Space will be at a premium.

居住空間將供不應求。

High-rise offers a solution, but concrete and steel, the materials we currently use to build high, have a large carbon footprint.

高樓是解決方針，但我們目前用來建造高樓的鋼筋水泥卻有很大的碳足跡。

An answer might lie in a natural material we've used for millennia.

這個問題的解決方法可能是一個人類使用了數千年的天然素材。

Our view is that all buildings should be made of timber.

我們的觀點是所有的建築都應以木材建造。

We think that we should be looking at concrete and steel like we look at petrol and diesel.

我們認為我們看待鋼筋水泥的態度應該跟看待石化燃料的態度相同。

I think it's very realistic to think that someone will build a wooden skyscraper in the coming years.

我認為，在不久的將來有人會用木材蓋高樓大廈這樣的想法並非不切實際。

There's a lot of potential that's unrealized for using timber at a very large scale.

木材的大規模使用還有很多尚未發掘的潛力。

Throughout history, buildings have been made of wood.

綜觀歷史，木材一直以來都是建材。

But it has one major drawback: It acts as kindling.

但它有一個很大的缺點：它會著火。

Fire has destroyed large swathes of some of the world's great cities.

火災在過去波及了許多大城市。

But by the early twentieth century, the era of modern steelmaking had arrived.

然而，到了二十世紀初，現代鋼鐵製造技術出現了。

Steel was strong; could be molded into any shape and used to reinforce concrete.

鋼鐵非常堅韌，可以被塑造成任何形狀、強化水泥。

It allowed architects to build higher than ever before.

鋼鐵讓建築師可以突破以往建築的高度。

So, why, after more than a century of concrete and steel, are some architects proposing a return to wood?

既然如此，為什麼在使用了鋼筋水泥超過了一世紀，有些建築師卻主張回歸木材的懷抱呢？

If concrete were to arrive as a new material on "Dragon's Den",

如果水泥是以新研發材料出現在《龍穴》這個電視節目上，

if you were to pitch it and then say, "I've got this brand-new material; it's liquid, and you can pour it into any shape and it'll solidify."

如果你想要提案，並說：「我手上有這個新發名的材料，它是液態的，可以灌進任何形狀的模板中固化。」

That sounds great.

這聽起來很棒。

But then, when you say, "We need a whole new fleet of trucks to move it around."

可是如果你接著說：「可是我們需要一整隊新型的卡車作為運輸工具。」

"And actually, when it solidifies, it's not strong enough; we have to stick this other stuff in it, called steel."

「而且，事實上，它固化之後其實沒那麼堅固，我們還需要插入這個叫做鋼鐵的東西。」

I don't think it would be a compelling case.

我不認為這樣的一個方案有什麼說服力。

Concrete and steel are costly to produce and heavy to transport.

水泥和鋼鐵的生產成本很高，而且很重，不容易運輸。

Wood, however, can be grown sustainably, and it's lighter than concrete.

但是木材卻得以永續種植，而且比水泥輕。

And crucially, as trees grow, they absorb carbon dioxide from the air, locking it into the timber.

很重要的是，樹木在生長時會吸收空氣中的二氧化碳，把碳儲存於枝幹中。

One study showed that using wood to construct a 125-meter skyscraper could reduce the building's carbon footprint by up to 75%.

有份研究顯示，使用木材建造一棟 125 公尺的高樓能減少該建築高達 75% 的碳足跡。

Regular timber isn't malleable like steel or concrete, and it isn't strong enough to build high.

一般木材不如鋼筋水泥般能任意形塑，也不如鋼筋水泥強韌，無法蓋很高。

But engineers have come up with a solution: It's called cross-laminated timber, or CLT, for short.

但是工程師找到了解決方法：這叫做交錯層壓木材，簡稱 CLT。

It's basically a new material, even though the underlying material is something we've used for millennia.

這基本上是一種新材料，即使其組成素材已經被人類使用了數千年。

It's cross-laminated, so the layers of wood are glued at 90 degrees to each other.

它是多層木材以直角堆疊、黏合形成的。

And that makes for a very, very stable material.

這使它非常、非常地堅韌。

CLT is light, and it's comparable in strength to concrete and steel, but how does it cope when burnt with a high heat source?

CLT 很輕，而且堅韌度和鋼筋水泥相當，但是遇到高溫怎麼辦呢？

Charred wood is extremely insulating ; that's the tree's natural protection against a forest fire.

燒焦的木材其實十分絕緣：那是樹木遇到森林大火時的自然保護機制。

It chars, it loses some of its structural mass, but when you remove the source of flame, it extinguishes itself.

