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)

Liquid Nitrogen Ice Cream

Liquid nitrogen, if you’re not familiar with it, is a liquid that is commonly used to preserve tissue samples, remove warts, help keep MRIs cool, or cool high performance computers. The reason for this is its incredibly low temperature: -196 C (compare this to ice, which is 0 C, or dry ice, which is only -78.5 C…).

And this is what makes it perfect for creating ice cream in a matter of minutes… the rapid freezing also results in smaller ice crystals, meaning a much smoother taste. See below for some easy to follow instructions.

You will need a food processor, spatula, access to liquid nitrogen and suitable PPE!


  • 1 cup milk
  • 1 cup double cream
  • 5 tablespoons sugar
  • 1 teaspoon vanilla
  • 1 cup of strawberries (or other fruit to taste)
  • 1 litre liquid nitrogen

Mix all the ingredients in the food processor and whisk for a few seconds. Start gradually pouring in the liquid nitrogen whilst whisking, keeping a spatula on the side of the bowl to break up any chunks of cold mixture. Eventually the mixture will freeze into a smooth, ice cream texture.

Caution: If you go too fast, or the bowl is too small, the rapid boil off of liquid nitrogen will cause your ice cream to bubble over the side of the bowl! (see above picture of the aftermath…)

Safety note about liquid nitrogen: Because it is so cold, and will expand to about 70 times its volume when it warms up, there are 3 major safety concerns when mixing liquid nitrogen and food:

  1. Wear appropriate gloves and clothing when handling, to avoid cold burns. If this does happen, hold the affected part under cold water for a few minutes.
  2. Make sure to perform the activity in a well ventilated room. If you are unsure there are calculators online that will let you determine the drop in relative oxygen content if your dewar of liquid nitrogen were to all boil off at once.
  3. Never eat or drink anything where the liquid nitrogen has not boiled off. This is simple to check as the ‘vapour’ that boils off when you add it to the ice cream will have stopped. Also, the ice cream would be too stiff for the food processor to mix if you had cooled it to -196 C.

STEM Community Day at Loughborough, 16th March 2019

Every year as part of British science week Loughborough University opens its doors to the community to host a range of STEM based activities. This year there are several activities organised by my group and in coordination with the UG reps:

If you’re in the area drop by for a chance to get messy, learn something new, or just have some fun! I will be posting summaries of each activity over the next few weeks.

Science in the Park 2019 – Light Painting

I have added rough times for the images below. They are organised by group(s) for the two separate SD cards that were used. If you do not see your photo in the top, please make sure to scroll through to the bottom for the other SD card.

“I am a Physicist” Challenge


The East Midlands Branch covers Derby, Leicester, Lincoln, Loughborough, Northampton and Nottingham, with centres based in Derby, Leicester, Loughborough and Nottingham. We organise a full programme of lectures, meetings and conferences in the East Midlands and work locally to promote physics, physics education and public understanding of physics.

The IOP East Midlands branch have recently launched the ‘I am a physicist’ Girlguiding badge and resource designed to introduce girls to the fascinating world of physics in a way that is accessible, fun and educational.

Currently being piloted in Nottinghamshire, the badge is open to all Girlguiding sections with age appropriate activities from the youngest Rainbow at 5 to the oldest Ranger at 18. We hope leaders will enjoy the activities too.

The challenge is in four sections:

  • Section 1: Experience
  • Section 2: Create
  • Section 3: Investigate
  • Section 4: Meet, visit, community

The pilot will run until the end of the year during which time workshops and events will be run to support leaders, such as a stand at Science in the Park at Wollaton Hall and Deer Park next weekend, or at County Day on 23 March. Look out in the Girlguiding Nottinghamshire diary for further dates.






Science meets art: painting with ferrofluid

Petri dish with ferrofluid and watercolours. A bar magnet is hidden underneath the petri dish, resulting in a competition between magnetic force (on the ferrofluid), surface tension, and the immiscibility of water and oil.

