可居住屋顶―建筑的范式

古斯塔夫·安布罗西尼/Gustavo Ambrosini

黄华青 译/Translated by HUANG Huaqing

可居住屋顶―建筑的范式

古斯塔夫·安布罗西尼/Gustavo Ambrosini

黄华青 译/Translated by HUANG Huaqing

The Inhabitable Roof: Paradigms in Architecture

一片虚空，一个纯粹的“技术空间”，一处被可怖之物（烟囱、管道、出风口、冷却机……）占据的无人区——它的作用基本就是交换建筑室内外空气，如同这个时代的幽灵。难道这就是现代城市中屋顶所注定呈现出的形象？然而，距离电梯的发明已过去一个半世纪，这项发明颠覆了欧洲城镇的秩序分层，改变了社会身份的表征和建筑的吸引力——从传统以建筑底层为尊贵的“主楼层”，转变为从底层至高层的身份递进。

但是，屋顶与视野及想象有着密切关联。

值得一提的是，亚历山大·加尔德于1974年在大急流城肯特县行政大楼屋顶上创造的抽象画作，展现了屋顶景观的双重含义：除了每座建筑屋顶显而易见的特征——即作为一处观景之场所，这幅1600m2的红白黑色画作，也是这位艺术家最大的一幅画，反而确立了它作为一处被观看之场所的地位。

论及与屋顶相关的意象，电影艺术无疑是最值得探索的源泉之一。在电影中能够找到屋顶景观与人的使用相关的多重身份：一处动作场面的理想场所，那些关于逃脱、打斗、复仇之类的戏剧化场面——往往是最高潮部分——皆可在此找到惊险之地；一处让音乐剧能量尽情释放的场所，一个歌舞场面的绝佳舞台，不受任何常规所限；一处亲密情感的抒发之所——无论是爱意、忧郁还是怀旧，一处面向天空、无人可见的空间。一处能够展现人造环境与周遭景观（即世界）之间超凡、惊人的关系的场所。因此，这是一处为不同寻常和张力而生的地方，它与日常生活相反，暗示着异常的观念。

实际上，由谷歌地球等虚拟地图软件带来的多尺度顶端视角，以及俯瞰城市的摄影类书籍的流行，展现了当代世界更为复杂的屋顶景观。从奢侈领地到日常社区，从收复的口袋花园到宽敞的公共绿地，屋顶空间为建筑和城市带来了不可估量的潜力。

新的屋顶：现代建筑的一种范式

有人会说，屋顶可居住空间的地位早在1926年勒·柯布西耶提出的“新建筑五要素”就得到了官方认定——屋顶花园，或屋顶平台。

这段文字明显提供了一种纯技术层面的解释，以展现混凝土结构的新可能性：一个站得住脚的功能目的，是为了替这种新建筑语汇寻求科学的客观性[1]。对于平整水泥板之潜力的强调，无疑源自那些混凝土建筑先驱的影响——例如弗朗索瓦·埃纳比克于1903年在布格拉罕镇建造的自宅，是这项新技术名符其实的宣言：一座空中花园覆盖了整座建筑，建筑师的格言就是“鲜花、阳光和通风”。此外，关于“居住目的的系统化利用”的观念，也指向建筑中逐步提升的卫生标准，这是在勒·柯布西耶的私人和集合住宅项目中不断重现的话题。最后，是对勒·柯布西耶的构想本身的讽刺性质疑：一个植被颜色及组合皆可变换的舞台，如罗伯特·布雷·马克斯在里约热内卢教育部大楼屋顶花园所做的那样——这栋建筑是在勒·柯布西耶的指导下，由巴西现代建筑大师们设计的。

如很多评论家所指出的[2]，将屋顶形象塑造为“建筑中最受喜爱之地”，背后存在多重来源——既源于历史遗产，也指向即将到来的机械时代：一方面，它在形式上呼应了地中海地区乡土建筑及东方传统建筑的平屋顶形象，它们出现在勒·柯布西耶的旅行素描本中；另一方面，是对于跨洋航线那光鲜形象的痴迷（“倚在游轮夹板的栏杆上……倚在屋顶的边缘”）。这个视觉及功能的隐喻，重现了前人乌托邦式的现代世界构想的辉煌[3]，开启了光明城市诗意的未来之路。

可生活的平屋顶，与传统的坡屋顶对比鲜明，成了现代建筑运动最有力的标志之一。

但这并不是个同质化的标志。屋顶所发挥的作用，就和勒·柯布西耶的作品一样，展现出多面性的特征：

一处纯粹的室外空间，作为对私人居住空间的延伸，如雪特龙住宅项目。

一个建筑漫步的顶点，如萨伏伊别墅，展现了在住宅空间中运动的最后几步：首先是紧邻客厅的室外平台，然后是屋顶上凸起的曲面围合的日光浴场，标识着坡道到达顶峰的时刻。

一种亲密的超现实主义体验手段，例如巴黎的德·贝斯特古屋顶：白色抹灰墙体部分遮蔽了远处的城市标志物，周围环绕着面向天空的绿地毯，其中惊人地充斥着通常只在公寓室内可见的元素（拥有壁炉台的假壁炉、起居室家具和一面镜子）。

