阿里亞納·威爾遜/Ariane Wilson

司馬蕾 譯/Translated by SIMA Lei

什么是合理的熱舒適性？
——保溫參數(shù)在法國(guó)和德國(guó)的變遷

阿里亞納·威爾遜/Ariane Wilson

司馬蕾 譯/Translated by SIMA Lei

從1970年代起，在法國(guó)和歐洲的其它國(guó)家，根據(jù)最舒服的溫度確定的熱舒適性開(kāi)始讓位于對(duì)建筑能耗問(wèn)題的思考。近10年來(lái)，對(duì)于建筑能耗的立法越來(lái)越嚴(yán)格，范圍也開(kāi)始不僅針對(duì)新建建筑，也涉及既有的歷史建筑。但同時(shí)，這些法規(guī)因?yàn)榇偈购形廴疚锏谋夭牧媳淮罅渴褂?，以及可能破壞歷史建筑、損害建筑表現(xiàn)形式多樣性而遭致了人們的批判。那么，有沒(méi)有可能在提高建筑的熱性能的同時(shí)兼顧建筑外觀(guān)的差異性和美觀(guān)性呢？而人們對(duì)于建筑能耗問(wèn)題的關(guān)心，是否會(huì)掩蓋了對(duì)其他能源浪費(fèi)現(xiàn)象的重視呢？

熱舒適，低能耗建筑，外墻外保溫，法國(guó)，德國(guó)，建筑多樣性

1970年代的一天，在一個(gè)有集中供暖、室溫為19℃的舒適公寓里，我來(lái)到了這個(gè)世界。當(dāng)時(shí)我并不知道那幾年剛好是“舒適度”的概念在法國(guó)的住宅政策中被提及，并被法國(guó)社會(huì)廣為重視的轉(zhuǎn)折點(diǎn)。與此同時(shí)，注重物質(zhì)舒適性的“現(xiàn)代主義”夢(mèng)想也正在向著“后現(xiàn)代主義的幸?！盵1]轉(zhuǎn)型，熱舒適第一的信條開(kāi)始逐漸讓位于對(duì)能源效率的考慮。

1970年代中期也剛好標(biāo)志著法國(guó)“光榮的30年”的終結(jié)，二戰(zhàn)之后長(zhǎng)達(dá)30余年的經(jīng)濟(jì)繁榮被1973年發(fā)生的石油危機(jī)打斷了?！肮鈽s的30年”見(jiàn)證了社會(huì)公共住宅的瘋狂建設(shè)。在1950年代后期，由政府興建的公共住宅占了新建住宅的80%以上——戰(zhàn)后重建的需要，以及安置不斷涌入的移民工人和棚戶(hù)區(qū)改造的需求催生了每年30萬(wàn)套的新住宅建設(shè)量。這種新形式的公共住宅讓人們能在家庭內(nèi)部更好地享受物質(zhì)上的舒適性，也為社會(huì)生活的標(biāo)準(zhǔn)化進(jìn)程做出了貢獻(xiàn)。

而在如何規(guī)范舒適度的問(wèn)題上，最早的全國(guó)性標(biāo)準(zhǔn)卻是誕生在20世紀(jì)的更早時(shí)期1）。這項(xiàng)法規(guī)規(guī)定了房間的最小面積（9m2），最小的室內(nèi)凈高（一層和二層2.8m，以上樓層2.6m，這項(xiàng)標(biāo)準(zhǔn)后來(lái)被逐漸降低），窗墻比（房間表面積的1/6），陽(yáng)光射入的角度，衛(wèi)生設(shè)施的最低標(biāo)準(zhǔn)（所有住戶(hù)需要通水，在大型的公寓中需要設(shè)衛(wèi)生間，并在其中配備洗臉盆和光滑防水的墻面與地板）。室內(nèi)溫度當(dāng)時(shí)尚未在規(guī)定之列，但是在同時(shí)期教導(dǎo)如何成為一個(gè)好主婦的培訓(xùn)用書(shū)中，推薦的室內(nèi)溫度為客廳14℃，客人來(lái)訪(fǎng)時(shí)15℃，臥室11℃。

從1920年代起，水、煤氣和電力也開(kāi)始成為了普通住宅中的硬性配備。而直到1950年代，公共住宅舒適度的最低標(biāo)準(zhǔn)中才開(kāi)始納入了供暖。1955年頒布的《功能技術(shù)硬性規(guī)范》2）中規(guī)定了公共住宅的臥室溫度根據(jù)所選用的不同的集中供暖系統(tǒng)，必須保證在12℃或16℃以上，但集中供暖本身并不是強(qiáng)制要求的。1960年代起的新規(guī)定開(kāi)始要求集合住宅中必須有集中供暖，而法定的最低室內(nèi)溫度為18℃。

同時(shí)，1955年出臺(tái)的建筑舒適度規(guī)范也得到了法國(guó)政府的健康部門(mén)和建設(shè)部門(mén)的承認(rèn)，并作為建設(shè)部門(mén)的一項(xiàng)建造標(biāo)準(zhǔn)得到推廣，加速了其立法。1958年頒布的“最低標(biāo)準(zhǔn)”旨在保證大眾的最低生活舒適度，但是當(dāng)時(shí)對(duì)“舒適”的概念本身的定義卻并不是那么統(tǒng)一。這一標(biāo)準(zhǔn)在文中將舒適定義為三檔：最低、一般和優(yōu)越，每一檔有其具體要求。而在法國(guó)人口普查部門(mén)的標(biāo)準(zhǔn)中，“舒適”意味著住宅配備有淋浴設(shè)施或浴缸，“非常舒適”則代表在配有淋浴或浴缸的同時(shí)有集中供暖。

1946年的一項(xiàng)民意調(diào)查顯示，88%的城鎮(zhèn)居民都希望住房中能有熱水，63%希望有集中供暖，59%希望有浴室。到了1968年，類(lèi)似的調(diào)查顯示僅有10%的人還沒(méi)能用上自來(lái)水，但有50%的人沒(méi)有熱水，65%沒(méi)有集中供暖。1970年代成了解決這些日常生活中的舒適性問(wèn)題的關(guān)鍵年代。到了此時(shí)，80%的住宅單元都已經(jīng)配備了自來(lái)水和集中供暖，而電飯鍋、洗衣機(jī)、冰箱、收音機(jī)、電視和電話(huà)等1950年代發(fā)明的家電設(shè)備也逐步得到了普及。

但與此同時(shí)，人們對(duì)舒適度問(wèn)題的看法卻也開(kāi)始發(fā)生了變化。在法國(guó)，1970年代中期是大規(guī)模公共住宅街區(qū)建設(shè)的最后階段，之后的新潮流則是去郊區(qū)購(gòu)買(mǎi)具有產(chǎn)權(quán)的私人住宅，而不再是租房了。政府對(duì)住宅市場(chǎng)的干預(yù)因此不再專(zhuān)注于建設(shè)新房，而是向著提高現(xiàn)有住宅品質(zhì)、重視過(guò)去被忽視的室內(nèi)舒適度問(wèn)題轉(zhuǎn)型，并希望通過(guò)財(cái)務(wù)優(yōu)惠政策鼓勵(lì)住戶(hù)翻新住所。