木材燒焦時會損失一些質量，可是拿掉了火源後，它會自動熄火。

When steel gets hot, it gets a bit softer.

鋼鐵遇熱時會變軟。

We've actually seen some steel roofs collapse in fires where wooden roofs have not.

其實我們曾經看過火災後，鋼質屋頂坍塌，可是木製屋頂卻沒有。

London architects Waugh Thistleton are already designing buildings with this new kind of timber.

位於倫敦的建築事務所 Waugh Thistleton 已經開始用這個新木材設計建築。

There's a CLT building behind, where the timber building sits behind timber clad, and then there's a really simple galvanized steel walkway.

這裡後方有個 CLT 建築，全由木材建造，然後這邊是一個很簡當的，經過鍍鋅防鏽處理的走道。

Cross-laminated timber is a material we work with a lot.

我們常使用 CLT 這個材料。

Once these panels arrive on site, we're building, you know, a floor a week, at least.

當這些木板運送到工地現場後，每個星期至少可以蓋好一層樓。

So, this is incredibly fast; this is maybe twice as fast as concrete.

這十分迅速，可能比用水泥快上兩倍。

Because when you build a concrete building⏤what we call concrete buildings are actually floor slabs and columns.

因為一棟水泥大樓——也就是我們說的水泥構造，其實是由地板和樑柱組成的。

When we build a cross-laminated timber building, it's building floor slabs, all the external walls, all the internal walls, the lift cores, the stairs, the stair cores⏤

可是，當我們建造一個 CLT 構造時，所有的元素，包含地板、所有的內、外牆、升降機槽、樓梯、樓梯間等，

everything is made of timber, so these are like honeycomb structures.

一切都會由木材所見，整個建築會像是個蜂巢式的結構。

Andrew and his colleagues designed Britain's first high-rise wooden apartment block, and have recently completed the world's largest timber-based building.

Andrew 和他的同事們設計了英國第一批木製公寓大樓，最近也完成了全世界最高的木製大樓。

Behind these bricks is a timber core made from more than 2,000 trees, sourced from sustainable forests.

這些磚頭後面是木材基底，從超過 2 千棵永續森林的樹木而來。

And this London practice is not alone in advocating the use of CLT.

而這家位於倫敦的建築事務所不是唯一倡議使用 CLT 的公司。

Ambitious wooden high-rise buildings are also being constructed in Scandinavia, central Europe, and North America.

許多雄心勃勃的木製高樓也在北歐、中歐、和北美出現。

As yet, nobody has used CLT to build beyond 55 meters.

目前為止，還沒有超過 55 層樓高的 CLT 大樓。

But Michael Ramage's research center in Cambridge working with another London practice has proposed a concept design of a 300-meter tower,

可是 Michael Ramage 位於劍橋的研究機構和另一家倫敦的事務所，一起設計了一座 300 公尺高的塔的藍圖，

to be built on top of one of London's most iconic concrete structures, the Barbican.

預計加蓋在倫敦其中一座最具代表性的水泥建築巴比肯藝術中心之上。

The way we've engineered the Oakwood Tower is to look at the global structure.

我們在設計橡木塔的時候著重於整體結構。

And is it stable, and would it stand up?

它穩固嗎？會屹立不搖嗎？

We believe the answer is yes.

我們相信答案是肯定的。

The columns at the base of the Oakwood Tower would be about 2.5 meters square, so that's solid timber made of small elements glued together.

橡木塔最底部的柱子大約長寬 2.5 公尺，全部以實木膠和製成。

I think we'll probably see incremental increases from the current height of about 50 meters.

我認為未來木製建築在高度上會有不斷的突破，可能可以再高 50 公尺。

And, at some point, someone will make a step change, probably to about 100 meters.

甚至在將來某個時刻有人會有辦法直接再突破 50 公尺，比現在多 100 公尺高。

Making that jump in height will be a difficult sell.

只是要吸引資金還是有困難的。

The cost of building wooden skyscrapers is largely unknown, but those costs could be reduced by prefabricating large sections of buildings in factories.

建造木質高樓大廈的成本基本上還是個未知數，不過有個節省成本的方式：在施工前先在工廠製造建築大部分的組成元件。

And city-dwellers will need to be persuaded that CLT does not burn like ordinary wood.

此外，也必須說服城市居民 CLT 不會像一般木材那樣著火。

As an attractive, natural material, wood is already popular for use in low buildings.

作為一個天然且極具吸引力的材料，木材已經大量使用於建造低矮的建築。

If planners approve, it could rise to new heights.

如果能得到官方的認可，木材將得以突破天際。