Ferrofluid, as described here in greater detail, is a suspension of iron oxide nanoparticles that are so small, that they align themselves immediately with an applied magnetic field (superparamagnetism). This results in a spiky pattern that gives an indication of the position of magnetic field lines, which I like to refer to as the ‘hedgehog’.

If you inject a water based paint into the ferrofluid, when a magnet is held on the other side, you will be able to form domains of colour suspended in the fluid – as seen above.

Academic Peer Review

What is the difference between online content and journal publications, when it comes to science?

The majority of published academic work will go through what is known as a ‘Peer Review Process’. The idea behind this is to provide quality control by having experts question the scientific method employed, the analysis of data obtained, and the arguments put forward to explain what is happening. This largely acts as a ‘fact-checking’ step in the publication process.

For a typical publication, a manuscript will be drafted and sent to the editors of a journal. These can either be employed, full time editors (such as at Nature or Science), volunteers from the academic community (such as most Conference proceedings), or a combination of both (e.g. European Physics Letters).

The manuscript will first be checked for a minimum standard (this varies between journals), and then sent out to experts in the international community who volunteer their time to perform these peer reviews.

The result of such peer review is normally one of the following:

  1. Acceptance – the article may require small changes, but is otherwise accepted for publication.
  2. Rejection – the article is not of sufficient quality or interest for the particular journal and is recommended to be published elsewhere.
  3. Respond to reviewers – the peer review process has identified potential questions or weaknesses in the manuscript. There are specific changes or questions that need to be addressed after which the manuscript will go through a second round of peer review and either accepted or rejected.

Open access publishing

Historically, scientific publications have fallen under the ‘subscription’ model, where an individual or their employer/institution paid a fee to access journal articles. You will have probably seen this if you ever tried to find a journal article whilst at home.

There has in recent years been a push from the academic community as well as some  Governments away from this model, so that the research is more readily available. This is where open access publishing comes in.

In the UK, for example, the Government requires some open access version of every publication that an institution wants to submit to the REF (a regular quality assessment of University research outputs). This can be done in one of 2 ways:

(1) By paying ‘open-access charges’ to the Publisher of any research outputs. There is some money available for this for UK funded research. Charges vary from publisher to publisher, and an also depend on the length and composition of the journal article (for example, whether colour images are included).

(2) By depositing a version of the publication on an institutional repository or archive. This requires some knowledge of the copyright restrictions for each publisher and is usually handled by the institution’s librarians. It is quite common for science articles to be deposited on the ArXiv prior to submission to a publisher for peer review.

The ArXiv

The ArXiv is a server that hosts pre-submitted journal articles. It was established by  Paul Ginsparg, originally at Los Alamos National Laboratory, who later moved to Cornell University. It is currently hosted by Cornell University’s library and is commonly used to quickly disseminate scientific results, especially for research that is moving quickly.

Conflict of interest

Of course some might argue that there is a conflict of interest in these proceedings, as the peer reviewers can be influenced by their own biases. There is often also anecdotal stories of ‘discoveries’ being blocked from publication by a peer reviewer working in the same field who wants to publish first, or who are proponents of alternative theories. This can largely be avoided at the submission stage by identifying specific individuals that may have a conflict of interest.

Characterisation Methods in Solid State and Materials Science

I’m in the process of writing a textbook for the IOP E-book portfolio that will focus on characterisation techniques, in particular for solid state physics.

This will include:

  • X-ray and Neutron Techniques
  • Microscopy Techniques
  • Spectroscopy Techniques
  • Magnetic, Electric, and Thermal Characterisation Techniques.

And will, as far as possible make use of open source data to provide real world problems for students to tackle (focusing on data analysis).

I am therefore, actively looking for journal articles that may use one or more of these techniques and where the original datafiles are accessible. If you have work that you think would be relevant then please contact me. Of course all relevant files and journal articles would be referenced.

Double Rainbow

Can you see the double rainbow?

Ever noticed how the order of the colours changes for the second rainbow (red – yellow – green – blue – violet…)

Typically rainbows are formed when light is refracted (bent) through a raindrop.

A double rainbow forms when light is refracted twice in a raindrop, and occurs commonly when the sunlight is low in the sky. See here for more.