一个独特的共享空间，在物理上及形式上都与下部楼层的居住空间相隔离，如马赛公寓：幼儿园、健身房、泳池和通风管道，形成了一个指向天空、精心设计的混凝土雕塑组，彰显了屋顶的社会可居性。

塑造可居住屋顶：建筑的二分法

论及屋顶的作用，若回溯至现代主义建筑的源头，或许能找到一些延续至今的设计态度的根源[4]。

有两组对比提供了有趣的线索。

第一组是关于“从地面脱离/与地面互动”的二分法。

1 空，柏林/Void, Berlin

2 人，伦敦/People, London

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

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

5 萨伏伊别墅，普瓦西/Ville Savoye, Poissy（摄影/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 Fançois 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·贝斯特古屋顶，巴黎/De Beistegui penthouse, Paris（图片来源/Source: Le Corbusier et Pierre Jeanneret oeuvre complete de 1929-1934, Zurich 1952）

7 马赛公寓/Unité d'Habitation, Marseille（摄影/Photo: G.Ambrosini）

8 铁云，莫斯科/Wolkenbügel, Moskow（图片来源/Source:Wikimedia Commons）

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

20世纪建筑师设计的很多体现技术进步的乌托邦式纪念碑，都多少受到埃尔·利西斯基1924年设计的“铁云”影响：这个漂浮于50m高基座之上的悬挑宽板，在莫斯科繁忙的放射路及环路交汇点上提供了可居住空间。该项目被称为“空中挂钩”，是一个远离地面的水平楼层，象征性地脱离了功能性支撑，呈现了一个基于“征服重力”的独立城市居所形象。

这是1960年代许多巨构梦中常见的线索：从尤纳·弗里德曼的“空间城市”（1958-1962）开始，他的城市拓展理念是在城市上空建造一个巨型结构框架，以支撑住房及办公单元；到超级工作室绘制的取代了城市或自然景观的巨型建筑，如1969年的“连续纪念碑”，或是同年由威曼诺伊尔、萨波、卡斯帕和迈耶为杜塞尔多夫设计的“新人工地面”[5]。这种脱离式策略在近期建成的项目中亦有体现，例如阿尔索普设计的多伦多夏普中心（2004）那个像素化的空中盒子，由彩色的倾斜柱子群支撑，漂浮在一个小尺度街景上空26m之处；或是扎哈·哈迪德事务所于2016年设计建成的安特卫普“港口之家”，这个钻石般、通体玻璃的巨大体量，悬浮在一座19世纪的老建筑之上。

讽刺的是，这一路径最近的典型案例之一来自摩西·萨夫迪，他或许是少数真正有机会将自己的白日梦实现的“乌托邦”建筑师。2010年建成的新加坡海滨湾金沙酒店，具备了一座纪念性标志物的所有要素：3座清晰明了的塔楼支柱，57层则是一个独一无二的船形体量：这个所谓的“空中花园”，面积12,000m2，一侧悬挑65m，容纳了餐厅、咖啡、250棵树、一个150m长的泳池、以及从200m高空俯瞰新加坡天际线的观景平台。或许存在争议的是，如此一个奢侈的社区如何能实现建筑师所谓的“公共领域”概念；但它无疑提供了一种不同于其下都市空间的“城市缩影”。

与此相反，我们亦可指出一种在建筑周围空间与建筑表皮之间寻求某种延续性流动的态度。将地面抬升为平面折板，就成了一个重要的融合方案。

阿达尔贝托·里贝拉于1938年设计的卡普里岛马拉巴特住宅，首要特征无疑是其屋顶平台：一座没有扶手的反转金字塔形阶梯，通往屋顶日光浴场，走向天空与海洋的风景；同时它又是一座剧场，面朝充满生机的植被与岩石的自然组合。它协助这个纯粹的红色几何体量达成了与自然景观的和谐关系。唯一的例外是一面白色抹灰曲线墙，它中和了屋顶的平整面，围合出一处面向地平线之外别无他物的隐秘之所。这是一个展现人类戏剧的完美舞台，就像让-吕克·戈达尔1963年的电影杰作《蔑视》所捕捉到的那样。

