多用木材，可能更環(huán)保！

The second little pig was unlucky. He built his house from sticks. It was blown away by a huffing, puffing wolf, which promptly gobbled him up. His brother, by contrast, built a wolf-proof house from bricks. The fairy tale could have been written by a flack for the construction industry, which strongly favours brick, concrete and steel. However, in the real world it would help reduce pollution and slow global warming if more builders copied the wood-loving second pig.

第二只小豬真倒霉。他用木板蓋了棟房子，結(jié)果一只狼猛吹一通，就給吹倒了，他自己隨后也被狼吞下了肚。而他的兄弟用磚蓋了間房，防住了狼。這則童話的作者可能是個建筑行業(yè)的宣傳員，這個行業(yè)十分偏愛磚、混凝土和鋼材這些建材。然而在現(xiàn)實世界中，如果有更多建筑公司效仿愛用木材的那只小豬，將有助于降低污染、減緩全球變暖。

In 2015 world leaders meeting in Paris agreed to move towards zero net greenhouse-gas emissions in the second half of this century. That is a tall order, and the building industry makes it even taller. Cement-making alone produces 6% of the world’s carbon emissions. Steel, half of which goes into buildings, accounts for another 8%. If you factor in all of the energy that goes into lighting, heating and cooling homes and offices, the world’s buildings start to look like a giant environmental problem.

各國領(lǐng)導人在2015 年齊聚巴黎，一致同意爭取到本世紀下半葉實現(xiàn)溫室氣體凈零排放。這絕非易事，而建筑業(yè)更讓這件事難上加難。僅水泥生產(chǎn)就占了全球碳排放的6%。一半用在了建筑業(yè)的鋼材的占比為8%。如果再算上用于家庭和辦公照明、采暖和制冷的能源，全世界的建筑就開始顯現(xiàn)為一個巨大的環(huán)境問題了。

Governments in the rich world are now trying to promote greener behaviour by obliging developers to build new projects to “zero carbon” standards. From January 1st 2019 all new public-sector buildings in the European Union must be built to “nearly zero-energy” standards. All other types of buildings will follow in January 2021. Governments in eight further countries are being lobbied to introduce a similar policy.

如今富裕國家的政府正嘗試推行更綠色的生產(chǎn)生活方式，要求開發(fā)商按照“零碳”標準建設(shè)新項目。自今年1 月1 日起，歐盟所有新建公共建筑必須達到“近零能耗”標準。到2021 年1 月，其他所有類型的建筑物都將遵循這一標準。在另外八個國家，人們正在游說政府推出類似的政策。

These standards are less green than they seem. Wind turbines and solar panels on top of buildings look good but are much less productive than wind and solar farms. And the standards only count the emissions from running a building, not those belched out when it was made. Those are thought to account for between 30% and 60% of the total over a structure’s lifetime.

這些標準并沒有表面看上去那么綠色。安裝在屋頂上的風輪機和太陽能電池板看著不錯，但效率遠不及風電場和太陽能電場。而且這些標準針對的只是建筑在使用過程中產(chǎn)生的排放，而并不涉及建設(shè)過程產(chǎn)生的排放。而一般認為，在一棟建筑整個生命周期的總排放量中，這部分排放占到了30%到60%。

Buildings can become greener. They can use more recycled steel and can be prefabricated in off-site factories, greatly reducing lorry journeys. But no other building material has environmental credentials as exciting and overlooked as wood.

建筑可以變得更綠色。它們可以增加再生鋼材的使用，還可以在工地外的工廠中預制組件，大大減少對貨運的需求。但各種建筑材料中，具有最讓人興奮的環(huán)保特性卻也最受忽視的還是木材。

The energy required to produce a laminated wooden beam is one-sixth of that required for a steel one of comparable strength. As trees take carbon out of the atmosphere when growing, wooden buildings contribute to negative emissions by storing the stuff. When a mature tree is cut down, a new one can be planted to replace it, capturing more carbon. After buildings are demolished, old beams and panels are easy to recycle into new structures. And for retrofitting older buildings to be more energy efficient, wood is a good insulator. A softwood window frame provides nearly 400 times as much insulation as a plain steel one of the same thickness and over a thousand times as much as an aluminium equivalent.

生產(chǎn)一個層壓木梁和一個強度相近的鋼梁，前者消耗的能源是后者的六分之一。由于樹木在生長過程中會從大氣中吸收碳，木構(gòu)建筑也就能通過儲存碳來幫助實現(xiàn)負排放。每砍伐一棵成材的樹，就可以再補種一棵，繼續(xù)捕集更多碳。舊建筑被拆除后，木梁和木板也很容易回收，用來建造新建筑。而如果想翻新舊建筑，讓它們更節(jié)能，木材也是種很好的隔熱材料。軟木窗框的隔熱效果幾乎是相同厚度的碳鋼窗框的400 倍，是相同厚度鋁制窗框的1000 多倍。

Carpentry alone will not bring the environmental cost of the world’s buildings into line. But using wood can do much more than is appreciated. The second little pig was not wrong, just before his time.

單靠木工行業(yè)并不能將全世界建筑帶來的環(huán)境成本降至符合需要。但使用木材能帶來的好處遠超出人們已認識到的程度。第二只小豬并沒有錯，只是超前了。