This study looked at a special kind of building called a zero-energy building. These buildings use the same amount of energy they generate, so it's like they don't use any extra energy from non-renewable sources. The researchers studied an office building that was designed to be very energy efficient. They found that the building could produce as much energy as it used over a whole year. This means the office building was pretty good at balancing the energy it needed with the energy it made, helping to reduce its overall impact on the environment.