多用木材，可能更环保！

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.

第二只小猪真倒霉。他用木板盖了栋房子，结果一只狼猛吹一通，就给吹倒了，他自己随后也被狼吞下了肚。而他的兄弟用砖盖了间房，防住了狼。这则童话的作者可能是个建筑行业的宣传员，这个行业十分偏爱砖、混凝土和钢材这些建材。然而在现实世界中，如果有更多建筑公司效仿爱用木材的那只小猪，将有助于降低污染、减缓全球变暖。

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.

各国领导人在2015 年齐聚巴黎，一致同意争取到本世纪下半叶实现温室气体净零排放。这绝非易事，而建筑业更让这件事难上加难。仅水泥生产就占了全球碳排放的6%。一半用在了建筑业的钢材的占比为8%。如果再算上用于家庭和办公照明、采暖和制冷的能源，全世界的建筑就开始显现为一个巨大的环境问题了。

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.

如今富裕国家的政府正尝试推行更绿色的生产生活方式，要求开发商按照“零碳”标准建设新项目。自今年1 月1 日起，欧盟所有新建公共建筑必须达到“近零能耗”标准。到2021 年1 月，其他所有类型的建筑物都将遵循这一标准。在另外八个国家，人们正在游说政府推出类似的政策。

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.

这些标准并没有表面看上去那么绿色。安装在屋顶上的风轮机和太阳能电池板看着不错，但效率远不及风电场和太阳能电场。而且这些标准针对的只是建筑在使用过程中产生的排放，而并不涉及建设过程产生的排放。而一般认为，在一栋建筑整个生命周期的总排放量中，这部分排放占到了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.

建筑可以变得更绿色。它们可以增加再生钢材的使用，还可以在工地外的工厂中预制组件，大大减少对货运的需求。但各种建筑材料中，具有最让人兴奋的环保特性却也最受忽视的还是木材。

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.

生产一个层压木梁和一个强度相近的钢梁，前者消耗的能源是后者的六分之一。由于树木在生长过程中会从大气中吸收碳，木构建筑也就能通过储存碳来帮助实现负排放。每砍伐一棵成材的树，就可以再补种一棵，继续捕集更多碳。旧建筑被拆除后，木梁和木板也很容易回收，用来建造新建筑。而如果想翻新旧建筑，让它们更节能，木材也是种很好的隔热材料。软木窗框的隔热效果几乎是相同厚度的碳钢窗框的400 倍，是相同厚度铝制窗框的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.

单靠木工行业并不能将全世界建筑带来的环境成本降至符合需要。但使用木材能带来的好处远超出人们已认识到的程度。第二只小猪并没有错，只是超前了。