Page 177 - Green Building Through Integrated Design

LEED RATING SYSTEM AND EVA 153

TABLE 8.5 WATER EFFICIENCY: CREDIT 3 WATER USE REDUCTION

LEED CREDIT SOLUTION LEED CREDIT SOLUTION
NON-LEED #1 WATER-EFFICIENT #2 RAINWATER CISTERN
BUILDING FIXTURES WITH FILTRATION
Soft Cost Impacts None None Additional MEP
engineering cost $5000
Hard Cost Impacts None Low-flow fixture Rainwater cistern
premium $5000 $25,000
Life-Cycle Benefits None Water cost reduction Water cost reduction
$5000/year $10,000/year

water-conserving fixtures or using captured (and treated) rainwater in place of pur-
chased potable water for toilet flushing and urinals (Table 8.5). In many projects, of
course, these approaches are used together, but for the purposes of illustration, they
are considered separate ways to get to the same goal. You might also note that if we
use both measures, such that the total water use is reduced by 50 percent, then we
may also achieve another LEED credit point, Water Efficiency credit 2. If the build-
ing is a low-rise building with a large roof area, typical in many situations, we might
have enough harvested rainwater to handle both the site irrigation and the internal
water-use reduction goals.
The simple change-out of plumbing fixtures has about a 1-year payback, while the
rainwater harvesting, treatment, and distribution system has a greater annual benefit,
but a 3-year payback (Fig. 8.4). Note that all rainwater collection and reuse options

Figure 8.4 Cumulative cash flow WE Credit 3: Water Use Reduction.
Paul Shahriari, GreenMind Inc.