More Comparisons

Having calculated [or rather tested] that my house uses 2kWh of energy per day when nearly everything is turned off I thought I ought to work out how far that would drive my car.

In this communication I wrote about the energy usage of my car, Bora Horza Gobuchul. I use 50kWh of energy for every 100km I drive, on average.

So, the energy I use to power my house; the fridge, a few clocks and the ADS-B receiver, would drive my car about 4km. That’s not quite enough to get me to work, but it would get me to the nearest supermarket.


I recently had my electricity and gas meters upgraded to “smart” meters. They aren’t that smart. All they do is upload my meter reading to the utility company at regular intervals along with this information being displayed on a screen. I look at the screen now and then but I do think that eventually I will turn it off. I know roughly how much I spend each day and it’s not really a surprise.

May Energy kWh
May Energy kWh

This graph shows the energy use each day with the lower darker bar being electricity and the light blue being gas. I have a gas boiler for water and heating along with a gas hob. The oven is electric. This can be translated into costs [at current market rates]:

May Energy Costs
May Energy Costs

At the end of May I went away for a while and I normally try to shut-down most of the energy using devices in the house. The physical process can take about 5 minutes walking around the house making sure that everything is shut down in the correct order.

If you look at the last week of May you can see low and consistent energy costs. Although no gas was used in this time period the monetary costs is the standing charge that I pay for the privilege of having a gas supply.

Minimum Running
Minimum Running

My daily energy use in a house that is mostly turned off is 2kWh. This accounts for the following items:

  • Fridge
  • Microwave clock
  • Oven clock
  • Modem / Router
  • ADS-B aircraft tracker in the loft
  • Alarm clock
  • That extension lead orange light

It is taking a while for my head to get around this bizarre and stupid unit the kWh. But here goes:

My house’s power usage at baseline is 83 Watts. A human during the normal day runs at about 100 Watts [as does a 100W incandescent light bulb]. Over the course of the day this ends up being 7.2 MJ. My house needs to consume about the same amount of food as a human to run at its lowest power consumption levels.

Wolfram Alpha has some lovely comparisons for energy usage, so 2 kWh is the same as:

  • ≈ 1.7 × energy released by explosion of one kilogram of TNT ( 1 kilogram of TNT )
  • ≈ 0.57 × average electrical energy required by an Apple iPhone 5 per year (≈ 1.3×10^7 J )

And my favourite is:

  • Relativistic mass m from E = mc^2: 80 ng (nanograms)

When I next go away it would be interesting to see how low I could get the consumption. To be fair, I could just turn the electricity off at the mains. But the only thing I could still power down is the ADS-B receiver and I like to keep that going because I can log into it from around the world.


A few communications ago I wrote about the energy consumption of different cars. I thought I would try and give some perspective to this. Now, I haven’t done the mathematics at this point and so will be writing this as I go. I don’t know what the results are going to be.

My car, Bora Horza Gobuchul, uses 50 kWh of energy, roughly, every 100 km I drive. Given that my insurers believe I drive about 10,000 miles per year that’s a grand total of:

8000 kWh per year

Let’s see how much this costs in fuel alone. 10,000 miles is about 200 gallons of petrol, which gives, at prices of £1.20 per litre, £1,080 per year on fuel alone.

I have a small Victorian house. While it is small it has poor thermal efficiency. It has brick-thick walls with no cavity insulation and is draughty. I do have a chimney balloon in one of the chimneys and the other is boarded up. The bathroom and kitchen stick out the back and are cold all year.

A Year’s Energy

I use gas for heating, hot water and hob cooking. I use electricity for some heating and then appliances and light. As the graph above shows I used 10.5 MWh of energy in the house last year [assuming the meters are correctly calibrated]. This cost me £840 for the year.

So, loosely speaking, the amount of energy I have used to transport me and a 1.5 tonne car around is about 30% more than that I’ve used to live in my home. Considering the time I spend in the car is minimal compared to my house this seems a poor deal. Granted, my car moves around relative to the Earth but this just goes to show how much energy is needed for transportation.

The costs turn up the following figures for comparison:

House £0.08 per kWh
Car £0.135 per kWh

I think it’s time to start voting Green. We also need to start a massive system to change societies need for personal, inefficient transport. There needs to be a cultural change and it needs to start now. It’ll take 20 years to change behaviours and it’s quite likely already too late.

Start of a solar farm

Here are the foundations of a solar farm. I guess it has received planning permission as the last I knew it was just a proposal. Clever work though as the panels are bolted to the concrete sections that were part of a packing site.
If I remember I’ll link to the company doing this. Just imagine that Eccles and Aylesford might be leading the way in green tech.