Mapping Advanced Facades

Introduction and Background

To make progress towards mitigation of climate change and managing local environmental impacts, it’s clear that broad and significant technological and policy advances are required for the building sector. For these initiatives to be effective, stakeholders need robust and reliable information about costs, benefits and risks in order to inform decision making. Researchers at the Center for the Built Environment (CBE) at UC Berkeley and the Polytechnic University of Bari, Italy, set out to identify and document high-performance facade case studies to disseminate information about best practices for appropriate and climate-responsive building envelope design. This resource is intended for a broad audience of design professionals, students, academics and others. This work updates and expands on previous case study research of buildings in Europe and North America conducted by UC Berkeley graduate students (Zelenay 2011).

For the purposes of identifying best practices for sustainable design, many aspects of the built environment can be reliably modeled and estimated; for example, whole-building energy simulations using advanced software tools, utility energy and water data, and design of simpler buildings based on performance or prescriptive building codes that have been developed and refined over decades. Building systems such as lighting and mechanical space conditioning (HVAC) connected to building management systems (BMS) generate detailed data that may be used for benchmarking and means for improvement.

Building facades, however, function as complex and generally bespoke integrated systems, and belie simple means for quantifying performance. While we have reliable metrics for the performance of individual elements — for glazing, insulation, infiltration, etc. — the complex interactions between these elements, with other building systems, and with the outdoor environment, are difficult to predict and understand. Design decisions around facades must also balance frequently conflicting performance objectives for daylighting, window views, solar control, energy conservation, comfort and prescriptive building standards. Overly simplistic approaches such as ‘maximizing daylight’ and/or prescriptive daylight standards can lead to over-glazed facades that have not taken into account these conflicting requirements.

Noteworthy attempts have been made to characterize facade performance, though these tend to be relatively complex and have not been widely applied in practice. One recent paper provides a systematic review of methods for building facade optimization, and notes that a ‘predominant focus is placed on improving energy efficiency, minimizing initial investment, life cycle costs, environmental impact, and improving thermal and visual comfort’ (Shan 2023). An integrated design workflow that takes into consideration ventilation, thermal and daylighting ‘autonomy’ has been described in the literature (Ko 2018). Approaches such as the voluntary standard Passivehaus are appropriate in specific climates, but may not be globally applicable, for example in warm and/or humid climates where external shading and natural ventilation are useful strategies. In common practice, design teams striving to optimize facade systems by relying on specialized consultants who apply multiple methods and tools to inform facade design related to heat transfer, daylighting, solar control, comfort and visual comfort.

As technology development and design methods evolve, advanced facades can vastly reduce energy consumption, they may enable the use of low-energy HVAC systems, and in some cases allow for fully passive approaches to ventilation and space conditioning. Advanced facade systems may even be energy producing and can also improve the well-being of the building occupants, by providing daylighting and high-quality window views (Ko 2020). New glazing and control technologies, along with new building standards, will continue to drive innovation in building facade design, adding more options as well as constraints to the designer’s palette. The wide range of creative solutions makes documentation of case studies a valuable endeavor.

Methods

While successful facade exemplars are available to design professionals, the engineering and architecture press generally does not include detailed information about product specifications, performance and design insight. The goal of this project is to bring detailed information together into a single, standardized for case studies that represent best practices for climate responsive facades, in order to assist industry professionals in their decision-making processes when considering the adoption of advanced facade designs and technologies, and also for students of architecture and building engineering in their studies.

This project uses lessons learned from a previous project, creating an online map with a database of over 400 commercial buildings using radiant cooling and heating, online at CBE Radiant Systems Map (Karman 2014). The mapping function was included to demonstrate that radiant systems could work within a wide variety of climate, construction and code requirements. This project mapping approach has been adopted for other case study documentation, for example by the International Living Future Institute, in which certified and pending projects are located, at https://living-future.org/our-living-future-map/ . Carbon Brief created a interactive map to view electrical power plants in the US and their relative electricity generating capacities, at https://www.carbonbrief.org/mapped-how-the-us-generates-electricity/

While the radiant systems map provided inspiration for the Facade map, it differs in significant ways. Because the goal of the radiant map was to include as many examples as possible of this emerging technology, there was no requirement to screen projects based on performance or other criteria. However, in the case of the facade case studies, the researchers viewed the selection of case studied as a key part of the process. This selection process is described below. The project team also recruited a technical advisory group (TAG) from among the CBE’s consortium of induct partners, including practicing architects and engineers, and representatives from product manufacturers. The TAG and the research team held virtual meetings to inform and validate key decisions about the development of the website design and project selection.

Creating taxonomy of building and facade characteristics

With a goal of including detailed technical information, the team worked to create a comprehensive taxonomy of building and facade data that would be used to collect, organize the display this information. Where possible, the team referred to facade performance literature, for example, the AIA COTE Top Ten Awards, and other sources (Romano 2018, Aksamija 2013). Ultimately, it was decided that a novel taxonomy would be needed for the purposes of this work.

