The increase in energy demand has motivated a large body of research, using a diverse collection of approaches to reduce domestic energy use. One promising approach to this societal problem is the development of systems that cooperate with the residents combined with digital behavior changes interventions. In this chapter, we present the Mondrian User Interface pattern intended to help system developers to structure and populate the interactive components of their system in order to inspire eco-responsibility. The Mondrian UI serves as an ambient decorative display that supports different levels of users' attention investment while sustaining daily use. Like Mondrian's Collections, the Mondrian UI pattern divides the screen into rectangles of different sizes painted in primary colors. The rectangles contain information that can be zoomed-in and zoomed-out to support multi-level representations of the same semantic information while maintaining informational context accessible. In order to minimize attentional effort, the toplevel content of a rectangle is intended to communicate information at-a-glance while the other levels provide analytic details on demand with minimalist oneclick interaction. Each rectangle of the Mondrian UI is populated with ecoinspiring content such as spatio-temporal information about energy use, recommendations and explanations, and social incentives, or with utilitarian content, such as the weather forecast, that family members have the habit of consulting frequently. Utilitarian content along with the display located in a socializing place, are intended to enforce the daily use of eco-inspiring information. We have applied the Mondrian UI pattern to the design and implementation of the user interface of an e-coach electricity management system.