circadian curtain wall by HOK is a curved glass façade that responds to the sun’s path

circadian curtain wall by HOK is a curved glass façade that responds to the sun’s path

architecture and engineering firm HOK proposes the circadian curtain wall, a façade of curved glass panels that responds to the sun’s path and the 24-hour circadian cycle. imagined for a building with an ovoid floor plate, the circadian concept boasts far greater inherent strength and wind resistance than flat-panel glass and allows for bigger window bays with fewer supportive aluminum mullions required to transfer wind load back to the primary structural frame. sustainability specialists at WSP built ecology collaborated with HOK on analyzing the performance of the façade and estimating operational energy savings.

all images courtesy of HOK



the circadian concept was born out of HOK’s ongoing research into building skins that reduce the use of carbon-heavy aluminum while also augmenting stiffness of the primary structure. besides reducing embodied energy, the curved windows offer 180-degree views flooding the building with natural daylight while connecting its occupants to the outdoors by extending the interior out past the building’s main footprint. as the sun moves through the sky, the façade’s bubbled glass provides self-shading on adjacent window glass that passively reduces solar heat gain.

the façade’s curved glass allows building occupants to walk out beyond the building’s main footprint to connect to the outdoors and daylight



the façade’s double skin offers additional benefits, including an extra level of thermal and sound insulation and a potential trombe wall effect to heat the building or mitigate cooling load. automated shades (housed in a cavity between the façade’s outer and inner skin where they’re kept clean and maintenance-free) provide additional glare and heat reduction during periods of intense sunlight. daylight and energy modelling for a 30-story building show that circadian curtain wall can reduce energy use by 16 percent; peak cooling load by 24 percent and peak heating load by 27 percent.

wind pressure analysis on traditional, flat-panel glass and the circadian curtain wall’s curved windows

a cavity between the façade’s exterior and interior glazing pulls heat off the building and provides a clean, maintenance-free housing for the automatic shades

the circadian curtain wall continues HOK façade specialist john neary’s research into building skins that increase energy efficiency while minimizing the use of carbon heavy aluminium

sketches of the circadian curtain wall

it is estimated the circadian curtain wall can save 300 to 400 tons of aluminum in a 1 million sq.ft. building with 300,000 sq.ft. of skin (when compared to using traditional flat-panel curtain walls)

inspired by the 24-hour circadian clock, the façade’s design maximizes building occupants’ exposure to daylight and the daily rhythms that influence human health


as the sun moves across the sky, the façade’s curved glass provides self-shading to adjacent windows – minimizing glare and heat gain

the circadian curtain wall’s shades deploy automatically depending on the location and strength of the sun – here fewer than half of the shades are deployed

WSP’s modelling analysis on a building with an ovoid floorplate shows that circadian curtain wall would reduce solar heat gain (top) while increasing interior daylight (below)



designboom has received this project from our ‘DIY submissions‘ feature, where we welcome our readers to submit their own work for publication. see more project submissions from our readers here.


edited by: sofia lekka angelopoulou | designboom

    have something to add? share your thoughts in our comments section below.
    all comments are reviewed for the purposes of moderation before publishing.

    comments policy
    LOG IN
    designboom's comment policy guidelines
    generally speaking, if we publish something, it's because we're genuinely interested in the subject. we hope you'll share this interest and if you know even more about it, please share! our goal in the discussion threads is to have good conversation and we prefer constructive opinions. we and our readers have fun with entertaining ones. designboom welcomes alerts about typos, incorrect names, and the like.
    the correction is at the discretion of the post editor and may not happen immediately.

    what if you disagree with what we or another commenter has to say?
    let's hear it! but please understand that offensive, inappropriate, or just plain annoying comments may be deleted or shortened.

    - please do not make racist, sexist, anti-semitic, homophobic or otherwise offensive comments.
    - please don't personally insult the writers or your fellow commenters.
    - please avoid using offensive words, replacing a few letters with asterisks is not a valid workaround.
    - please don't include your website or e-mail address in your comments for the purpose of self-promotion.
    - please respect jury verdicts and do not discuss offensively on the competition results
    (there is only one fist prize, and designboom usually asks renown professionals to help us to promote talent.
    in addition to the awarded designs, we do feel that almost all deserve our attention, that is why we publish
    the best 100-200 entries too.)

    a link is allowed in comments as long as they add value in the form of information, images, humor, etc. (links to the front page of your personal blog or website are not okay). unwelcome links (to commercial products or services of others, offensive material etc. ) will be redacted. and, ... yes, spam gets banned. no, we do not post fake comments.


    a diverse digital database that acts as a valuable guide in gaining insight and information about a product directly from the manufacturer, and serves as a rich reference point in developing a project or scheme.

    design news

    keep up with our daily and weekly stories
    491,979 subscribers
    - see sample
    - see sample