這些變化與國(guó)際石油危機(jī)以及“增長(zhǎng)極限”3）問(wèn)題開(kāi)始得到認(rèn)識(shí)基本是同時(shí)發(fā)生的。人們慢慢開(kāi)始意識(shí)到了保護(hù)地球資源的重要性，現(xiàn)代化的舒適性概念因而開(kāi)始從理論上受到了質(zhì)疑。雖然我們都知道能源的消費(fèi)量實(shí)際還是在迅速增長(zhǎng)的，而經(jīng)濟(jì)的發(fā)展也驅(qū)動(dòng)著能源消費(fèi)的加速而不是減速，但人們的觀(guān)念正從追求理想的生理舒適環(huán)境向著追求綜合的“幸福感”發(fā)生了轉(zhuǎn)變。這意味著對(duì)生理和心理、物質(zhì)與非物質(zhì)、個(gè)人與環(huán)境因素之間的更微妙的平衡關(guān)系的考慮。在法國(guó)的語(yǔ)言規(guī)范中，“質(zhì)量”一詞逐漸取代了“舒適”“宜居性”等用詞。不同于過(guò)去的最低標(biāo)準(zhǔn)概念，“質(zhì)量認(rèn)證”這一建筑質(zhì)量評(píng)價(jià)體系開(kāi)始同時(shí)應(yīng)用于公有和私有住宅。這一體系能通過(guò)復(fù)雜的計(jì)算方法，量化包括材料的可持續(xù)使用性、電氣設(shè)備完善性、建筑安全性、能耗、隔音性、維護(hù)成本、夏季熱舒適性、垃圾處理問(wèn)題等在內(nèi)的各種標(biāo)準(zhǔn)。

而在熱舒適的標(biāo)準(zhǔn)上，人們的觀(guān)念也發(fā)生了由內(nèi)而外的轉(zhuǎn)變。過(guò)去人們的注意力總是集中在如何通過(guò)主動(dòng)對(duì)內(nèi)部空間進(jìn)行加熱、提高室內(nèi)溫度來(lái)滿(mǎn)足使用者，現(xiàn)在的立法則開(kāi)始假設(shè)建筑作為溫度調(diào)節(jié)的中介，也能與外部空間發(fā)生互動(dòng)。因此建筑的圍護(hù)結(jié)構(gòu)，而不僅僅是供熱系統(tǒng)，也開(kāi)始得到了重視，從而使整體環(huán)境，而非僅僅是人類(lèi)能夠受益于這種“舒適性”。當(dāng)然，這并不意味著熱舒適性的標(biāo)準(zhǔn)發(fā)生了倒退，而只是開(kāi)始更多地關(guān)注節(jié)能的問(wèn)題。尤其是1988年出臺(tái)的建筑產(chǎn)品的官方目錄4）上，開(kāi)始使用“建筑節(jié)能理念”這章來(lái)代替原來(lái)的“使用者需求”一章。

新興的對(duì)于能源效率的關(guān)注也改變了建造和建筑文化：“光榮的30年”的建設(shè)中最受青睞的鋼筋混凝土、煤渣砌塊、鋁窗等建材都很少考慮保溫隔熱問(wèn)題，這使得法國(guó)的大量既有建筑都與新的能耗標(biāo)準(zhǔn)相去甚遠(yuǎn)。德國(guó)和瑞士的建筑節(jié)能標(biāo)準(zhǔn)“Passivhaus”和“Minergie”都具有很強(qiáng)的先鋒性，相比之下，法國(guó)的建筑文化在適應(yīng)新的標(biāo)準(zhǔn)和對(duì)其進(jìn)行立法上都進(jìn)展得非常緩慢。法國(guó)自1970年代后期開(kāi)始就出臺(tái)了國(guó)家規(guī)范，并開(kāi)展了幾項(xiàng)相關(guān)的使用太陽(yáng)能和其他節(jié)能技術(shù)的實(shí)驗(yàn)性建筑項(xiàng)目。但這一規(guī)范真正得到嚴(yán)格執(zhí)行卻是在2000年之后了，而公眾能真正理解建筑節(jié)能的概念則是近10年的事情，這還要感謝國(guó)家和商業(yè)機(jī)構(gòu)的積極推廣?，F(xiàn)在，“熱效率”已經(jīng)成為了熱門(mén)詞匯，催生了各種改善措施的實(shí)施，也引發(fā)了各種周全或有欠周全的實(shí)踐，以及人們對(duì)此的各種矛盾態(tài)度、爭(zhēng)議和憂(yōu)慮。

RT1974是一系列相關(guān)規(guī)定中第一部規(guī)范了新建筑的熱能耗要求，并對(duì)供暖、通風(fēng)、氣候適應(yīng)、熱水供應(yīng)和照明的能耗做了限制的法案。起初，規(guī)定只針對(duì)新建住宅。RT1974中出現(xiàn)了對(duì)墻體保溫和通風(fēng)系統(tǒng)的要求，而在第二次石油危機(jī)之后出臺(tái)的RT1982則希望通過(guò)利用太陽(yáng)能來(lái)減少供暖的能耗。到了RT1988，兩部分的條款都開(kāi)始延伸到非住宅建筑領(lǐng)域，同時(shí)也引入了基于能源消費(fèi)非能量損失的計(jì)算法則，并基于此創(chuàng)造出了“建筑能耗”這一新概念。而相比RT1988，RT2000則將針對(duì)新建住宅建筑的最大能耗標(biāo)準(zhǔn)削減了20%，對(duì)其他第三產(chǎn)業(yè)建筑物的能耗標(biāo)準(zhǔn)削減了40%。僅僅又經(jīng)過(guò)了5年，RT2005在RT2000的要求基礎(chǔ)上又提出了再削減15%的進(jìn)一步要求。

這一規(guī)范的最新版本為RT2012。這一版本再次提出了對(duì)供暖、照明、空調(diào)能耗的限制策略，旨在減少溫室氣體的排放，鼓勵(lì)新技術(shù)發(fā)展，對(duì)象則涵蓋了包括大學(xué)、商場(chǎng)、機(jī)場(chǎng)、醫(yī)院在內(nèi)的各種公共、私人和商業(yè)建筑。法規(guī)為新建建筑設(shè)置了根據(jù)不同地區(qū)確定的50kWh/m2的最大能耗標(biāo)準(zhǔn)（在1960年代這一標(biāo)準(zhǔn)為250kWh/m2，1970年代則為100-150kWh/m2）5）。RT2012同時(shí)也設(shè)置了在申請(qǐng)建造許可時(shí)必須提交能耗證明的要求。到2020年，新版本的RT則將會(huì)要求所有的新建建筑都實(shí)現(xiàn)正能量平衡（能量生產(chǎn)大于消費(fèi)）。

為了鼓勵(lì)使用更高效的供暖和空調(diào)系統(tǒng)、雙層玻璃和隔熱措施，最近出臺(tái)的與能耗相關(guān)的規(guī)范都關(guān)注一個(gè)新關(guān)鍵詞：保溫。在1970年代，為了糾正建筑的立面構(gòu)件熱傳導(dǎo)性過(guò)強(qiáng)的問(wèn)題，建筑的保溫措施都被設(shè)置在外墻的內(nèi)側(cè)。而今天，外墻外保溫——即在整個(gè)外立面包裹連續(xù)的保溫材料，被證實(shí)比使用同等厚度的內(nèi)保溫材料有效兩倍，能夠徹底解決熱橋問(wèn)題，也不會(huì)侵占室內(nèi)的使用面積。但這種貌似理想的方式卻受到了環(huán)保主義者、保守人士、建筑師們，甚至是公眾的強(qiáng)烈批評(píng)。其中的一條批評(píng)是關(guān)于保溫材料自身的環(huán)境和技術(shù)性能。另一條批評(píng)則指出其使用可能破壞歷史建筑的外觀(guān)，并損害建筑表現(xiàn)形式的多樣性。

