Nghe TOEFL

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Listen to part of a lecture in an environmental science class. Professor: Today we're going to discuss a surprising factor that affects urban temperatures: the color of roofs. You might know that dark surfaces absorb more heat from the sun, while light surfaces reflect it. This principle underlies the 'cool roof' movement, where buildings in hot climates have white or reflective coatings to reduce air conditioning needs. However, a recent study from a team at MIT suggests that in colder regions, cool roofs might actually increase heating costs. In these areas, dark roofs help absorb heat during winter, reducing the energy needed to warm buildings. The researchers simulated different roof colors in various climates and found that the optimal choice depends on a balance between summer cooling and winter heating. They also noted that cool roofs can lower city-wide temperatures, which helps mitigate the urban heat island effect. So, the decision isn't as simple as 'always use white roofs.' It requires a local analysis. Any questions?