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Chapter 1. EnVisioneering a Systems Approach - To a Net Zero Energy Infrastructure
The tension between energy efficiency technology and the "first cost" orientation of the commercial building marketplace has long challenged energy efficiency advocates who know that progress will be slow unless the cost problem is solved. More recently, however, new factors have entered the equation, with the demand for efficiency boiling up just as the technical limits of many building component technologies to achieve higher efficiencies seem to get perilously close.
With the public policy arena newly refocused on energy but still unsettled on specifics, industry leaders need to take a fresh look at energy efficiency strategy and how more could be done with less.
To assist in that effort, Danfoss convened an EnVisioneering Symposium entitled Rx: A Systems Approach to Net Zero in Washington, D.C., on May 13 for leaders in the HVAC&R and related industries, which explored the basics of the building delivery system and new paths to high efficiency buildings. The event provided an opportunity for industry executives to examine ways to break through the limits that threatened progress on energy efficiency and new opportunities that might be gained by focusing on not only component improvements, but on relations between components through a whole building systems approach as well.
Chapter 2. Turning Point in Building Delivery
The discussion of a systems approach to building efficiency was launched with a presentation by Drake Erbe of Airxchange Inc. that opened the exploration of the commercial building delivery industry by peeling back its assumptions and traditions. The American commercial building circa 1900, Erbe explained, was a comparatively simple affair, and the industries that fed into its construction were managed in traditional "silos" defined mainly by products or the function they performed. But the 1902 invention of the electrically powered air-conditioning unit opened novel possibilities. Buildings could serve their primary function and also provide a comfortable work environment-which meant vast improvements in productivity and quality of life. The new possibilities were derailed when two world wars and a global depression swept attention elsewhere. But in post-WWII America, new buildings were needed fast and on a large scale to house rapidly growing industry that needed a highly productive workforce. Replicability was important to rapid construction and helped to contain costs. A new era in building delivery had arrived.
Simultaneously, Erbe suggested, engineering found itself driven by ever narrower functions, which fostered concentration on components. Since few components were needed to produce revolutionary building technologies, manufacturing and construction acquired a simplicity that seemed natural. Developments in manufacturing reinforced the component focus. Little was known of complex building systems, and few tools existed for thinking about them. As components were susceptible to steady incremental improvements, a corresponding engineering culture of research and development emerged.
| Managerial silos encouraged concentration on components and their refinement, and the new engineering culture welcomed it. Cheaply available energy initially made energy efficiency a low priority. Later, when oil shocks made efficiency more urgent, it was easily absorbed into the prevailing culture and treated as a new arena for the incremental improvement of components that was already successfully underway. |
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Design-Bid-Build v. Master Builder
For the next sixty years, the creation of a high quality working environment in commercial buildings would require a component-driven process that spawned and was reinforced by a specific building delivery strategy. Design-Bid-Build or Plan & Spec, both names for the same approach, became the DNA of a building industry that produced by far the most rapid expansion of commercial building stock the world had ever witnessed.
But, as Erbe explained, the new strategy largely separated architecture and design from building engineering and construction. The core design of commercial buildings became remarkably static and uniform, and components were specified without much attention to the dynamics of their relation to building design. Moreover, the move toward the automated Plan & Spec meant a move away from the historic building delivery system-the Design- Build or Master Builder system.
| Master builders had dominated the building industry since the Egyptian era and, even today, remain dominant in the rest of the world. In the U.S., however, they were now superseded. The main features of the Master Builder system included, first and foremost, an integration of the design and engineering function. Hence, an adaptive design process was central to building delivery and the elements of the building; its systems were treated as integrated parts of a "whole" building. Viewed from a master builder standpoint, then, Design-Bid-Build involved an unspoken bias in favor of a component's orientation precisely because it largely ignored whole building dynamics. |
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A Master Builder delivery system may well have fallen short in facilitating rapid expansion of available commercial square footage, but it retained overarching command and control of the building delivery system and a whole building systems orientation. Thus, when energy efficiency emerged as a priority, perhaps it would more likely have been treated as a systems issue. As Erbe underscored, the shift to Plan & Spec precluded such treatment and fortified a component-focused orientation.
