古斯塔夫·安布羅西尼/Gustavo Ambrosini

黃華青 譯/Translated by HUANG Huaqing

可居住屋頂―建筑的范式

古斯塔夫·安布羅西尼/Gustavo Ambrosini

黃華青 譯/Translated by HUANG Huaqing

The Inhabitable Roof: Paradigms in Architecture

一片虛空，一個純粹的“技術(shù)空間”，一處被可怖之物（煙囪、管道、出風口、冷卻機……）占據(jù)的無人區(qū)——它的作用基本就是交換建筑室內(nèi)外空氣，如同這個時代的幽靈。難道這就是現(xiàn)代城市中屋頂所注定呈現(xiàn)出的形象？然而，距離電梯的發(fā)明已過去一個半世紀，這項發(fā)明顛覆了歐洲城鎮(zhèn)的秩序分層，改變了社會身份的表征和建筑的吸引力——從傳統(tǒng)以建筑底層為尊貴的“主樓層”，轉(zhuǎn)變?yōu)閺牡讓又粮邔拥纳矸葸f進。

但是，屋頂與視野及想象有著密切關(guān)聯(lián)。

值得一提的是，亞歷山大·加爾德于1974年在大急流城肯特縣行政大樓屋頂上創(chuàng)造的抽象畫作，展現(xiàn)了屋頂景觀的雙重含義：除了每座建筑屋頂顯而易見的特征——即作為一處觀景之場所，這幅1600m2的紅白黑色畫作，也是這位藝術(shù)家最大的一幅畫，反而確立了它作為一處被觀看之場所的地位。

論及與屋頂相關(guān)的意象，電影藝術(shù)無疑是最值得探索的源泉之一。在電影中能夠找到屋頂景觀與人的使用相關(guān)的多重身份：一處動作場面的理想場所，那些關(guān)于逃脫、打斗、復(fù)仇之類的戲劇化場面——往往是最高潮部分——皆可在此找到驚險之地；一處讓音樂劇能量盡情釋放的場所，一個歌舞場面的絕佳舞臺，不受任何常規(guī)所限；一處親密情感的抒發(fā)之所——無論是愛意、憂郁還是懷舊，一處面向天空、無人可見的空間。一處能夠展現(xiàn)人造環(huán)境與周遭景觀（即世界）之間超凡、驚人的關(guān)系的場所。因此，這是一處為不同尋常和張力而生的地方，它與日常生活相反，暗示著異常的觀念。

實際上，由谷歌地球等虛擬地圖軟件帶來的多尺度頂端視角，以及俯瞰城市的攝影類書籍的流行，展現(xiàn)了當代世界更為復(fù)雜的屋頂景觀。從奢侈領(lǐng)地到日常社區(qū)，從收復(fù)的口袋花園到寬敞的公共綠地，屋頂空間為建筑和城市帶來了不可估量的潛力。

新的屋頂：現(xiàn)代建筑的一種范式

有人會說，屋頂可居住空間的地位早在1926年勒·柯布西耶提出的“新建筑五要素”就得到了官方認定——屋頂花園，或屋頂平臺。

這段文字明顯提供了一種純技術(shù)層面的解釋，以展現(xiàn)混凝土結(jié)構(gòu)的新可能性：一個站得住腳的功能目的，是為了替這種新建筑語匯尋求科學的客觀性[1]。對于平整水泥板之潛力的強調(diào)，無疑源自那些混凝土建筑先驅(qū)的影響——例如弗朗索瓦·埃納比克于1903年在布格拉罕鎮(zhèn)建造的自宅，是這項新技術(shù)名符其實的宣言：一座空中花園覆蓋了整座建筑，建筑師的格言就是“鮮花、陽光和通風”。此外，關(guān)于“居住目的的系統(tǒng)化利用”的觀念，也指向建筑中逐步提升的衛(wèi)生標準，這是在勒·柯布西耶的私人和集合住宅項目中不斷重現(xiàn)的話題。最后，是對勒·柯布西耶的構(gòu)想本身的諷刺性質(zhì)疑：一個植被顏色及組合皆可變換的舞臺，如羅伯特·布雷·馬克斯在里約熱內(nèi)盧教育部大樓屋頂花園所做的那樣——這棟建筑是在勒·柯布西耶的指導(dǎo)下，由巴西現(xiàn)代建筑大師們設(shè)計的。

如很多評論家所指出的[2]，將屋頂形象塑造為“建筑中最受喜愛之地”，背后存在多重來源——既源于歷史遺產(chǎn)，也指向即將到來的機械時代：一方面，它在形式上呼應(yīng)了地中海地區(qū)鄉(xiāng)土建筑及東方傳統(tǒng)建筑的平屋頂形象，它們出現(xiàn)在勒·柯布西耶的旅行素描本中；另一方面，是對于跨洋航線那光鮮形象的癡迷（“倚在游輪夾板的欄桿上……倚在屋頂?shù)倪吘墶保?。這個視覺及功能的隱喻，重現(xiàn)了前人烏托邦式的現(xiàn)代世界構(gòu)想的輝煌[3]，開啟了光明城市詩意的未來之路。

