Last week I was kindly invited to talk about my “Smart home” experience to the AMO. When I started my journey 8 years ago energy bills were not a big discussion topic and so I found it hard to get anyone else interested in what I was doing. 8 years later and everyone wants to know!
When I bought my 25-year-old house a lot of things like the boiler, water tanks, radiators and windows needed replacing. I have a south facing garage roof, ideal for solar panels so the opportunity to replace and upgrade my home with products that might save me money in the long run seemed to be a no brainer. I’ll be honest in saying I didn’t do a payback calculation for each investment and my calculations/guesstimates that follow are simplistic to say the least but overall it felt like it would benefit me in the long run.
I admit I also like the “tech” and I had the luxury of having a budget set aside to improve the house. Roll forward 8 years and I estimate I save around £5,000 a year on my energy bills using Smart technology but what is interesting to me and hopefully to you is where the savings come from. Please note, my calculations are very simplistic and illustrative. I recognise that my family uses more than the national average. Each home and user is different, so your calculations may come up with different savings.
Gas
Usage before upgrades = 45,000 kWh per year, after 29,000 kWh per year (saving 35%)
- Condensing boiler, properly adjusted – circa 10% energy saved
- Triple glazing – circa 10% energy saved
- Mega flow hot water tank and new larger radiators allowing lower boiler flow temperature – circa 10%
- Extra insulation and NEST controls – 5%
Conclusion = In my case all of the savings on gas come from lower energy use made possible by energy efficient products and not from a material change in the family’s behaviour. My circa 35% saving would widely differ house by house depending on what you had before.
Electricity
My total consumption has gone up due to buying an electric car and having a growing and energy hungry household, however on a like for like basis the annual saving is circa £3,160. The interesting conclusion is that unlike gas the annual savings come mainly from “load shifting” with an off-peak tariff and not from lower total energy use.
Energy ‘saving’ (less power taken from the Grid) = £660 per year
- £600 pa – solar panels (approx. 12p kWh to generate (capital cost + losses) vs 34p to buy from the Grid) – (the benefit would be less if you don’t use all of the power offset by any export tariff)
- £60 pa – LED bulbs and lower energy appliances
Load shifting to take power off peak saving £2500 per year
- 9,500 kWh grid use x 7.5p/kWh (off-peak) instead of 34.5p/ kWh Ofgem energy price cap = £2500 per year (not including cost of Tesla battery**)
To load shift like this you really need two things and ideally three. Firstly, you need an off-peak tariff such as Octopus Go. This allows you to buy electricity for a significantly reduced price; in my case 7.5p/ kWh between 12:30 – 4:30AM. Secondly, you need to use timers (often built into appliances or electric vehicles) to move your consumption from the peak times of the day to the off-peak. Most washing machines and dishwashers have this functionality if you look for it but many other appliances also do. The third thing that really allows you to maximise load-shifting is a battery (in my case a 14kWh Tesla Powerwall 2). With this you can also charge the battery using off-peak energy and then use it to supply the daytime loads you can’t load shift. For example, if you use your 3kWh oven between 5-6pm this energy will come from the battery which was charged off-peak at 7.5p/ kWh and not directly from the Grid at 34.4p/ kWh). When this whole system is optimised (and in my experience) it can be possible to buy all or nearly all of your energy needs at the off-peak rate therefore saving the difference between the Ofgem Energy Cap of 34.5p and the off-peak rate of 7.5p (saving 26p/ kWh).
** My very rough maths tells me it costs me about 12p/ kWh to store electricity in my battery and so the “real” saving per kWh is similar to solar at 22.5p/ kWh.
Conclusions
- Solar PV and batteries work really well
- The majority of my savings come from load shifting which can be maximised by using a battery such as a Tesla PW2
- With Smart products great results are possible without any inconvenient changes in behaviour
- The tech just works
- Each case will be different so do your own research (beyond what I did), work out what will and will not work for you and make a plan.
- Live long and prosper (stay warm)
Steve Adams – Smart consumer.