A  Rooftops covered with grass, vegetable gardens and lush foliage are now a common sight in many cities around the world. More and more private companies and city authorities are investing in green roofs, drawn to their wide-ranging benefits. Among the benefits are saving on energy costs, mitigating the risk of floods, making habitats for urban wildlife, tackling air pollution and even growing food. These increasingly radical urban designs can help cities adapt to the monumental problems they face, such as access to resources and a lack of green space due to development. But the involvement of city authorities, businesses and other institutions is crucial to ensuring their success – as is research investigating different options to suit the variety of rooftop spaces found in cities. The UK is relatively new to developing green roofs, and local governments and institutions are playing a major role in spreading the practice. London is home to much of the UK's green roof market, mainly due to forward-thinking policies such as the London Plan, which has paved the way to more than doubling the area of green roofs in the capital.

A  在世界各地的许多城市，屋顶上铺满青草、菜园和郁郁葱葱的树叶已成为一道常见的风景。越来越多的私营公司和城市当局投资于屋顶绿化，因为屋顶绿化具有广泛的好处。这些好处包括节约能源成本、降低洪水风险、为城市野生动物提供栖息地、解决空气污染问题，甚至还能种植粮食。这些日益激进的城市设计可以帮助城市适应其面临的巨大问题，如资源获取和因开发而导致的绿地缺乏。但是，城市当局、企业和其他机构的参与对于确保其成功至关重要--研究不同的方案以适应城市屋顶空间的多样性也是如此。英国在发展屋顶绿化方面相对较新，地方政府和机构在推广屋顶绿化方面发挥着重要作用。伦敦是英国大部分屋顶绿化市场的发源地，这主要归功于伦敦计划等具有前瞻性的政策，该计划为将首都屋顶绿化面积增加一倍以上铺平了道路。

B  Ongoing research is showcasing how green roofs in cities can integrate with 'living walls': environmentally friendly walls which are partially or completely covered with greenery, including a growing medium, such as soil or water. Research also indicates that green roofs can be integrated with drainage systems on the ground, such as street trees, so that the water is managed better and the built environment is made more sustainable. There is also evidence to demonstrate the social value of green roofs. Doctors are increasingly prescribing time spent gardening outdoors for patients dealing with anxiety and depression. And research has found that access to even the most basic green spaces can provide a better quality of life for dementia sufferers and help people avoid obesity.

B  正在进行的研究展示了城市中的绿色屋顶如何与 “活墙 ”相结合：即部分或全部用绿色植物（包括土壤或水等生长介质）覆盖的环保型墙壁。研究还表明，屋顶绿化可以与地面排水系统（如行道树）相结合，从而更好地管理水资源，使建筑环境更具可持续性。还有证据表明屋顶绿化的社会价值。越来越多的医生为焦虑症和抑郁症患者开出户外园艺的处方。研究发现，即使是最基本的绿地，也能提高痴呆症患者的生活质量，帮助人们避免肥胖。

C  In North America, green roofs have become mainstream, with a wide array of expansive, accessible and food-producing roofs installed in buildings. Again, city leaders and authorities have helped push the movement forward – only recently, San Francisco, USA, created a policy requiring new buildings to have green roofs. Toronto, Canada, has policies dating from the 1990s, encouraging the development of urban farms on rooftops. These countries also benefit from having newer buildings than in many parts of the world, which makes it easier to install green roofs. Being able to keep enough water at roof height and distribute it right across the rooftop is crucial to maintaining the plants on any green roof – especially on 'edible roofs' where fruit and vegetables are farmed. And it's much easier to do this in newer buildings, which can typically hold greater weight, than to retro-fit old ones. Having a stronger roof also makes it easier to grow a greater variety of plants, since the soil can be deeper.

C  在北美洲，屋顶绿化已成为主流，在建筑物中安装了大量宽阔、方便和可生产食物的屋顶。同样，城市领导者和管理机构也帮助推动了这一运动的发展--就在最近，美国旧金山制定了一项政策，要求新建筑必须有绿色屋顶。加拿大多伦多早在 20 世纪 90 年代就制定了政策，鼓励在屋顶发展城市农场。与世界上许多地方相比，这些国家的建筑较新，因此更容易安装屋顶绿化设施。能够在屋顶高度保持足够的水量，并将其直接分配到整个屋顶，对于维护任何绿色屋顶上的植物都至关重要，尤其是在种植水果和蔬菜的 “可食用屋顶 ”上。新建筑通常能承受更大的重量，因此在新建筑中做到这一点要比改造旧建筑容易得多。屋顶更坚固也更容易种植更多种类的植物，因为土壤可以更深。

D  For green roofs to become the norm for new developments, there needs to be support from public authorities and private investors. Those responsible for maintaining buildings may have to acquire new skills, such as landscaping, and in some cases, volunteers may be needed to help out. Other considerations include installing drainage paths, meeting health and safety requirements and perhaps allowing access for the public, as well as planning restrictions and disruption from regular activities in and around the buildings during installation. To convince investors and developers that installing green roofs is worthwhile, economic arguments are still the most important. The term 'natural capital' has been developed to explain the economic value of nature; for example, measuring the money saved by installing natural solutions to protect against flood damage, adapt to climate change or help people lead healthier and happier lives.

D 要使屋顶绿化成为新开发项目的规范，需要得到公共机构和私人投资者的支持。负责维护建筑物的人员可能需要学习新的技能，如景观美化，在某些情况下，可能需要志愿者提供帮助。其他考虑因素还包括安装排水路径、满足健康和安全要求、可能允许公众进入，以及规划限制和安装期间对建筑物内和周围正常活动的干扰。要说服投资者和开发商安装绿色屋顶是值得的，经济方面的论据仍然是最重要的。自然资本 "一词被用来解释大自然的经济价值；例如，衡量通过安装自然解决方案来防止洪水破坏、适应气候变化或帮助人们过上更健康、更快乐的生活所节省的资金。

E  As the expertise about green roofs grows, official standards have been developed to ensure that they are designed, constructed and maintained properly, and function well. Improvements in the science and technology underpinning green roof development have also led to new variations in the concept. For example, 'blue roofs' enable buildings to hold water over longer periods of time, rather than draining it away quickly – crucial in times of heavier rainfall. There are also combinations of green roofs with solar panels, and 'brown roofs' which are wilder in nature and maximise biodiversity. If the trend continues, it could create new jobs and a more vibrant and sustainable local food economy – alongside many other benefits. There are still barriers to overcome, but the evidence so far indicates that green roofs have the potential to transform cities and help them function sustainably long into the future. The success stories need to be studied and replicated elsewhere, to make green, blue, brown and food-producing roofs the norm in cities around the world.

E  随着绿色屋顶专业知识的增长，已经制定了官方标准，以确保其设计、建造和维护得当，并发挥良好的功能。作为绿色屋顶发展基础的科学技术的进步也使这一概念有了新的变化。例如，“蓝色屋顶 ”使建筑物能够长时间蓄水，而不是快速排水--这在降雨量较大时至关重要。此外，还有绿色屋顶与太阳能电池板的组合，以及 “棕色屋顶”，后者更具有野性，能最大限度地提高生物多样性。如果这一趋势持续下去，它将创造新的就业机会，并为当地食品经济带来更多活力和可持续发展，同时还能带来许多其他好处。虽然仍有一些障碍需要克服，但迄今为止的证据表明，绿色屋顶有可能改变城市，帮助城市在未来长期可持续地运转。我们需要对成功案例进行研究，并将其推广到其他地方，使绿色、蓝色、棕色和可生产粮食的屋顶成为世界各地城市的常态。