可生活的平屋頂，與傳統(tǒng)的坡屋頂對比鮮明，成了現(xiàn)代建筑運動最有力的標志之一。

但這并不是個同質(zhì)化的標志。屋頂所發(fā)揮的作用，就和勒·柯布西耶的作品一樣，展現(xiàn)出多面性的特征：

一處純粹的室外空間，作為對私人居住空間的延伸，如雪特龍住宅項目。

一個建筑漫步的頂點，如薩伏伊別墅，展現(xiàn)了在住宅空間中運動的最后幾步：首先是緊鄰客廳的室外平臺，然后是屋頂上凸起的曲面圍合的日光浴場，標識著坡道到達頂峰的時刻。

一種親密的超現(xiàn)實主義體驗手段，例如巴黎的德·貝斯特古屋頂：白色抹灰墻體部分遮蔽了遠處的城市標志物，周圍環(huán)繞著面向天空的綠地毯，其中驚人地充斥著通常只在公寓室內(nèi)可見的元素（擁有壁爐臺的假壁爐、起居室家具和一面鏡子）。

一個獨特的共享空間，在物理上及形式上都與下部樓層的居住空間相隔離，如馬賽公寓：幼兒園、健身房、泳池和通風管道，形成了一個指向天空、精心設(shè)計的混凝土雕塑組，彰顯了屋頂?shù)纳鐣删有浴?/p>

塑造可居住屋頂：建筑的二分法

論及屋頂?shù)淖饔?，若回溯至現(xiàn)代主義建筑的源頭，或許能找到一些延續(xù)至今的設(shè)計態(tài)度的根源[4]。

有兩組對比提供了有趣的線索。

第一組是關(guān)于“從地面脫離/與地面互動”的二分法。

1 空，柏林/Void, Berlin

2 人，倫敦/People, London

3 人，圣托里尼/People, Santorini（1-3攝影/Photos: G. Ambrosini）

4 私人花園，蒙特卡洛/Private paradise, Montecarlo（攝影/Photo: G. Ambrosini）

5 薩伏伊別墅，普瓦西/Ville Savoye, Poissy（攝影/Photo: Rory Hyde, CC BY-SA 2.0）

A void, a pure "technical space", a no-man's land inhabited by uncanny objects (chimneys, pipes,vents, refrigeration machines…) that basically shuffle air inside and outside our buildings,like spirits of our time. Is it simply this one the caricature to which the roof is sentenced in the modern city? Although about a century and a half has passed from the moment the invention of the lift had revolved the hierarchical stratification of European towns, turning the social status representation and the attractiveness, traditionally related to the low piano nobile, into a crescendo towards the top.

But roofs have a lot to deal with view and with imagery.

The abstract painting Alexander Calder created in 1974 on the roof of Kent County Administration Building in Grand Rapids should be mentioned as an example in order to recall the double significance of the view concerning rooftops: the obvious character of every building top aside – a place to look from –the red-white-black 1600-square-metre painting,the largest by the artist, merely affirms the status of a place to be looked at.

Regarding the imagery associated with rooftops, filmmaking is undoubtedly one of the best sources to investigate. It's in movies that it is possible to find a multiple role taken by the rooftop scenery in relation to people's use: a privileged place for action, where dramatic scenes portraying escape, fight, vengeance etc., very often the culminating ones, find a thrilling location; a place where musical energies can open wide and an outstanding stage for dance scenes, free from ordinary constrictions and conventions; a place for intimate feelings, love, melancholy, nostalgia, as an out of sight room open to the sky. A place able to display extraordinary and surprising relationships between the human sphere and the landscape (the world) around. Thus it is a place for unusual and tension, in opposition to ordinary life, alluding to the notion of difference.

As a matter of fact, the multiple scales of zenith vision, made possible by virtual globe software systems like Google Earth, as well as the spread of city's portraits photo-books from the sky, reveal a more complex landscape of roof in the world. From luxury domains to informal communities, from re-conquered pocket gardens to extensive green areas, the space of the roof offers an extraordinary potentiality to architecture and to the town.

The new roof: a paradigm of modern architecture

One can argue that the status of inhabitable space of the roof had been officially codified by means of one of the celeb Five Points, articulated by Le Corbusier in 1926: the roof garden, or roof terrace.

The text presents an apparently pure technical explanation displaying the new possibilities of concrete construction: a veritable programmatic purpose, aiming at lending scientific objectivity to the selection of a new architectural vocabulary[1]. The accent on the potentialities of the flat cement slab certainly recalled the outcomes of the pioneers of concrete building – such as the veritable manifesto of the new technology built by Fan?ois Hennebique in Bourg La Reine in 1903, his own home, where a suspended garden covered the entire building,according to the author's motto "flowers, light,and ventilation". Besides, the notation concerning a "systematic utilization for domestic purposes"referred to the growing issues for hygienic criteria in architecture, a recurring issue in Le Corbusier's projects regarding both individual and collective housing.