Chapter 3. The Present Situation Emerges
The first energy shock of the 1970s ratcheted up the demand for energy efficiency, Erbe observed, but not so much as to shake the pre-existing framework. Efficiency was absorbed into a component-focused industrial culture.
However, as U.S. energy efficiency requirements turned up sharply in more recent years-especially in the wake of concern for climate change, energy security, and the difficulty of investment in new power generation capacity, the capacity of the primary components of building systems to provide the needed energy savings began to plateau. The term "Max-Tech" emerged in recent years to express the fact that many component technologies were nearing the limit of their range of possible efficiency improvement, crystallizing the ultimate dilemma faced by U.S. industry in meeting dramatically higher efficiency standards. The contemporary American building industry was beginning to entertain the thought that movement from a component and incremental orientation would soon be necessary to ensure meeting new efficiency expectations, and, furthermore, that standards, tools, metrics and measurement would all need rethinking.
Participants at the EnVisioneering Symposium discuss the path to Net Zero
In such a context, Erbe maintained, only additional concentration on the relationships between components could be expected to generate the new levels of energy efficiency sought. Though adoption of the Design/Spec delivery system, a comparatively recent step, had obscured the importance of those relationships as a source of significant energy efficiencies, the future would see expensive power and enlarged risk-to the economy, climate, and national security. Incremental efficiency improvements would fall short of new targets. Engineering would see multiple competing, concurrent values and objectives, and risk becoming incoherent in the absence of a building delivery strategy that focused on the whole building and designed integration of the building's systems.
Command-driven and silo-housed industrial management would not meet the new challenges of systems integration. In short, questions needed to be raised about the entire culture of the building industry and regulatory regime- including the dominant definitions of the efficiency of buildings, written into professional standards and codes that assumed component-based metrics.
| Looking ahead, Erbe contended, the industry would need very different criteria to guide its development. It would need to define efficiency in ways that encouraged creative leveraging of relations between systems. It would need correspondingly new metrics rooted in building systems to calculate whole building efficiency. |
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It would need "marketplace enforcement" of higher efficiency through labeling and maintenance programs taking the value of energy savings to the market value of the building. And it would need an analytic matrix to facilitate concrete evaluation of "targets of opportunity," as envisioned by the systems approach. Taken together, the requisites of success pointed toward and was best cultivated by a Master Builder delivery system, albeit one updated to accommodate a wealth of new technological possibilities, and Erbe expects the best minds in building delivery to turn in that direction.
Chapter 4. EnVisioning a "Systems" Building Engineering Industry
Carrier Fellow Richard Lord took the discussion to the next level by outlining what a transformed building delivery strategy would involve. The path to efficiency, as Lord outlined it, had produced an extraordinarily complex landscape of new standards like the ASHRAE 90.1 and International Energy Conservation Code (IECC) energy efficiency initiatives. A market regulation matrix of multiple tiers, regional requirements, differing (and competing) rating systems, and state, city, and locally generated and modified standards had also emerged.
Attention was focused on new applications but with too little attention to maintaining operational excellence, while standards had become both complex and difficult to enforce. He sketched a schema of the U.S. regulatory landscape that included four tiers and a blizzard of standards and guidelines for buildings, rebates and codes, with over a half dozen either recently revised or undergoing revision.
Overshadowing the regulatory maze was a forceful aspiration for improved efficiency. The draft American Clean Energy and Security Act, for example, included mandates for new national energy reduction targets ranging from 30 percent below baseline energy code in 2010, 50 percent below in 2014-15 and additional five percent reductions every three years until 2029-30. With residential and commercial buildings accounting for 39 percent of total U.S. energy consumption, policy makers hoped to make a transformative shift by achieving "net zero" for buildings by 2030. Lord's assessment, however, was that while the 2010 target might be achieved, there is little chance of meeting the further targets without some new approach to energy efficiency.
| Lord noted that certain rigidities in the current approach to standards offered, by implication, something of a light on a possible new direction. For example, while the current approach to standards defines efficiency levels at full load based on a component-focused assessment, all actual operations are at part load and under reduced ambient conditions. Examination of a typical large hospital building load profile revealed a substantial ambient temperature range within which various parts of the building are being heated and cooled simultaneously. Finally, while industry is in possession of tools for building system analysis (such as DOE2, EnergyPlus, Energy-10, EQUEST and others), studies show that less than 20 percent of buildings are actually modeled with advanced system analysis tools-and then, typically only the very large buildings are modeled. |
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The conclusion looms that a meaningful disconnect is occurring between the assumptions of the prevailing approach to efficiency analysis and the realities of building systems and building operations.
