Saving with Smart Plugs

Saving with Smart Plugs

A few months ago, we gifted our schools a set of very smart Smart Plugs, which can be used to measure consumption, set timers, remotely turn off appliances, and set holidays. We wanted to use the data from these smart plugs to inform our behavioural recommendations, hoping that we could use it to prove how much money and electricity could be saved by turning off key appliances.  

Our findings 

One of the plugs was attached to a microwave, which was left on almost 100% of the time, even during the summer holidays. The graph below shows the total watts consumed per hour over a period of almost 3 months (July-September). As you can see the consumption increases during the school day, but the difference is not as pronounced as you would expect, because the base load of the microwave means that it is consuming an average of 37W, even when it is sitting empty. 

This means that the school is paying for a microwave that no one is using. Using the school’s (pre-energy crisis) electricity tariffs, we were able to calculate that this microwave cost them £13.08 over this period. We were also able to work out that if they turned it off overnight (between 19.30-06.30) they would have saved £5.50. Now, this may not sound like a lot of money, but it serves to demonstrate that turning appliances and devices off overnight actually can save you money. To put it in perspective, we visited a school in the summer that had 16 microwaves dotted around the school. Assuming that they could make similar savings to school with our smart plugs, that would be £88 over 3 months and £350 in a year. Now that is a good saving!  

Graph showing total electricity consumption from a microwave, per hour, over 3 month period

Similarly, when looking at the data from a chromebook charging trolley, which has space to charge up to 30 laptops at once, we found that when idle and plugged in the trolley was using 15Wh. Opposite to the microwave, however, we recommend that the school use our smart plugs to put the trolleys on a timer so that they charge the laptops overnight, making use of the cheaper electricity tariff, and timed to turned off after a few hours of charging. This should maximise efficiency and minimise costs. All of the schools we work with have chromebook trolleys, sometimes as many as 1 per class. Schools can save at least £10 per trolley – and every little helps.  

We hope that this data will help demonstrate to the teachers and pupils in our schools that small acts like switching off appliances at the end of the day can end up having a big impact. And of course, the same applies to all of your appliances at home. It is a smaller scale (assuming you don’t have 16 microwaves at home) but changing your habits and turning off devices that you don’t need will have an impact on your bills – and the planet.  

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