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Airflow within the cavity of double-skin facades is a key component of adaptive building envelopes which change thermophysical properties to meet changing environmental conditions, occupant comfort demands, ventilation rates, etc. To consistently balance these requirements, adaptive building envelopes incorporate intelligent controls. Contemporary double-skin facades include configurations of two glazed panes with an in-between air gap, two opaque layers with an air gap, or a transparent layer and opaque layer with and air gap (i.e., Trombe wall). In high-rise buildings, the system can be separated by floor level with air intake and outlet installed per floor, or it can be built across multiple stories that share bottom air intakes and top outlets.
In this paper, the authors examine novel applications of ETFE (ethylene-tetrafluoroethylene) membranes in double-skin facades to discuss the opportunities and challenges for adaptive building envelopes. ETFE is a contemporary building material sought for its characteristics of 95% light transmission, lightweight, durability, and recyclability. The primary research questions are: 1. How does ETFE compare against other transparent materials that are typically used in double-skin facades? 2. What are the potential design strategies with ETFE for dynamic double-skin controls that can balance energy and human comfort? 3. What are the specific requirements for construction?
To address these questions, two case studies developed by the authors will be discussed in detail, (1) a proposed retrofit application for a high-rise building in New York that integrates a single skin ETFE membrane with a vent system integrating shape-memory alloy wire; and (2) a single-family home double-skin façade which encloses a solarium and green roof/wall that is to be constructed in Zhangjiakou, China. These case studies discuss the implications of innovative design concepts (i.e., embedding smart materials and environmental control systems) while elaborating on practical design considerations of inflated air cushion vs. single membrane systems.
We as a species have been aware for some time now that our actions have a large and lasting impact on this planet. From the first photos of our ‘pale blue dot’ to the high-definition veins and clusters of light stretching across the earth's surface, humans have made a home for ourselves with our structures and transportation networks. Our building techniques have changed over millennia in accordance with our lifestyles; from early bone huts, to portable tent structures, stone castles, wood tract homes and aluminum, steel, and glass skyscrapers. The goal has been pretty much the same, seeking comfort from the elements.
As our construction methods have evolved, there continues to be somewhat of a transitory mentality to our buildings, which has only been exacerbated by the general culture of conspicuous consumption. Commodity construction has taken hold over the last 100+ years, unlike our predecessors in the nomadic tents who could easily deploy and dismantle their architecture reusing the same material, or the stone structures which, though more permanent, were carefully tended to and maintained over centuries and still stand to this day. Today we build, then 15-30 years later we demolish and build something new. The construction methodologies of the building industry in the last 100 years, coupled with exponential population, and the belief that buildings have a designated lifespan has created an interesting problem and one of the highest contributing factors to global carbon emissions.
Our built environment takes up a relatively small footprint of the earth's surface but our buildings (in material and operations) contribute to approximately 40% of all the global emissions (Hamilton et al., 2020) . Much of the focus on building energy and performance in the last 20 years has been on the high-rise towers in the urban centers of US cities, both commercial and residential, and though this is an extremely important building category, we estimate that the single family detached home takes 68% more land area and 12% more total building square footage on average than its high-rise counterpart. Here we have an opportunity to look at how we can find ways of retrofitting not only existing high rises but also single-family homes to become more energy efficient and carbon neutral.
We have an opportunity to blend old techniques and new materials to approach the single-family home and high-rise building typologies in different ways. The focus of this paper is to offer new insights from our design research of membrane based cladding strategies rather than presenting a complete and comprehensive study for performance upgrade strategies of the US building stock. With that, we ask the questions:
- What might it look like if a developer tract home was wrapped in a skin of ETFE (Ethylene Tetrafluoro-Ethylene) pillows to reduce winter heating and passively cool in the summer?
- Could a 1960’s high-rise office tower become a passive kinetic façade of stretched ETFE with increased ventilation, reducing air-conditioning and heating seasonally, while being one of the most carbon lean solutions and still honor the original architecture?
Climate-responsive energy-free architectural design practices which evolved with the 20th century studies of vernacular architecture have led to various building approaches which integrate adaptive systems that respond to the specific
Generally, lowest performing elements in a building façade are the transparent areas of glass and glazing versus opaque systems. In the last 30 years, the glass industry has made exceptional
The Solar Decathlon China 2021 Y-House Project (Single Family Detached House)
Overview of the Project
Developed for the Solar Decathlon China 2021 Competition, this project was developed by an international
In this paper we discussed ETFE based membrane strategies for residential and high-rise envelope applications for new and retrofit purposes. As mentioned in the earlier sections, the studies presented here
The authors thank the sponsoring organizations Solar Decathlon China 2021, Xi’an Jiaotong-Liverpool University, Thomas Jefferson University, Zhejiang University-University of Illinois Urbana Champaign Joint Institute, and industry partners GCL Nanotech, Taohuajiang, and Flying Architecture. We also thank professional advisors Kewei Liu (INBAR), Changqi Ma (CAS), Petra Stanev and Ryan Lohbauer (Stanev Potts), Alex Worden and Audrey Worden (StudioTJOA), John Shields (PointB Design), Matt Naugle (New Hudson Facades), Bjoern Beckert (Fabritecture), Florian Meier (Knippers Helbig), Matthew Cleary (Saint Gobin). All images of the SDC 2021 project case study are credited to Y-Team faculty and student team members who participated in developing this project.
Hamilton, I., Kennard, H., Rapf, O., Kockat, J., and Zuhaib, S. (2020), 2020 Global Status Report for Buildings and Construction, https://globalabc.org/sites/default/files/inline-files/2020%20Buildings%20GSR_FULL%20REPORT.pdf
Martinez Arias, Andrea & Patterson, Mic & Carlson, Anders & Noble, Douglas. (2015). Fundamentals in Façade Retrofit Practice. Procedia Engineering.
Wilson, E, Christensen, C., Horowitz, S., Robertson, J., and Maguire, J. (2017) Energy Efficiency Potential in the U.S. Single-Family Housing Stock, National Renewable Energy Laboratory