31. October 2022

Cir­cu­lar building

Recy­cling with aesthetics

by Joachim Goetz

With the estab­lish­ment of the cir­cu­lar econ­o­my, con­struc­tion should make its con­tri­bu­tion to the EU’s cli­mate goals. And not lose sight of aes­thet­ics in the process.

Reused mate­ri­als in archi­tec­ture? Accord­ing to a wide­spread cliché, you only build a house once in your life — if at all. Should we be con­tent with sec­ond-hand materials?

The recycling house Kronsberg by the office Cityförster is an experimental residential building, which was created from used, recycled and recyclable components in a recycling-friendly construction method. (© Cityförster / Foto: Olaf Mahlstedt)
The recycling house Kronsberg by the office Cityförster is an experimental residential building, which was created from used, recycled and recyclable components in a recycling-friendly construction method. (© Cityförster / Foto: Olaf Mahlstedt)
For example, the interior walls of the kitchen were made of demolition bricks, terrazzo "Opus Signium" with brick chip aggregate, and the built-in furniture was made of used exhibition boards. (© Cityförster, Foto: Gundlach)
For example, the interior walls of the kitchen were made of demolition bricks, terrazzo "Opus Signium" with brick chip aggregate, and the built-in furniture was made of used exhibition boards. (© Cityförster, Foto: Gundlach)

In any case, the exam­ples real­ized by avant-gardists (of archi­tec­ture) do not look like scraped-off suits from the flea mar­ket. Most of the build­ings — so far few in num­ber — do not even show that the (sec­ond) mate­ri­als used have been giv­en a new lease of life, so to speak. This applies to the build­ings real­ized by the Rot­ter­dam-based Supe­ruse Stu­dio as well as to the Land­shut “Schatztruhe” (trea­sure chest) total­ly ren­o­vat­ed by the Munich-based archi­tects Stenger2, the recy­cling house by Cityförster in Hanover or the Ham­burg “Moringa” by kadawit­tfel­dar­chitek­tur, which is still in the process of being built.

Archi­tects have tak­en up the chal­lenge, as light­house projects and ini­tia­tives illus­trate. But there are still many reser­va­tions, prej­u­dices and prob­lems in imple­ment­ing this almost rev­o­lu­tion­ary rede­f­i­n­i­tion of building.

A con­sumer soci­ety in which a new shirt often costs less than wash­ing and iron­ing it is ini­tial­ly over­whelmed by such uncon­ven­tion­al ideas. Even among down-to-earth crafts­men and estab­lished archi­tects, the idea of reuse did not trig­ger any stormy enthu­si­asm for a long time. Not to men­tion the build­ing indus­try, which would then have to realign itself or, in the worst case, would have noth­ing left to do.

Build­ing author­i­ties, reg­u­la­tions and laws are also not yet prop­er­ly pre­pared for a “cir­cu­lar econ­o­my” in the con­struc­tion industry.

Recy­cling left­overs is some­thing deeply tra­di­tion­al, some­thing wide­spread and by no means dis­rep­utable. Just think of the cui­sine, where piz­za, pael­la and stew are extreme­ly pop­u­lar dish­es that were orig­i­nal­ly invent­ed as a way of using left­overs after a sump­tu­ous feast. The patch­work tech­nique also has a long tra­di­tion, for exam­ple with the quilts of the Amish, the ancient Japan­ese tech­niques Ran­ru and Boro or the patch­work car­pet from our culture.

Left­over recy­cling at the con­struc­tion site?

Now, one has to admit that build­ings gen­er­al­ly last longer than clothes or the rem­nants of a fes­ti­val. More­over, it is not only among the mon­u­ments that there are exam­ples that have hun­dreds of years under their belt and have been repeat­ed­ly adapt­ed to new func­tions and uses. More­over, in ear­ly times, even in build­ing, there exist­ed an admit­ted­ly not par­tic­u­lar­ly imitable sec­ondary use of (pre­cious) build­ing mate­ri­als. The Egypt­ian tomb pyra­mids were part­ly demol­ished in order to build sim­ple hous­es. The same hap­pened with knights’ cas­tles, whose ruinous con­di­tion was not first caused by wind and weath­er — but by resource­ful minds that pre­ferred to build their medieval homes with old stones rather than with new crooked timbers.

