ADVENTURES IN HOME AUTOMATION

Guest blogger Ruth Mills talks us through her exploration of saving energy via Home Automation. This article is a companion piece to a workshop event by Ruth (available in our members area) on 27/09/2022.

Energy bills, especially in the UK, have rocketed, with further price hikes planned for October. Likewise, we continue to live in a time of climate emergency, with the urgent need to cut down on carbon dioxide emissions. Both factors led me to have a serious think about my energy usage.

Fortunately, I am a home automation enthusiast, with my preferred system being Home Assistant, which I have been running since December 2018. Home Assistant have introduced an excellent energy management feature, which helps keep track of energy usage (and even energy production and/or storage if you have solar panels or storage batteries) — and, being an open platform, you aren’t restricted to specific hardware.

I’ve had a smart meter for my electricity since July 2020 (I had a gas smart meter installed at the same time, but it’s never worked in “smart” mode, despite frequent complaints to my energy company).

Initially, I used Bulb’s SmartThings integration, which gave me an electricity meter reading in kWh every minute or so. This worked with the Chameleon IHD (In-Home Display) that Bulb originally supplied when their engineer installed my smart meter.

But in March, I upgraded to a geo Trio IHD from Green Energy Options, which I bought for £14.99 from Drayton, and which gives me a lot more information on my energy usage, including tariff rates and instantaneous power usage in watts:

There is a HACS component available for connecting to the geo Home API, or alternatively you can configure sensors in Home Assistant yourself (I took the latter approach). Please note that you need to connect your geo IHD to Wi-Fi and sign up to the geo Home app before you can connect to the geo Home API.

It’s also possible to track the energy usage of individual appliances in Home Assistant — so far, I am estimating the energy usage of some of our more power-hungry appliances using smart plugs, and our Philips Hue and IKEA TRADFRI light bulbs using the Powercalc custom component:

Having all this data made me have a big think about my electricity usage, and the steps I could take to reduce it.

I started by thinking about the “heavy hitters” — appliances that eat electricity for breakfast. One of the biggest culprits here was the tumble drier, which could easily consume a kWh (or two) for drying a load of clothes from the washing machine (as per the big spike between 5 and 6 pm in the chart below):

This can easily become a substantial proportion of the day’s electricity usage — perhaps 20–30% of the total even!

So, while the tumble drier can be really useful when you need clothes dried in a hurry, we are now trying to use it as little as possible — instead choosing to dry clothes in the conservatory whenever possible (which gets really hot in the summer) — even though this tends to take a day or two before they are dry.

Likewise, we’ve switched to “eco mode” for the washing machine and the dishwasher; although the eco cycles do tend to take longer, they do use a fair bit less energy overall!

I then decided to look at a rather more insidious contributor to the electricity bill — zombie base load from lower power devices that were consuming energy 24/7. Devices on standby (e.g. the television) or which were consuming energy without actually being used (e.g. the printer). Being a geek, I had rather a lot of such devices. Even though many would be using only a watt or two each, they all add up.

With my current electricity tariff of 27.36p per kWh, every watt of electricity being consumed 24/7 costs me approximately 20p per month. So a saving of 10 watts off my base load is £2 off my electricity bill every month — thats £24 per year! Or an even bigger saving come October, when energy bills are due to be hiked yet again!

A recent electricity bill from Bulb stated that we were using 2kWh less electricity per day on average, compared with a year ago. That’s a saving of almost 55p per day, or a whopping £16 per month, at current rates! A real win!

Future projects I have planned involve using smart plugs (e.g. IKEA TRADFRI) in conjunction with Home Assistant automations, to automatically turn appliances on and off, to save even more electricity!

To save on my gas bill, I upgraded our home to Drayton Wiser smart heating at the end of 2020 (I got an amazing deal on Black Friday from Amazon). This was fairly easy to install; the most complex part of the installation was replacing the existing boiler controls with the new Wiser hub.

Every radiator in the house is fitted with a Wiser radiator thermostat — each of these are powered by a couple of AA batteries, which tend to last a good few months.

The big advantage of this is that each room in the house can have its own individual heating schedule — so we aren’t paying to heat rooms that are not being used.

Likewise, there are features such as Eco Mode (which estimates the rate of heat loss for each room to turn the radiators off sooner, so the boiler fires for less time and uses less gas) which further help reduce energy usage, and Away Mode (which can be configured to heat the house to a much lower temperature when you are away).

Naturally, there is a Drayton Wiser integration for Home Assistant. This has meant that I’ve been able to create automations such as automatically switching to Away Mode (to save gas by heating to a lower temperature) when the burglar alarm is switched to “Armed Away”. As well as being able to use Home Assistant to control our heating as well as via the Wiser app:

If my gas smart meter actually worked, then I’d also be able to take advantage of Wiser Insights+ — which integrates gas smart meter readings in with Drayton Wiser, to further optimise gas usage. Hopefully one day, my energy company will work out what’s up with my gas meter so I’ll be able to!

Ruth Mills is a Senior Software Engineer for a global Business Travel company.