Weather-Based Irrigation Controllers
Locations: Hamilton, Middleton, Peabody, North
- Demonstrate the use of weather-based irrigation technology as
a means to reduce water use for outdoor landscaping, while maintaining
- Reduce overall water demand on public water supplies.
- Quantify the water savings associated with use of weather-based
irrigation controller switches, designed to deliver water only when needed.
Description: A total of 25 weather-based irrigation controller switches were installed on both residential properties and municipal athletic fields in five communities. These devices contain an on-site rain gage and receive continuously transmitted wireless data on solar radiation, temperature, relative humidity, and wind. Based on this information, and device settings established from a detailed landscape assessment, the system determines when the landscape needs irrigation, and allows an irrigation cycle to be delivered. Until such times, the device keeps the irrigation system in over-ride, preventing unnecessary watering. Fifteen residential properties in Reading and ten municipal athletic fields in Hamilton, Middleton, Peabody, North Reading, and Reading participated in this demonstration project.
Communication with individual project participants was an important component of this project. All residential participants were invited to attend season kick-off meetings in the spring of 2006 and 2007 to learn about the study and the low-flow concerns about the Ipswich River, discuss their newly-installed weather-based systems, and receive information on data collection and system operation for the current season. A project close-out meeting was also held with residential participants in April 2008. Attendants celebrated the conclusion of the data collection, listened to preliminary study results, provided feedback about the systems, and heard tips on eco-friendly landscaping techniques. Additionally, individual “conclusion interviews” were held with each of the five municipal partners in the spring of 2008 to present preliminary results and receive feedback on their experience with the weather-based irrigation control systems.
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Data Collection and Analysis: Data on water use by each irrigation system was recorded using readings from water meters dedicated to the irrigation system. The project used two approaches to analyze water savings in a residential setting. The first analysis compared outdoor water use at residences where weather-based controllers were installed to outdoor water use at residences with similar irrigation systems but where controllers were not installed (a “control” group), both before and after installation of the weather-based controllers.
Secondly, a retrospective analysis compared each participating household’s actual outdoor water use in 2003 and 2004, prior to the installation of the weather-based controller, to the estimated volume of water that would have been applied by the weather-based controller during that same period. To perform this analysis, historic weather records were used, along with information on settings for each system and measurements of the volume of water delivered with each irrigation cycle for each system.
To analyze water savings in the municipal athletic field setting, only the retrospective analysis was used, because there were not a sufficient number of fields available as a control group.
Due to some gaps in historical water use records, the residential analysis included twelve participating households (and 71 control households) and five municipal athletic fields.
- Weather-based irrigation controllers installed at both residential and municipal sites, May to August 2005
- Season kickoff meetings for residential participants, spring 2006 and 2007
- Monthly contacts with project participants during the irrigation season, April to October, 2005, 2006, and 2007
- Project close-out meetings, spring 2008
Costs: Weather-based irrigation controllers (including the control unit, rain gauge, and installation) were valued at $962 each, at the time of installation.
Key Results and Conclusions:
- The municipal athletic field sites showed consistent reductions in water use, with average savings of 36% or 16,000 cubic feet (about 120,000 gallons) per acre per year.
- The effect of the weather-based controllers on residential water-use patterns was more variable, with some participants decreasing water use after installation and others increasing water use after installation.
- Participants with the highest historical water use showed large and statistically significant water savings after installation.
- Participants with relatively conservative watering habits initially tended to show an increase in water use after the weather-based systems were installed.
- The residential retrospective analysis led to similar conclusions, indicating that some participants would have saved water in 2003 and 2004 with the weather-based system, while others would have used more water with the weather-based system than they did without it.
- For all participants, the weather-based systems appeared to save customers the most water during periods of wetter weather.
Final Reports and Publications:
In-kind cooperation: Towns of Hamilton, Middleton, North Reading, and Reading and the city of Peabody
Equipment supply, installation, and maintenance: AquaSave LLC, Ipswich, MA
Monitoring and Analysis: DCR and Tufts University with oversight from a Technical Advisory Committee comprised of eight water conservation professionals
Acknowledgements: DCR would like to acknowledge data contributions to this project from all participating towns and residents.