|Energy Balance Diagram, Solar
2 (click to enlarge)
To be productive in terms of energy, a building must produce more
renewable energy than it consumes. We use a graphic scale describing the energy
performance of our buildings (at right, the example of Solar 2). This scale
is measured per square meter, not in terms of the total consumption
of the building, to allow easy comparison between buildings. Other data analyses
are sometimes measured in different units, such as btus/square foot. Conversions
between units can be found at a number of web
Energy use within the building is labeled Project Consumption;
energy generation is labeled Project Generation, each indicated
by a dotted rectangle. Consumption is a negative number, production a positive.
Adding the two gives a net total.
If production exceeds consumption, the total is positive, and the building
produces a surplus of energy.
Building energy consumption and production are highly dependent on two factors:
building type (i.e., office, residence, restaurant), and climate. For comparison,
two additional data points are provided for each project. One is the average
operating energy consumption for this building type, in a similar
based on NREL/DOE
Commercial Building Energy Benchmarks, July 2008. The second reference
point is the operating energy benchmark for this project,
which is a software simulation for this specific building in its actual location,
based on ASHRAE 90.1 energy consumption standard, and used as part of the LEED
Note that this analysis covers operating energy only. The embodied energy
of construction and maintenance over time is not included.
Other metrics are important to measure a building's sustainability, including
water use, waste generation, and others. Of all the metrics, energy is arguably
the most significant in terms of the net environmental impact of a building
over its lifetime, and is also the easiest to model , measure, and compare
to other projects. For this reason, we document the energy performance of as
many of our projects as possible.
working principles >