外墻外保溫讓建筑外墻的軟硬兩面發(fā)生了反轉(zhuǎn)。德國(guó)許多民族的文化都在外墻上使用抹灰，因此外保溫的實(shí)施不會(huì)造成像在法國(guó)那樣大的文化沖擊——在法國(guó)，古典主義和新古典主義的建筑多喜歡通過(guò)使用石材結(jié)構(gòu)或貼面來(lái)表現(xiàn)高貴感，而現(xiàn)代主義的建筑則喜歡使用清水混凝土來(lái)彰顯其先進(jìn)性。

因此，德國(guó)成了歐洲實(shí)踐外保溫的冠軍國(guó)家。數(shù)百萬(wàn)立方米的W?rmed?mm-Verbundsysteme（一種整合了防水層、保溫層、鋼絲網(wǎng)、防水底層和完成面的外墻外保溫復(fù)合材料系統(tǒng)）取代了過(guò)去德國(guó)住宅中使用的抹灰（Putz）。在整個(gè)德國(guó)，外保溫不僅大量地使用在新建建筑上，也被應(yīng)用于大量戰(zhàn)后建造的質(zhì)量欠佳的建筑改造工程中。通過(guò)加設(shè)一層又一層非裝飾性的表層，戰(zhàn)后建造的這些建筑在材質(zhì)、立面陰影、窗戶(hù)周?chē)木€(xiàn)腳等細(xì)部上都發(fā)生了變化，品質(zhì)因此得到了提高。這種改造其實(shí)從整整一代人之前就開(kāi)始進(jìn)行了，但是德國(guó)2010年出臺(tái)的雄心勃勃的新能源政策加速了這一進(jìn)程——新政策定下了在2050年讓存量建筑（包括新建筑和舊建筑）全部達(dá)到氣候平衡的目標(biāo)，并計(jì)劃讓每年進(jìn)行節(jié)能改造的建筑數(shù)量翻一倍。

《愚蠢的外保溫》 （Wahnsinn W?rmed?mmung）是于2011年和2012年上映的兩部電視紀(jì)錄片，由此引發(fā)了對(duì)外保溫問(wèn)題的一股批判風(fēng)潮。該片對(duì)廣泛使用聚苯乙烯等石油制品作為外保溫材料提出了質(zhì)疑，認(rèn)為雖然持有作為建材的安全認(rèn)證，這種材料仍然非常易燃，會(huì)加速火勢(shì)蔓延，釋放有害氣體，并讓整堵外墻迅速地全部燃燒起來(lái)。片中同時(shí)也指出了這種材料不可循環(huán)使用、使用壽命短、可能將動(dòng)物困在其內(nèi)部、并常常因?yàn)榘惭b錯(cuò)誤造成凝結(jié)的水汽無(wú)法正常排出、讓材料從內(nèi)部發(fā)霉的問(wèn)題。此外，保溫材料外層涂料中包含的有毒成分會(huì)隨著雨水滲入周邊環(huán)境，污染土壤和河流。影片同時(shí)也指出，保溫過(guò)于嚴(yán)密的住宅需要另外設(shè)置窗縫和需要消耗能源的機(jī)械系統(tǒng)來(lái)進(jìn)行通風(fēng)，促使空氣進(jìn)入室內(nèi)，這是非常荒謬的。

片中也提到了生產(chǎn)這些保溫材料的公司的經(jīng)濟(jì)利益問(wèn)題（在德國(guó)，這是一個(gè)有著18億歐元產(chǎn)值的市場(chǎng)）。這些公司會(huì)不會(huì)通過(guò)鼓勵(lì)出臺(tái)嚴(yán)格的保溫規(guī)范，來(lái)促使住宅的業(yè)主們將房屋用保溫材料包裹起來(lái)，或是購(gòu)買(mǎi)通風(fēng)設(shè)備呢？2005年，德國(guó)的建筑上用了2450萬(wàn)m3的保溫材料（包括外墻的內(nèi)外兩側(cè)、墻體和屋頂?shù)人械慕ㄖ砻嫔系氖褂昧浚＿@些材料中，約41%是經(jīng)過(guò)膨化或擠壓的聚苯乙烯和聚氨酯，54%是礦棉6）。但即使是污染性較小的材料，也還是含有添加劑和溶劑。而較為天然和有機(jī)的材料，例如軟木、亞麻和羊毛則因?yàn)閮r(jià)格更貴而很少被使用。雖然據(jù)稱(chēng)這20～30年來(lái)，由于外保溫的推廣而節(jié)約的能源要比取得這些原材料、進(jìn)行生產(chǎn)、加工成合成材料所消耗的能源要多，但生產(chǎn)所需的這部分灰色能耗，以及因?yàn)樵谏a(chǎn)中排放有害物質(zhì)而造成的環(huán)境問(wèn)題都不應(yīng)該被忽視。此外，拆除原有的窗戶(hù)、使用新的塑料框雙層玻璃窗的過(guò)程也會(huì)對(duì)環(huán)境造成影響。而其中，究竟哪種材料最有利于建筑節(jié)能仍是最關(guān)鍵的問(wèn)題，但相關(guān)的規(guī)范以及對(duì)于低能耗住宅的定義中都沒(méi)有提及這一點(diǎn)。

另一條對(duì)于徹底轉(zhuǎn)向使用外墻外保溫的批判則是源自建筑學(xué)的角度。對(duì)于新建項(xiàng)目，人們確實(shí)希望新的建筑規(guī)范能更多地支持使用新科技、新材料、新形式和新的建造方法，以便形成新的建筑語(yǔ)言——例如使用柔軟的外圍護(hù)結(jié)構(gòu)，將建筑用多層表皮、具有一定厚度的金屬板包裹、覆蓋或穿戴起來(lái)，也許也能藉此形成一種全新的裝飾設(shè)計(jì)效果。但這些元素被應(yīng)用在既有建筑時(shí)則會(huì)產(chǎn)生種種問(wèn)題。

在法國(guó)，由于規(guī)范不僅涉及新建筑，也涉及根據(jù)新的能耗要求對(duì)舊建筑進(jìn)行改造，批判者因此描述這將會(huì)讓巴洛克宮殿、羅馬教堂、19世紀(jì)裝飾風(fēng)格的住宅街區(qū)，以及整個(gè)歷史保護(hù)區(qū)都像被包裹在茶壺套里的茶壺一樣凄慘。2007年起實(shí)施的一些規(guī)范已經(jīng)將節(jié)能要求加諸到了既有建筑之上——建筑的改造工程必須滿(mǎn)足相應(yīng)規(guī)范，進(jìn)行能耗評(píng)測(cè)，在房屋進(jìn)行買(mǎi)賣(mài)和租賃的時(shí)候都需要出示其結(jié)果。其中決定性的一步是在2015年5月出臺(tái)的法國(guó)“能源過(guò)渡法案”，這一法案經(jīng)過(guò)了重重爭(zhēng)議，目前仍在修訂中。該法案希望在2050年前實(shí)現(xiàn)減少4倍的溫室氣體排放量，并讓能源消耗量相比2012年的標(biāo)準(zhǔn)減少一半，并減少核能的使用比例（這是法國(guó)政治中的一個(gè)敏感點(diǎn)）。這些目標(biāo)也有賴(lài)于對(duì)既有建筑進(jìn)行改造，以使其符合新的建筑節(jié)能標(biāo)準(zhǔn)。這些措施都涉及了法國(guó)大量的既有建筑，外保溫問(wèn)題也因此在這個(gè)時(shí)間點(diǎn)上成為了重中之重。

