A WALL~'UK

ALL SEASONSMike Davies ofChrysalis Architects and Richard Rogers

and Partners describes some radical new proposals for the waywe use glass in building.

Top left: Mies' glass cowerproject. Right: Clwneal/

Homc. Middle: Ste'uc Baa'sm'"ll/al(1' operated

I II E STEADILY increasing use of glass in',"i1dings over the last 1,500 years has seen a·.ll:Irp acceleration since the industrial revolu-:"n. In this century, glass has been instrumen­

·.iI in an almost complete reversal of the; iIvsical forms of Mediaeval times. Buildingsh'I;'e evolved from structures of massive walls,1"'lletrated by small openings to diaphanous·.kins of minimal material, clothing skeleton'.1 ructural frames and cores.

During this gradual evolution, glass hasIIlldergone technological refinement. Two:lIajor factors are apparent - increased size.llld increased material strength - which have

I pcrmitted a greater and greater range of uses.12ualitatively, however, glass remains un­,hanged; its properties of light transmissioni"l\le not been modified. Nevertheless, great ar­, iIitectural changes were built around the in­,Icased capabilities of glass as small panels\\cre replaced by elements of the scale of a\\·all.

The pioneers of modern architectureI'"wered their way forward using glass as aIllI1damental tool in the exploitation of new,patial dynamics.

In 1921 Mies van del' Rohe revealed his::Iass sky-scraper project - the precursor ofIhc curtain wall building of today; no clearer11,11' more fundamental statement of the glass'.kin concept has subsequently been made.')cventy years earlier, in another greatlI1ilestone of glass application - the CrystalI'<dace - glass became the total infill surface111 an iron frame, the two elements forming an"Ilvelope of great clarity.

When transparency was a problem but light'I ill vital, glass block was developed and used"~[ensively as a uniformly grained translucent·.\·alling system in the 1920s and 30s. Gropius'Bauhaus building in Germany, Pierre Char­I cau's all-glass conversion in Paris and Sir\ hven Williams' factory for Boots Ltd inI:ngland in 1932 continued the articulation of.hc large scale transparent and translucent

, ,,,,,lli.Further increases in size and material

'lrength led to yet more spectacular uses of,:lass. The refinement of frameless glazing andIhc development of suspended glass techni­'lues allowed even greater glass facades to be,llnstructed with no visible structural support.\\' ails became vistas rather than barriers and,'lear glass, as a completely transparent sur­1.lce, uncluttered by structural constraints,:cached its conceptual limit. The gap betweenIhe technology of glass and Mies' vision of theIIltimate wall finally closed; the fortress win­,low after 1,500 years finally became the whole,·'lstle.

II I\i\} Februarv 1981

.. '"' ........... ,."",.,,!, .-~" "I\' ,

Burgeoning developments in the size andstrength of glass since the 1950s, notably therevolutionary float process and the tougheningand armouring of glass have resulted in itscomplete integration as a major element inmodern construction. But all was not well.Lurking alongside the increasing use of glassand the architect's exploitation of its light andweathering properties, was the growing pro­blem of environmental control.

The 60s saw the first general awareness ofecology as a science, of global and strategicresource planning and of resource depletionand energy crisis. The energy crisis freed ar­chitects and users to look at the performanceof their buildings: Mies' wonderwall wasrecognised as an energy problem. We werecaught admiring the concept but with ourtechnological panties round our knees. Singleglazing became a problem. Undaunted, theglass industry, drawing on the precedents of

thermal shl/ccers. Boccom:IRCAM ill Paris bv Pialloalld Rogers; a dyll;mical/yvariable space.

colder climates came up with their perfectanswer - more glass!

Double glazing - twice the performance ata little more than twice the price. Light, spaceand glass could live again and our architecturalconsciences were clear; there was even an up­market vote to the idea of double glazing.Thermal losses were halved from 5.6wattslm 110C, a figure conjuring up images ofburning pound notes to keep warm, to thetotal of 2.8 watts1m 1/0c. With the cost ofenergy steadily rising and energy artificiallycheap at the price, even 2.8 wattslm 110c lookeddubious in terms of a reasonable architecturalfreedom under the new thermal buildingregulations, which linked the amount of glassin an envelope to the performance of theenvelope in general. In a matter of a few yearsthe great glass wall had come under direct at­tack, not from an aesthetic standpoint whichmight perhaps have been expected and defend­ed but from an energy, economic and perfor­mance viewpoint, a new upstart in a territoryhitherto largely peopled by aesthetic concerns.

The glass industry backed the idea ofenergy budgeting. The industry pointed outthat a south facing window in the right sort ofbuilding is a net energy gainer over the yearand thus our architectural consciences mightbe assuaged again. But things began to lookbleak. North walls lost everything except somegeneralised all-sky radiation. South-facingglass with woolly overcoats is the new look, orlong thin east·west buildings maximising theirsolar gain potential like lizards basking on asunlit stone.