The project team used Miro, an online collaborative whiteboarding tool (Fig.1) This tool provided a visual and interactive way for the development of the taxonomy, including hierarchical relationships between categories, parameters and values. The final taxonomy was broken down into building characteristics (Table 1) and facade characteristics (Table 2). This taxonomy has been used for the collection of building information, for organizing the display of information, and for filtering and viewing a subset of projects.

Table 1. Taxonomy of general building information

Table 2. Taxonomy of facade characteristics

Selection of case studies

Key to the development of this resource is the selection of the case studies, with a goal to include examples that demonstrate high-performance facades in terms of energy and indoor environmental quality, as well as architectural expression and technological innovation. The project team set out to define a set of screening criteria for inclusion, and planning to rely on third-party validation related to performance and/or architectural standards, for example LEED, sustainable building awards (e.g., AIA COTE Top Ten Awards), EnergyStar, BREAM or WELL, plus recognition in the architectural press and/or awards for innovation and architectural merit.

However, after reviewing numerous projects with these accolades or certifications, the team quickly realized that the selection process would inherently require a significant level of subjective judgement. As noted above, there is no simple approach to qualifying facade performance independent of the common whole-building certifications available. Through this curation process required the authors to grapple with numerous subjective and objective measures, and defining exactly what constitutes a high-performing and climate-responsive solution. For example, can a glass curtainwall facade in an extreme desert climate ever be considered a sustainable solution? The authors also considered what performance metrics can be applied in the selection process, while still allowing for a wide range of innovative and diverse examples. The authors ultimately decided on seven fundamental strategies relevant to the creation of high-performance facades, which are described as ‘reasons for inclusion,’: daylight control, solar control, natural ventilation, noise control, low embodied carbon, energy generation, and innovative insulation systems. Generally, we are seeking candidate projects that showcase best practices with respect to two or more of these strategies, though in some cases for example with an especially innovative application, or to represent an emerging or relevant technology, one reason for inclusion has been deemed sufficient.

For the first phase, the team focused on projects in Europe and North America, mainly due to familiarity with both precedents and the climatic context. At the time of this writing, we have begun to identify and include projects beyond these areas.

Creation of a mapping website

The project team built a website on the common WordPress platform with multiple ‘plugins’ to provide many of the features desired, and customized these to align with CBE’s visual standards, and adding building and facade taxonomy ‘custom fields’ per the parlance of WordPress, integrated into the website backend. The page layout is structured with the body of the map in the center of the page, with filtering options on the left panel, and boxes featuring the case studies below, listed in reverse chronology based on dates projects are added, with those most recently added at the top. The filters allow users to parse the case study projects based on the ‘reasons for inclusion,’ and/or characteristics of interest or relevance to a specific investigation or design question. From the complete or filtered list of case studies, users can click to view the complete details and images in an overlay box (commonly called a pop-up) each having with a unique URL so that any project can be saved or shared.

As the climatic response of case studies was considered a key aspect of the selection process, the map was also enhanced by translucent climate map overlay. The project team considered several alternative climate maps, including the ASHRAE Climate Zones, and decided that the Köppen-Geiger would be the most acceptable for the worldwide range of case studies eventually expected to be included in this resource.

Case study documentation

To capture the desired level of detail, the website was configured with an imput form that prompted users to input data for all the building and facade taxonomy fields. After candidate buildings were identified, the team moved used two methods to populate the website with project information. For the initial set of case studies, researchers and architecture graduate students used available online information to fill out the case study details, including images such as photographs, construction details, plans and sections. While this approach was beneficial in quickly filling out the initial set of projects, the amount of information was limited to what is available online or in publications, and represent a small set of details and specifications outlined in the taxonomy.

Because design and construction team members are generally the gatekeepers of such technical details, a significant effort was made to connect to them, and requesting assistance to directly fill out the online form. We tapped into the network of CBE industry partners and others, with some success. Project information has been provided by team members from firms including DIALOG, Foster + Partners, and Transsolar/KlimaEngineering.

Results and Discussion

The map was launched as a beta version in January 2021, with a dozen projects and the website development mostly complete, with filtering and display of the building taxonomy. Feedback from the TAG in early 2021 generated useful feedback and informed a round of improvements to the website design and taxonomy. This progress was presented to CBE’s Industry Advisory Board, consisting of design professionals and other industry stakeholders, in April 2021 to gain additional feedback and identify more case study candidates. At the time of this writing, 37 projects have been included. It’s noteworthy that case studies for which information was provided by a design team member are the most extensive, with detailed set of taxonomy data, for example, down to the typical thermal transmittance (U-values and G-values) and visual light transmittance (VLT) for typical glazed elements, and U-values for typical solid facade elements. Examples of case studies providing high levels of detail include the linked Hunter Student Commons and MacKimmie Tower at the University of Calgary, with architecture by DIALOG, and Bloomberg European Headquarters, architecture by Foster+Partners.