但同時(shí)，“能源過(guò)渡法案”豁免了在1948年前7）使用傳統(tǒng)技術(shù)建造的建筑，以及被認(rèn)定為20世紀(jì)建筑遺產(chǎn)的建筑。法案也允許舊建筑按照“逐個(gè)元素”進(jìn)行改造。盡管如此，處于對(duì)建筑遺產(chǎn)保護(hù)和建筑多樣性問(wèn)題的關(guān)心，建筑師們?nèi)匀粚?duì)這種缺乏細(xì)致考慮的節(jié)能法案，以及為了獲得節(jié)能建筑補(bǔ)助而進(jìn)行的輕率的改造工程心懷警惕。他們尤其對(duì)其中的一條條款非常不滿(mǎn)，即讓當(dāng)局（即市長(zhǎng)）有權(quán)對(duì)城鎮(zhèn)的規(guī)劃條例進(jìn)行修改，以利于節(jié)能措施的實(shí)施。這使得即使在歷史和自然文化保護(hù)區(qū)內(nèi)，使用依據(jù)能源過(guò)渡法案確定的材料和設(shè)備將會(huì)“不能被阻止”。這些保守者的組織“法國(guó)農(nóng)民之家”（Maisons paysannes de France）在其雜志中發(fā)表了幾篇文章，其中展示了各種建筑立面被套上了外保溫材料后的可怕情景：盧瓦爾河畔19世紀(jì)裝飾風(fēng)格的教堂，在厚厚的保溫層形成的光滑、潔白的表皮的包裹下完全認(rèn)不出原來(lái)的樣子了，上索恩省的石砌的農(nóng)民住宅表面被貼上工業(yè)化的木材質(zhì)，阿爾薩斯地區(qū)的半木結(jié)構(gòu)住宅外被裹上了聚苯乙烯材料，木制窗框也被換成了厚塑料框[2]。

這些不幸的結(jié)果都源自對(duì)熱性能標(biāo)準(zhǔn)的簡(jiǎn)單化、膚淺的應(yīng)用，而忽視了根據(jù)實(shí)際情況進(jìn)行評(píng)估、以及根據(jù)歷史建筑的建造技術(shù)確定解決方案（顯然會(huì)更貴）的重要性。要解決這些問(wèn)題，就需要對(duì)建筑物的不同部分采取“區(qū)分各個(gè)元素”的態(tài)度進(jìn)行分別討論，并綜合使用高技術(shù)和低技術(shù)的不同保溫材料，例如含有麻成分的涂料，含有高科技粒子的傳統(tǒng)涂層，以及由混合石膏和石灰的空氣構(gòu)成的噴涂泡沫等。

巴黎作為一個(gè)有趣的案例，明顯地體現(xiàn)了這種建筑美學(xué)品質(zhì)和熱性能規(guī)范要求之間的矛盾。作為首都，巴黎在2007年頒布了自己的“氣候計(jì)劃”：溫室氣體排放量和建筑能耗能各自降低25%，而可再生能源的使用量增加25%。根據(jù)這些目標(biāo)，2009年，《城市規(guī)劃條例》（PLU）中部分與建筑歷史遺產(chǎn)保護(hù)相關(guān)的條文進(jìn)行了修改，以便在建筑外立面上嵌入太陽(yáng)能電池板，并允許外保溫層能向公共空間外凸20cm。由于巴黎有80%的建筑都建于1940年之前，人們開(kāi)始討論這種為了熱性能標(biāo)準(zhǔn)而進(jìn)行的改造會(huì)不會(huì)讓巴黎鮮明的建筑特色發(fā)生變化。

較為樂(lè)觀(guān)的一派認(rèn)為建于奧斯曼時(shí)期8）之前的巴黎街區(qū)，建筑立面多使用抹灰而較少進(jìn)行裝飾。因此，加設(shè)外保溫材料不會(huì)從根本上改變建筑外觀(guān)（但是在增加的立面層的影響下窗戶(hù)會(huì)看上去凹陷的更深，出檐則會(huì)變淺）。此外，這部分人認(rèn)為面向城市街道的立面通常裝飾得最繁復(fù)，但這部分墻體只占熱量損耗的20%，因此可以考慮排除沿街面，而將山墻、屋頂、面向內(nèi)院的簡(jiǎn)單抹灰墻面以及窗戶(hù)作為改造的重點(diǎn)，在不影響沿街立面的石材裝飾效果的情況下對(duì)這些建筑進(jìn)行保溫改造。

而針對(duì)這些老建筑提出改造對(duì)策無(wú)疑還是相對(duì)容易的，更難對(duì)付的是飽受詬病的“光榮的30年”期間建設(shè)的那些過(guò)于舒適、保溫性能卻不佳的建筑。這些建筑的平均年能耗量為400kWh/m2，因此成為了巴黎既有建筑中的黑天鵝。對(duì)這些建筑的改造中涉及了一種不同的審美立場(chǎng)。和德國(guó)人不甚欣賞那些在戰(zhàn)后時(shí)期建造的建筑情況類(lèi)似，法國(guó)人對(duì)于維持國(guó)家和當(dāng)局在1970年代建造的那些大型公寓街區(qū)的立面形象無(wú)甚興趣。這些建筑被認(rèn)為是平庸和丑陋的，因此改造涉及的建筑美學(xué)品質(zhì)主要是關(guān)于能帶來(lái)何種新的建筑形象，而不是如何保持其原有特色的。最近的一期德國(guó)建筑雜志《建筑細(xì)部》（Detail）上刊登了幾個(gè)較為成功的辦公樓或住宅街區(qū)的外保溫改造案例[3]。在這些案例中，加設(shè)的保溫性能優(yōu)異的玻璃外墻將建筑從完全被不透明墻體包裹的狀態(tài)中解放了出來(lái)。同時(shí)，加設(shè)的外保溫層讓墻體設(shè)計(jì)可以在厚度上大做文章：倒角窗、經(jīng)過(guò)裝飾的外表皮、不同紋理的完成面取代了原本貌似無(wú)趣的現(xiàn)代化、光潔的墻面。一般而言，在當(dāng)時(shí)不受人喜愛(ài)的建筑，其建筑美學(xué)特質(zhì)通常會(huì)在隔了幾代人之后被重新欣賞，但這些建筑沒(méi)有這種機(jī)會(huì)了：在他們的價(jià)值被發(fā)現(xiàn)之前，外觀(guān)就已經(jīng)為了增加保溫性能而變了樣。

如果說(shuō)這些戰(zhàn)后建造的建筑的能耗浪費(fèi)問(wèn)題確實(shí)無(wú)可爭(zhēng)議的話(huà)，在1948年之前建造的那些建筑則并沒(méi)有那么糟糕。不少研究都發(fā)現(xiàn)，在工業(yè)時(shí)代之前建造的本土建筑其實(shí)并不存在能源浪費(fèi)問(wèn)題9）[4]。事實(shí)上，在法國(guó)，直到RT2000要求新建建筑提高節(jié)能性能之前，新建建筑的能耗表現(xiàn)一直都不如老建筑。按照傳統(tǒng)經(jīng)驗(yàn)和知識(shí)建造的這些老建筑既然能引入空氣和水分，自然也能讓它們順利排放出去。這些建筑的朝向一般都最為符合當(dāng)?shù)氐臍夂蛱卣?，墻體則具有熱惰性，利于熱量的保存?；诿?xì)管作用的透氣性能讓水蒸汽自動(dòng)進(jìn)行調(diào)節(jié)。厚厚的石灰和麻布內(nèi)層、灰泥或泥土外層、方格窗、傳統(tǒng)掛毯等的使用都減少了墻體的熱能損耗。蘆葦席或是薄薄的空氣層則充當(dāng)了保溫層。在鋼筋混凝土出現(xiàn)之前的石砌墻體和木構(gòu)造的民居建筑中，其實(shí)都沒(méi)有出現(xiàn)過(guò)熱橋的問(wèn)題。