Mies' wonderwall was heavily under attack.Must we say goodbye to glass? Can we neverreturn to the transparent skin? Has the pendu­lum begun to swing back again towards theleaded lights in the massive walls of yester­year? Can we stave ofT the problem by greaterfeats of ingenuity? Can we ever evolve a newarchitecture based upon intelligent passiveenergy design?

Clearly architects and the building indus­tries are responding to the energy crisis indesign terms. In the USA where governmentenergy policy is relatively clear and alreadybacked by several hundred million dollars inresearch funds, considerable evolution istaking place towards a new solar-capitalising,energy conscious architecture.

But what of northern Europe and the UK?Sitting at the same latitude as Hudson Bay inCanada, where only with good weather condi­tions, clear sites and buildings specificallydesigned as thermal collectors and processorscan one hope to gain really significant con­tributions to winter energy budgets.

Top: Lig/I/ n!<u bv Mi/~c

Dt.l'i.:ics 197i, plh'if}l/(}j i(t1/~,'

Opllru(('t./ /ig/ii lrvll.ouissioll(011/1'01. Bc/",,': Kill Peall

soldr telescopic ,:}i1l1icmpen.1lIfl'(.· rt.'fJult.llillg fluid

ill il,,' d"ddillg. Bd",,,: Mill,'Dtl'i..'it"S I st.'(f udjusrillg f/!crgy

!lollse. BOllOI1l: PhOIO-'l..'O!h:it"(dl.

An architecture of high insulation valuesand small window areas, preferably on south­erly walls only, is the logical response to theenergy problem and the new thermal regula­tions. Yet our architectural concerns with lightand space, legibility, appropriateness, func­tion, meaning and quality will not be submerg­ed in an acceptance of an architecture ofinsulated overcoats and minimal window areaswhatever the price of energy.

Mies' great glass wall is not up to rigours ofthe new thermal demands: our 20th-centurywall, the very fabric which defines ourbuilding volumes is not performing adequate­ly in the new context of energy economy. Wemust redesign again.

We must evolve general design strategies forenergy economical buildings, in which highlyinsulated fabric and efficient services measureswill playa major part. But we will still besearching for light, for views, for a contactwith the external world; and that means glass,large amounts of glass as part of the buildingfabric.

What is the glass industry's answer thistime? Triple glazing, gas filled triple glazing,quadruple glazing, even deeper filters andtints, more reflectivity, more blind one-sidedwalls; more elements which work well in onesituation and miserablv in another? It is clearin the energy context o-fthe next decad.e or twothat the future of glass lies in high perfor­mance products with much greater thermalcredibility.

An investigation of the industry shows thatradical change is not about to' take place.Among the British glass giants the 2tlitude isclear; production of basic glass is what makesthe money and high performance glass pro­ducts are efTecti\'ely a by-product.

Even the largest double glazing plantsassemble in hand craft operations, and hopethat evelllual standardisation of double glazingsizes wii! aIio\\' automation of the assembl'·process. an 2ttirudt: th,il is as antedelu\'ian as [t1 delusory. \\'hat is needed is ~ completereview of the W8\' in which high ptrforn{anc~glass can be made. An objective look 8.I g13ssand its use immedime!v re\'eals thal the glasscurtain wall and the windo\\' have beco111lmajor elemenrs in building fabric not onl!' forarchitectural and spatial reasons but '11sobecause glass is an incredibly long-lived. e:lSilymaint2.ineci: cost-efTec:i~;\:' n1atCti21. and is ~

\veather enYclope ciespite irs thernlai \\"r!~-\Y:1!"d­

ness.Glass is ecolosicallv ai'.d strategical!\' tOD 0:­

the contents Est. Th:e D<.se material of giass:silic~, is the most abundant element 0:: earth;our oceans :i:-'-c. ,iese:"rs c.!"~ ce"i.·eree 11": _ ::-:"<.::-

tically inexhaustible supply of the raw materialand we find that glass is a totally recyclableinert material which by simple hearingbecomes a totally transparent and homogenoussheet of rigid waterproof stone. In fact we ha\'e011 our hands an almost perfect building skinmaterial with enviable q'ualities S8\'e f~r theproblems of thermal transfer and radiariOl:c0ntro!.

