Date | 2021.02.17
Weather | Sunny | Afternoon
靜讀工作室
Sustainable construction
Urban growth
The AAAS hears about cities made of wooden buildings
AAAS - American Association for the Advancement of Science
More than half the world’s population dwell in cities, and by 2050 the UN expects that proportion to reach 68%. This means more homes, roads and other infrastructure. In India alone, the equivalent of a city the size of Chicago will have to be developed every year to meet demand for housing. Such a construction boom does, though, bode ill for tackling climate change, because making steel and concrete, two of the most common building materials, generates around 8% of the world’s anthropogenic carbon-dioxide emissions. If cities are to expand and become greener at the same time, they will have to be made from something else.
世界上超過一半人口居住在城市中，UN專家預計到2050年這個比例會到達68%。這意味著需要更多的家室，道路和其他基礎設施。僅拿印度來說，為滿足住房需求，每年需要建設一個和Chicago差不多大的城市。這種建築業的繁榮卻預示著糟糕的氣候變化。因為製造鋼鐵和混泥土，這兩種最常見的建築材料，產生的二氧化碳排放量佔全球二氧化碳人為排放量的8%。如果城市想同時擴張並且有綠色的環境，不得不換一種建築材料。
the equivalent of a city | the size of Chicago | will have to be developed every year | to meet demand for housing.
anthropogenic - 人為的；
As it happens, Chicago might become part of the answer. In recent years, as architects have become increasingly interested in modern timber-construction methods, wooden buildings have been getting steadily taller. The current record is held by the 85-metre-tall Mjostarnet building in Norway (see picture), completed in 2019. But this would be dwarfed by the River Beech Tower, a 228-metre edifice proposed for a site beside the Chicago river.
正在嘗試另一種建造材料的芝加哥可能有一部分解決方案。近年來，建築設計師逐漸對現代木材建築產生了興趣。木製建築的高度正逐步攀升。目前最高的紀錄是Norway的Mojostarnet，高達85米，於2019年完成。但其與將位於Chicago河畔建造的228米高的大廈River Beech Tower相比還十分矮小。
timber - 木材；dwarfed - 矮；edifice - 大廈；
As the AAAS meeting heard this week, wood is one of the most promising sustainable alternatives to steel and concrete. It is not, however, everyday lumber, chipboard or plywood that is attracting the interest of architects. Rather, it is a material called engineered timber. This is a composite of different layers, each designed to meet the requirements of specific components such as floors, panels, cross-braces and beams. Besides engineering the shape of a component, designers can align the grains in the layers to provide levels of strength that rival steel, in a product that is up to 80% lighter. Engineered timber is, moreover, usually prefabricated into large sections of a building in a factory. That cuts down on the number of deliveries that have to be made to a construction site.
本周在AAAS會議上，可用於替換鋼鐵和混泥土的可持續材料中，木材成為最值得肯定的選擇。然而，並不是日常的木材、刨花板或膠合板引起了架構師的興趣。而是一種名為工程木材的材料。這種木材由多個層次構成，每一層的設計都為了滿足特定的成分要求，比如，地板，面板，橫撐杆和梁。除了設計每一成分的形狀，設計師還可以根據不同強度要求設計每一層的顆粒度，使得該材料可以達到鋼材的強度，但比鋼材輕80%。此外，工程木材還可以在工廠中提前加工成建築所需的大件材料。這會減少往返建築工地的託運次數。
lumber, chipboard or plywood - 木材、刨花板或膠合板；cross-braces and beams - 跨杆，橫梁；grains - 顆粒；
All this makes a big difference to carbon-dioxide emissions. Michael Ramage of the University of Cambridge told the meeting of a 300-square-metre four-storey wooden building constructed in that city. Erecting this generated 126 tonnes of CO2. Had it been made with concrete the tally would have risen to 310 tonnes. If steel had been used, emissions would have topped 498 tonnes. Indeed, from one point of view, this building might actually be viewed as 「carbon negative」. When trees grow they lock carbon up in their wood—in this case the equivalent of 540 tonnes of CO2. Preserved in Cambridge rather than recycled by beetles, fungi and bacteria, that carbon represents a long-term subtraction of CO2 from the atmosphere.
這些舉措對二氧化碳的排放有著很大影響。劍橋大學的Michael Ramage在會上以劍橋一棟4層300平方米的木製建築為例。該建築建成產生了126噸二氧化碳。而如果使用混泥土材料，這個數字將上升至310噸。如果使用鋼鐵，排放量將增至498噸。的確，從某種角度來看，這座建築實際上可以被視為「負碳建築」。當樹木增長時，可以吸收二氧化碳，在這個例子中，該建築已經吸收540噸二氧化碳在其體內。這些碳保存在劍橋，而非被甲蟲，真菌以及微生物循環利用，這意味著大氣中的二氧化碳量將長期得到減少。
Had it been made with concrete the tally would have risen to 310 tonnes. Had引導虛擬語氣。
beetles - 甲蟲，木槌；
If building with wood takes off, it does raise concern about there being enough trees to go round. But with sustainably managed forests that should not be a problem, says Dr Ramage. A family-sized apartment requires about 30 cubic metres of timber, and he estimates Europe’s sustainable forests alone grow that amount every seven seconds. Nor is fire a risk, for engineered timber does not burn easily. According to a report by the Potsdam Institute for Climate Impact Research, in Germany, large structural timbers are fire resistant because their inner cores are protected by a charring layer if burnt. It is therefore hard for a fire to destroy them. And, for extra incombustibility, fireproofing layers can be added to the timber. All in all, then, it looks as if wood as a building material may get a new lease of life.
Ramage博士認為，如果木材建築流行起來，是否還有足夠的樹來運轉可能會成為問題。但如果可持續地利用和管理森林，這應該不是一個問題。一個家庭大小的公寓需要30立方米的木材，僅歐洲的可持續森林每7秒就可以產生這麼多木材。也不存在火災風險，工程木材並不容易燃燒。根據波茨坦氣候影響研究所，德國大型建築木材都是防火的，因為木材內部核心受一層碳化層保護。這使得木材很難被火破壞。此外還可以再在木材之外加上防火層以達到極度不燃性。總而言之，用於建築材料的木材看起來獲得了新生。
charring - 碳化；incombustibility - 不燃性；
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