progress, significant barriers to increased energy efficiency persist in current design, construction, and/or operation practices. These phases are typically too fragmented to allow the timely and effective implementation and integration of these energy efficiency methods and technologies on every new building and renovation project.

In addition to cost, aesthetics is the other main criterion for decision making about design alternatives in the early phases of a project. Therefore, decision making in early project phases, when the influence on overall project performance is largest, is mostly based on what can be seen (aesthetics) and what can be quantified relatively easily (first cost). This process minimizes cost at every step, but does not describe when and how to consider other criteria, such as energy concerns and end-user needs, and thus limits the incorporation of such lifecycle knowledge into the planning and design process in a consistent, predictable, and valuable way; the incorporation of methods and technologies for energy efficiency comes often as an afterthought. The lack of a more integrated design, construction, and operation process leads to the following three main problems:

  1. Ineffective Design: The best or most effective building is rarely designed and built. For example, the wrong square footage is often built that has little functional value and consumes energy to heat and cool.
  2. Ineffective Operation: End users often do not know how to operate the building to minimize energy use, which, in some cases, has led to buildings consuming twice the amount of energy originally calculated by the design team.
  3. Lack of Feedback Learning: Feedback loops from the use phase to the design phase are rare, making learning about effective methods and technologies slow and haphazard.

Currently, lifecycle energy efficiency and the resulting value and corresponding cost savings are not key criteria in the building development process, which makes it unlikely that every building is designed to maximize the use of energy efficient building design and technology options for a particular site, building, and use.

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Overcoming the Barriers

PEEC researchers are working to address these problems by developing and testing guidelines and methods for building owners and design teams to incorporate energy efficiency and end-user input into the design process. The application of these methods needs to span from early project definition through design development, construction, commissioning, operation, and disassembly and must consider not only the energy performance of buildings (the "product" that is designed, built, and used), but also the organizations that plan, design, build, and operate a building and the processes of the various project stakeholders. These performance-based models will enable project teams to design and manage the product, organization, and process (POP) for a project in an integrated way, and provide guidance for the timely and effective incorporation of specific energy efficiency technologies and design methods by specifying the appropriate design steps, stakeholders, and decision criteria at each point along the way. The models will make concerns other than aesthetics and first cost visible to the affected stakeholders and relevant decision makers. Our research on these methods includes developing, implementing in practice and education, and testing the following four sub methods:

  1. Performance-based models and metrics of the building product, including components, systems, spaces, occupants, and operators
  2. Performance-based models and metrics of the organizations and processes that design and manage buildings
  3. Methods for integrating these product, organization, and process models into projects that consistently deliver effective, energy efficient buildings
  4. Implementation, verification, and calibration of these models, methods, and metrics in education and practice

These state-of-the-art models and methods are already being developed, implemented, and evaluated in two high-profile energy conscious projects currently in early design on the Stanford campus: the Stanford Green Dorm, and the Jerry Yang and Akiko Yamazaki Environment and Energy (Y2E2) Building. These projects will provide invaluable, first-hand documentation and measured data with which to feed PEEC's research. The expected outcome of such research and leadership will be gains in building energy intensity and, eventually, an industry-wide shift towards the design and construction of more truly effective, energy efficient buildings.

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Performance-based Building Project Modeling

Significant progress has been made in many forms of building performance models. For example, structural analysis and daylighting software yield highly accurate predictions of building performance for specific criteria. Other performance models, such as energy prediction and building ventilation, continue to progress, although the gap between predicted and actual building performance can often still be large. Other, more subjective or difficult to formalize models of building performance, such as building egress, constructability, durability, and even aesthetics, continue to evolve.

The Center for Integrated Facility Engineering (CIFE) at Stanford has been developing performance-based models since 1988. Professors John Haymaker and Martin Fischer, and perhaps others, will continue in this tradition, but will focus on performance-based models developed explicitly for assessing energy efficiency and on integrating energy efficiency concepts into other performance-based models.

An initial research focus – one that we believe will have an enormous impact on the energy efficiency and overall effectiveness of buildings – is to formalize and test models of building operants: the collection of humans who occupy, operate, and maintain the facility through its lifecycle. Surprisingly, we find that well-founded models of building operants are largely missing from the early phases of the design process. Instead, gross square footage per occupant and operating schedule and temperature are the extent to which the operants are modeled on actual projects today.

Professor Haymaker and Caroline Clevenger are addressing the often wide gap between predicted and actual building performance by studying actual building operants and comparing them to the design assumptions to improve both the values and variables used to describe building operants. For example, one variable not currently considered is building operants familiarity with energy efficiency technology, and we find operant misuse and misunderstanding of this technology to be a key factor in building underperformance.