As many critics pointed out[2], several multiple references lied behind the imagery of the element that had to become "most favoured place in the building", referring both to the past heritage, both to the coming machinery age: on the one hand the formal suggestions from the flat roof in vernacular buildings from Mediterranean and Oriental tradition,as reported in Le Corbusier travel sketch books; on the other hand the fascination for the vibrant image of the ocean liner ("Leaning against the deck rail of the vessel […] Leaning against the edge of the roof"),a visual and functional metaphor that re-launched the grandeur of previous utopian modern vision[3],opening the way for the future Plan Obus poetics.

6 德·貝斯特古屋頂，巴黎/De Beistegui penthouse, Paris（圖片來源/Source: Le Corbusier et Pierre Jeanneret oeuvre complete de 1929-1934, Zurich 1952）

7 馬賽公寓/Unité d'Habitation, Marseille（攝影/Photo: G.Ambrosini）

8 鐵云，莫斯科/Wolkenbügel, Moskow（圖片來源/Source:Wikimedia Commons）

9 金沙酒店，新加坡/Marina Bay Sands, Singapore（攝影/Photo: Bianca Rinaldi）

20世紀建筑師設(shè)計的很多體現(xiàn)技術(shù)進步的烏托邦式紀念碑，都多少受到埃爾·利西斯基1924年設(shè)計的“鐵云”影響：這個漂浮于50m高基座之上的懸挑寬板，在莫斯科繁忙的放射路及環(huán)路交匯點上提供了可居住空間。該項目被稱為“空中掛鉤”，是一個遠離地面的水平樓層，象征性地脫離了功能性支撐，呈現(xiàn)了一個基于“征服重力”的獨立城市居所形象。

這是1960年代許多巨構(gòu)夢中常見的線索：從尤納·弗里德曼的“空間城市”（1958-1962）開始，他的城市拓展理念是在城市上空建造一個巨型結(jié)構(gòu)框架，以支撐住房及辦公單元；到超級工作室繪制的取代了城市或自然景觀的巨型建筑，如1969年的“連續(xù)紀念碑”，或是同年由威曼諾伊爾、薩波、卡斯帕和邁耶為杜塞爾多夫設(shè)計的“新人工地面”[5]。這種脫離式策略在近期建成的項目中亦有體現(xiàn)，例如阿爾索普設(shè)計的多倫多夏普中心（2004）那個像素化的空中盒子，由彩色的傾斜柱子群支撐，漂浮在一個小尺度街景上空26m之處；或是扎哈·哈迪德事務(wù)所于2016年設(shè)計建成的安特衛(wèi)普“港口之家”，這個鉆石般、通體玻璃的巨大體量，懸浮在一座19世紀的老建筑之上。

諷刺的是，這一路徑最近的典型案例之一來自摩西·薩夫迪，他或許是少數(shù)真正有機會將自己的白日夢實現(xiàn)的“烏托邦”建筑師。2010年建成的新加坡海濱灣金沙酒店，具備了一座紀念性標志物的所有要素：3座清晰明了的塔樓支柱，57層則是一個獨一無二的船形體量：這個所謂的“空中花園”，面積12,000m2，一側(cè)懸挑65m，容納了餐廳、咖啡、250棵樹、一個150m長的泳池、以及從200m高空俯瞰新加坡天際線的觀景平臺?；蛟S存在爭議的是，如此一個奢侈的社區(qū)如何能實現(xiàn)建筑師所謂的“公共領(lǐng)域”概念；但它無疑提供了一種不同于其下都市空間的“城市縮影”。

與此相反，我們亦可指出一種在建筑周圍空間與建筑表皮之間尋求某種延續(xù)性流動的態(tài)度。將地面抬升為平面折板，就成了一個重要的融合方案。

阿達爾貝托·里貝拉于1938年設(shè)計的卡普里島馬拉巴特住宅，首要特征無疑是其屋頂平臺：一座沒有扶手的反轉(zhuǎn)金字塔形階梯，通往屋頂日光浴場，走向天空與海洋的風景；同時它又是一座劇場，面朝充滿生機的植被與巖石的自然組合。它協(xié)助這個純粹的紅色幾何體量達成了與自然景觀的和諧關(guān)系。唯一的例外是一面白色抹灰曲線墻，它中和了屋頂?shù)钠秸妫瑖铣鲆惶幟嫦虻仄骄€之外別無他物的隱秘之所。這是一個展現(xiàn)人類戲劇的完美舞臺，就像讓-呂克·戈達爾1963年的電影杰作《蔑視》所捕捉到的那樣。

10 馬拉巴特住宅，卡普里/Villa Malaparte, Capri（圖片來源/Source: movie Le Mépris）

而且，這確實就是大部分人與屋頂?shù)奈镔|(zhì)性進行交互的方式，也是多個當代建筑項目成功的關(guān)鍵。

草。Mecanoo建筑事務(wù)所于1997年設(shè)計的代爾夫特理工大學圖書館，如同一片傾斜的草坡、荷蘭平原上一座獨特山丘，其間貫穿著幾個基本幾何元素：一個接近三角形的缺口為入口空間；一個錐形體提供了采光井和主要的室內(nèi)參照物。這是一座優(yōu)雅的地標，公園平面毫無阻礙地傾斜而上，直至建筑邊緣：這是一片真正意義上的公共綠地，人們在此聚集、坐臥和休憩。此外，這個綠色屋頂也具備那些眾所周知的技術(shù)優(yōu)勢，例如積蓄能量、緩解城市熱島效應(yīng)、控制泄洪、減輕空氣污染、提升城市生態(tài)多樣性。

