Efficient Energy Android App

Although smart home appliances have their own apps which can do this stuff, the percentage of people with out smart appliances is very high. So, I think this app targets those people who cannot afford or have privacy concerns with smart appliances. This Androd app allows users to estimate daily/monthly/annual* energy usage for each appliance. Estimating energy usage can be very useful in getting some knowledge on how much we are spending on each of the appliances(roughly).


When you open the app for the first time, it will show you an empty list which is to be filled by the user. The fields in the list are as follows:

  1. Name of the Appliance
  2. Wattage
  3. Hours of usage

Now, there are several ways to estimate the number of hours per day an appliance runs. Either estimate it roughly or keep a log for few days. For example, we can record each time we use oven to bake something or television etc..

To find the wattage of the product, we can either look at the stamped paper on the bottom or back of the product. Or, we can look it up online.

When the user is done entering the information, user can tap submit button.

Then, the app calculates the daily consumptipon using the folllowing equation: (Wattage × Hours Used Per Day) ÷ 1000 = Daily Kilowatt-hour (kWh) consumption

Then, the app calculates annual energy consumption using the following equation: Daily kWh consumption × number of days used per year = annual energy consumption

To calculate annual cost, Annual energy consumption × utility rate per kWh = annual cost to run appliance

Let me explain all the above steps with an example

  1. Consider a Coffee machine that runs several times in a day , for about 1 hour in total.
  2. Assume the wattage is labeled as 1500 W
  3. Daily Energy Consumption: (1500 W )/1000 = 1.5 kWh
  4. Annual Energy Consumption: 1.5 kWh x 365 = 547.5 kWh
  5. Annual Cost: if utility rate is 11 cents per kWh 547.5 kWh x $0.11/kWh = $60.23/year

I have used aws lambda to send occasional push notifications on how to save energy efficiently.

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