?Passage Five

For most architects, moss (苔藓) and lichen (地衣) growing up the side of astructure is a bad sign. Building materials are designed specifically to resistgrowth, and much research has been done to develop paint treatments andbiocides that make sure the concreteand wood and bricksthat sheathe a buildingaren't colonized by living things. But a new group is trying to change all that.Instead of developing suces resistant to moss and lichen, the BiotA lab wants tobuild [facades]that are“bioreceptive”.

BiotA lab, based in University College London's Bartlett School ofArchitecture, was founded last year. The lab's architects and engineers areworking on materials that can foster the growth of organisms like lichensand mosses. The idea is that ultimately they'll be able to build buildings ontowhich a variety of these plants can grow. Right now, they re particularly focusedon designing a type of bioreceptive concrete.

Marcos Cruz, one of the directors of the BiotA lab, says that he has long beeninterested in what he sees as a conflicted way of thinking about buildings andbeauty:“We admire mosses growing on old buildings, we identify them with ourromantic past, but we don't like them on contemporary buildings," he says. Cruzsays that he wants the BiotA project to push back against the idea that cleanlinessis the ideal that buildings should strive for. “Architects were wearing astraightjacket, that only in the last 20 years architects started shredding off."

Richard Beckett, another director of the BiotA lab, says that he's interested inthe project flipping the usual way that buildings are designed, at least in a smallway. "Traditionally architecture is a top-down process, you decide what thebuilding will look like, and then you build it. Here we' re designing for a specificspecies or group of species, the material and geometry we' re using is so specificthat it only allows certain species to grow." It's controlled chaos.

Both Cruz and Beckett talked about a particular way of thinking about theirbuildings. “Every architect you speak to talks about the skin of the building," saysBeckett. But they want to propose a different way of seeing things. Instead of skin,the lab wants people to think of the exterior of a building as bark. “'Not just aprotective thing, a host; it allows other things to grow on it, it integrates as well,"says Beckett.

But these living systems can be expensive and hard to maintain. Sometimesall the plants die, and have to be replaced. Cruz tells a story of a plant nursery inEast London that had a green wall.“When 1 saw it for the first time, I thought itwas wonderful!" he says. But six months later when he passed the nursery again,he noticed that the plants were all dead and falling off the wall. “A year later,much to my surprise, they were putting up steel panels with photographs of aforest on them," he says, laughing.

Questions 21-25 are based on Passage Five.

In paragraph I, the word“facades”means_____.