木。當然，木材是橫濱國際客運港的主要元素，這座建筑由FOA事務(wù)所于1995年設(shè)計，2002年建成開放。建筑屋頂由一系列木制折板面組成，其間穿插著一些覆土表面，室內(nèi)元素通過這套體系自然溢出至室外。在這座建筑中可以體驗到強烈的觸覺感知：人們在上層夾板行走、爬行和重踏，同時在下方的3層空間內(nèi)“摸索”室內(nèi)的路徑及坡道。在這座基礎(chǔ)設(shè)施節(jié)點建筑中，滲透著一種整體上的運動感，這是一個獻給動線延續(xù)流動的空間：同時它又提供了一座公共城市花園，作為城市與海洋之間的門戶。

The flat liveable roof, in contrast with the old inclined roof, thus became one of most powerful icons of Modern Movement.

But not a homogeneous one. The role played by the roof in the same Le Corbusier's works shows a multifaceted character.

A pure open air extension of private domestic space, like in the Citrohan houses projects.

An acme of the architectural promenade, like in Ville Savoye, revealing the final steps of the movement through the spaces of the house: first the outdoor terrace bordered by the living spaces, then the enclosure of the curved solarium crowning the house, marking the ramp culminating moment.

A means of an intimate and surrealist experience, like in the de Beistegui penthouse in Paris: where white plastered walls partially hide the view of some city monuments beyond and surround a grass carpet open to the sky, surprisingly filled by elements usually found inside an apartment (a false fireplace with a mantelpiece, living-room furniture and a mirror).

A distinct collective space, physically and formally separated by the residential sphere below,like in the Unitéd'Habitation in Marseille: the kindergarten, the gym, the pool and the ventilation stacks give form to an articulated composition of concrete sculptures toward the sky, expressing the social habitability of the roof.

Finally, as an ironic questioning of Le Corbusier's imagery itself, a stage for a changeable set of vegetation colours and masses in the roof garden that Roberto Burle Marx displayed on the roof of the Ministry of Education in Rio de Janeiro,a building designed by some Brazilian modern masters, with the supervision of the Swiss architect.

Shaping the liveable roof: architectural dichotomies

As regards the role of the roof, if we look back to the beginning of Modernity in architecture we should find the roots of some attitudes still present today[4].

Two couples of opposites can provide an interesting trace.

The first one is related to the dichotomy"detachment from /interaction with the ground".

Many utopian monuments of technological progress designed in the 20 Century have so much to owe to El Lissitzky's Wolkenbügel of 1924: the wide cantilevered slabs standing on 50-metre-elevated piers were intended to provide inhabitable space over busy intersections of radial and ring-rods in Moscow.Featuring a horizontal layer far from the ground,figuratively separated from the functional support,the so-called "sky-hook" expressed a separated urban habitat based on "the conquest of gravity".

It is a common trait recurring in many megastructural dreams of the Sixties: starting from by Yona Friedman's Ville Spatiale (1958-1962) based on the idea to expand the city by building above it a gigantic structural skeleton able to support housing and working units; to the enormous buildings overtaking cities or natural landscapes drawn by Superstudio, such as the Continuous Monument of 1969, or, in the same year, the New Artificial Ground Layer for Dusseldorf by Wimmenauer,Szabo, Kasper & Meyer[5]. It is a detaching strategy that echoes in recent realisations, as, among others,the pixelated raised box of Sharp Center in Toronto by Alsop (2004), standing on coloured bending pillars 26 metres above a small-scale streetscape; or the Antwerp Port House completed by Zaha Hadid Architects in 2016, a diamond-like glased huge volume floating above a XIX building.

Ironically, we can find one of the most recent examples of this approach in a realisation of Moshe Safdie, probably one of the few "utopian"architects who really had the possibility to build his day-dreams. Marina Bay Sands in Singapore,completed in 2010, displays all the ingredients of a monumental icon: three distinct towers support,at the 57th floor, a unique boat-shaped volume:the so-called Sky Park on the top measures 1.2 hectares and cantilevers out 65-metre on one side,hosting restaurants, cafés, 250 trees, a 150-metre long pool and viewing decks that offer sights of Singapore's skyline 200 metres above the city. It is debatable how such a luxury community could fulfil the designer's concept of "public realm"; it surely provides, nevertheless, a "microcosm of a city"alternative to the metropolis' spaces below.

On the opposite side, we can point out the attitude of searching an uninterrupted flow between the space around the building and the cover of the building itself. The raising of the ground as a folded surface becomes the main inclusive dispositive.

