We need collective action to tackle global warming. However, research shows that people switch off from being concerned about the environment because they are often too busy, or fail to appreciate their ability to make a difference. An alternative approach is to run campaigns that are able to engage large numbers of people and engender feelings of concern and empowerment. This could then kick-start a range of pro-environmental habits. We present the development and evaluation of a playful installation that aimed to attract attention, and stimulate discussion about environmental issues amongst university staff and students. The first prototype was shown to successfully attract people to engage and interact with the installation. The second prototype was deployed in-the-wild, over the course of a week. We evaluated the extent to which the installation was successful at attracting attention, and in encouraging people to interact with it, to reflect on their habits and to discuss environmental issues with others. We found the Green Ball Kiosk was a fun way to raise discussions about green issues, to encourage the adoption of new environmentally friendly behaviours and to prompt people to maintain existing ones. We suggest that interactive installations such as this can be effective at promoting awareness and generating a 'social buzz' about environmental topics when exhibited as a temporary installation.