具有諷刺意味的是，這些發(fā)現(xiàn)都說(shuō)明許多歷史建筑需要的其實(shí)不是改造，而是去除過(guò)去的改造！后期被加到這些建筑上的現(xiàn)代元素，例如水泥砂漿抹面層、墻體防水層等都阻止了建筑原本精妙的溫度和濕度調(diào)節(jié)系統(tǒng)發(fā)揮作用，因此應(yīng)該被去除。在許多案例中，這都應(yīng)該是改善老建筑熱性能的第一步。

而對(duì)老建筑熱性能的檢驗(yàn)同時(shí)也啟發(fā)了另一種應(yīng)對(duì)節(jié)能規(guī)范的方法。這涉及對(duì)于舒適的一種完全不同的定義。在過(guò)去，對(duì)于舒適度的最低要求，以及對(duì)于低能耗的追求都基于希望能形成穩(wěn)定、均質(zhì)的室內(nèi)熱環(huán)境。但是在20世紀(jì)以前，或是在工業(yè)社會(huì)到來(lái)之前，建筑、氣候和社會(huì)行為在對(duì)熱舒適性的追求上卻是互相作用的。建筑應(yīng)對(duì)不同氣候的方法具有社會(huì)和文化上的雙重重大意義：這既表現(xiàn)在建筑的環(huán)境適應(yīng)性上，也融入到了建筑的外觀(guān)設(shè)計(jì)中。各個(gè)房間在夏季和冬季、白天和夜晚會(huì)有不同的使用方式，人們則根據(jù)熱環(huán)境的變化在一棟建筑的朝南側(cè)到朝北側(cè)、底層到頂層中不停移動(dòng)著。壁爐、陽(yáng)臺(tái)、百葉和窗簾、窗洞口和四柱床等與熱性能相關(guān)的元素同時(shí)也成為了建筑中的裝飾要素。芬蘭的桑拿浴室、羅馬和日本的浴池、伊斯蘭的園林這些建筑形態(tài)都是源自于對(duì)氣候、溫度、健康上的功能性的追求，但同時(shí)也具有重要的社會(huì)和象征意義。在這些文化中，熱舒適性都超越了原有的意義，并且因?yàn)殛P(guān)系到人們的記憶和感情而具有了心理上的價(jià)值。同時(shí)，在冷的環(huán)境中時(shí)感到溫暖，在熱的環(huán)境中感到?jīng)鏊?，在不舒適的環(huán)境中感到舒適——這種不停的變化也構(gòu)成了環(huán)境的舒適性能被人察覺(jué)和感知的要素。

莉薩·海斯莊在1979年所寫(xiě)的《建筑中的熱環(huán)境舒適性》一文剛好發(fā)表于舒適性觀(guān)念發(fā)生變革的時(shí)期。她在當(dāng)時(shí)就提出了不應(yīng)該使用機(jī)械的熱環(huán)境控制系統(tǒng)（通常能耗很高）來(lái)中和熱環(huán)境[5]，認(rèn)為現(xiàn)代社會(huì)依賴(lài)集中供暖、空調(diào)和密閉的建筑環(huán)境來(lái)維持室內(nèi)的恒定環(huán)境的做法損害了我們自身調(diào)節(jié)和感知熱環(huán)境變化的能力。通風(fēng)設(shè)備藏在了天花吊頂中，熱水管道則埋在混凝土樓板里，這些建筑設(shè)備都被隱藏了起來(lái)，使得現(xiàn)在的供暖設(shè)備大多數(shù)時(shí)候都看不見(jiàn)，而能耗似乎成了一種“抽象”的物質(zhì)。我們很少有機(jī)會(huì)與這些為了維持我們的熱舒適而存在的機(jī)械設(shè)備產(chǎn)生互動(dòng)。海斯莊強(qiáng)調(diào)相關(guān)規(guī)范已經(jīng)成為了高度自治的對(duì)象，與社會(huì)和文化系統(tǒng)毫無(wú)關(guān)聯(lián)，僅僅根據(jù)自身的邏輯來(lái)維持運(yùn)作。

那么在今天，應(yīng)該如何在迫切的節(jié)能需求下，以更符合人類(lèi)學(xué)的方式來(lái)追求熱舒適度呢？如何才能改變我們的行為，巧妙地將一個(gè)建筑中的不同環(huán)境區(qū)域用作不同功能，并且用建筑學(xué)的方式來(lái)表現(xiàn)這些不同，進(jìn)而以不那么一刀切的方法來(lái)達(dá)到節(jié)能的目的呢？建筑學(xué)領(lǐng)域的太陽(yáng)能和生物氣候運(yùn)動(dòng)都在引領(lǐng)這一新方向，并已經(jīng)出現(xiàn)了一些獨(dú)立但具有象征意義的案例，例如威爾士議會(huì)大樓（英國(guó)）和尼翁城堡歷史博物館（瑞士）的改造10）等。但這些例子目前尚屬特例，大部分歐洲的新建筑和改造工程都還沒(méi)有站在文化層面考慮熱舒適性和能耗的問(wèn)題。

最后，讓建筑的能耗變得“隱形”也可能會(huì)掩蓋一些其它的能源浪費(fèi)問(wèn)題。例如，計(jì)算機(jī)、手機(jī)、互聯(lián)網(wǎng)、照明、近來(lái)在公共場(chǎng)所越來(lái)越多見(jiàn)的視頻廣告、每個(gè)商店和機(jī)構(gòu)櫥窗里的液晶屏都在日夜不停地運(yùn)行著。因?yàn)樗究找?jiàn)慣，這些設(shè)備的能耗很少被人注意到，成為了日常生活中被忽視的問(wèn)題。而技術(shù)的“非物質(zhì)化”神話(huà)也掩蓋了數(shù)字時(shí)代的這些人工制品給環(huán)境帶來(lái)的沉重負(fù)擔(dān)。即使如此，那些支持執(zhí)行嚴(yán)苛的節(jié)能規(guī)范條文的人還是強(qiáng)調(diào)建筑占了所有能源消耗的30%。即使如此，建筑是不是就有必要犧牲其外表的美觀(guān)和個(gè)性，從而背負(fù)起節(jié)能的重責(zé)？而作為一個(gè)關(guān)心環(huán)境、但是也熱愛(ài)建筑的人，我不禁要問(wèn)：在其它的能源浪費(fèi)行為如此大行其道的情況下，建筑憑什么就沒(méi)有權(quán)利保有一定的特色和基本的美感呢？□

注釋?zhuān)?/p>

1）第一部標(biāo)準(zhǔn)為1902年頒布的《省級(jí)衛(wèi)生規(guī)范》。2）也被稱(chēng)為C.P.T.F.M. 功能技術(shù)硬性規(guī)范。

3）此為1972年出版的著作的書(shū)名。該書(shū)由羅馬俱樂(lè)部主編、Donella H. Meadows, Dennis L/ Meadows, J?rgen Randers 和Wiliiam W. Behrens III撰寫(xiě)。

4）也稱(chēng)為R.E.E.F. 建造元件與零件目錄。

5） 指?jìng)鹘y(tǒng)的主要建筑能耗內(nèi)容，包括了供暖、空調(diào)、通風(fēng)、附屬設(shè)備、熱水和照明能耗。這些建筑將被授予BBC（低能耗）標(biāo)志。

6）這些材料的市場(chǎng)占有率出自德國(guó)保溫材料行業(yè)的相關(guān)機(jī)構(gòu)：德國(guó)保溫行業(yè)協(xié)會(huì)的調(diào)查。

7）1948年是法律認(rèn)定的分界線(xiàn)，之前建設(shè)的建筑屬于“老”建筑，之后的則被認(rèn)定為現(xiàn)當(dāng)代建筑。

8）奧斯曼男爵在1853年至1870年間對(duì)巴黎進(jìn)行了大規(guī)模的城市改造，提升了巴黎市中心的建筑與公共空間的個(gè)性。

9）相關(guān)案例見(jiàn)于“法國(guó)農(nóng)民之家”的調(diào)查。

10）威爾士議會(huì)大樓 : 理查德·羅杰斯建筑事務(wù)所, 2001-2006。尼翁城堡歷史博物館 : 克里斯托弗·阿姆斯負(fù)責(zé), 1993-2006。

Little did I know, when I came into the world in the mid-1970s, in a comfortable, centrally heated apartment with an ambient room temperature of 19°C, that these very years were a turning point in the notion of comfort promoted by French housing policies and aspired to by French society. At the same time as the "modernist"’s dream of material comfort reshaped itself into one of "post-modern well-being"[1], the creed of thermal comfort gave way to that of energy efficiency.

