Reduce your energy bill in 5 steps

I regularly get the question how I use the data that comes from my P1 meter and how I use it to reduce my energy bill. Insights are great of course, however if you don’t do anything with the data it doesn’t really add any value or save you money.

In this article we’ll show in how to reduce your energy bill in five steps:

1. Build or buy a P1 reader
2. Collect data
3. Turning data into action
4. Make changes and automate
5. Profit!

So how can you get the most out of the data from the P1 meter and turn data into action?

Step 1: Build or buy a P1 reader

Well, no rocket science here. To get real-time data from your energy meter, we need a device that can read the data from your P1 port. You can either build it yourself, or buy a P1 reader like the P1 Primo.

Step 2: Collect data

Once connected to the P1 port, the P1 reader should automatically collect the data. The most important metrics are energy consumed and energy produced, if you have solar panels. The P1 Primo uses ESPHome and can show the data live on a webpage. Great to quickly glance what’s happening, even though it’s only a snapshot.

To really make an impact, historical trending is key. Your energy usage demands are different per hour, day or season so what’s normal today might not be in a week’s time or when the weather changes. You want to do side-by-side comparison to monitor progress and usage over time. For the most detailed overview you should also use smart sockets for per-device monitoring, however the aggregate data is a great starting point.

For trending you can use Home Assistant, which stores data by default for 10 days. This can be configured to be longer, alternatively you can use an external database like InfluxDB with Grafana in Home Assistant.

Step 3: Turning data into action

Option 1: the energy dashboard

Once you have all of this in place and data is coming in, it’s time to visualise this data. The built-in Energy Dashboard in Home Assistant is a great start as it shows your energy usage by hour. The data is aggregated so you won’t see any details here, here’s what it looks like for me.

I use smart plugs for my single phase appliances, as you can see that doesn’t add up to the total amount. My 3-phase appliances are the main culprits, however I have no dedicated smart power monitoring for those. That brings me to the custom dashboards, which is the preferred way to derive the usage of those appliances.

Option 2: your own dashboard

Building your own dashboard takes a bit more time, but it’s worth it! Here’s a simple dashboard that shows today’s energy consumption. This one is from Grafana, but the History dashboards in Home Assistant can show something similar. As you can see, it provides lot more context than the aggregated amount per hour. You’re probably immediately drawn to the spikes, we’ll get to that soon!

Let’s focus on the other side first: what’s your minimum usage? You can probably get some quick wins there. There might be devices that are on standby at night. Turning them off completely or on a schedule using a smart power plug could already save some money which adds up over time. I’ve heard stories of people that found 60W light bulbs this way, not realising they hadn’t changed those yet.

Step 4: Make changes and automate

Once you have brought your minimum usage down to a level that you’re happy with, do the math on what that would like like for a whole day. In my case, my minimum is around 260W with fridges, a freezer and primarily a heat pump. Extrapolating that to a full day that would be ~6.25 kWh. With energy prices in The Netherlands of over €0.80ct/kWh that’s €5 per day or €150 per month already. Every little bit of improvement helps to reduce your energy bill! Home Assistant is great for automating things to help with this. You can turn off your office power after hours or put timers on lights to be more efficient.

The big consumers often take a bit longer to optimise. This could be your EV, heaters or compressors for example. Some of them are key in providing your home with some comfort so turning them off isn’t really feasible. The spikes in my graph are from a 2007 Stiebel Eltron WPC13 heat pump. It’s not ‘smart’ and uses 3000W-5000W when it’s heating up the house and/or the water. By adjusting parameters on the heat pump I’m gauging the impact on the usage without sacrificing comfort. It takes 24 hours to see the difference so it is a slow process unfortunately. It has certainly helped though in bringing the energy consumption down by a significant amount.

I’m currently tweaking it even further by looking at CAN bus data from the heat pump – more on that in a separate blog post. Key takeaway is to really look at the consumption over time, not just aggregated per hour. The great thing about the P1 port is that the data is instant: if you turn on the kettle you’ll immediately see how much it consumes.

Step 5: Profit!

Once you’re happy with the energy usage, sit back and relax – for now. Over time you’ll probably add more devices or replace certain appliances that have a better energy label and you’ll get some fresh insights. You might buy an EV, which potentially has a big impact on energy usage. If you want to take matters in your own hand and you have solar panels, it’s worthwhile to adapt your energy consumption to the energy produced where possible using automation. You can heat up the water or house a bit earlier to benefit from the sun, or charge your electric vehicle whenever there’s spare capacity.

I’m keen to hear your experience and how you managed to reduce your energy bill using Home Assistant!