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Homeowners who enjoy the out-of-doors are transforming suburban lawns into lush landscapes for outside living and entertaining. With careful planning such landscapes can be designed to need no irrigation, but this practice, known as xeriscaping, is not yet common in the U.S. Increasingly, when irrigation is required, outdoor designs are including automatic irrigation devices to aid owners in the effortless protection of their investment in landscaping.
The Environmental Protection Agency (EPA) estimates that 30 percent of the average household’s daily water consumption, or 120 gallons of water per day is used outdoors. And experts say that 50% of that usage is wasted due to evaporation, runoff, or over-watering. In a typical metropolitan area saving one half of the water used to irrigate landscaping could result in an annual water bill savings of $146, but saving money isn’t the only consideration, as water shortages are common in many regions of the country and supply is not keeping pace with population growth. Proper control of irrigation system watering cycles will reduce the impact of water resource depletion, erosion and water runoff that may result from irrigation.
Irrigation controllers are available for outdoor or indoor mounting. Simple residential models will cover anywhere from six to sixteen stations or zones. Some controllers can be add-ons to existing controllers or timers. There are two primary types of controllers that go way beyond a simple timer to be sure that water only flows when and where it is needed.
Evapotranspiration Controls
Water loss from the landscape is largely the result of evaporation or transpiration (a plant process) and is known as evapotranspiration (ET). Controls based on ET contain, at the minimum, program algorithms specific to climate regions that are based primarily on solar radiation, temperature, relative humidity and wind to estimate a plant’s water requirement. Mathematical formulas that predict the water replacement rate and volume for given areas have been developed to a reasonable level of accuracy over the last 50 years, so ET systems are fairly reliable at meeting irrigation needs without over-watering.
Weather and ET Controls
Weather-based irrigation controls factor actual observed climate conditions with the ET algorithms assuring that watering patterns are based on local conditions. Several systems integrate a realtime weather interface with an ET controller via locally installed rain and wind gauges, temperature and humidity sensors, or a backyard weather station.
Weather and ET controllers can be networked via household internet connection or wirelessly to weather satellites and local weather stations to adjust the internal controller based on actual meteorological data in the area. These systems will also require a monthly subscription to the weather service.
With proper planning and smart control systems, homeowners can have the backyard paradise they seek, while reducing water costs and conserving resources.
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Weather and ET controlled irrigation systems save water over systems operating on timers. These controls use actual weather conditions and ET algorithms to set watering patterns.
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Most irrigation systems are not do-it-yourself installations. Experienced irrigation system installers will be familiar with ET systems with weather interfaces and whether controllers can be added to existing systems.
Controlled irrigation devices can be even more effective at conserving water when they are built into planned landscapes with plants that are adaptive to the climate - natives and plant species accustomed to the local climate will reduce overall water requirements. Plantings should be grouped by water requirements as well as sun exposure, and individual irrigation emission devices should be adjusted to deliver the amount of water specific to the needs of each group of plants. Channeling hardscape runoff, like downspout outfalls and walkways, to garden or lawn area can provide additional irrigation. Finally, when choosing irrigation system devices, bubblers, drip emitters and diffusers are some of the more conservative alternatives to sprinklers because they soak the ground, and don’t spray water through the air.
Intelligent controllers range in price from $400 to $1000, depending on station capacity, features and manufacturer.
Irrigation controls should net a water savings of 25-50% or an average of 30 to 60 gallons per day. Dependent upon the cost per 1,000 gallons, this savings could offset the cost of a subscription to a weather service. Absent a live weather interface, intelligently controlling irrigation should net a cost reduction to systems controlled by timers.
Systems that have real time weather adjustment require a subscription to access the realtime weather networks. Monthly subscription prices vary from $4-25 dependent on provider and number of stations in the system. Fees do not include internet access, if applicable.
Model building codes do not cover anything but backflow protection of irrigation systems.
None available
Installation is similar to other controllers. Controllers that will capture internet based weather will require a broad band connection.
Many systems have 3 year warranties. Review manufacturer’s literature, as warranties do vary.
Intelligent irrigation controls will save water and money over irrigation controls based on timers. Plants will receive the proper amount of water and should be healthier. Homeowners also enjoy the convenience of a self-regulated system.
Some local governments offer rebates for installing intelligent irrigation control systems.
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