Tag Archives: electricity

Reducing Energy Usage

I’m writing this as we approach autumn in 2022, with general increases in the cost of living as well as the spectacularly high increases in energy costs projected for the UK from October (and then again in January). Yes, this is a cost of living crisis. And yes, energy is but one – fairly large – part of this. Mindful of the fact that many will not be able to afford even small increases in the cost of energy, nevermind what is predicted for October, I’m going to describe several approaches to minimising energy that can be applied as possible.

The first consideration is to identify where your main sources of energy usage are. Typically it would include:

  1. Central heating (gas or electric)
  2. Heating water
  3. Cooking
  4. Freezers and refrigerators
  5. Washing machine
  6. TV
  7. Dishwasher (if you have one)
  8. Tumbledryer (if you have one)
  9. Computers (if you have/use one at home)
  10. Other small electronics (phones, tablets)

Let’s start with central heating.

a) If you have a condensing combi boiler without a hot water cylinder: by turning down the flow temperature on your boiler you could save between 6-8% on your gas usage. The flow temperature is the temperature of the water passed out to the radiators (not set on the thermostat) and the temperature at which it returns. By lowering the flow temperature you can set the system to run in ‘condensing’ mode more than it may currently be doing, which increases the overall efficiency of the system. Usually it runs at 80/60: 80 degrees Celsius out to the radiators and 60 degrees Celsius on return.

However this is tricky to get right, and would usually be set by an engineer during a service (so worth asking about). If you do reduce the flow temperature note that it will increase the time it takes for your rooms to warm up. In other words, you’re trading speed (of heating) for efficiency.

b) Explore the use of valves on your radiator, to tailor the level of heating in each room. These come in two general types:

(1) Manual valves – which adjust the flow of water to each radiator.

(2) Thermostatic Radiator Valves (TRVs) – which control for the temperature in a specific room.

You could choose to only heat rooms that you are using, or if the thermostat in your house is in a room that is usually warmer/colder than the rest of the house, it allows you to adjust each room as needed. (For example, I usually close the valve in my office as work most of the way as I prefer it cooler than most.)

Heating water

As with your boiler, you have some choice on the temperature of hot water (that will vary depending on your system):

  1. With a combi, for example, the hot water is heated as you need it to a set temperature.
  2. With immersion tanks you heat the ‘tank’ and use this throughout the day (or until you switch it on again). These should be surrounded by thermal insulation to prevent loss of heat as you wait to use the hot water. For newer tanks this insulation is integrated into the design with solid foam; for older tanks it will be more obvious (and is worth checking that the insulation is still in good condition).


There are several options now for cooking meals, with a wide variety of energy costs associated with them. The most efficient of these will be the microwave, air fryer and pressure cookers. Part of the reason for this is the reduced volume of space that needs to be heated (you can often feel the kitchen warm up as you cook a roast, for example). Another element is that less steam is lost to the environment during cooking (so that heat can be used to keep cooking your meal).

As a ballpark figure, an Instant Pot Pressure cooker, or air fryer uses about 10% of the energy that an electric oven would to cook the same meal.

Freezers and Refrigerators

The main aim of a freezers or refrigerator is to keep a volume of space cooler than the rest of the house: the freezer is usually -18 degrees Celsius, whilst the fridge is usually +1-4 degrees Celsius. After heating (and possibly depending on your usage, cooking), your refrigeration will likely be the largest consumer of energy in your household. This stems from the difficulty in moving heat from one area to another (it’s not particularly efficient!) and will obviously be impacted on how often that fridge/freezer door is opened throughout the day as you let heat in. Whilst there have been advances in the efficiency of these appliances over the last 20 years, they can easily use 1 kWh per day (which on an electricity rate of ~50p/kWh, would equate to £182.5 per year).

To ease the burden on your fridge/freezer, pick a location in the house which is the coolest (it is easier to move heat to a cooler room than a warmer one), make sure that there is some space between the ‘fins’ at the back of the fridge/freezer and the wall (so air can flow past), and make sure that the seals on the door are kept clean. All of this should help to keep it running as efficiently as it was designed to.

Refrigerator cycle (vapour compression and MCE)

Useful Resources

I will be adding resources here as I find them – mostly Maths and Physics themed.

Online Mathematics Course

Loughborough’s Mathematics Education Centre runs a free, three-week MOOC – Getting a Grip on Mathematical Symbolism – designed for those students aspiring to become scientists or engineers but who lack mathematical confidence.

It will run again on the FutureLearn platform starting May 8th. Registration is open now:


The course is designed for students who have some engineering or science knowledge gained through vocational qualifications or through workplace experience but who perhaps have not studied mathematics formally since leaving school. It will be appropriate for those who lack confidence but who need to establish a bedrock of knowledge in order to further their education.
This is a foundation, entry-level course and is not intended for those who already possess recent post-GCSE mathematics qualifications. It is highly recommended for those students going to university who have not studied maths beyond GCSE. Please share when appropriate.
Note that it is planned to run this course again shortly before the start of the new academic year in September.

Magnet Academy

Magnet Academy is an online resource provided by the National High Magnetic Field Laboratory — the largest, most high-powered magnet lab in the world. It has a wide selection of useful tutorials about electromagnetism for ages 5 upwards.

Interactive Magnetic Tutorials

British Science Week

As part of British Science Week, Loughborough University hosts a ‘Community Day’ event where Loughborough locals are invited on campus to take part in various ‘science based’ activities.

This year it falls on 25th March I will be:

  • Coordinating an Electrodough workshop – for which we’re looking for student ambassadors.
  • Running a ‘Cold Science’ demonstration with liquid nitrogen.
  • Working with the East Midlands Institute of Physics to deliver several ‘busking’ activities –  for which I’m looking for student ambassadors.

If you’re interested in getting involved please let me know.


Fleming’s Left Hand Rule

Any charged particle moving through a magnetic field will experience a force that will cause it to move in a particular direction. An easy way to remember the direction of this force is Fleming’s Left Hand Rule (where the direction of current is the direction in which positive charges move).

Illustration of Fleming's Left Hand Rule

Illustration of Fleming’s Left Hand Rule

So for the example above, a positive particle moving into a uniform magnetic field experiences a force that pushes it up away from the magnetic field. This “motion” of the charged particle is due to the magnetic field that the moving charge makes, interacting with the magnetic field it is moving through (just like two magnets can repel each other).

We can use this rule to figure out the direction in which the rotating arm of a motor will move.


This effect is used to define the standard international (S.I.) unit of magnetic field – the Tesla.

1 Tesla = the value of magnetic field (B) that causes a force of 1 Newton to act on a 1 meter length of conductor (i.e. copper) carrying a current of 1 Ampere at right angles to the magnetic field.