The main feature of Villa Malaparte, built by Adalberto Libera on the Isle of Capri in 1938, is undoubtedly the roof-terrace: an inverted pyramidal stair without rails allows to ascend at the solarium,toward the landscape of sky and sea, and in the meantime acts as a theatre headed for the natural vibrant composition of plants and rocks. It helps the pure geometrical red volume in achieving a harmonious relationship with landscape. Only a white plastered curvilinear wall counterpoints the flat plane roof and provides a hidden place encompassing nothing but the view towards the horizon. A perfect stage for the representation of human dramas, as admirably caught by Jean Luc Godard in the 1963 movie Le Mépris.

And it's really the way a considerable number of people interact with the materiality of the roof as the key to the success of several contemporary projects.

Grass. The 1997 Library of Delft University of Technology, by Mecanoo Architects, appears like a sloped lawn, as a unique hill in the flat land of the Netherlands, intersected by basic geometric elements: a nearly triangular cut providing the entrance; a cone providing light and the main internal reference point. It's a gentle landmark,where the surface of the park is tilted up without interruption till the edge of the building: it is a veritable public green where people can gather, sit,lay down and rest. In addition, the green roof keeps the well-known benefits of such technical solution,like the capacity to conserve energy, mitigate the urban heat island, control storm water runoff,reduce air pollution, increase urban biodiversity.

石。為了創(chuàng)造一處供人聚集的開放公共建筑，設(shè)計奧斯陸歌劇院的建筑事務(wù)所（Sn?hetta，2007）將任務(wù)書所要求的紀念性轉(zhuǎn)變?yōu)槟撤N傾斜的幾何學，其水平向度遠強于垂直向度：一系列石材鋪設(shè)的步行表面，如同真正的城市街道一般，從海平面盤桓直抵頂部平臺。這座建筑就是一條路徑：即實體部分；而所有垂直立面都是透明玻璃面，以促進室內(nèi)外視野的互通。

第二組范式與建筑特征相關(guān)：“純粹派、簡潔、線性/雕塑感、表現(xiàn)主義、有機” 。

11 國民廣場住宅公寓，芝加哥/Commonwealth Promenade Apartments, Chicago（攝影/Photo: C. Rossi）

12 米拉公寓，巴塞羅那/La Pedrera, Barcelona（攝影/Photo:Mauro Volpiano）

密斯·凡·德·羅為芝加哥國民廣場住宅公寓設(shè)計的屋頂閣樓（1956）是一個簡單的平行六面體，就像是按照下方建筑輪廓縮減后凸出形成的體量：它包括一座為密斯的主要客戶赫伯特·格林瓦爾德設(shè)計的公寓——以原計劃在湖畔大道860號大樓實現(xiàn)的前一版平面為基礎(chǔ)。這個體量保持了與包裹整座建筑的玻璃幕墻相同的垂直及水平韻律感：一面鋁框玻璃表皮，寬闊的玻璃表面由均勻的垂直窗欞及水平層間帶劃分。

如今，成千上萬的屋頂閣樓呈現(xiàn)出相同的特質(zhì)：奢侈內(nèi)涵的表達不再依賴復(fù)雜的建筑形式，而恰恰相反，來自于凝煉室外獨一無二的壯闊視野的能力。簡而言之，就是純粹的視野。

另一方面，安東尼·高迪的杰作之一米拉公寓——在屋頂上營造了一處真正的雕塑景觀。它并不是平屋頂，而擁有豐富的高差變化，這源自原始的承重結(jié)構(gòu)：共270個拋物線磚拱券，根據(jù)建筑寬度采取不同高度。屋頂?shù)钠鸱窂缴宵c綴著一組驚人的采取擬人化雕塑形態(tài)的技術(shù)設(shè)施：樓梯出口、采光井、獨立或成組的煙囪，有的覆蓋碎瓷片，有的只是涂上色彩。在觀賞建筑立面的流線形式后，人們對于有機本質(zhì)的感知會在屋頂上得到進一步豐富——通過在雕塑森林中上下穿梭的直接體驗。

適應(yīng)：范式的改變

回顧1980年代末的設(shè)計，或許能為我們提供些許線索，以理解當代建筑語境中形態(tài)上及概念上的屋頂重塑背后的潛力。它將建筑的身份定位為“修正”——來自于維多利奧·格里高蒂著名的定義[6]——不再是調(diào)和，而是通過差異和并置發(fā)生作用，這一轉(zhuǎn)變發(fā)生在歐洲及北美的城市化轉(zhuǎn)型之初。有幾個例子值得一提。

1984年，胡安·納瓦羅·巴爾德維格設(shè)計的穆爾西亞老磨坊修復(fù)，是對建筑頂部的徹底重塑，是減法與加法的雙重操作。原先的單體構(gòu)筑物在經(jīng)歷數(shù)個世紀的產(chǎn)權(quán)分割之后，形成了異質(zhì)的垂直加建空間。新項目試圖展開一場古與今的對話，拒絕單純的保護性態(tài)度。一方面，它恢復(fù)了這組建筑下部原有的棱柱形體量——一座容納水車機械的狹長大廳，以此彰顯建筑公共職能的回歸：大廳頂部成為了一個俯瞰河流的步行平臺。另一方面，這個基座上沿著步道矗立著一組相互連通的雕塑體量：分別是文化中心、圖書館、咖啡及餐廳所在的新建筑，采取同一種當?shù)佤魇?，與老建筑墻體形成視覺上的呼應(yīng)，卻以線性序列自由布置。因此，這項屋頂改造確立而又更新了歷史分層的理念：這個名符其實的公共“建筑漫步道”允許人們重新利用這個場所，激發(fā)起對于城市發(fā)展累積過程的細膩感知，平衡了相似性與差異性。

