August, 2008

Conserving Water in the Home

New techniques take green building to the next level

By Steve Easley

A builder asks, “Water efficiency seems to be becoming a bigger component in green building. What are your recommendations?”

The four main tenets of green building are energy efficiency, resource efficiency, water efficiency, and indoor air quality.

Much of the focus in green building lately has been given to energy- and resource efficiency, and rightfully so.

Sealing the building envelope, upgrading insulation and HVAC systems, using high-performance windows, and installing energy-efficient appliances and lighting are all key ingredients when building a green home.

As green becomes more mainstream, these fundamentals of building science are becoming more common in the industry, but it’s also making it harder for builders to differentiate their homes. Water efficiency is the next step in taking building to the next level of green.

Water scarcity is becoming a big deal throughout much of the country. Atlanta has been in a drought since 2000 and its main water supply is running dry. Lake Mead, Las Vegas’ major water source, is more than half empty. The Southwest and Southeast have been hit hard by drought. Consumers in these and other droughtstricken regions are being forced to limit water usage.

Water scarcity isn’t the only reason saving water makes good environmental sense. Energy production accounts for 48% of all water used in the US. Each kilowatt of electricity used equates to 1 to 1.5 lbs of greenhouse gas emissions. Decreasing your carbon footprint by saving water is a little known added benefit of focusing on water efficiency.

Water-Efficient Homes

The two main areas to focus on when considering how to make a home more water efficient are indoor use and outdoor use.

For a modest increase in up-front costs, you can install the latest in water efficiency: dual flush toilets, efficient front loading clothes washers, low-flow faucets and shower heads, and energy-efficient dishwashers.

Simply installing a low-flow toilet can save homeowners between 14,000 and 17,000 gallons of water per year when compared to the older models (models made prior to 1993). Kohler makes a great dual flush toilet that only uses 1.28 gallons of water per flush. The second biggest water hog in the home is the clothes washer. By installing a high-efficiency front loader, the average family of four will save more than 8,000 gallons of water per year.

When it comes to faucets and shower heads, look for the Envionmental Protection Agency’s (EPA) WaterSense label.

One feature not typically considered that also saves indoor water is a kitchen composter. Using flow restrictors on faucets also makes a lot of sense. About 70% of all the water use in homes is hot water, so 1.5 GPM for lavatories and 2.5 for kitchen sinks can save a lot of water and energy.

Outdoor Water Use

Outdoor water use for irrigation accounts for about 37% of residential water use on average. One of the best ways to cut down on outdoor water use is to convert turf areas to low water-use plantings, also known as xeriscaping. Choose plants that thrive in local climates and that are more likely to survive local watering restrictions.

There are two ways to save water when it comes to irrigation. For trees and flowerbeds, use drip irrigation. This delivers water directly to the roots of the plant at a lower flow rate than conventional sprinkler systems.

Sprinklers, in contrast, spray water into the air first before it ever reaches the ground. Wind can carry this airborne water away, distributing it to places other than those where it was intended. This inefficiency is not conducive to water conservation.

Spray water irrigation systems are still the preferred method for watering lawns. These can be made water efficient by adding manual flow control valves, a rain shut off, and a timer with multiple start times for various zones.

Most green building programs give points for water efficiency, including NAHB’s Model Green Home Building Guidelines and LEED for Homes Water Efficiency Points.

HOUSEHOLD INDOOR WATER USAGE TOILET 26.7%
CLOTHES WASHER 21.7%
FAUCETS 16.7%
SHOWERS 15.9%
LEAKS 13.7%
OTHER DOMESTIC 2.2%
BATHTUB 1.7%
DISHWASHER 1.4%
NAHB’S WATER EFFICIENCY POINTS
4.1.1 Hot water delivery to remote locations aided by installation 6 pts of on-demand water
4.1.2 Water heater located within 30 feet of pipe run of all 9 bathrooms and kitchen
4.1.3 ENERGY STAR water-conserving appliances 7 per installed (dishwasher, etc)
4.1.4 Water-efficient showerhead with flow rate < 2.5 gpm 2 per
4.1.5 Water-efficient sink faucets with < 2.2 gpm 2 per
4.1.6 Ultra low flow toilets
A. Power-assist 4
B. Dual-flush 6
4.1.7 Low-volume, non-spray irrigation system 7
4.1.8 Irrigation system zoned separately for turf and bedding 6
4.1.9 Weather-based irrigation controls 7
4.1.10 Collect and use rainwater as permitted by local code 9
4.1.11 Innovative wastewater technology as permitted by code 7

LEED-H WATER EFFICIENCY POINTS- MAXIMUM OF 15 POINTS AVAILABLE FOR WATER EFFICIENCY

Water reuse 5 pts max

Rainwater Harvesting System 4
Graywater Reuse System 1
Use of Municipal Recycled Water System 3
High Efficiency Irrigation System 3
Irrigation system 4 pts max
Third-party inspection 1
Reduce Overall Irrigation Demand by at Least 45% 4
Indoor water use 6 pts max
High Efficiency Fixtures and Fittings 3
Very High Efficiency Fixtures and Fittings 6

STEVE EASLEY is president of Steve Easley & Associates, which consults and trains on building science issues. His seminar topics include reducing call backs, high-performance building envelopes, and cost-effective strategies for green building. For more information, visit www.codecollegenetwork.com.