10 马拉巴特住宅，卡普里/Villa Malaparte, Capri（图片来源/Source: movie Le Mépris）

而且，这确实就是大部分人与屋顶的物质性进行交互的方式，也是多个当代建筑项目成功的关键。

草。Mecanoo建筑事务所于1997年设计的代尔夫特理工大学图书馆，如同一片倾斜的草坡、荷兰平原上一座独特山丘，其间贯穿着几个基本几何元素：一个接近三角形的缺口为入口空间；一个锥形体提供了采光井和主要的室内参照物。这是一座优雅的地标，公园平面毫无阻碍地倾斜而上，直至建筑边缘：这是一片真正意义上的公共绿地，人们在此聚集、坐卧和休憩。此外，这个绿色屋顶也具备那些众所周知的技术优势，例如积蓄能量、缓解城市热岛效应、控制泄洪、减轻空气污染、提升城市生态多样性。

木。当然，木材是横滨国际客运港的主要元素，这座建筑由FOA事务所于1995年设计，2002年建成开放。建筑屋顶由一系列木制折板面组成，其间穿插着一些覆土表面，室内元素通过这套体系自然溢出至室外。在这座建筑中可以体验到强烈的触觉感知：人们在上层夹板行走、爬行和重踏，同时在下方的3层空间内“摸索”室内的路径及坡道。在这座基础设施节点建筑中，渗透着一种整体上的运动感，这是一个献给动线延续流动的空间：同时它又提供了一座公共城市花园，作为城市与海洋之间的门户。

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。为了创造一处供人聚集的开放公共建筑，设计奥斯陆歌剧院的建筑事务所（Snøhetta，2007）将任务书所要求的纪念性转变为某种倾斜的几何学，其水平向度远强于垂直向度：一系列石材铺设的步行表面，如同真正的城市街道一般，从海平面盘桓直抵顶部平台。这座建筑就是一条路径：即实体部分；而所有垂直立面都是透明玻璃面，以促进室内外视野的互通。

第二组范式与建筑特征相关：“纯粹派、简洁、线性/雕塑感、表现主义、有机” 。

11 国民广场住宅公寓，芝加哥/Commonwealth Promenade Apartments, Chicago（摄影/Photo: C. Rossi）

12 米拉公寓，巴塞罗那/La Pedrera, Barcelona（摄影/Photo:Mauro Volpiano）

密斯·凡·德·罗为芝加哥国民广场住宅公寓设计的屋顶阁楼（1956）是一个简单的平行六面体，就像是按照下方建筑轮廓缩减后凸出形成的体量：它包括一座为密斯的主要客户赫伯特·格林瓦尔德设计的公寓——以原计划在湖畔大道860号大楼实现的前一版平面为基础。这个体量保持了与包裹整座建筑的玻璃幕墙相同的垂直及水平韵律感：一面铝框玻璃表皮，宽阔的玻璃表面由均匀的垂直窗棂及水平层间带划分。

如今，成千上万的屋顶阁楼呈现出相同的特质：奢侈内涵的表达不再依赖复杂的建筑形式，而恰恰相反，来自于凝炼室外独一无二的壮阔视野的能力。简而言之，就是纯粹的视野。

另一方面，安东尼·高迪的杰作之一米拉公寓——在屋顶上营造了一处真正的雕塑景观。它并不是平屋顶，而拥有丰富的高差变化，这源自原始的承重结构：共270个抛物线砖拱券，根据建筑宽度采取不同高度。屋顶的起伏路径上点缀着一组惊人的采取拟人化雕塑形态的技术设施：楼梯出口、采光井、独立或成组的烟囱，有的覆盖碎瓷片，有的只是涂上色彩。在观赏建筑立面的流线形式后，人们对于有机本质的感知会在屋顶上得到进一步丰富——通过在雕塑森林中上下穿梭的直接体验。

适应：范式的改变

回顾1980年代末的设计，或许能为我们提供些许线索，以理解当代建筑语境中形态上及概念上的屋顶重塑背后的潜力。它将建筑的身份定位为“修正”——来自于维多利奥·格里高蒂著名的定义[6]——不再是调和，而是通过差异和并置发生作用，这一转变发生在欧洲及北美的城市化转型之初。有几个例子值得一提。

1984年，胡安·纳瓦罗·巴尔德维格设计的穆尔西亚老磨坊修复，是对建筑顶部的彻底重塑，是减法与加法的双重操作。原先的单体构筑物在经历数个世纪的产权分割之后，形成了异质的垂直加建空间。新项目试图展开一场古与今的对话，拒绝单纯的保护性态度。一方面，它恢复了这组建筑下部原有的棱柱形体量——一座容纳水车机械的狭长大厅，以此彰显建筑公共职能的回归：大厅顶部成为了一个俯瞰河流的步行平台。另一方面，这个基座上沿着步道矗立着一组相互连通的雕塑体量：分别是文化中心、图书馆、咖啡及餐厅所在的新建筑，采取同一种当地赭石，与老建筑墙体形成视觉上的呼应，却以线性序列自由布置。因此，这项屋顶改造确立而又更新了历史分层的理念：这个名符其实的公共“建筑漫步道”允许人们重新利用这个场所，激发起对于城市发展累积过程的细腻感知，平衡了相似性与差异性。