Wood. Certainly, wood is the main actor of Yokohama International Passenger Terminal,designed by Foreign Office Architects in 1995 and opened in 2002. Its roof consists on a series of wooden folded surfaces, mixed with some grass ones, where the inside elements naturally flows outside. There's a strong tactile feeling in this architecture: people experience the building by walking, climbing and stomping the upper deck,as well as "navigating" the internal pathways and ramps along three levels. An overall dynamic feature permeates the identity of this infrastructural hub, as a space devoted to a continuous flow of circulation:it provides in the meantime a public urban park as a threshold between the city and the sea.

Stone. In order to realize a gathering and open public building, the designers of Oslo Opera House (Sn?hetta, 2007) have turned the required monumentality into a sort of sloped geometry,more horizontal than vertical: a series of pedestrian surfaces, paved in stone like veritable urban streets,wave from the sea level to the upper terrace. The architecture here is the pathway: this is the solid component; on the contrary, all the vertical facades are transparent glass surfaces, allowing the view from and into the inside.

The second couple of paradigms regards architectural features: "purism, simple, lineal/sculpture-like, expressionism, organic".

The rooftop penthouse designed by Mies Van der Rohe for the Commonwealth Promenade Apartments in Chicago (1956) is a simple parallelepiped that appears like a reduced volume extruded by the building below: it included an apartment for Herbert Greenwald, his major client,on the basis of a previous plan to be originally realized in 860 Lake Shore Drive building. The volume keeps the same vertical and horizontal rhythm of the curtain wall fa?ade encasing the entire building: a glass-and-aluminium skin, where wide glass surfaces are regularly marked by vertical projecting mullions and horizontal spandrel ribbons.

Nowadays, thousands of top penthouses display the same features: in these cases, the luxury connotation is not devoted to complex architectural forms but, on the contrary, derives from the capacity to sublimate the spectacular and unique vision of the outside. In short, pure view.

On the other hand, one of the masterpieces by Antoni Gaudì – Milà House (La Pedrera) – displays on the roof a veritable landscape of sculptural forms. It is not a flat roof, but a varying in height one, thanks to the original bearing structure: a series of 270 parabolic brick arches of various heights according to the widths of the building. The continuous waving path on the top is punctuated by a surprising composition of technical elements realized as anthropomorphic sculptures: staircase exits, skylights, standing alone or grouped chimneys,sometimes covered with ceramic fragments,sometimes just rendered and painted. After the vision of the fluid curvilinear forms of the fa?ade,people's perception of the organic essence of the building is enriched by direct experience of walking up and down through a forest-like set of sculptures.

Adaptation: a change of paradigm

A look to late eighties should offer some clues to investigate potentialities of the physical and conceptual re-shaping of the roof in nowadays architectural discourse. It helps to locate the status of architecture as "modification", according to the famous definition by Vittorio Gregotti[6], acting through disparities and juxtaposition, rather than reconciliation, in the wake of urban transformations in European and North American cities. A few examples can be cited.

The restoration of the Old Watermills in Murcia by Juan Navarro Baldeweg in 1984 envisaged a complete remodelling of the upper part of the building, performing a double action of excavation and extension. The original monolithic configuration had been altered in the course of the century by a process of property fragmentation leading to heterogeneous vertical extensions. The new project aims at a dialogue between the past and new, rejecting a pure preservation attitude.On the one hand it recovers the original prismatic shape of the lower part of the complex, a long hall hosting the machinery of hydraulic mills, in order to stress the return to a public use of the building: the top becomes a terrace-promenade looking onto the river. On the other hand, a series of interconnected sculptural volumes stands on this base accompanying the pathway: the new buildings for a cultural centre, library and café-restaurant are made in the same local ochre stone, providing a visual analogy with the old walls, but they are freely laid out in the shape of a linear sequence. The roof remodelling thus confirms, but also renews, the idea of historical stratification: this veritable public promenade architecturale allows a re-appropriation of the place, activating a subtle understanding of the accumulative process of city growth, balancing similarities and differences.

