Interview with
Heike Klussmann from
Bau Kunst Erfinden

In: The Pow­er of ... Where de­sign meets so­lar en­er­gy,
Hrg. Prof. Mareike Gast, Burg Gie­bichen­stein, Halle

MG: The in­ter­dis­ci­pli­nary re­search of Bau Kunst Erfin­d­en deals, among other things, with in­tel­li­gent sur­faces and ma­te­rials in the con­text of civ­il en­gi­neer­ing. What was your mo­ti­va­tion be­hind re­search­ing dye-sen­si­tised so­lar cells in com­bi­na­tion with con­crete?

HK: We are cur­rent­ly fac­ing enor­mous so­cial chal­lenges. To­day, 75 per­cent of the pop­u­la­tion in Eu­rope and 55 per­cent of the world’s pop­u­la­tion live in conur­ba­tions, which ac­count for 60–80 per­cent of the world’s to­tal en­er­gy con­sump­tion. If the cur­rent con­di­tions are main­tained, glob­al en­er­gy con­sump­tion in build­ings is ex­pect­ed to dou­ble or even tri­ple by 2050. As in­dus­trial na­tions burn fos­sil fu­els more than a mil­lion times faster than they can re­new them, and as the needs of de­vel­op­ing E7 coun­tries in­crease, cur­rent es­ti­mates suggest that fos­sil fu­el as a re­source will be de­plet­ed in less than 100 years. In short, build­ings con­sume en­er­gy, wa­ter and ma­te­rials, and con­struc­tion caus­es waste as well as CO2 and par­tic­u­late emis­sions. Giv­en the enor­mous size of the con­struc­tion sec­tor, even small re­duc­tions can help to make a big dif­fer­ence. The re­search pro­ject Dye-Sen­si­tised So­lar Con­crete (DysCrete, Dss­Crete) fo­cus­es on elec­tric­i­ty pro­duc­tion re­sult­ing from the tar­get­ed ma­te­rial syn­th­e­sis of ce­ment-based build­ing ma­te­rials and pho­tore­ac­tive par­ti­cles. Func­tio­n­al lay­ers that can con­vert light in­to elec­tri­cal en­er­gy ac­cord­ing to the prin­ci­ples of tech­ni­cal pho­to­syn­th­e­sis are ap­plied to con­crete sur­faces and are thus refined. The ad­van­tage is that sus­tain­able en­er­gy gen­er­a­tion is al­so pos­si­ble with at­mo­spher­ic light, us­ing free­ly avai­l­able com­po­nents at com­par­a­tive­ly low pro­duc­tion costs. For this rea­son, the in­no­va­tive ma­te­rial sys­tem has the po­ten­tial of a low-cost en­er­gy source.

MG: Dye so­lar cells have been pa­tent­ed since 1992. Nev­er­the­less, ar­tis­ti­cal­ly mo­ti­vat­ed re­search in­to dye so­lar cells is rel­a­tive­ly rare. Where do you see the po­ten­tial of dye-sen­si­tised so­lar cells (com­pared to sil­i­con so­lar cells)?

HK: For some years now, there has been in­vesti­ga­tion in­to so­lar cells made of or­gan­ic ma­te­rials (e.g. dye-sen­si­tised so­lar cell) and in­or­gan­ic ma­te­rials (e.g. Kes­terite and Per­owskite). How­ev­er, their ap­pli­ca­tion in opaque build­ing ma­te­rials such as con­crete has so far been ig­nored, since at­ten­tion was ini­tial­ly fo­cused on the great de­vel­op­ment po­ten­tial of glass-based trans­lu­cent mo­d­ules. Based on the tech­nol­o­gy of dye-sen­si­tised so­lar cell (O’Re­gan and Grätzel, 1991), or­gan­ic dyes are used in the ma­te­rial sys­tem dye-sen­si­tised so­lar con­crete in or­der to ab­sorb light and gen­er­ate en­er­gy by elec­tro­chem­i­cal re­ac­tions. The ad­van­tages that re­sult in­clude the bet­ter avai­l­a­bil­i­ty of all raw ma­te­rials, a rel­a­tive­ly in­ex­pen­sive pro­duc­tion, vari­ous de­sign pos­si­bil­i­ties and the abil­i­ty to use at­mo­spher­ic light, so that no spe­cial ori­en­ta­tion to the sun is ne­ces­sary. The ma­te­rial sys­tem is al­so re­gen­er­able, large­ly re­cy­clable and of­fers great po­ten­tial in terms of de­sign.

