In 2014, I started work on an app for delivering smart advice to people about energy saving. The app was designed based on my own experience as part of the LADWP SmartGrid project where I worked to develop algorithms for energy consumption and curtailment forecasts as well as for customer selection. For a long time, the project has been shelved as I could not find the time for it. As of 2021 and partly motivated by the unfolding energy crisis putting a lot of strain on families around the world I resurrected this project. On this page, you will learn more about it and you can try it out on Google Play (in open tests right now). 
Why save energy? (a realistic reason)
According to a report from REN21 (see page 33 for an infographic) the share of renewable energy of the total final energy consumption has barely changed in the past decade to about 11.2% in 2019 (from 8.7% back in 2009). The causes for this are diverse and include rising global energy demand and investment in new fossil fuels. Most of the consumption went into electricity followed by heat and transport. By burning fossil fuels our power plants contribute partially to global warming, acid rain, and oil spillage. All these impact our and our children’s health by inhaling their toxic by-products. The time has never been better to take action, and to be honest the reasons may not be entirely out of our goodwill. The current energy crisis has not made things easier and its effects are wreaking havoc in our pockets with energy prices set to double, for instance, in the UK by the end of 2022 (simply because of the increase in the protective price cap). We can either pay double or learn to keep up our level of comfort by following some basic rules. But before we proceed let us learn more about energy consumption measurement.
Energy vs. Watt-hours
Each device you have in your home requires a certain amount of power expressed in watts (W) to operate. When you leave the device plugged in or powered on for a certain time it consumes energy which is the product between the required power and the time it is operating. When time is expressed in hours the energy can be measured in watt-hours (Wh). For instance, a 60W light bulb operating for one hour consumes 60Wh, while when operating for 15 minutes (0.25 hours) it consumes 15Wh. When saving energy a watt-hour is also that moment in the day when for one hour you decide to reduce your consumption by increasing/decreasing the thermostat temperature set point by a few degrees during hot/cold hours, dim lights during daylight, or decreasing refrigerator cooling level if the in-house temperature is low, to name just a few options you have.
Using temperature to your advantage
Temperature reset is a common approach to saving energy and it is widely used in certain places such as households and offices. The reason you get substantial savings when increasing the thermostat setpoint during hot days and reducing it during cold days by a few degrees is that between 40-60% of your energy consumption comes from A/C and heaters. The human body can tolerate being a few degrees from the ideal temperature of 71°F or 21°C and by not letting your A/C or heater work too much you can save a lot.
Another option is to use the building’s thermal inertia, that is its capacity to preserve heat/cold even when the difference from the outside temperature is high. By pre-cooling/heating your home one hour before the outside temperature exceeds a certain threshold (maximal or minimal) your A/C or heater will not do as much work when it gets too hot/cold. In the EU space heating represents around 63% of the energy bill with cooling being under 1%. Another 15% is added for heating the water during our baths and showers. For the UK water heating accounts for roughly 6% and electric heating a staggering 65%.
As heating/cooling is the major culprit in your energy bill this is probably the area that we can influence to our advantage. According to a source citing the US Department of Energy, decreasing/increasing (depending on whether it is winter or summer), the thermostat by 1°F (about 0.5°C at the optimal 21°C temperature) saves about 1% of your energy bill. The reality is we do not really need to live at the optimal temperature and most of us are comfortable at 18-19°C during winter and 23-24°C during summer.
Finally, an easy way of saving energy is to decrease the refrigerator cooling level by one or two levels if the inside temperature is low. This can happen during nighttime or when you are absent from your home and do not need to heat the environment too much. Remember the refrigerator contributes to around 10% of your total energy consumption.
Time is your ally
Utilities usually charge more during peak hours, when the aggregated customer consumption becomes high. This usually happens on days that are either too hot or too cold. When this happens their generation capacity is in danger of being exceeded and they are forced to buy from the open market. This impacts both your wallet and the overall environment because power plants need to produce more.
By using your appliances (washing machine, dishwasher, etc.) outside the peak consumption period which usually coincides with the very hot or very cold periods of the day you can help save money and reduce the overall energy consumption and thus energy generation. When possible try to minimize their usage by hand washing dishes for instance. Appliances consume around 9% of your home energy.
During long summer days by dimming or turning off lights, you can also save a significant portion of energy. Furthermore during nighttime try to use only as much light as needed and don’t forget to turn lights off when leaving a room. Lights contribute to as much as 11% of your total energy consumption.
In the EU lighting and appliances account for up to 14% of the energy bill while in the UK lights contribute to an average of 6% while appliances to about 18% depending on what you consider.
The data shown above was taken from the Eurostat – Energy Consumption in Households (June 2021) and the Intertek Report on Household Electricity Survey – A Study of Domestic Electrical Product Usage (May 2012).
If you want to know more
Those interested in a detailed discussion on the optimal temperature and light @ work can have a look at the research article on The effect of indoor office environment on the work performance, health and well-being of office workers by Vimalanathan and Babu published in 2014 in the Journal of Environmental Health Science & Engineering. Results from experiments have shown that the optimal work setup comprises of a temperature set at 21°C and the illumination at 1000 lux (typically achieved during overcast daylight; indoor lights are typically below this value with the average room being around 200 lux).
How can SaveAWattHour App help?
SaveYourWattHour is an Android App that gives you personalized advice on how to reduce consumption based on nearby outside temperature and your energy billing plan. It gives you personalized advice by monitoring the temperature right outside your home and the appliances you have in your home.
Current versions
The app currently comes in two versions. By default, you get the Light version but by purchasing an in-app product you can upgrade to the LightPro version which brings more features:
Light: Enables users to receive recommendations based on outside temperature taken from external weather services such as WorldWeatherOnline. Users can act on the recommendations earning in return badges and share their energy-saving actions on Facebook. Their actions are stored online and identified based on their ID (email) and password.
LightPro: In addition to the Light version, here users receive notifications when they are not using their app. Another feature is that they can see various statistics such as their badge level and worldwide stats including how many more days (action days) they need to advance in the worldwide ranking to become champions of the month.