In the same years, the Lingotto factory in Turin – one of the most well-known plant in the world, due to the exceptionality of the roof,whose test track for cars with parabolic curves greatly fascinated Le Corbusier – went under an overall conversion process. The 500-metrelong factory designed by engineer Mattè Trucco of Fiat Company from 1915 to 1926 closed in 1982. Shortly afterwards, in 1985, Renzo Piano's Building Workshop was commissioned to convert it into a multipurpose centre, so now a complex layout allows the building to be crossed by people at many levels and to host a conference centre,an auditorium, university classrooms, cinemas,commercial spaces, hotels, offices. An almost"silent" formal approach (a respectful intervention on the original fa?ades, light glazed coverings of the courtyards, wooden auditoriums sunken inside the base) is counterpointed by two "aliens" landed on the roof: the 150-square-metre bubble-shaped conference room made up of about 400 glased elements forming a glass ellipse, directly connected to a steel cantilevered helipad; the "Treasure Chest"picture gallery, a 450-square-metre steel structure covered by a glased roof and a suspended 1000-square-metre canopy made up of four layers of profiled steel and 1600 glass plates able to ensure natural lighting but avoiding direct sunlight. The building expresses the capacity to be lived as a veritable urban organism and at the same time it maintains its mass features counterpointed by roof innovative elements (no more cars but architectural spaces): it pushes the limits of high technology calling for extraordinariness, acting as an icon of Fiat brand; although, as a paradox, the outmost suggestive character – the roof car track –still remain unexploited.

同年，都靈的林格托工廠——因其獨特的屋頂而成為世界上最著名的工廠之一，其屋頂上用于車輛測試的拋物線跑道曾令柯布西耶著迷——經(jīng)歷了一次整體性改造。這座由工程師馬特·特魯科于1915–1926年為菲亞特公司設(shè)計的長達500m的工廠，于1982年正式關(guān)閉。不久后的1985年，倫佐·皮亞諾建筑事務(wù)所受委托將它改造為一座多功能中心。如今這座綜合體的各樓層間交錯相通，容納了會議中心、講堂、大學教室、電影院、商業(yè)空間、賓館、辦公室。形式上近乎“沉默”的介入方式（極為尊重原始立面的改造，庭院采用輕盈的玻璃幕墻圍合，木制講堂則沉入地下）通過屋頂上降落的兩個“外星物體”找到了平衡：一座150m2的泡泡形會議室，一個由400塊玻璃板組成的玻璃橢圓體，直接與鋼結(jié)構(gòu)懸挑直升機坪相連；一座作為影像資料館的“珍寶庫”，這是個450m2的鋼結(jié)構(gòu)構(gòu)筑物，上覆玻璃屋頂及1000m2的懸浮頂棚，后者由4層精制鋼材及1600塊玻璃板組成，提供了過濾直射的自然光。這座建筑不僅展現(xiàn)了作為一個城市有機體供人生活的能力，同時也保持了它原先的體量特征，對應(yīng)以屋頂上的創(chuàng)新元素（只是汽車被建筑空間所替代）：它推進了追求超凡的高科技的極限，成為菲亞特品牌的標志；而似乎悖論的是，這座建筑最引人聯(lián)想的特征——屋頂跑道——卻依然未得到利用。

一個屋頂改造項目登上了1988年“解構(gòu)主義者展覽”目錄的封面頭條。這個由菲利普·約翰遜在紐約現(xiàn)代藝術(shù)博物館策劃的展覽，標志著現(xiàn)代主義與后現(xiàn)代主義持續(xù)辯論的轉(zhuǎn)折點。它成功地組合了兩個術(shù)語——哲學上的“解構(gòu)”和源自俄國先鋒藝術(shù)的“構(gòu)成主義”，擁抱不規(guī)則性和不穩(wěn)定性已成為自那以后的建筑界主角們作品中的共同線索（彼得·埃森曼、弗蘭克·蓋里、扎哈·哈迪德、雷姆·庫哈斯、丹尼爾·里伯斯金、伯納德·屈米、藍天組）。藍天組為維也納法爾克街一座傳統(tǒng)公寓樓所做的屋頂改造，成為了當代城市更新的某種建成宣言。在建筑師的世界中，“源自街道的一條可視能量線拓展了這個項目，擊碎了現(xiàn)有的屋頂，使它敞開?！币粋€看似不穩(wěn)定的鋼結(jié)構(gòu)貫穿了這個兩層空間，直截了當?shù)貙⑹覂?nèi)暴露于天空、噴射至室外：翅膀般的骨架承載著玻璃面板，暴力地打斷立面的延續(xù)性，在屋頂和街道之間形成一種鮮活的張力。當時對這種“全新”美學的歌頌，是為了對抗另一種如今已過時的純形式領(lǐng)域（“從熟悉的正交結(jié)構(gòu)、屋頂條板瓦片等限制之中解放出來”），但如今依然值得討論的是，它的目的是提供“一種比功能復(fù)雜性更為和諧的特定情境復(fù)雜性”，并定位出“與日常形式相交織的建筑前沿和極限”，以此尋求“舊物件中的新領(lǐng)域”[7]。

總而言之，對于不斷累積的城市歷史分層的考量、對技術(shù)創(chuàng)新的探尋、為了見證城市復(fù)雜性的表現(xiàn)方式轉(zhuǎn)變，是當今情境下常見的一些主題。

如今這個當代范式的轉(zhuǎn)變已得到公認，即從對新建筑的信念——作為與舊建筑間刻意保持的距離——轉(zhuǎn)向一種適應(yīng)性的態(tài)度：這種進路，基于對物質(zhì)領(lǐng)域的適應(yīng)及轉(zhuǎn)變這一動態(tài)過程的理解，遠不只是一種僅做保護的倒退式操作。在這個意義上，對屋頂?shù)闹匦滤妓骰蚰芴峁┮环N處理城市轉(zhuǎn)型的獨特視角，一把用以試驗城市身份的鑰匙——建筑通過一個又一個的案例，不斷調(diào)試它的適應(yīng)技巧[8]。

