是什么阻止我们丢弃砖头?

Wander down any street in London and there is one material that you’ll see more than any other: brick. The humble brick has been around in some form for thousands of years, and more traditional mud bricks are a fantastically low carbon building material. But fired clay bricks, the kind that we see everywhere in London (and much of the rest of the UK, for that matter), are pretty much the opposite.

Many of these historic buildings are incredibly attractive, and at the time that bricks were first developed, it made sense to use them. Following the Great Fire of London, timber framing was banned, and the London Building Act of 1667 dictated that new buildings should be constructed in masonry. Those historic brick buildings are a beautiful part of London’s heritage. The craftsmanship is often incredible, and the ornate details are just the kind of jazzy that I like.

But nestled in among these beautifully crafted buildings are some imposters – modern buildings which are clad in brick despite it making very little sense to do so. Buildings where the brick is supported from the edge of a concrete slab and structurally it’s a bit of a lie.

For a structural engineer, bricks are not a brilliant material. They work best in compression, carrying vertical loads down through the building, but the capacity is limited. If you apply a horizontal load, such as wind or a person leaning on it, then the capacity is even worse. Not really ideal for a wall. Bricks are also heavy, which is not what you want if you’re trying to support them from the edge of a third-floor slab.

So why do we continue to clad buildings in brick? The main reason seems to be to fit in with the buildings around us – to continue to create a similar aesthetic throughout our cities. But in the middle of a climate crisis does it really make sense to do that? And if it’s just about aesthetics, can we create the same appearance in a more sustainable way?

石头的含碳量大约是砖的三分之二。It’s also heavy and not cheap, but it is still a lot stronger than traditional brick

Perhaps the easiest substitution would be to use stone. There’s already a precedent for building in stone, so it’s still in keeping with our cities, but stone has around two-thirds the embodied carbon of brick. It’s also heavy and not cheap, but it is still a lot stronger than traditional brick.

或者我们把砖的使用限制在回收砖上怎么样?每年我们都会拆除成千上万的建筑，其中很多都是砖砌的，然而我们只再利用了5%的砖。是的，这些建筑需要更小心地拆除，我们需要找到清理砖块的方法，以确保它们不会被损坏，但我们可以继续用砖块建造，而不会产生碳成本。

近年来，回收砖也开始被研究作为一种结构选择。赫里奥特瓦特大学开发了一种名为“K-Briq”的砖，这种砖由90%的建筑和拆迁垃圾制成。这样的产品可能还没有在市场上上市，但它们在减少碳排放方面有巨大的潜力，同时仍然像传统的砖一样。

或者，我们可能会接受这样一个事实:到2022年，我们已经有了比砖更好的材料，我们不能继续建造这么高碳成本的建筑。我们应该回到木材这样的材料，它更轻，更通用，仍然创造了一种美丽的，如果不同，美学。

What would the Victorians think of us?! We have all these new construction methods and materials that are much more efficient, yet we continue to build in brick just to mimic the buildings that they designed. Isn’t it time we started to create new cities for ourselves? Yes, keep the heritage, preserve the beautiful buildings we already have. But when we build something new, isn’t it time to prioritise our future over the past?