Introduction to Sustainable Design - Simplified Design of Reinforced Concrete Buildings - page 316

SYSTEM SELECTION
Concrete is an economical, cost-effective solution, consuming minimal materials, energy, and other resources
for construction, maintenance, and rehabilitation over its lifetime, while providing essential infrastructure to
society. (Ref.12.3)
Concrete is strong in compression and has good stiffness (large elastic modulus). It can support heavy loads
and resist horizontal forces (wind, seismic) with only small amounts of deflection. This increases both the
safety and comfort of building occupants. If the concrete strength is increased, smaller sized members can be
used. Strength can be selected to reduce floor-ceiling heights to save on material quantities—exterior finishes
and glass/glazing, stair runs, etc. Due to its strength, durability, and solid construction, concrete is also a good
structural system for building green roofs.
WATER MANAGEMENT
Although Simplified Design is geared toward buildings, there are usually paved areas for walkways, parking,
and other uses that must be considered as part of the installation. As noted in the site selection information,
anything that decreases the amount of impervious surface on a site promotes better water infiltration into the
natural soil. Water that percolates into the ground finds its way into local waterways such as rivers, streams,
and lakes.
Two ways in which concrete can assist in managing water are by decreasing the size of the building footprint
and through the use of pervious pavements. Concrete products such as pervious concrete and permeable
interlocking concrete pavers (PICP) both promote recharging ground water. In addition to allowing natural
water to be replenished, pervious surfaces also improve water quality by helping to break down pollutants.
They may decrease the burden on a storm water system, reducing its size or eliminating it completely, with an
associated potential for saving money.
ENERGY AND ATMOSPHERE
This category generally reinforces the idea that buildings should not be energy drains. In fact, as we improve
the energy performance of buildings, we progress first toward minimal negative impact on the environment,
to net zero energy structures, to, ideally, buildings that help return energy to the grid. There are many exam-
ples of buildings being constructed today in each of these categories. The reason that concrete systems are
beneficial from an energy perspective is because they serve as useful structural elements and because they can
also help provide durable, energy efficient envelopes. Both the frame and the envelope have the potential to
provide thermal mass.
Energy codes are driving construction toward more efficient operations. With proper insulation strategies,
concrete systems create tight, energy efficient envelopes. The mass in these systems, which can act like a
“battery” to store heat or cool, reduces energy uses and improves occupant comfort. Depending on the
designer's goals, it might be possible to expose some of the concrete frame—columns, walls, or floors—to
further enhance the thermal mass performance. And the building's orientation and layout can be considered,
too. Exposing surfaces strategically to the sun can influence both the heating and cooling needs. Further, the