Figure 2.9 An Example of a Meta Diagram

Figure 2.9 An Example of a Meta Diagram

Source: Author elaboration (Sebastian Moffatt). Note: This meta diagram uses the fi ve standard partitions to visualize water fl ow (liters per day) for a new, advanced detached home in New Delhi.

backgrounds. Few people understand the whole picture. In fact, in most cases, there is nobody in the entire city who is able to describe the energy system, including the diversity and relative weights of primary energy inputs, the relative importance of each energy demand, the amount of fossil fuels embodied in local electricity, and the share of energy that is cascaded to secondary uses. However, after a few minutes with a meta diagram, people will likely understand the basics (fi gure 2.11).

Typically, a meta diagram is constructed to refl ect the substances, processes, and time periods relevant to specifi c decisions. Sometimes, a combination of meta diagrams is most eff ective. If energy fl ows are averaged over a year, for example, they provide a good benchmark for tracking overall effi ciency and understanding ecological footprints. However, annual energy fl ows fail to reveal the seasonal and daily peaks that aff ect costs, which are often key determinants in system design. Thus, a meta diagram based on peak-hour energy fl ows for the peak month (or daily fl ows for water during the driest month) might be useful for understanding the big picture, especially in evaluating alternative system designs.