Using Data in an Energy Crisis

The way energy prices are going, I thought I would share the data-driven approach we've used in our home, to get a grip on our energy consumption profile, and to understand our options. I really enjoy playing with data and tweaking things around the house to squeeze out just a little bit more performance.

The baseline requirement to understanding our energy consumption was the installation of a smart meter. Without this, we did not have enough fine grained data. I downloaded our historical energy consumption data, in increments of half hour intervals, from n3rgy.com. This is a free service for domestic consumers.

1. Reduction and efficiency. Apart from reducing discretionary consumption, the biggest driver is insulation. We have a decently insulated home, thanks to previous owners. This winter, I have requested the local council for a loan of their thermal camera - I can point it at my house for it to show me where the thermal leaks are. This is a free facility from most local councils - you just need to get in the queue. To reduce radiator heat going out through the external walls, I inserted reflective insulation betwen the radiators and the walls - this is invisible, and costs less than ￡1 per radiator, so, worth doing even if the benefits are tiny. I found inexpensive car windscreen reflectors at Lidl, and each was big enough for two radiators. I switched all radiators to smart TRVs - so the radiators get switched on only if the room needs it - this was expensive, but felt like the fine grained control we needed to heat only the parts of the house in use at any time. For example, we don't use the bedroom during the day, especially as we are out and about a lot more these days. For the summer, though tempted by the odd warm week, we decided against air-conditioning, as we get a nice breeze through our windows.

2. Understanding our energy consumption profile. The graph below shows key weather data for our postcode by hour. I downloaded weather data from visualcrossing.com, which provides historical weather data in hourly increments per UK postcode. The red graph is the average hourly temperature for the month, and quite obviously, correlates to our energy usage, the green graph.

3. Getting off gas. We made the switch to an air source heat pump (ASHP). Having used it through the winter, we found that our energy consumption has actually reduced. From using 20,000 kWh a year down to 12,000 kWh. This is because the ASHP operates at 350% efficiency vs. gas boilers operating at 70%. However, our ASHP only heats water to 55 C while gas boilers crank it up to 80 C - gas boilers get you warmer quicker than ASHPs. These are tradeoffs that still appear to tip this in favour of ASHPs because we see it in reduced energy consumption. Plus getting off gas is a major plus for the planet. The green graph show our hourly consumption - and clearly, it peaks in winter. But, what are the troughs in the middle of every day? Solar panels.

4. Solar Panels. Any microgeneration infrastructure being set up at home is essentially a way of pre-paying for energy. Swapping operating expense for capital expense. Solar panels are zero maintenance, so, once they were up there, we forgot all about them. But how useful are they? Back to the data. The orange graph is the average solar radiation my postcode receives. This is directly proportional to the troughs in our energy usage profile through the day. Clearly, this is when the solar panels are kicking in to reduce the power we draw from the grid. With roughly 4kWp generation capacity, I can see that it is not enough for our winter energy use. The data tells us that doubling the solar capacity would save us roughly ￡3/day at current electricity costs in winter. That's nearly a 4 year payback on the cost of the expanded array. If energy prices go up further, this payback period reduces. Back when we installed our panels, the energy prices were much lower than they are today, giving us a 7 year payback period. This window keeps reducing as energy prices go up, but will reset as inflation drives up the cost of the panels. This graph also told us that at the current rate of energy production, we wouldn't benefit greatly from installing a home battery like a Tesla Powerwall (unless we went in for the Tesla Energy Plan, which is a big win if you are able to stump up for a rather expensive battery).

5. Other Microgeneration. Clearly, our solar panels are not the answer to getting off-grid. They only work when the sun is out, and the sun is barely out when we need energy the most - in winter. Looking at the weather data again, the windspeed in our postcode rarely drops below 7mph through the year. A wind turbine would work regardless of the sun. This is far from straightforward, though. Wind turbine capacity is linked to the size of the blades, which take us into complex Planning Permissions territory. The silver bullet for our situation is to find a vertical turbine (not the expansive spinning blades) that can generate 5kWp at windspeeds of 10mph. That's not going to happen any time soon.

6. Tweaks. Wearing a sweater. We set our thermostat to 18-19 C and wear a light sweater around the house. We use draft excluder tape on door and window edges to stop leaks, as well as on room thresholds to isolate heating to where we need it. This is an inexpensive way to increase the thermal efficiency of the house. Floor insulation is always a difficult question - the floor was laid down before we bought the house, so, we aren't quite sure if the stone floored hallway is insulated below. We use a rug running down the entire length to insulate it to some extent. Around 10 years ago, we replaced all carpets with insulation and hard flooring, so, that's something we know we can trust.

7. Electric Cars. This is a slightly different calculus, and all you need for it is your electricity rate, and the cost of fuel. I won't go into that in this article, but this is where you start wondering about night time electricity rates, and complicate your life further!

There is a ton of data available to help understand energy consumption profiles and how microgeneration solutions might help. Here's a quick recap of the tools I used:

1. Historical smart meter data: https://n3rgy.com, click on "I am a consumer", and enter your smart meter info to download data. You can go as far back as you like, but it only gives you 90 days worth of data from the start date of your report. So, you'll need to run 4 reports to get a year's worth of data.
2. Historical weather data: https://visualcrossing.com. You can choose the weather elements you want to include in your report, and there is a rich variety of data that is available. You need to pay to download the report, but it is less than $1 a report.
3. Analytics: You can mash all this data up and come up with your own visualisations using Tableau for free. Most of us use Tableau or consumer reports from it at work. Why not use it to your advantage for your own finances? It is free at https://public.tableau.com.

Hope this was fun and helpful - let me know in the comments if you have discovered any more data hacks towards a better way for households to plan around energy consumption and generation.