MG: The in­s­tal­la­tion of so­lar cells on build­ings is a ma­jor is­sue – al­so be­cause the build­ing sec­tor is re­spon­si­ble for a con­sid­er­able amount of green­house gas emis­sions in Ger­many. Do you see re­stric­tions for cre­a­tive free­dom in the use of so­lar en­er­gy – and if so, where would you see such re­stric­tions?

HK: The abil­i­ty to al­so use the en­er­gy of at­mo­spher­ic light is a par­tic­u­lar­ly note­wor­thy fea­ture of dye-sen­si­tised so­lar con­crete, as there are hard­ly any re­stric­tions with re­gard to struc­tu­ral im­ple­men­ta­tion com­pared to con­ven­tio­n­al PV sys­tems. This opens up al­most un­limit­ed ap­pli­ca­tion and de­sign pos­si­bil­i­ties in terms of form, de­sign and lo­ca­tion.

MG: Where do you see the biggest chal­lenge in the use and spread of so­lar pan­els in public space?

HK: Nowa­days, build­ing is char­ac­terised by tra­di­tion, is high­ly riska­verse and, as far as pos­si­ble, of­f­line. The con­struc­tion in­dus­try should use new tech­nolo­gies and ma­te­rials in its own in­ter­est and both adapt and re­new its pro­cess­es and busi­ness mod­els. Other­wise there is a risk that the suc­cess ex­pe­ri­enced over a long pe­ri­od of time will re­sult in ne­glect of de­vel­op­ments that can un­der­mine the suc­cess of its own busi­ness mod­el. The public sec­tor is al­so chal­lenged. It should act as a “s­mart client” – in other words, make tar­get­ed use of public pro­cure­ment, set an ex­am­ple with best-prac­tice pro­jects and best-prac­tice shar­ing as well as im­ple­ment pi­lot pro­jects. Ten­der­ing pro­ce­dures must be re­formed so that the cheap­est bid is not the one that wins, but rather the best bid in terms of qual­i­ty. Bids must be eval­u­at­ed with re­gard to in­no­va­tion, use of new tech­nolo­gies and pro­cess­es as well as life-cy­cle costs and sus­tain­a­bil­i­ty.

MG: In the mag­azine Zukunft Bau, dyscrete is de­scribed as a ‘ce­men­ti­tious ma­te­rial for in­no­va­tive fa­cade, wall and floor sys­tems in the con­struc­tion in­dus­try’. What other goals do you have for your re­search? What role does the Plot­bot/Crawler play in this con­text?

HK: The aim is to de­vel­op a ful­ly com­po­nent-in­te­grat­ed pho­to­vol­ta­ic ma­te­rial. For this spe­cif­ic ap­pli­ca­tion, we de­vel­oped an easy-touse, web-based, sen­sor-guid­ed au­to­mat­ic mo­tion con­troller – the Plot­bot/Crawler – at the Bau Kunst Erfin­d­en re­search plat­form. Thanks to the Plot­bot/Crawler, com­plex lay­er­ing sys­tems for the func­tio­n­al­i­sa­tion of build­ing sur­faces can be ap­plied. By means of a con­sis­tent­ly in­ter­locked log­ic be­tween tool and soft­ware, the sur­faces of con­struc­tion el­e­ments of any ge­ome­try are in­s­tant­ly con­trolled or coat­ed ac­cord­ing to a pre­vi­ous­ly dig­i­tal­ly cre­at­ed pro­cess­ing sys­tem. The Plot­bot/ Crawler is main­ly used to ap­p­ly and re­new pho­tore­ac­tive lay­ers on fa­cades. The fa­cade robot is suit­able for ap­p­ly­ing th­ese func­tio­n­al lay­ers, but can al­so be mod­i­fied to ac­com­mo­date other func­tio­n­al sys­tems – for ex­am­ple, to ap­p­ly pig­ment coat­ings, sealants, gui­dance sys­tems and de­c­o­ra­tive lay­ers or to de­tect mois­ture, cracks and other de­fects on fa­cades.

MG: In gen­er­al, how do you imagine us­ing dyscrete or so­lar en­er­gy in a fu­ture sce­nario?