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 (Snøhetta, 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 façade 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 façade,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 façades, 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，都灵的林格托工厂——因其独特的屋顶而成为世界上最著名的工厂之一，其屋顶上用于车辆测试的抛物线跑道曾令柯布西耶着迷——经历了一次整体性改造。这座由工程师马特·特鲁科于1915–1926年为菲亚特公司设计的长达500m的工厂，于1982年正式关闭。不久后的1985年，伦佐·皮亚诺建筑事务所受委托将它改造为一座多功能中心。如今这座综合体的各楼层间交错相通，容纳了会议中心、讲堂、大学教室、电影院、商业空间、宾馆、办公室。形式上近乎“沉默”的介入方式（极为尊重原始立面的改造，庭院采用轻盈的玻璃幕墙围合，木制讲堂则沉入地下）通过屋顶上降落的两个“外星物体”找到了平衡：一座150m2的泡泡形会议室，一个由400块玻璃板组成的玻璃椭圆体，直接与钢结构悬挑直升机坪相连；一座作为影像资料馆的“珍宝库”，这是个450m2的钢结构构筑物，上覆玻璃屋顶及1000m2的悬浮顶棚，后者由4层精制钢材及1600块玻璃板组成，提供了过滤直射的自然光。这座建筑不仅展现了作为一个城市有机体供人生活的能力，同时也保持了它原先的体量特征，对应以屋顶上的创新元素（只是汽车被建筑空间所替代）：它推进了追求超凡的高科技的极限，成为菲亚特品牌的标志；而似乎悖论的是，这座建筑最引人联想的特征——屋顶跑道——却依然未得到利用。

一个屋顶改造项目登上了1988年“解构主义者展览”目录的封面头条。这个由菲利普·约翰逊在纽约现代艺术博物馆策划的展览，标志着现代主义与后现代主义持续辩论的转折点。它成功地组合了两个术语——哲学上的“解构”和源自俄国先锋艺术的“构成主义”，拥抱不规则性和不稳定性已成为自那以后的建筑界主角们作品中的共同线索（彼得·埃森曼、弗兰克·盖里、扎哈·哈迪德、雷姆·库哈斯、丹尼尔·里伯斯金、伯纳德·屈米、蓝天组）。蓝天组为维也纳法尔克街一座传统公寓楼所做的屋顶改造，成为了当代城市更新的某种建成宣言。在建筑师的世界中，“源自街道的一条可视能量线拓展了这个项目，击碎了现有的屋顶，使它敞开。”一个看似不稳定的钢结构贯穿了这个两层空间，直截了当地将室内暴露于天空、喷射至室外：翅膀般的骨架承载着玻璃面板，暴力地打断立面的延续性，在屋顶和街道之间形成一种鲜活的张力。当时对这种“全新”美学的歌颂，是为了对抗另一种如今已过时的纯形式领域（“从熟悉的正交结构、屋顶条板瓦片等限制之中解放出来”），但如今依然值得讨论的是，它的目的是提供“一种比功能复杂性更为和谐的特定情境复杂性”，并定位出“与日常形式相交织的建筑前沿和极限”，以此寻求“旧物件中的新领域”[7]。

总而言之，对于不断累积的城市历史分层的考量、对技术创新的探寻、为了见证城市复杂性的表现方式转变，是当今情境下常见的一些主题。

如今这个当代范式的转变已得到公认，即从对新建筑的信念——作为与旧建筑间刻意保持的距离——转向一种适应性的态度：这种进路，基于对物质领域的适应及转变这一动态过程的理解，远不只是一种仅做保护的倒退式操作。在这个意义上，对屋顶的重新思索或能提供一种处理城市转型的独特视角，一把用以试验城市身份的钥匙——建筑通过一个又一个的案例，不断调试它的适应技巧[8]。

总体来说，利用屋顶改造以承载新的功能——公共和共享空间、工作空间、住房——应该加入到建成环境节制增长的柔性策略之中，扮演城市“针灸”的角色。它们共同表达了一种完全介入现存建筑、重塑建筑特征的共生性态度。这依然是个开放的研究领域。□

13 老磨坊改造，穆尔西亚/Restoration of the Old Watermills,Murcia（摄影/Photo: Paolo Rosselli）

14 林格托，都灵/Lingotto, Turin（摄影/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 法尔克街屋顶改造项目，维也纳/Falkestrasse rooftop remodelling, Vienna（摄影/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.

都灵理工大学

2017-10-12