Lord agreed with Erbe that "the most logical approach is to attack the building at the system level." Concretely, such an approach would include integration of efforts on such items as:
- designs to reduce heating and cooling loads
- high efficiency and low leakage envelopes
- reduction of internal loads
- use of renewable resources
- energy recovery
- natural lighting
- natural ventilation
- advanced controls
- diagnostics and prognostics
- high annualized efficiency equipment
- hybrid equipment
More broadly, the approach would attempt to leverage the interrelationships between the range of energy consumption driving factors, activities, and forces operative in a building.
Similarly, building system analysis could be brought much closer to operational realities. Currently, many rebate and other incentive programs employ prescriptive component requirements instead of supporting use of a whole system model. Modeling tools are complex and require significant effort by trained modelers, which contributes to the high cost of modeling-a serious disincentive in an economic slowdown. The resulting gap between expectation and performance further dampens the already weak enthusiasm for system modeling; however, the targeted efficiency goals are unlikely to be achieved without practical modeling capabilities that allow assessments of the efficiency gained by alternative system designs.
These considerations led Lord to outline a series of specific recommendations for change within the building delivery industry:
- Efficiency regulations should move from prescriptive to rewarding innovative designs.
- Technologies should concentrate on interdependencies in building energy use (i.e., heat reclamation, thermal storage and the like), and better incorporate varied loads and operating conditions.
- Easier to operate, less expensive modeling tools that can be used quickly by the typical design professional.
- Tools should be validated on real buildings to improve modeling assumptions.
- Innovative energy efficient building designs should be incentivized.
- Energy saving technology development initiatives should be funded.
- A new emphasis should be established and tools and methods developed to facilitate maintaining the as designed performance of buildings.
Taken together, these recommendations constitute a redefinition of the building delivery strategy operative in the United States, and they point toward a redefinition of critical metrics for evaluating efficiency. Lord suggested that the goal should be to establish an effective measurement of building energy intensity-a rating of the total energy consumed by the entire building matched to building size-as the key indicator as efforts are made to move whole building performance to net zero.
But paralleling focus on a new metric is a new approach to achieving whole building energy performance: integrated design. And central to the shift in building delivery strategy is a reconception of the way the industry does its day-to-day work. Instead of concentrating on component improvement and selection, the industry would need to focus on key points of access to the overall performance of the building as a total system. High energy intensity requirements and sources should be reduced. Energy recovery within the building should be expanded. Steps should be taken to prevent overheating and overcooling, with greater emphasis on advanced controls and control logic. Green energy sources should be integrated into the building's energy profile, and hybrid systems developed and deployed to take advantage of changes in building load and ambient temperatures. Additionally, designers should add conservation of resources, such as water and materials, to the criteria of sound building design.
Still, Lord suggested modeling would need much improved tools for the overall shift in strategy to be effective, and was quite specific. Tools that allow for quick transition from the design to the model and for testing sub-system interactions to optimizing design are required. The tools need to be usable by the average design professional, and key components in the building (e.g., HVAC, envelope, lighting and power) need to be electronically linked into the models using standardized protocols. Those steps further suggested the need for building CAD drawings to be electronically linked to the building modeling tools, new rating methods for key components and new approaches to certification. Central to the revolution in building modeling is that the models must be able to link technology solutions and evaluate the interdependencies of the technologies. To bring greater realism to the process, modeling assumptions would need to better reflect real building measurements.
And finally, regulations would need to encourage the use of modeling and refrain from excessive pre-definition of the systems to be used in buildings.
| The detailed vision that Lord outlined elaborated Erbe's historical and implied deep changes in the DNA of U.S. building delivery, with R&D focusing on systems technology innovation, industry seeking novel workforce capacities and new modeling and diagnostic tools joining more systematic enforcement of codes, building commissioning, re-commissioning and continuous commissioning. |
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With such radical change on the horizon, questions inevitably emerge about the feasibility of bridging the gap between the vision and the contemporary point of departure-and of the steps and risks to be taken in bridging that gap.
