As the world becomes hotter, our cities are being hit especially hard.
随着世界变热，我们的城市受到的影响尤其严重。
All their concrete holds onto heat from the sun, and they're filled with cars and other machines that release even more heat of their own.
所有的混凝土都吸收太阳的热量，而且城市里充满了汽车和其他机器，它们自己也释放出更多的热量。
Air conditioning can help fight the heat — but it can't be the only solution.
空调可以帮助对抗炎热，但不能是唯一的解决方案。
Rather, we need building designs that include passive cooling technologies that can lower the temperature even without air conditioning.
相反，我们需要包含被动冷却技术的建筑设计，即使没有空调也能降低温度。
These were some of the findings of a review published in Nature Reviews Clean Technology.
这些是发表在《自然综述：清洁技术》上的一项评论的一些发现。
"We cannot air condition our way out of climate change," said researcher Mat Santamouris from Australia's University of New South Wales.
“我们不能通过空调来摆脱气候变化，”来自澳大利亚新南威尔士大学的研究员马特·圣塔穆里斯说。
"If every building depends entirely on mechanical cooling, we create enormous pressure on electricity systems while adding even more heat to our cities," he explained.
“如果每座建筑都完全依赖机械冷却，我们就会给电力系统带来巨大压力，同时给城市增加更多热量，”他解释说。
According to the review, 10% of the world's electricity is now used for cooling, and demand is growing.
根据这项评论，全球10%的电力现在用于冷却，而且需求还在增长。
Around 10 new air conditioners are sold every second — and billions of people in hot countries can't access affordable cooling.
每秒大约售出10台新空调，而在炎热国家，数十亿人无法获得负担得起的冷却。
Passive cooling technologies can make buildings safer and more comfortable for everyone while reducing energy demand.
被动冷却技术可以使建筑更安全、更舒适，同时减少能源需求。
In fact, passive cooling technologies could lower peak temperature in cities by up to 4.5 degrees Celsius, the review says.
事实上，评论称被动冷却技术可以将城市峰值温度降低高达4.5摄氏度。
So, what are these technologies?
那么，这些技术是什么？
They include simple things like using better ventilation to reduce heat.
它们包括简单的方法，比如利用更好的通风来减少热量。
For example, a separate study found that angled roofs encourage much better air flow than flat roofs.
例如，另一项研究发现，倾斜屋顶比平屋顶更能促进空气流通。
The review also suggested using heat reflective and cooling materials for buildings — which can be as simple as using heat reflective paint.
该评论还建议使用热反射和冷却材料来建造建筑，可以像使用热反射涂料一样简单。
Buildings could also benefit from using more advanced shading systems, which might include using sensors to automatically open and close blinds based on occupancy and environmental conditions.
建筑也可以从使用更先进的遮阳系统中受益，其中可能包括使用传感器根据占用情况和环境条件自动打开和关闭百叶窗。
The researchers didn't argue that air conditioners should be replaced completely, though.
不过，研究人员并没有主张完全取代空调。
Instead, they said that passive cooling should be our first defense against rising temperatures, with air conditioning offering extra help when needed.
相反，他们说被动冷却应该是对抗气温上升的第一道防线，在需要时空调提供额外帮助。
