Hot Stuff
Universal Thermal Climate Index, or UTCI, for a proposed highrise

Hot Stuff

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For the last five years, I have taught a graduate class at the Southern California Institute of Architecture that I have informally called “Hot Stuff.” Hey, I grew up listening to Donna Summer at a very early age, probably too early, so I cannot resist forcing my students to think about climate change through the lens of disco. We might as well have fun as we try to keep the global average temperature rise below three degrees celsius, right?

I talk a lot about urban heat in this newsletter because it is at the top of the charts for risks associated with the climate crisis and, yet, we are still designing most buildings around the world based on typical meteorological year (TMY) weather data. That is, we take data from a historical set of observations from a 30-year period and assume the most typical conditions from that period will exist over the life of the building we are designing. The extreme heat waves and expanded summer seasons we now see are just the start of a century of increasing temperatures, none of which are reflected in a TMY weather file you might download.  

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a. The Universal Thermal Climate Index, or UTCI, is an equivalent air temperature that represents a combination of air temperature, wind, radiation, and humidity at the time. Shown at left, the annual historical weather data that is used to inform typical weather files, in this case Melbourne, is represented with UTCI taking those factors into account. By morphing weather data based on UNIPCC climate change scenarios, the annual UTCI chart for Melbourne on the right demonstrates some clear differences from the historical model. Extreme temperatures, whether cold or hot, become more common in the predicted weather model. This window into the future climate of the city leads designers to ask different questions about how outdoor or semi-outdoor spaces may feel in these likely conditions.

Our energy models, thermal comfort models, urban microclimate studies—whatever it is you may be modeling and analyzing in the digital space—reflects a climate that no longer exists. An engineer will tell you not to worry since we probably have 20 percent or more safety factors built into various system capacities. You can disagree with me on that one if you want (or if you are an engineer), but show me the numbers (or ask a lawyer). Also, we cannot just keep throwing air conditioning at this problem…we need a design agenda that provides credible alternatives. or at least plans for redundancy for systems, in a way that anticipates actual future conditions.

For the last two months, we have been assessing the climate risk of our seventeen studio locations as part of our annual sustainability report, the Woods Bagot Climate Playbook. We started by reviewing city and regional climate action and adaptation plans for each location to understand the risks and opportunities for our clients and our own operations. The first thing I will say is that it is impressive to look at the incredible body of knowledge captured in these plans. From New York City’s OneNYC 2050 to Melbourne’s Climate Change Mitigation Strategy to 2050 or, my favorite, Los Angeles’s Green New Deal, these plans have done the work to lay out the challenges and opportunities with clear implications for designers of the built environment. They are required reading for any climate activist in architecture.

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b. The modeled view on the left illustrates the Universal Thermal Climate Index, or UTCI, for a proposed highrise in Melbourne, Australia. Designers incorporated outdoor terraces into the project, which necessitated an investigation into the environmental conditions that would support occupancy of those spaces throughout the year. This image shows UTCI data for June 15, which would be early winter months and shows a daytime UTCI of between 17-18˚C, which would be considered comfortable. In comparison to the historical UTCI model, the outdoor spaces in the same proposed highrise in Melbourne reveal a much colder condition when modeled using WeatherShift data as shown on the right. A UTCI of nearly 13˚C would suggest these terraces may not be comfortable during winter months or may necessitate a design change to provide some wind protection to improve the outcome. Although we often focus on extreme heat in the future given the climate crisis, understanding the potential for seasonal extremes can inform many different design outcomes.

Not surprisingly, in every city we work, extreme heat is a key climate risk. Other risks run the gamut from sea level rise, coastal flooding, extreme rain events or drought, to indirect risks associated with infrastructure capacity or vulnerable populations. You also stumble across surprise risks you may not consider, like in New York City where a projection in groundwater rise can pose serious risks to basements, especially those used as apartments.

How do you take a city’s climate action plan and instrumentalize it as part of a design process? This is where we have to question those distorted weather files. To ensure Woods Bagot is designing with reliable data, our approach was to partner with the global engineering firm, Arup, and invest in a set of future weather files based on UNIPCC climate change scenarios for all our studios. Using Arup’s WeatherShift tool, we have embedded future weather data as an option in our own Environmental Performance Toolkit (EPT). The EPT is a set of modules we have developed for our Rhino workflow to help teams quickly assess environmental design opportunities early enough in the concept phase to inform major design decisions.

WeatherShift is a powerful data set that morphs TMY files and generates 8,760 hours of likely future dry bulb temperatures, wet bulb temperatures, and relative humidity numbers, among other outputs, to establish a reasonable approximation of how a climate will change given increased emissions scenarios and global warming.

This technology provides our design teams with a way to frame early support for passive design opportunities like natural ventilation, solar control, thermal comfort, or daylighting in a way that can anticipate likely scenarios of increasing temperatures. Comparing it to the historical TMY output may alter our appreciation for how the solar reflectance index of a pavement finish impacts heat islands, or whether the number of hours you can comfortably naturally ventilate an office building makes sense for an occupant.

Of course, a weather file is a weather file, so you can plug a future file into any software you use and compare it to the TMY file output (you can also play around with WeatherShift for free on the website). This approach is not going to answer every question we as designers have, nor will it unlock some secret knowledge about our practice and climate change, but it provides credible evidence as a basis for conversations with our colleagues and clients about risks.

These sorts of tools are a way for architects to chip away at the uncertainty we face with a planet that is changing faster than we can imagine. We need many more hot takes on hot stuff given the challenges we collectively face.

Russell Fortmeyer


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WHAT AM I READING?

Funding San Francisco’s Climate Action: Strategies for Revenue, Implementation, and EquityBerkley Law’s Center for Law, Energy, & the Environment

Atmosphere Anatomies: On Design, Weather, and Sensation, by Silvia Benedito, Lars Müller Publishers (2021)

2022 Status Report, The Task Force on Climate-Related Financial Disclosures

Scarlat Dias

Creative Architectural Designer | Passionate about Tech, Sustainability, & Interior Design | Innovative Solutions

1y

Awesome post! Got some really valuable insights and practical tips to try out. Thanks for sharing!

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Jessica Merritt

Communications and Strategy Leader – Architecture and Culture Focus

1y

Another great one, Russell Fortmeyer!

Lizette McNeill

Managing Partner, IXO - Decarbonization Engineering & Advisory

1y

Such a great read! Thanks for sharing.

Jango Wong

Principal | Kellogg-HKUST Executive MBA Candidate

1y

Great reading list that you have! Very humble title "NOT SO MUCH", but in fact so much more. Russell Fortmeyer

Sharon Wiley

Principal Designer & Project Director

1y

Informative proactive reading, thank you for sharing.

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