The Science of ET

We've had a lot of customers ask how our "smart" features work. Questions like: Where do the recommended watering times come from? Why did the Iro suggest those numbers? How does Water Budgeting know what my new watering times should be? The answer to all of those questions is the same: through the magic of ET.

ET and the Water Cycle

Evapotranspiration, or ET, is a measure of how much water a group of plants (like your lawn or trees) loses in a given period. It's basically the combination of how much water evaporates from the soil itself, and how much water the plant transpires, or "breathes out". (That's where the word comes from.)

ET is part of the water cycle, which describes how water falls to the ground as precipitation like rain or snow, is absorbed by plants and the soil itself and then returns to the clouds. Understanding the water cycle is important for climate scientists, meteorologists, and agricultural scientists, and lots of people spend their whole lives studying it. Fortunately, we're really just interested in how it works in one area: your yard!

ET and Your Yard

All of the science boils down to this: your yard gains moisture from precipitation, and loses moisture from ET. If you lose more than you gain, you get dry soil and brown foliage. That's what irrigation is for--but it's tricky. Irrigate too little, and you're just delaying your yard's demise. Irrigate too much, and you're wasting water, eroding your topsoil, and sending all kinds of junk into your storm drains (and thus our rivers and streams).

Figuring out just the right amount can be hard, and that's where ET comes in. A lot of smart people have researched how much ET occurs when you take all kinds of things into account: soil type, plant type, average temperatures, wind speed, humidity levels, latitude, average sun exposure, you name it. Figure out which equations to use, feed in the right variables, and you can decide exactly how much water your lawn needs in a given week. Know the watering rates of your sprinklers, and you can calculate just how long to water.

We Think Hard, So You Don't Have To

Fortunately, you don't have to be a climate scientist to figure it out. Our software uses your zone details, location, climate data, and weather to run the numbers and recommend the best watering schedule for your lawn. And, as conditions change, Water Budgeting changes your schedule to match. It's not perfect - there are a lot of different types of sprinklers out there, for example - but we're working every day to collect more data to make our system smarter. We're not going to be happy until everybody has a great yard, that never wastes a drop of water!

The Secret Life of Bees

When I was a kid I liked to imagine what the world looked like to a bee. I had read or heard somewhere that bees are able to see ultraviolet light. In the secret world of bees, flowers that look the same to you and I may look very different to the bee. Some flowers, for example, have brightly colored ultraviolet pedals that direct the bees to pollen and nectar, like little bee runways. Most biologists think the bees and flowers co-evolved this special relationship. So what do bees and flowers have to do with Rachio?

When I first heard about Rachio, I was excited about the possibility of having a convenient way to manage my sprinklers using my smartphone. I’ve been in my house for almost 15 years and have pretty much left my sprinkler settings where I found them when I moved in. With an Iro, I thought, I can easily adjust my watering schedule and run my sprinklers from anywhere. And that’s about as far as I let my imagination go until I finally received a working Iro and installed it at my house. Even though I had worked on creating the Rachio iOS app for several months, nothing really prepared me for the experience of using it with an actual Iro and Rachio’s cloud services to manage my sprinklers. The first time I set up my zones and created a watering schedule I realized that I have been completely unaware of the secret world that is my yard.

Over the past few months, because of my Iro and Rachio’s intelligent software, my relationship with my yard has evolved. For the first time in 15 years I am beginning to understand my yard and its needs. Where before we were strangers at best, and enemies at worse, now my yard and I are becoming friends and partners. I am becoming much more sensitive to my yard’s needs and my yard is thanking me by looking beautiful and healthy (and drinking a lot less water). Who knows, maybe some day I might actually experience what it feels like to be a bee.

Epilogue

When it comes to the Internet of Things (IoT), it’s easy to imagine smart devices taking over all aspects of our lives “freeing us” to focus on other things. When you think about it in those terms, the brave new IoT world seems like one that will leave us even more disconnected from nature and each other. But it doesn’t have to be that way! Here at Rachio, we are passionate about helping people enjoy their yards and, more importantly, get back in touch with that little bit of nature that’s right outside the door. While the Iro smart sprinkler controller definitely frees people from having to figure out and manage their irrigation system, I have discovered first hand that it does so in a way that actually creates a deeper connection with nature and the environment...while saving lots of water and money!