We envision a design process in which the project team first designs a realistic model of the building operants, and then designs and analyzes building performance taking into account the behavior of these stakeholders. These models will need to be flexible and probabilistic to anticipate changing building demands, but without a better model of the drivers of our buildings, we cannot realistically hope to achieve buildings that are efficient and effective.

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Performance-based Models of Organizations and Processes

To design and manage an effective building, a project must also design and manage an effective organization and process to deliver that building. CIFE has been a leader in organization and process modeling. Raymond Levitt et al. have developed the Virtual Design Team model that represents the design organization and the process that an organization must execute, and analyzes the model for schedule and design error risk which leads to ineffective building performance. Fischer et al. have pioneered the use of 4D modeling, enabling design and construction professionals to integrate their 3-dimensional designs with time-based processes to identify efficient project phasing and scheduling strategies and identify costly and ineffective processes.

Such process and organization models help project teams design, visualize, and analyze the multidisciplinary performance of their projects (products, organizations, and processes). PEEC will continue to develop such models and apply them to the design and construction of energy efficient buildings. These organization and process models will highlight when specific decisions with respect to energy efficiency need to be made, who needs to be involved when in a project, what tasks they will perform based on what input, etc. In summary, these organization and process models will provide a roadmap for implementing energy efficient methods and technologies and complement product-based guidelines for installation of a particular technology.

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Methods for Integrating Product, Organization, and Process Models

A major challenge to professionals will be how to integrate the growing list of requirements and models into multidisciplinary design and analysis processes that produce effective buildings. We propose to develop formal models of integration that help multidisciplinary design teams explicitly balance their requirements. Haymaker et al. are developing the Narrative methodology to help teams formalize and manage the dependencies between information models. Narratives inform the design process by representing, communicating, and managing the integration of the dependencies between information models.

Within PEEC, we are developing Narratives that describe the products, processes, and organizations employed to develop effective, energy efficient buildings, as is currently being done for the Stanford Green Dorm project. These Narratives can then be reused and adapted to suit unique project requirements and can evolve to incorporate new performance models as they are developed.

We are developing information environments in which to construct, view, and control the integration of Narratives and their rich collection of information and dependencies. Such environments, which provide collective, visual, and computationally responsive interaction with this information, are becoming economically feasible and, in our experience, are critical to bringing different disciplines together to overcome the objective asymmetries and lack of understanding that inhibits the incorporation of energy efficiency considerations into effective buildings today. Professor Haymaker is heading this focus area with his students.

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Implementation, Verification, and Calibration of Models, Methods, and Metrics in Education and Practice

Our view is that integrated POP (Product, Organization, and Process) models, methods, and metrics are needed to achieve far-reaching and quantifiable industry results of decreased energy use and increased environmental quality in constructed buildings. To achieve these results, we are working with students and industry to implement these models, methods, and metrics in education and practice, and to verify and calibrate their performance.

Unparalleled industry partnerships available through CIFE and that will be created through PEEC will see implementation and evaluations on ongoing actual building design, construction, and operation projects. Through PEEC, CIFE's current work in improving the building delivery process and its underlying mission to speed the transfer of the integration and virtual design and construction technologies into practice will be applied to directly advance the goal of energy efficiency in built projects. CIFE members include such prominent, diverse, and influential industry leaders, such as owners like the General Services Administration (GSA), engineers like the Fluor Corporation, builders like Swinerton Builders, and software providers like Autodesk. Leveraging these industry relationships, we are able to realize industry-wide change in the area of performance modeling and energy efficiency by implementing and recording the impact of our innovations in real-world projects.

In addition to the Green Dorm and Environment and Energy buildings described earlier, CIFE is working with the U.S. General Services Administration (GSA) to improve life-cycle cost decision making techniques to capture energy and other cost savings throughout millions of square feet of constructed space. CIFE is also currently in discussion with the Collaboration for High Performance Schools (CHPS) as funded in large part by the California Energy Commission (CEC) and Pacific Gas & Electric Company (PG&E), to develop and participate in a sweeping study of existing California school buildings to comprehensively address energy efficiency problems in existing school facilities. We expect this study to provide data that will help us develop better models of the operants of these schools and to understand how the products, processes, and organizations on these projects might be better integrated to achieve higher energy performance.

Stanford also has new strengths in the building sector, including a new program in architecture. In addition to Professor Haymaker, another faculty position in building energy efficiency is likely to be opened soon. PEEC would come to provide clear direction to the Stanford Department of Civil & Environmental Engineering (CEE), CIFE, Construction Engineering & Management Program at Stanford, and the Stanford Architectural Design Program to continue to lead the field in sustainability, with a focus on the core issue of energy efficiency.

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