Inci­den­tal­ly, the use of so-called spo­lia has also been pop­u­lar among archi­tects for cen­turies. These are usu­al­ly build­ing ele­ments from ear­li­er times and styles. A good exam­ple is the Bavar­i­an Nation­al Muse­um in Munich. Here, the his­to­ri­an Gabriel von Sei­dl skill­ful­ly mixed styles and eras. Thus, carved por­tals, wrought-iron grilles, ceil­ings, murals and much more have been installed there for the sec­ond time.

The rooms were designed specif­i­cal­ly for the use of such ele­ments. They were sup­ple­ment­ed with invent­ed and imi­tat­ed archi­tec­tur­al details. The result is a muse­um build­ing with a very spe­cial, very unusu­al flair that may seem strange to some.

In accor­dance with Robert Venturi’s clas­sic “Com­plex­i­ty and Con­tra­dic­tion in Archi­tec­ture”, the result was not a genius architect’s design, but some­thing baked togeth­er, a pot­pour­ri of styles. The most famous exam­ple of this is sure­ly St. Mark’s Basil­i­ca in Venice.

Away from demo­li­tion and new construction

Now some­thing is chang­ing — at least in words, demands, man­i­festos or the EU ini­tia­tive of the New Euro­pean Bauhaus. Why? The con­struc­tion indus­try is falling into dis­re­pute as a cli­mate killer. Through the pro­duc­tion and trans­port of build­ing mate­ri­als and the oper­a­tion of build­ings, it is respon­si­ble for 60% of mate­r­i­al con­sump­tion, 50% of mass waste gen­er­a­tion, around 40% of CO2 emis­sions and 20% of plas­tic con­sump­tion worldwide.

The cur­rent prac­tice of demo­li­tion and new con­struc­tion gen­er­ates untold amounts of use­less con­struc­tion waste, as it often con­sists of com­pos­ite and mixed mate­ri­als that can no longer be sep­a­rat­ed. The spe­cial sand suit­able for mak­ing con­crete is becom­ing scarce and expen­sive. Inci­den­tal­ly, desert sand that has been ground round by wind and weath­er is no good for this pur­pose. And it is prob­a­bly only a mat­ter of time before the increas­ing­ly pop­u­lar renew­able build­ing mate­r­i­al wood (link) also becomes a scarce commodity.

Here, too, it is worth tak­ing a look at his­to­ry: In Roman times, the forests of Italy were cut down to build war fleets. The regrowth was main­ly the mac­chia, the thorn bush scrub. It would not be pos­i­tive if some­thing sim­i­lar were to hap­pen again in the Ama­zon rain­for­est and in the forests of our latitudes.

How more recy­cling can suc­ceed is shown not only by inno­v­a­tive projects and uni­ver­si­ty cours­es, but also by remark­able ini­tia­tives deal­ing with “urban min­ing” and “har­vest­ing.

Re-use mate­ri­als

In Munich, the “ini­tia­tive zirkulæres bauen” is plan­ning a pilot project for cir­cu­lar build­ing in Met­zger­strasse togeth­er with Koop­er­a­tive Großs­tadt e.G.. The ini­tia­tive, which acts as a com­po­nent hunter and spe­cial­ist for com­po­nent reuse, is also set­ting up a net­work between politi­cians, plan­ners, builders and companies.

The Vien­nese “mate­ri­al­no­mads” have estab­lished them­selves as pio­neers of process­es for the cir­cu­lar econ­o­my in Aus­tria. They explore the mate­r­i­al and cul­tur­al val­ue of vacant build­ings that are to be demol­ished due to safe­ty reg­u­la­tions, eco­nom­ic or polit­i­cal deci­sions. Since its found­ing in 2017, the Vien­nese have already picked up more than 60,000 build­ing com­po­nents and made them avail­able for reuse.

Nat­ur­al raw mate­ri­als such as wood, glass, met­al and stone are par­tic­u­lar­ly suit­able. In the case of the new build­ing project mag­das Social Busi­ness, a sub­sidiary of Car­i­tas of the Arch­dio­cese of Vien­na, main­ly mate­ri­als “har­vest­ed” in the vicin­i­ty of the city were used. Among the 13.6 tons of re-use mate­r­i­al were, for exam­ple, oak strip floor­ing, mobile par­ti­tion wall ele­ments, alu­minum per­fo­rat­ed sheet ele­ments, nat­ur­al stone pan­els, box doors, mail­box­es, handrails made of oak, steel pan­els and larch wood, door frames and door leaves as well as pen­dant lights. A total of 17.258 met­ric tons of CO2 equiv­a­lents were saved, thanks in part to the short trans­porta­tion dis­tances. This could heat a sin­gle-fam­i­ly house for over five years.

