Overview

A Possible Way Forward

The challenges that we face in the near term are clear: global climate change and world-wide competition for dwindling resources that drive our economy, security, and future well-being.

Meeting the challenge of reducing building energy use to net zero is one of many "stabilization wedges" we can use toward reducing carbon emissions to 2005 levels, as suggested by Pacala and Socolow [1]. Buildings constitute 39% of total energy use in the US. Commercial building energy use is almost half of that percentage, or 18% of the US total. Heating, cooling, and lighting constitute 57% of the total energy end uses in commercial buildings and façades have a large influence over these loads.

High-performance, low-energy façades actively recognize and optimize synergistic impacts on lighting and heating, ventilation, and air-conditioning (HVAC) energy uses, achieving greater energy-efficiency, comfort, and amenity than conventional piecemeal solutions. But, how does one achieve high performance?

• Concepts: Understand the basic energy- and non-energy relationships between façades, lighting and HVAC systems and the occupants of buildings, then use this knowledge to move toward low-energy or even net zero energy buildings.
• Technologies: Consider façade technologies that make it easier to achieve a balance between competing performance criteria.
• Performance: Understand how well innovative technologies perform in the real world.
• Tools: Use early schematic design tools to investigate façade performance for specific building designs, then follow up with powerful simulation tools for detailed design if the budget allows.
• Resources: Research additional resources if time permits.

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Project Overview

Content for this website is the result of an on-going collaborative research and development (R&D) project, supported by the U.S. Department of Energy and the California Energy Commission Public Interest Energy Research (PIER). The project was launched in 2007 and content will be updated as new work is completed.

The project focuses on the remaining significant untapped near-term opportunity to capture large savings in the commercial building stock by:

• targeting voluntary, design-based opportunities derived from the use of better design guidelines and tools, and
• employing more efficient glazings, shading systems, daylighting systems, façade systems and integrated controls.

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Project Objectives

• To evaluate, optimize and develop, as needed, integrated, high performance building façade systems that enable reliable, routine, and cost-effective reductions in energy use and peak demand at the perimeter zone in commercial buildings with both commercially available mainstream technologies and with emerging technologies while maintaining and/or improving occupant comfort and amenity (e.g., connection to outdoors via view).
• To facilitate the widespread deployment of such systems into the U.S. commercial buildings market so as to exceed California's Title 24 and ASHRAE 90.1 performance requirements and achieve desired green building performance goals.
• To provide designers and owners with the data and tools needed to achieve these performance objectives.

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Approach

The technical approach builds on the Berkeley Lab's experience with innovation in the building industry, recognizing that there are different needs and pathways to reach different sub-sectors in the commercial market.

For mainstream and near-term market impacts, the challenge is to identify, develop as needed and then evaluate and optimize robust, off-the-shelf design solutions that meet the basic practical constraints for typical commercial buildings. The technical challenges are admittance of adequate daylight while limiting cooling loads and glare. There is a range of potential solutions with different cost, performance and applicability to various climates, building types and site conditions. The design challenge for architects and engineers is to quickly identify and evaluate the cost-benefit tradeoffs of solutions that address factors such as cooling, daylight, glare, view, cost, and maintenance. The technical approach is two-fold, addressing both the "supply" and "demand" side of the industry:

1. develop the tools and performance data that allow designers to navigate the complex decision-making process to select the best available solutions, and
2. work with manufacturers to improve their products when they fall short in terms of optimizing energy efficiency. The approach develops a series of "solution pathways" that provide answers to common needs.

For more innovative owners and design teams with more financial resources and greater risk tolerance, this project develops and evaluates solutions that optimize trade-offs and deliver better value via more sophisticated façade systems utilizing automated control systems. These solutions will initially be adopted less widely (retrofit + new commercial markets) due to complexity and cost constraints but in prior work the Berkeley Lab has demonstrated that they have the potential to deliver much greater and more reliable energy and demand savings, and at affordable costs. The potential for consistency and reliability of these automated systems, as contrasted with the uncertainty in any manually operated system, is a powerful reason R&D should be invested in these approaches. Over time the best of these solutions should "migrate" from use by early adopters into mainstream use and application.

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Outcomes

Technology portfolio report that includes descriptions of the metrics, performance requirements, technology options, discussion of architectural and business issues, performance results from simulations and testing, and summaries of demonstration activities. June 2009.

Expansion of features and capabilities of the US Department of Energy-supported simulation tools (on-going through 2009) including:

• Development of optical property models for frits, shades and blinds, and more complex systems, and expansion of the WINDOW solar-optical properties database to incorporate a wide range of commercially available products.
• Enable the direct linkage between WINDOW, Radiance, and EnergyPlus so that optically complex, operable façade systems can be better addressed.
• Release of the COMFEN tool.

[1] Pacala, S. and R. Socolow. Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies. Science 305: 968-972.

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