How an Irrigation System can protect your house in a wildfire
In part due to the warming climate wildfires are becoming more prevalent every year. According to the National Interagency Fire Center the amount of land burned by wildfires has more than doubled since the 1990s, from 3.3 million acres to 7 million acres per year. This growth in wildfire damage is almost entirely in the Western US.
Many of us in the West enjoy living in the urban wildland interface (UWI) among the trees or close to grasslands. These areas are beautiful to live in but they are also prone to wildfires. With the increase in wildfires it is no surprise that more and more structures are burned down every year. In just the last few years entire towns have been destroyed by wildfires. In 2018 Paradise, California, was destroyed, in 2020 Talent and Phoenix in Oregon burned down, Lytton in British Columbia was lost in 2021, Lahaina in Hawaii in 2023 and the town of Stinnett, Texas this year.
Add dedicated fire protection irrigation lines
There are some fairly simple measurements that you can take to reduce the chance that your house is destroyed by wildfire. Most structures catch on fire by wildfires that spread over the ground. In an earlier blog posting we showed how to create buffers around your house that are free of combustible materials to reduce the chance that a ground fire reaches your home. As a full service landscape architecture firm LandCurrent regularly designs irrigation systems. Sprinkler systems always consist of multiple zones to water different areas with different frequencies and intensity. When designing an irrigation system we suggested to add zones to water the house in addition to watering the plants. The result is an irrigation system that doubles as a wildfire protection system. Click here to watch a video of our system.
Whereas plants are best served with small amounts of water over time a wildfire protection system needs to be able to soak the house as fast as possible when a fire approaches. Instead of drip irrigation we installed a spray heads that push out five gallons per minute. The result is, literally, a fixed firehose that soaks the façade in minutes and brings down the entire ambient temperature around the house. A fire first needs to evaporate the water content in the façade materials and increase the ambient temperature before the house can catch on fire. The goal of the system is to continue to soak the house with water as the environment around it burns. This prevents the house facades and roof to ever heat up enough to combust.
The fire protection system consists of several zones with different spray heads depending on the proximity of the house to combustible materials. By cycling through the zones, the system never pulls too much water. In case of a wildfire the regular plant irrigation zones can be set to a higher frequency in order to increase water output; there are many examples where houses have been saved because people increased the irrigation time and frequency in the zone directly around the home.
Irrigation system can be expensive to install but adding fire protection zones when an irrigation system is being installed only adds 10-20% to the cost of the system. The fire protection lines use the same trenches and control boxes as the regular irrigation system.
During a wildfire people are evacuated, power may be cut and internet may not be available. For these reasons the system needs to be designed so it can operate when regular power and internet are not available. Irrigation system controllers take very little power and can be hooked up to an uninterrupted power supply to make sure the system continues to function when power is lost. LandCurrent can design the system so it can be controlled remotely over the Internet. By installing a dedicated mobile device such as a router or phone the system can be controlled as long as cellular access is available. The zones can also be configured to cycle through a watering schedule continuously. This ensures that the system continues to water the house and plants when power and cellular service are lost.
Additional protection measures
There are a couple of additional measures that can be added to the sprinkler system design for additional protection.
The house in the image above has the additional benefit of a 9,000-gallon cistern that is fed by rainwater. LandCurrent designed the system so it can switch to cistern water if city water is lost. The ground portion of the fire protection system on this house has been installed. We are planning to add sprinklers in the eaves to release clouds of water from above and protect the house if the tree crowns catch fire. These sprinklers will also be controlled remotely. The house has a metal roof which reduces the chance the roof will catch fire. We are also planning to install some sprayers on the roof so the metal can be cooled down to a temperature that prevents ignition of the wooden frame underneath. Landcurrent is working with a software developer to complement the system with IoT (Internet of Things) devices that measure the ambient temperature, water content of the surface materials, and heat of the surrounding trees so the system can recognize fire danger and respond autonomously based on the inputs it receives.
For more information contact: info [at] landcurrent.com
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