Chapter 5. The Challenge of Building Modeling
Private sector driven progress toward net zero buildings is dependent on an array of factors. High among them: industry's capacity to model energy performance, especially at the whole building systems level. Only modeling can provide the experience and data essential to rational, confident and responsible decision making. Yet as Richard Lord had underscored, modeling to be functional needs to meet specifications it has not yet widely achieved, including low-cost, ease of use, in touch with the reality of buildings and the like. And until the challenge of modeling is better penetrated, hope for a shift to whole building systems engineering would likely be frustrated. Critical energy savings remain beyond reach, component manufacturers are thwarted by the laws of physics and the building industry is caught between risks, uncertainties, pressure for improvements and untimely costs.
In that context, Professor Godfried Augenbroe of the Georgia Institute of Technology College of Architecture spoke to the symposium of the challenge of modeling and creating the instruments that can lead to a net zero era in buildings.
Augenbroe took the systems approach as his point of departure, taking in building dimensions from façade treatments to PV panels, integrated wind power and hybrid ventilation strategies to total light management.
But a review of the more dramatic recent work in systems buildings revealed some "extreme challenges"- in scalability, confirming correctness, verifying design idealizations, defining systems within systems, modeling the building occupant, supporting evolution of the design and knowing the level of model fidelity required for the project. To his first maxim "Don't over-engineer the model," Augenbroe added a second, "Think about uncertainties in your assumptions," and perhaps a third, "Make the uncertainties explicit in order to perform intelligent risk analysis, which can then be linked to cost analysis."
The degree of uncertainty in modeling does not disqualify the modeling process, nor render its results useless. The building industry deals mainly with routine cases that have knowable opportunities for systems integration. The overarching trend in energy simulation tools, however, is toward ever increasing levels of sophistication, so that novices produce highly varied results from the same design. Or to say the same thing another way, a skilled tool user is not the same as a good energy modeler. Becoming a good energy modeler requires a significant body of training and experience, and, in the end, the exercise of a mature judgment and acceptance of the prospect of deviations between predicted and monitored performance.
But risk and cost analysis techniques have long dealt with the levels of uncertainty coincident with the work of a seasoned energy modeler, especially when working with a reasonably routine building concept. What is certain, Augenbroe reminded, is that maintaining separate systems will produce failing buildings from an energy standpoint.
The question, therefore, cannot be formulated in terms of need for certainty, but rather how to deal rationally with identifiable levels of uncertainty.
The key challenge, as Augenbroe sees it, is to provide instrumentation for the distinct phases of the delivery process: early, mid and then final implementation. For the first stage, he proposed use of a "Normative Model"-a simple model that can be applied to any building based on first order principles, and good enough to provide sufficient accuracy for normative energy assessment.
Such a tool would avoid the need for elaborate and costly building simulation and could be used for performance benchmarking. Second stage simulation would be able to draw on the current tool base. All the physical phenomena would be represented, including location, orientation, weather details, shape, material properties and other specifics of building design.
The third stage would represent the "next generation" of energy modeling: integrated simulation. Acknowledging that physical integration cannot be equated with design integration, the emphasis would be on revealing risks and finding problems and anomalies in building behavior.
By staging the modeling effort, a degree of precision appropriate to the immediate need could be achieved, and greater emphasis can be given to highlighting uncertainties that can then be calibrated into the value of the building and building operation and maintenance strategies.
But most broadly, the models of the future, Augenbroe suggested, need to draw on multidisciplinary analysis in order to capture at the modeling level the comprehensive perspective of a whole building systems approach, and be linked realistically to the genuine operation of the building.
Chapter 6. Looking to the Future
The revolution in building delivery as outlined by Erbe and detailed by Lord would require a nuanced strategy to manage the complex interface between advanced technology and operational realities. Such a strategy would need to recognize the logic for a shift to systems based building delivery and management, the logic of such a shift, and the practical limits and demands of the technologies required for its implementation.
The history of building delivery was arriving at a turning point-one with intricacies altogether new but intrinsic to an era when the promise of buildings collides with a world of unintended consequences and limited resources. It remains to be seen how an industry so decentralized and driven by market pressures of the moment will manage that transition in the face of the powerful dynamics of advanced development.