But if the thermal qualities (lfthe \\'all are sobad, how did glass get so farr The scale of itsuse before the turn of the ccntu~;' \,'as inV8.11­abl\' related to the \\·indo\\·. it~ ~urro:li1ci silland it:3 secondary ~qulpn!el t Glass v·:orkec. i:-lcombination \\'iti: otht:!" de:~1eCts:. cunaiEs toStOP light ana sound entering. 1.:0 -s~op leaKageof heat, shuttc,s W reflen he,ll, linds to stop!lIar:::. lace curtains tel screen ,"ie\A,:s 2nC to pee-i.­thro~gh. Glass worked in combinatior. \\'ltnother sin1ple but etTectl\'e ei:\'ironnlerlt"l ccn~

tro~ d:yi-:es" (or;tr~:dleQ by :he 0CCUP2IlIS of!ne..•._._--------------

space.Much of our modern building fabric h,,"

evolved without recourse to these small scaktraditional environmental control device,.relying on increasingly powerful and ene,~\

consuming building services plant and equi!'ment to heat and cool the various buiIGin!',zones.

In summer, excessive incoming radiatio]]entering through glass makes the servicim:system work hard to combat heat build-up. Tilwinter excessive heat loss makes the servicingsystem work to add heat to the internal environment. In both cases energy is be!l1~:

wasted owing to the poor facade performancl'Mies' tower equipped with lace curtains, sh\.1tel'S, blinds and velvet drapes would actualhperform beller than it would as a clear gi<."tower although the building clearly cannothave such devices.

One conclusion seems inevitable. On tb,·one hand we have glass with its attributes (11

impermeability, longevity and transmissiYl'properties, and on the other hand, a range "Iquality modulators of heat, light and sOUi1dtransfer, both of which are needed for a tor'"performance. We need to develop a new inte'grated window wall where all these elemen:,are one where multiple performance is int,.'·grated in one single element. What is. needed :'an environmental diode, a progressive therr"" Iand spectral switching device, a dynamic int,,;·actiw multi-capability processor acting as ;building skin. The diode is logically based cthe remarkable physical properties of glas,.but will have to incorporate a greater range r·1thermal and visual adaptive performa~.l·

capabilities in one polyvalent product. T!'environmental diode, a polyvalent wall as c:­envelope of a building will remove the disti~..tion bel\\'een solid and transparent, as it W~;

be capable of replacin!, both conditions ~:i" I

wili dynamically regulate energy flow in eithcdirection depending upon external and inte:nal conditions, monitor and cQiltrol lig..ie\'e!s 2nd constant ratios as necessary at ~.

points i;: the envelope. The wall \\'ould .capable or energv traDSfer along its surLad·ding to or re!~1o\·ing energy fton1 builci~~-'ZOl1f.S \\"hich are too hot or coid, tradi·e'lerg\' surplus for energy need.

Tte polnalem ."ali is tbels .i chamele'skin ad2"pti"ng itSelf to provide ocst possible:te~ior conditior,s.

The v.l211. in acting 2~ a nlulti~functional Ce­ment - absorber, radiator, reflector, filter a~ Itransfer device - will need to have a locmicro-logic and sensing nodes connected tcconn'oi proces,o, \\'hich carries information cuse ~ched~~es) hc:bits anc environn:.ental pt _J

I

CA· C(:,./: _.;' .'

..........:

8 am 113m

~:'.r

."

) pm

D [;).· .· .· .· .· .'· .'· .· .· .".. .....

8 pill ...... 0 oO'

11 pill

Top: Po/yvalell/ 10all; lypica/waII respollse all a SI/IlIlYsprillg day. BaHam: Davies'image of /he polyva/clI/ wall.

J Sihl:l \H"alill'r skill ami lkl'''!<olliull ~uh:'lrmc.

.~ St"IP.lIf ;Ind t"IInlll,1 JI1~1l'la\'n - t':\:llTnal.J I'hnhl dn:tlll crill, .I ""KIIll;J1 shn'I'r;Jdi:uur/l-l:h:("liw :lhMHh,:t,'l E1l'l'l HI rdln'll\"l' ~kpusllllln,

ft ,\ \ i~'f(l pua' 1!:Jl- l1nw layl:fl-.j I-:Il'l.."'rtl rl'lln'IIW dl'pllMllllll,

S .sl'lI~lll ,.lIlJ llllllfllllll)!ll kI\l'f - lUll'llI.ll,

II SJlI~:1 dqlll\lllllll l-tlh~lf,lll' ,lI1J IIl11ll ~I..II1,

still not yet perfected, would have a radical ef­fect on the thermal performance of glass andbuilding. An electronically-switched deposi­tion surface whose properties vary between 15per cent reflective and 85 per cent reflectivecontrollable progressively by electrical inputwould provide an instantly selectable thermaldiode for incoming radiation in the day andoutgoing radiation at night. A "window" withthose properties would have significant effectson architecture. We would be in possession ofthe first dynamically adaptive buildingmaterial of a large range of possibilities andproperties.