The authors hope that as a critical mass is reached, perhaps in the range of 50 or more well-documented case studies, that practitioners will see value in having their projects included, and we can accelerate the addition of case studies. We plan to continue to seek emerging trends and innovations in building facade design, with potential for creating sustainable, decarbonized buildings. For example, dynamic facades with responsive shading systems, adjustable louvers and or ventilation. We will also work to keep abreast of more exotic proposals, such as biophilic designs that integrate living walls, green facades, or materials that mimic natural textures; and aspirational concepts such as carbon-capture solutions created with a goal of absorbing carbon dioxide from the surrounding air, contributing to the reduction of greenhouse gas emissions. While we seek to include cutting-edge concepts, we will continue to rely on third-party performance documentation.

Conclusions

The facade map remains a work in progress, and we expect this to be the case as projects are identified and added, and also as new innovative case studies are completed. The authors believe this resource will reach a mature when it has approximately 100 or more case studies, and ideally including comprehensive details and specifications related to these exemplary facades.

The authors hope that practitioners, researchers and students in the fields of architecture, facade engineering and sustainable design may be able to leverage this case study repository for studying trends and innovations in facade design. It may eventually also provide a resource for presenting case studies and success stories from similar climates or contexts to help build community support for sustainable building initiatives.

There are several primary lessons learned from making this resource. These include the challenges of identifying case studies that represent best practices in climate-responsive facade and building design, as reliable performance data are often unavailable through public sources, and facades serve competing goals. An additional challenge is recruiting design team members who have access to the full range of details that are desired for the case study documentation. Only for a few case studies was the full range of desired taxonomy questions addressed, these were for projects for which design team members submitted information using the website’s input form. While such projects represent a relatively small subset of the featured case studies, we assume that this mostly results from time and priority constraints, rather than concerns about sharing intellectual property represented in building designs. On exception in the case of technology firms which are highly protective and resistant to share information of any kind, and design team members are precluded from sharing information not already published. As this work is continued, we plan to discuss ideas for incentives and/or alternative methods for collecting documentation, that may improve responses to the project questionnaires.

The authors wish to thank Giovanni Betti for his contributions towards the development of the facade taxonomy, identifying case studies and providing details about the Bloomberg European Headquarters. We also thank Minghao Xu and Yunzhu Ji for documenting projects, Paul Raftery for his initial conception of a facade map, and Tom Parkinson for his early participation. We also thank the many Technical Advisory Group members, and design team members for contributing design specifications and data.

Aksamija, A., Perkins+Will, (2013). Sustainable Facades: Design Methods for High-Performance Building Envelopes, John Wiley & Sons, Inc., Hoboken, New Jersey, ISBN: 978-1-118-45860-0

Karmann, C., Schiavon, S., & Bauman, F. (2014). Online Map of Buildings Using Radiant Technologies. UC Berkeley: Center for the Built Environment. Retrieved from https://escholarship.org/uc/item/9rs8t4wb

Michael, M., Favoino, F., Jin, Q., Luna-Navarro, A., & Overend, M. A Systematic Review and Classification of Glazing Technologies for Building Facades. Energies 2023, 16, 5357. https://doi.org/10.3390/en16145357

Ko, W., Michael, G. Kent, Schiavon, S., Levitt, B. & Betti, G. (2022). A Window View Quality Assessment Framework, LEUKOS, 18:3, 268-293, DOI: 10.1080/15502724.2021.1965889

Ko, W., Schiavon, S., Brager, G., & Levitt, B. (2018). Ventilation, Thermal and Luminous Autonomy Metrics for am Integrated Design Process. UC Berkeley: Center for the Built Environment. http://dx.doi.org/10.1016/j.buildenv.2018.08.038

Romano, R., Aelenei, L., Aelenei, D., & Mazzucchelli, E. S. (2018). What is an Adaptive Facade? Analysis of Recent Terms and Definitions from an International Perspective. Journal of Facade Design and Engineering, 6(3), 65–76.https://doi.org/10.7480/jfde.2018.3.2478

Shan, R., & Junghans, L., (2023). Multi-Objective Optimization for High-Performance Building Facade Design: A Systematic Literature Review. Sustainability. 2023; 15(21):15596. https://doi.org/10.3390/su152115596

Zelenay, K., Perepelitza, M., & Lehrer, D. (2011). High-Performance Facades Design Strategies and Applications in North America and Northern Europe. UC Berkeley: Center for the Built Environment. Retrieved from https://escholarship.org/uc/item/4vq936rc