The mid-1970s marked the end of the Trente Glorieuses in France, three decades of economic boom that began just after the Second World War and were interrupted by the petrol crisis of 1973. In particular, the Trente Glorieuses witnessed frenetic building of public apartment blocks. At the end of the 1950s, housing supported by the State constituted more than 80% of new homes, with 300,000 units built yearly, to respond to the postwar need for reconstruction, to accommodate the inflow of migrant workers and to eradicate shanty towns. Efforts to bring material comfort to families – contributing also to a process of social normalisation – were realised principally through this new social housing.

The first nation-wide regulations that sought to establish a norm for comfort were enacted in the early twentieth century.1)Criteria covered minimum size of rooms (9m2), minimum ceiling height (2.80m for the two lower floors, 2.60m for subsequent floors – a height significantly reduced since then), the proportion of openings (1/6 of room surface), a suitable orientation for sunlight to enter, and minimum sanitary equipment (water in the building accessible to all inhabitants and, for larger flats, a toilet with a sink and smooth, water-proof walls and floors). Room temperature did not yet feature in these regulations. We know however, through manuals of the same period for the education of good housewives, that recommended temperatures were 14°C for the living room, 15°C when guests visited, 11°C in bedrooms.

While water, gas and electricity became compulsory for mid-standard housing in the late 1920s, only in the 1950s did heating become part of the minimal requirements for comfort in social housing. The "minimum technical functional prescriptions"2)of 1955 stipulated a bedroom temperature in social housing of 12°C or 16°C according to two different types of central heating, but central heating was not obligatory. In 1960, new prescriptions established 18°C as the minimum legal temperature and made central heating mandatory in collective housing.

In the meantime, in 1955, the regulation of comfort in buildings had passed from the Ministry of Health to the Ministry of Construction and expanded in parallel with the latter's building activity. Legislation proliferated. The "minimal prescriptions" issued in 1958 were intended to guarantee minimal comfort to all, but the notion of comfort was not quite universal: another body of texts defined three categories, modest, middle and superior, each with its criteria. For the French population census office "comfort" meant homes equipped with a shower or bath, and "full comfort" with a shower or bath and central heating.

In 1946, a poll had shown that 88% of town dwellers dreamt of having hot water, 63% of central heating, and 59% of a bathroom. In 1968, 10% did not yet benefit from running water, 50% did not have hot water and 65% were not equipped with central heating. But the 1970s were the decisive decade for the inscription of such comfort in daily life, shown by the fact that 80% of housing units were now equipped with running water and central heating, as well as by generalised use of electric household equipment yearned for since the 1950s -electric cookers, washing machines, fridges, radios, televisions and telephones.

Simultaneously, however, the first signs of a change in perspective appeared. In France, the mid-1970s saw the end of massive construction of large-scale public apartment blocks, and new trends towards suburban individual private housing and ownership rather than rental of homes. State intervention was now directed less towards new construction and more towards the improvement of existing buildings that had often been neglected by programmes for domestic comfort, through financial incentives allocated to encourage owners to refurbish their homes.

These changes coincided with the international oil crises and realisation of the "limits to growth".3)The notion of modern comfort, theoretically at least, was challenged. It came head to head with the need to preserve the planet's resources. Though we all know that, in reality, consumption continued to accelerate, and that economic forces have a greater interest in fostering than in slowing it, there was a shift in discourse from an ideal of physical comfort for all to one of "well-being", implying a more subtle balance between physical and psychological, material and immaterial, individual and environmental factors. In the language of regulations in France, the word "quality" gradually replaced "comfort" or "liveability". Rather than the previous notion of minimal requirements, a ranking system of quality labels was instituted for both state-aided and independent housing: the Qualitel label. Its complex method of calculation included criteria such as sustainability of materials, electric installations, safety, energy consumption, acoustic protection, maintenance costs, summer thermal comfort and disposal of garbage.

In matters of thermal standards, there was a kind of turning inside-out of concerns. While attention had been bent on improving room temperature for human beings through active heating of inner space, legislation now contemplated the building in interaction with outside space, as an active agent in regulating temperature. The building envelope, more than the heating system, became the performer. The environment, more than or as much as the human being, became the beneficiary of "comfort". Though of course, there was no turning back on standards of thermal comfort, a shift had occurred towards a concern for energy performance. Significantly, the 1988 official inventory of building products4)replaced its chapter on "human requirements" by a section entitled "concept of performance in the building" .

This new emphasis on energy efficiency required a change in building and architectural culture: the Trente Glorieuses had favoured reinforced concrete, breeze blocks and aluminum windows with little regard for thermal insulation, leaving France with a large legacy of buildings in outright contradiction with new thermal requirements. In France, compared for example to Germany or Switzerland, known for their pioneering Passivhaus and Minergie standards, building culture has been slow to adapt and legislation slow to evolve. The French State had, since the late 1970s, introduced regulations and several programmes in experimental solar and other low-energy buildings, but standards became truly demanding only from 2000, and only in the last decade has the general public become conscious of the notion of energy-efficient buildings thanks to active State – but also commercial – campaigns. Today, thermal efficiency is a buzz-word, leading all at once to improvements, thoughtless or thoughtful implementation, contradictory attitudes, controversies and worries.

The RT (réglementation thermique) 1974 was the first of a series of regulations framing thermal requirements for new buildings and fixing a limit to the consumption of energy by heating, ventilation, climatization, the production of hot water and lighting. At first, only new residential buildings were concerned. The RT 1974 imposed insulation of walls and regulation of ventilation systems, while the RT 1982, after the second petrol crisis, aspired to reduce needs for heating by using solar energy. Their provisions were extended to new non-residential buildings in the RT 1988, which also introduced calculations based not on energy loss but on consumption, thus coining a notion of performance of the buildings. Compared to the 1988 standards, the RT 2000 reduced maximum consumption of new residential buildings by 20% and by 40% for buildings of the tertiary sector. Only five years later, RT 2005 stipulated a further improvement by 15% of the RT 2000 requirements.

The regulation currently applied is RT 2012. It returns to the strategy of limiting consumption of heating, lighting and cooling, aims to reduce the emission of greenhouse gases, encourages the development of new technologies and covers a large range of public, private and commercial buildings including universities, shops, airports and hospitals.For new housing, it sets the standard of a maximum consumption of 50 kWh/m2.year, with variations according to regions (for comparison, the standard in 1960 was a consumption of 250 kWh/m2·year and in 1970, 100-150).5)RT 2012 also instituted the submission of an energy performance certificate when asking for a building permit. In 2020, a new RT should require all new buildings to have a positive energy balance (production exceeding consumption) and will take into account the grey energy of insulation products.

