Western Alaska averages around 14,000 heating degree days per year. Energy use for space heating here is among the highest in the nation. The region is not connected by a road system and there is no deep water port. Fuel can only be delivered to remote communities by ocean barge during summer months; the cost of that fuel is high.
The financial benefit of increased energy efficiency in such an environment is high. Recognizing this when fuel prices soared, not long ago, the State of Alaska began to make a significant investment in weatherization and energy efficiency. To date, decisions about what types of investment would produce the maximum benefit were based on building theory... eg: the numbers tell us that doubling the insulation thickness will increase energy efficiency by X%. While savings predictions based on building theory are compelling, the savings associated with different types of investments in efficiency have never been proven. In the past the data wasn't available, and the cost of gathering using legacy technology was prohibitively high. A couple of years ago I set out to develop a device, using low cost internet of things technologies, that tracks the actual amount of fuel used for space heating in real time in remote isolated Alaskan homes. I have been met with some success. I will share that with you today.
Low-volume fuel flow metering devices are relatively expensive. Fortunately they are not needed for this task. Residential boilers always use the same amount of fuel per unit time when they are operating. Fuel consumption per unit time can be accurately estimated when the fuel pressure and nozzle size are known, and information about how much fuel is left in the storage tank can be used to fine tune those estimates over time. The upshot of all this is that all we need to know is the amount of time a boiler has been operating in order to calculate its fuel consumption. That's one piece of the puzzle... every time a boiler changes states, from off to on or from on to off, it creates a database record via the internet. But that's not all that is needed; the problem is a bit more complex.
Residential boilers also burn fuel to heat water, so the amount of fuel used for water heating needs to be subtracted from overall fuel usage to arrive at fuel used for space heating. Fortunately, water flow meters with a digital interface are relatively affordable. If the cold water temperature, the hot water temperature, and the amount of water consumed are known then the amount of energy used for water heating can be accurately determined... incorporating two thermometer chips and a flow meter into the device solves this problem.
What I'm really trying to quantify the relationship between temperature differential (Indoor - outdoor temperature) and fuel consumption. On a more macro scale what I'm after is the relationship between fuel consumption and heating degree days. Adding an indoor and an outdoor thermometer to the package provides the data I need to solve this problem. To make the thing work, however, one more data point is needed.
How much fuel is in the tank? We need this to nail down the boiler's exact fuel consumption per unit time, since we started with a theoretical estimate. An ultrasonic range finder mounted in the top of the tank can gather the data. I found a low cost one and incorporated it into my system.
What we now have is a device, costing well under $100 in small quantities, that tracks the inside temperature, the outside temperature, the on/off state of the boiler, the volume of hot water consumed, the inlet and outlet temperature of the hot water, and the amount of fuel in the tank. Every time the state of the boiler changes from on to off or off to on it publishes data to the web. The internet of things device I'm using, available in both WiFi and Cellular flavors, handles the data communications seamlessly. It's powered by a USB wall-wart and has battery backup. I'ts a fabulous child of the internet of things!
I know hundreds of homeowners across the Bering Straits Region as a consequence of my job. My employer built five "extremely energy efficient homes" in a remote village a couple of years ago; I have my eye on them. I'm still waiting for an affordable reliable wireless interface for my sensors, but I can move forward without them. The plan is to deploy working prototypes to the field in early October. I will keep you posted.
In conclusion: My device, built using affordable reliable internet of things technologies, will gather data in real time that is currently unavailable from any other sources. Aggregated data will facilitate better informed energy related decisions at the macro scale, and individual homeowners will be able to see how different behaviors affects energy consumption from day to day.... and that's only the tip of the Iceberg.