Demo­li­tion architecture

The Ger­man impact start­up Con­cu­lar, which describes itself as a “mar­ket leader for the rein­tro­duc­tion of mate­ri­als,” works in a sim­i­lar way. Cir­cu­lar con­struc­tion is made eas­i­er with the help of intel­li­gent data-based medi­a­tion. Com­po­nents of a state library in Augs­burg, for exam­ple, or the Siemens con­fer­ence cen­ter in Feldaf­ing, which is to be replaced by a new sol­id wood build­ing, have been and are being offered.

Of course, min­er­al build­ing mate­ri­als — nat­ur­al stone, bricks, con­crete, etc. — are par­tic­u­lar­ly inter­est­ing for con­struc­tion. — are of par­tic­u­lar inter­est. A lot of so-called gray ener­gy is stored in these mate­ri­als. A work­shop held by the Insti­tute of Archi­tec­tur­al Tech­nol­o­gy at the Graz Uni­ver­si­ty of Tech­nol­o­gy inves­ti­gat­ed the poten­tial of build­ing mate­r­i­al recy­cling in a demol­ished build­ing under the title “city remixed”. As a result, the decon­struc­tion of build­ings must be car­ried out in a sim­i­lar­ly planned and detailed man­ner as the new con­struc­tion or erec­tion. In order to recov­er raw mate­ri­als, an “archi­tec­ture of demo­li­tion” is required.

Built exam­ples

In Land­shut, Stenger2 Architek­ten over­hauled a 500-year-old log house in Pfet­tra­ch­gasse. They used beams and boards from a Land­shut town­house whose roof truss had been dis­man­tled. Only what was no longer struc­tural­ly sound was replaced.

The great age of the build­ing, which was once built in a CO2-neu­tral man­ner using region­al build­ing mate­ri­als, com­mand­ed the respect of the archi­tects and own­ers. They want­ed to allow this house, which had been home to a vari­ety of dif­fer­ent uses for half a mil­len­ni­um, to live on in the form of “end­less use.”

This means that future users should also be able to repair the house. Thus, cement, plas­tics, plas­ter, dis­per­sion and bitu­mi­nous build­ing mate­ri­als were large­ly avoid­ed. Instead, almost for­got­ten mate­ri­als such as swamp lime, clay bricks, clay, wood, reed, hemp and lin­seed oil cel­e­brat­ed a joy­ful revival.

Joachim Goetz
Joachim Goetz (Foto: Ralf Dombrowski)

The author Joachim Goetz stud­ied archi­tec­ture in Munich and Denver/Colorado with sub­jects such as art and build­ing his­to­ry, sculp­ture, pho­tog­ra­phy, water­col­or, land­scape and prod­uct design. He worked in archi­tec­tur­al offices includ­ing GMP, won com­pe­ti­tions with Josef Götz and built a house with Thomas Rös­sel and Heinz Franke. He has been a full-time writer since 1990, and was an edi­tor at Baumeis­ter and Wohn­De­sign. Pub­li­ca­tions were made in nation­al and inter­na­tion­al dai­ly, pub­lic, art and design mag­a­zines such as SZ, Madame, AIT, Münch­n­er Feuil­leton, AZ or Design Report. Inter­views were con­duct­ed — for exam­ple with Ettore Sottsass, Gün­ter Behnisch, Alessan­dro Men­di­ni, Zaha Hadid, James Dyson, Jen­ny Holz­er, Wal­ter Nie­der­mayr or Daniel Libe­skind. He has also worked for com­pa­nies such as Siedle, Phoenix Design and Hyve. For Sedus he was co-respon­si­ble for the first dig­i­tal archi­tec­ture mag­a­zine a‑matter.com (1999–2004) as well as the com­pe­tence mag­a­zine “Place2.5” (2011–2014). For bay­ern design and the MCBW he is repeat­ed­ly active as an author. His work was award­ed a media prize for archi­tec­ture and urban plan­ning by the Ger­man Fed­er­al Cham­ber of Archi­tects. J. Goetz is also a ded­i­cat­ed con­sul­tant to small­er com­pa­nies on spe­cial design, mar­ket­ing and off­beat issues.