As well as encouraging more efficient heating and cooling systems, double-glazing and suitable exposition to the sun, recent thermal legislation has led to a watchword: insulate! In the 1970s, to correct building faults and the excessive conductivity of fa?ades, insulation was stuck on the inner side of walls. Today, exterior insulation – a continuous insulation covering the entire facade – is promoted as being twice more efficient for an equivalent thickness of insulating material, a palliative to thermal bridges and a solution that does not reduce the surfaces of living spaces. This apparently angelic measure, however, is meeting strong criticism from environmentalists, conservationists and architects, but also the broader public. One criticism addresses the environmental and technical viability of insulation materials. Another alerts to the risk of disfiguring historical buildings and reducing the variety of architectural expressions.

External insulation inverses the relation between soft and hard in a building's envelope. In Germany, whose vernacular tradition is largely one of plastered buildings, exterior insulation did not come as a cultural shock as much as it did in France, where architecture of the Classical and Neoclassical traditions tends to express its nobility in visible stone construction or finishings and modern architecture its progressiveness in raw concrete.

Germany is the European champion of thermal insulation. The Putz (plastering) of German housing is being replaced by millions of cubic meters of W?rmed?mm-Verbundsysteme (an integrated composite system for external insulation including a water-resistive barrier, insulation board, reinforcing mesh, water-resistant base coat and finish coat). Across the country, exterior insulation is massively implemented on new buildings but also on the large legacy of little-loved post-war housing. A coated non-ornamented surface for a coated nonornamented surface: none but the enlightened lover of post-war buildings sees the difference in texture, fa?ade depth or detail like a thin imprinted line around a window. The phenomenon started a full generation ago, but accelerated with Germany's ambitious 2010 energy policy, aiming to reach a climate-neutral building stock (old and new) in 2050 and to double the proportion of buildings submitted yearly to energetic refurbishment.

Wahnsinn W?rmed?mmung ("The folly of thermal insulation"), two TV documentary films shown in 2011 and 2012, gave the trend a bashing.The programmes inquired into the extensive use of polysterene and other oil-based products as external insulation. They showed the insulation systems to be dangerously inflammable, despite their certification as safe building products, conducive to fires that release toxic gases and swiftly inflame the entire facade. They showed them to be unrecyclable and short-lived, to shelter animals and to cause rot under their surface when water vapour from condensation is not properly released, often because of faulty mounting. They also revealed the extent of soil and river pollution provoked by pesticides contained in the paint that coats the insulation, washed out by rain. They pointed at the absurdity of over-insulated homes requiring ventilation to let air back in, through slits in windows or via mechanical systems that consume energy.

The programmes also raised the question of the financial interests of companies producing these insulating materials (a market of 1.8 billion euros in Germany). Do they not encourage stringent thermal norms in order to incite owners of houses to wrap up their buildings or buy ventilation devices? In 2005, 24.5 million cubic meters of insulating materials had been used in German buildings (all surfaces, inner and outer, walls and roofs). Then, as today, about 41% were polystyrene – expanded or extruded –and polyurethane, 54% were mineral wools6), but even these less polluting materials contain additives and solvents. More natural organic materials like cork or hemp or sheep's wool are more expensive, and thus seldom used. Despite the claim that the thermal energy saved over a period of 20 or 30 years thanks to external insulation is superior to the energy required for the acquisition of raw materials, production and processing of its synthetic materials, this grey energy cannot be ignored. Neither can the toxic substances released in their production. Added to the equation is the environmental impact of removing old windows and introducing new plastic-framed double glazing. The question of what materials will make sense of efforts to reduce energy consumption of buildings is thus vital, but is not included in regulations or in the attribution of aid to low-energy housing.

A second critique of systematic resort to external insulation is an architectural one. For new buildings, there is scope to invent a new architectural language based on the technologies, materials, and construction logic created by the new regulations – a language composed of soft envelopes, cladded, coated or dressed, with multiple layers, with thickness and the relative depths of material planes, perhaps leading to a novel design of ornament. However, adapting existing buildings poses problems.

In France, as regulations begin to encompass not only new buildings but the refurbishment of older ones according to current energy requirements, critics depict apocalyptic visions of Baroque palaces, Romanesque churches, nineteenth century ornamented housing blocks, entire historic town centres clad in tea cosies! Since 2007, a number of decrees have extended thermal legislation to existing buildings. Buildings undergoing refurbishment must meet the norms, and a diagnosis of energetic performance must be presented whenever a house is sold or rented. The decisive step however will be the enactment of the French "law on energy transition", that was adopted in May 2015 and is currently under revision, after much controversy. Besides aiming at a fourfold reduction of the emission of greenhouse gases by 2050, halving energy consumption compared to 2012 standards, and reducing the proportion of nuclear energy (a sore point in French politics), itimposes the refurbishment of existing buildings to the standards of low energy buildings. These measures concern an enormous proportion of the French building stock. Exterior insulation is therefore a burning issue at this very moment.

The law on energy transition provides for exemptions such as listed buildings, buildings built before 19487), buildings constructed with traditional techniques and buildings labelled as 20th century heritage. It also allows for a treatment of older buildings "element by element". Nevertheless, architects concerned with architectural heritage and diversity are wary of insensitive interpretations of thermal regulations or thoughtless refurbishment stimulated by the wish to tap public aid towards low-energy buildings. In particular, they are worried by an article of the law that allows authorities delivering building permits (namely mayors) to waive town planning rules in favour of energysaving measures. Even in preserved historic or natural areas, it will be "forbidden to forbid" materials or devices that allegedly forward the energetic transition. The conservationist group Maisons paysannes de France has circulated several articles in its magazine showing nightmare cases of exterior insulation covered with diverse materials : an ornamented nineteenth century church in the Loire unrecognisable under a thick layer of insulation with smooth white rendering, a stone farmhouse of the Haute Sa?ne clad with industrial wood, half-timbered houses in the Alsace region covered in polystyrene, their wood-frame windows replaced by thick plastic frames.[2]

These mishaps are obvious results of simplistic, blanket application of thermal standards, ignorant of the importance of case by case diagnosis or of (admittedly more expensive) solutions adapted to the construction techniques of historic buildings.These alternatives include the "element by element" attitude of multiple interventions on different parts of the building or current developments in low-tech and high-tech insulating materials such as coatings containing hemp, traditional coatings with hightech particles, or the projection of foams composed essentially of air, covered by plaster and lime.

Paris is an interesting case of the apparent conflict between architectural quality and thermal regulation. The capital city enacted its own "climate plan" in 2007, aiming to reduce both greenhouse gases and energy consumption by 25% and to use 25% more renewable energies. In accordance with these objectives, certain rules of the 2009 planning regulations (PLU) that contributed to preserving historical heritage were changed, in order to allow solar panels to be fixed to fa?ades or for external insulation to stick out by 20 cm into public spaces. 80% of Parisian buildings date from before 1940. Will refurbishment to meet requirements in thermal performance transform the strong architectural identity of Paris ?

The more optimistic parties argue that most Parisian housing blocks built before Haussmann8)were coated with plaster and had few ornaments. Applying external insulation will therefore not radically modify their aspect (but won't windows be sunken deep and cornices drown in the additional layering?). Besides, argue these parties, fa?ades on the street side, those that are usually most elaborate, represent only 20% of thermal losses, and so need not be treated. Gable ends, roofs, simple plastered fa?ades on the courtyards and windows carry most of the responsibility and can be insulated without affecting the ornamented stone fa?ades along the street.