總體來說，利用屋頂改造以承載新的功能——公共和共享空間、工作空間、住房——應(yīng)該加入到建成環(huán)境節(jié)制增長的柔性策略之中，扮演城市“針灸”的角色。它們共同表達了一種完全介入現(xiàn)存建筑、重塑建筑特征的共生性態(tài)度。這依然是個開放的研究領(lǐng)域?！?/p>

13 老磨坊改造，穆爾西亞/Restoration of the Old Watermills,Murcia（攝影/Photo: Paolo Rosselli）

14 林格托，都靈/Lingotto, Turin（攝影/Photos: G Ambrosini）

A rooftop remodelling project hit the headlines from the cover of the Deconstructivist Exhibition catalogue in 1988. The exhibition organized by Philip Johnson at New York Museum of Modern Art marked a turning point in the ongoing debate Modernism-Post Modernism. It successfully combined two terms – philosophical"deconstruction" and Constructivism from Russian avant-garde – in order to celebrate the irregular and the unstable as a common thread across the work of some protagonists of the architectural scene since then (Peter Eisenman, Frank Gehry, Zaha Hadid,Rem Koolhaas, Daniel Libeskind, Bernard Tschumi,Coop Himmelblau). The renovation of a traditional apartment building in Falkestrasse, Wien, by Coop Himmelblau appeared as a sort of built Manifesto for renewing the existing city. In the designers'world, "a visualized line of energy coming from the street spans the project, thus breaking the existing roof and thereby opening it." A seemingly unstable steel structure crosses the space occupying two storeys, literally exposing its interior to the sky and ejecting it outside: wing-like skeletal elements bearing glazed panels violently break the cover continuity, producing a vivid tension between roof and street. The accent on a "new" aesthetic wisdom was at the time driven to struggle against a – now outdated – domain of pure form ("Released from the familiar constraints of orthogonal structure,the roof splits, shears and buckles"), but what still emerges as topical is the aim to provide "a dynamic complexity of local conditions that is more congruent with functional complexity" and to locate"the frontiers, the limits of architecture, coiled up within everyday forms" in order to find "new territories within old objects"[7].

15 法爾克街屋頂改造項目，維也納/Falkestrasse rooftop remodelling, Vienna（攝影/Photo: Rory Hyde, CC BY-SA 2.0）

To sum up, the consideration of the cumulative process of urban stratification, the search for technological innovation and the shift in expressiveness to witness the complexity of urban realms are some recurring issues in the present condition.

It is now widely accepted a change in contemporary paradigm, from the faith in new realisations – as a conquered distance from the old ones – to an adaptive attitude: it is an approach based on the knowledge of the dynamic process of adaptation and transformation of the physical realm, far from a preservation-only regressive behaviour. In this sense, the re-thinking of the roof could offer a peculiar point of view to deal with urban transformations, a key for testing city identities where architecture re-negotiates, case by case, its adaptive skill[8].

In general, the rooftop exploitation to host new functions – public and collective spaces, workplaces,housing – should take part in a soft strategy of moderate growth upon the existing tissues, acting like an urban "acupuncture". Together, it expresses a symbiotic attitude making possible an entire involvement of existing architecture, re-shaping its whole identity. It's an open research field.□

[1] Le Corbusier, Jeanneret P. Five Points Towards a New Architecture. 1926.

[2] Croset P. A. Il tetto giardino: ragione tecnica e ideale estetico. "Rassegna", n. 8, 2009; Von Moos S., Le Corbusier: Elements of a Synthesis, Rotterdam: 010 Publishers (edition revised and expanded); Lucan J. (200),Composition, non-composition: architecture et théories,XIXe-XXe siècles, Lausanne: PPUR édition, 1981.

[3] "With all the varied advantages which the employment of armoured cement offers, the coveringin of our houses with a level platform has become a simple matter, and this platform could be planted with small flower gardens or adorned with verdure clad trellises. But a still more important function to be performed by these terraces is that in the near future they will be used as landing stages for aeroplanes."Hénard E. Transactions. London: The Royal Institute of British Architects, 1911.

[4] Martínez A. Habitar la cubierta/Dwelling on the Roof. Barcelona: Editorial Gustavo Gili, 2005.

[5] Melet E., Vreedenburgh E. Rooftop Architecture.Buildin on Elevated Surface. Rotterdam: Nai Publishers, 2005.

[6] Gregotti V. Modificazione. "Casabella", n. 498/9,JanuaryFebruary, 1984.

[7] Jonshon P., Wigley M. Deconstructivist Architecture,New York: The Museum of Modern Art, 1988.

[8] Cfr. from early Robert, P. Adaptations. New Uses for Old Buildings, Paris: Editions du Moniteur to recent Wong L. (2017), Adaptive Reuse. Extending the Lives of Buildings, Basel: Birkhauser, 1989.

都靈理工大學

2017-10-12