HK: The sun is al­ready an im­por­tant source of en­er­gy to­day, and pho­to­vol­taics will be­come one of the most im­por­tant pow­er sup­p­ly tech­nolo­gies of the fu­ture. Build­ings play an im­por­tant role here. They in­creas­ing­ly op­er­ate with the en­er­gy sys­tem and have the po­ten­tial to be­come de­cen­tralised en­er­gy cen­tres. The dom­i­nant ma­te­rial in build­ing-in­te­grat­ed pho­to­vol­taics (BIPV) to­day is the sil­i­con so­lar cell. Pan­els con­nect­ed to so­lar mo­d­ules have large­ly estab­lished them­selves as on-roof so­lar pow­er sys­tems. While sil­i­con, the ba­sic ma­te­rial re­quired for its man­u­fac­ture, is avai­l­able in un­limit­ed quan­ti­ties, ma­te­rials such as in­di­um, gal­li­um, tel­luri­um and se­le­ni­um, which are al­so ne­ces­sary, must be crit­i­cal­ly eval­u­at­ed in terms of their ma­te­rial econ­o­my, re­source con­sump­tion and en­vi­ron­men­tal com­pat­i­bil­i­ty. Such plants al­so re­quire space, which is on­ly avai­l­able to a limit­ed ex­tent in conur­ba­tions. Fur­ther­more, sil­i­con-based pho­to­vol­taics must be ori­ent­ed to the south in or­der to use the sun­light ef­fec­tive­ly. Since the ge­ome­try of build­ings and pan­els are not co­or­d­i­nat­ed, an unat­trac­tive aes­thet­ic is ad­di­tio­n­al­ly cre­at­ed that does not al­low any artis­tic com­po­si­tion. The pho­to­vol­ta­ic im­ple­men­ta­tion of opaque build­ing ma­te­rials of­fers a high de­gree of flex­i­bil­i­ty for ar­chi­tec­ture and gives the build­ing in­dus­try the op­por­tu­ni­ty to sig­ni­f­i­cant­ly in­crease the amount of space avai­l­able for gen­er­at­ing so­lar en­er­gy and al­so to shape this new tech­nol­o­gy at an ear­ly stage – in or­der to de­vel­op aes­thet­i­cal­ly so­phis­ti­cat­ed sys­tems that can be in­cor­po­rat­ed in­to plan­n­ing as pho­toac­tive and struc­tu­ral­ly shap­ing sys­tems at the same time.

MG: Your work at Bau Kunst Erfin­d­en is based on in­ter­dis­ci­pli­nar­i­ty be­tween dif­fer­ent cre­a­tive and sci­en­tif­ic fields. What does re­search by de­sign­ers look like and to what ex­tent does it dif­fer from sci­ence in terms of your ex­pe­ri­ences?

HK: To­day, de­sign­ers, ar­chi­tects, en­gi­neers, com­put­er sci­en­tists and re­search­ers are in­volved at dif­fer­ent times in the de­vel­op­ment of prod­ucts, build­ings and in­fras­truc­tures. At the re­search plat­form Bau Kunst Erfin­d­en, we work to­gether in a way that is defi­nite­ly in­ter­dis­ci­pli­nary right from the very be­gin­n­ing of a pro­ject and at a very ear­ly stage. In the pro­jects, artis­tic strate­gies, ba­sic sci­ence and ap­pli­ca­tion-ori­ent­ed en­gi­neer­ing strate­gies over­lap. This cre­ates bet­ter dove­tail­ing of the pro­cess­es in­volved as well as add­ed val­ue for all par­ti­ci­pants. Art means ask­ing ques­tions and con­nect­ing knowl­edge. In­ter­dis­ci­pli­nary work is about think­ing ahead and plac­ing one’s own dis­ci­p­line and one’s own work in a dif­fer­ent con­text. Leav­ing one’s own com­fort zone is some­thing that one sim­p­ly has to get in­volved in.

Heike Kluss­mann is an artist and a pro­fes­sor work­ing in the field of fine arts and ar­chi­tec­ture at the Uni­ver­si­ty of Kas­sel since 2005. She al­so runs her own stu­dio in Ber­lin, is rep­re­sent­ed in ex­hi­bi­tions, films and publi­ca­tions, and has re­ceived nu­mer­ous awards. In 2009, she found­ed the in­ter­dis­ci­pli­nary re­search plat­form BAU KUNST ERFIN­D­EN in Kas­sel. The plat­form com­bines ex­per­tise from vari­ous fields, in­clud­ing the fine arts, ar­chi­tec­ture, ur­ban plan­n­ing, ex­per­i­men­tal physics and tech­no­log­i­cal ma­te­rial re­search. BAU KUNST ERFIN­D­EN is ded­i­cat­ed to the de­vel­op­ment of in­no­va­tive ma­te­rials sys­tems and in­tel­li­gent sur­faces.

In­­ter­view Ma­rie Gehr­hardt