No doubt will it be easier to defend the specific care needed for older buildings than the decried buildings of the Trente Glorieuses, that bear the stigma of good comfort and bad performance. With an average consumption of 400kWh/m2·year, they are the black swans of the French building stock. The aesthetic question of their refurbishment is posed in different terms. Little interest is seen in preserving the original aspect of large apartment blocks built by the State or 1970s offices, as is the case in Germany for under-appreciated post-war architecture. They are generally considered to be banal and ugly. The architectural quality of their refurbishment is judged not according to whether it respects their original characteristics but in terms of the new architectural status it confers. A recent issue of the German architectural magazine Detail shows examples that it deems successful of thermal refurbishment of office buildings or housing blocks.[3]In these examples, thermally efficient glass liberates buildings of their opaque walls ; external insulation offers the possibility to play with its thickness: chamfered window openings, ornament in the coating, finishings with different textures replace the supposed drabness of smooth modernist walls. These buildings, however, will never benefit from the distance of a generation needed to appreciate the architectural qualities of unloved buildings: they will have been thermally redeemed before they are architecturally recognized!

If nothing can save these post-war buildings from the accusation of thermal wastefulness, pre-1948 buildings can more easily be discharged. A number of studies have raised awareness that preindustrial vernacular buildings are not wasteful of energy.9)[4]Indeed, in France, until the performance of new constructions improved following the RT 2000, new buildings performed less well than older ones. If houses built according to traditional empirical knowledge let in air and humidity, they are also able to let them out. Their orientation is most often climatically sensible. The thermal inertia of their walls stocks and restitutes warmth. Their permeability, through micro-capilarity, allows self-regulation of the movement of water vapour. Thick lime and hemp, plaster or earth renderings, panelling, or tapestries traditionally reduce the effect of cold walls. Reed sheeting or thin blades of air play the role of insulators. Dreaded thermal bridges do not occur in the masonry walls or wooden structures of residential buildings predating reinforced concrete.

Ironically, rather than their refurbishment, these conclusions call for the de-refurbishment of many historic buildings! Modern additions to these buildings, such as cement renderings or waterproofing of walls that prevent them from functioning according to their subtle thermal and hygrometric logic, should be removed. In many cases, this would be the first step towards improvement of the thermal performance of older buildings.

But examining the thermal performance of older buildings suggests yet another response to thermal regulation. This amounts to a very different notion of comfort. Both the effort to establish minimal comfort standards and the objective of low energy consumption are approaches that suppose stable, homogeneous thermal environments. Yet before the twentieth century, or in pre-industrial societies, architecture, climate and social behaviour interacted in a quest for thermal comfort. Adapting to different climatic situations within a house took on a ritualised social and cultural meaning, that made environmental sense and was translated expressively in building design. Rooms were used differently in summer and winter, daytime and evening, with migrations from the southern to the northern side, from the bottom to the top of the same house, according to thermal conditions. The hearth fire, the loggia, shutters and blinds, window openings and four-poster beds, are all elements of thermal regulation that became elaborate architectural elements. The Finnish sauna, Roman and Japanese baths, the Islamic garden are amongst architectural typologies that arose from functional needs linked to climate, temperature and health and had a central social role and symbolic status. Thermal comfort, in these contexts, is as much psychologicial, and linked to memory or affection, than absolute. Its variability is part of what makes it perceptible and therefore appreciable: warmth when it is cold, coolness when it is hot, comfort after discomfort.

In her essay "Thermal delight in Architecture", Lisa Heschong had, in 1979, just at the time of the change of paradigm, already sounded the alarm against thermal systems using (often high-energyconsuming) mechanical methods to neutralise the thermal environment[5]. She argued that the modern emphasis on central heating systems, air conditioning and hermetically sealed buildings to reach constant indoor conditions has actually impaired our strategies for adapting to and sensing thermal variations. Ventilators in false ceilings and hot water pipes in concrete slabs conceal thermal mechanisms: today, heat production is largely invisible and energy is an "abstraction". The machines destined to maintain our thermal comfort are mechanical servants with which we rarely interact. The norm, stresses Heschong, has become a largely autonomous object, isolated from social and cultural systems and operating according to its own logic.

Today, how could an anthropological approach to thermal comfort contribute to the urgent necessity of reducing energy consumption? How could adapting our behaviour, using different climatic zones within a same building for different functions and expressing these architecturally, condition a less standardised approach to reaching global energy performance ? The solar or bioclimatic movement in architecture has worked in this direction, as have isolated emblematic examples of public architecture like the Welsh Assembly (Great Britain) or the refurbished Nyon Castle Historical Museum (Switzerland).10)But these are exceptions, and most new buildings or refurbishment projects in Europe are not designed with a cultural understanding of thermal comfort and performance.

Finally, the problem with the "invisibility" of energy consumption is that it eclipses other forms of wasteful consumption. Computers, cell-phones, the internet, lighting, the recent proliferation of video advertising in public space, plasma screens in every shop window or institution are left permanently running. Little is done to raise awareness of the energy guzzling of these devices that very quickly become normal and therefore unnoticed elements of our daily environment. The myth of the "dematerialisation" of technology conceals the heavy environmental impact of artefacts of the digital age. Even though supporters of stringent regulations emphasize that buildings are accountable for 30% of energy consumption, should buildings bear the brunt of this responsibility to the extent of sacrificing their architectural expression or identity? As someone both concerned with the environment and a lover of architecture, I ask : Why violate buildings of exceptional or even modest architectural quality when other wasteful practices remain unbridled ? □

Reference:

[1] Sèze, Claudette. Confort moderne. Une nouvelle culture du bien-être, Paris, éditionsAutrement, 1994.

[2] Maisons paysannes de France, nr. 195, March 2015: 38-39.

[3] Schoof, Jakob. "Klimarettung oder Kulturst?rung. Energische Sanierung am Scheideweg", Detail Green 01/2015: 22-30.

[4] Fredet, Jacques "Les enseignements hygrothermiques des batiments d'habitation préindustriels", in d'A nr 207, April 2012: 48-51.

[5] Heschong, Lisa. Thermal delight in architecture, MIT Press, 1979.

Note:

1) The first being the 1902 réglement sanitaire départemental.

2) The C.P.T.F.M. (Cahier des prescriptions techniques fonctionnelles minimales).

3) This was the title of a 1972 book commissioned by the Club of Rome and written by Donella H. Meadows, Dennis L/ Meadows, J?rgen Randers and Wiliiam W. Behrens III.

4) The R.E.E.F. (répertoire des éléments et ensembles fabriqués).

5) Taken into account is the consumption of socalled conventional primary energy : heating, cooling, ventilation, auxiliaries, production of domestic hot water and lighting facilities. Such buildings are assigned the BBC (low-energy) label.

6) Figures for market shares of the materials : Gesamtverband D?mmstoffindustrie–German umbrella organisation for the insulating materials industry.

7) 1948 is the date before which legislation considers architecture to be "old" and after which it considers buldings to be modern or recent.

8) The baron Haussmann undertook a vast urban renovation of the city of Paris between 1853 and 1870 and gave rise to the distinct aspect of the architecture and public spaces of the centre of Paris.

9) See for example the studies produced by Maisons paysannes de France.

10) Welsh National Assembly : Richard Rogers Architects, 2001-2006. Nyon Castle Historical Museum: refurbished by Christophe Amsler, 1993-2006.

Thermally Correct? – Sliding Parameters in the French and German Contexts

In the 1970s, in France as in other European countries, the concern for thermal comfort in terms of optimal temperature gave way to a notion of energetic performance of buildings. Legislation on energy consumption of buildings has become more stringent in the last decade and now encompasses not only new but historical buildings. Criticism is arising of the massive use of polluting insulating materials and of the risk of disfiguring old buildings and reducing the variety of architectural expressions. Can an improvement of the thermal performance be made compatible with the preservation of architectural diversity and quality? Does the focus on the energy consumption of buildings conceal other wasteful practices?

thermal comfort, low-energy buildings, external thermal insulation, France, Germany, architectural variety

巴黎－馬拉蓋國(guó)立高等建筑設(shè)計(jì)學(xué)院

2015-06-19