Many control and monitoring systems ofgreat complexity but low cost exist owing tothe processing power of the microchip. Thesecond, present, industrial revolution is almostentirely based upon molecular scale effects andthose effects will be coupled with otherelements of the built environment which canoperate at a molecular scale rather thanmaterials science. In fact the construction baseand the switching capabilities of the microchipare not unlike a possible model for the surfaceof the polyvalent wall, but there will be manymultiple layers imposed one upon another in athree-dimensional matrix with variable opticalthermal properties and even acoustic proper­ties. There is enormous potential for new pro­ducts based upon new attitudes to glassfabrication and their combustion with multi­ple dynamic chemical phenomena.

A clear future for advanced high perfor­mance glass-based products exists; it is essen­tial that multi-disciplinary groups are broughttogether to combine diverse skills. Muchknowledge exists; it is really a question of theintelligent and creative combination of scienceand industry. Over and above the cleartechnological potentials of glass, architectshave not in the least lost sight of its potentialbeauty and visual performance.

The polyvalent wall, a dynamic processorshould not only be the logical response to adynamic environment at a technical perfor­mance level but also fulfill the role of magicianin its visual potential and virtuosity. Look upat a spectrum-washed envelope whose surfaceis a map of its instantaneous performance,stealing energy from the air with an irridescentshrug, rippling its photogrids as a cloud runsacross the sun; a wall which as the night chillfalls, flufTs up its feathers and turning whiteon its north face and blue on the south, closesits eyes but not without remembering to pumpa little glow down to the night porter, clear aview-patch for the lovers on the south side oflevel 22 and to turn 12 per cent silver just afterdawn.

Sam

~Low ghm.- ocut fa I

light p4lSS wall

.~OUIJ.!oing radial ion

rcOI..-clor

2:J1ll

Solar f:ldiationrdll'cliun

raJi:.llion surf:Kt:

·w:::··················· 0·······"0 "0.. •

<. ...<:::::., '.' ...-0:.::::: .:,..;:. \" . . . . . .

PholO Volraic effecr: where light is convertedinto electricity by photochemical reaction ­the well known solar cell.

Thcn/loc!celric cffea: generation of electricityby thermally stimulated chemical junctions.

E/cCiro-orieli/a/ivlI <llId opuciiy: liquidcrystals are oriented by small electric chargesrendering their surface opaque, translucent ortransparent; the calculator readout is our mostcommon example. A genuine electric shutler.

Elce/m-O/gallie c!fcClS: microscopic algal ac­tivity of many sons including density charge,migration and stimulated growth efTects.

The above phenomena and other suchas electro-luminosity electromagnetism, staticcharge efTects, fibre optical transfer, polarisa­tion ofIight, etc, are all in use and although ex­pensive at the research stage their costs havedropped dramatically bringing them into therealms of common usage.

A fully reversible electro-reflecti\'e reaction,

I"rmance data from the users of the building.Thus, building uses, skin performance and ex­lernal and internal environmental conditionswill all be optimised to give the best energyIdance and comfort conditions, in a con­11I1uously evolving cybernetic system.

The polyvalent wall operates at a molecularkvel rather than at a mechanical level, tappingenergy from mains power supplies or the en­"ironment depending upon ambient condi­lions. It is a dynamic performance dementwhich responds to continuously changing en­"ironmental conditions.. If the concept ofdynamic rather than static performance ap­pears somewhat ambitious, it must be said thatdements and concepts inherent in thepolyvalent wall exist in many other areas oflechnology which are in current use. A briefreview of some precedents in this field wouldinevitably commence with mechanical meansand include traditional elements such as cur­tains, venetian blinds, etc. Further examplesinclude: the use of highly insulative mobileshutters and wall elements epitomised bySteve Baer's "zome walls" near Albuquerque,New Mexico; automatically operated lightcontrol blinds for maintenance of light levels- such as the system recently installed in theTate Gallery in London; use of mobilepumped insulation - bead wall - a systemutilising loose pellet insulation blown into orout of a glass sandwich cavity wall/window.The system is simple but nevertheless an ex­ample of qualitative property change over timein a "fixed" element.

More advanced examples ofdynamic changesvstems tend to be chemical in nature ando'perate at a molecular scale.

Clo/ldgc!: originally developed by DayChahroudi and colleagues - one of the firstexamples ofa thermo-chemical control device..'\. clear transparent material as the centre layerin a glass sandwich turns white with increasedtemperature and clears again as temperaturedrops. As temperature increases the devicebecomes a more and more eHective shadingdevice, which thus lowers the tem perature in agreenhouse to the point where the materialbecomes clearer again etc. An autonomoussolar powered reversible temperature comrolsystem.

PJwlOchroll1ic udup/ioll: in which a light­activated photochemical reversible reactionoccurs darkening the photochromc surfacewhich lightens again in low light conditions.Pilkington's Reactolite spectacles are an ex­cellent example of this phenomenon.

Pae:,:,oc/cCirio' cjrca: crystals act as a tinyelectrical jack or muscle and change their formwhen charged electrically.