Current patterns of consumption

What do we use energy for?

The government publishes annual statistics about how energy is used at the UK level.  Bear in mind that this is a slightly different geographic boundary to the regulation of gas and electricity networks at GB level. In government statistics on energy consumption, energy use is divided into three main categories: domestic; transportation; industrial and other final uses of energy.

Total final energy consumption in the UK, in 2017, was 81 TWh (terrawatt hours). The pie charts below show how this is shared between different uses . In 2017, 40% of final energy use was for transport, and another 30% was used in our homes (‘domestic’).

Total final energy consumption in TWh, UK, 2017

The non-transport energy uses are categorised according to what the energy is used for, not just what sector of the economy it is used by. This tells us something about the form of energy that is needed, and how the level of consumption could be reduced. For example, space heating needs heat at 30-70 degrees celsius, and can be reduced through insulation of buildings, whereas process use may require high temperatures (e.g. 1000 degrees celsius), and motors/drivers need motion which could be delivered directly e.g. by a water-wheel.  As discussed in the section on the physics of energy, every time we convert from one form of energy to another there is a loss, and high temperature heat can do more different things for us than lower temperature heat. Managing flows of energy from ‘high quality’ to ‘low quality’ uses can help reduce waste.

Non-transport energy uses in UK, TWh, all sectors, 2017

The pie chart above shows that energy for space heating has the biggest impact after transport, with 46% of all non-transport energy going to this final use. The next biggest category is in lighting and appliances, at 13%.

Space heating needs ‘low quality’ energy so there is a good opportunity here for making use of ‘waste heat’ from other processes, via heat networks.

These different use-types of energy vary in proportion according to sector, as shown in the charts below (units are TWh).

Domestic Energy use in UK, 2017

Industrial energy use in UK, 2017

Service energy use in UK, 2017

These charts show where the most impact can be had in each sector. The biggest energy consumption in the domestic sector and in the service sector is space heating, followed by lighting and appliances. In the industrial sector, the biggest energy consumption is for process use.

We can also ask what form of energy is used to produce each type of energy end use. For example, domestic space heating comes from a mix of: gas, oil, solid fuel, electricity, heat sold and bioenergy & waste, whereas industrial motors and compressed air are all powered from electricity.

The statistics above are derived from the ‘Energy Consumption in the UK‘ tables published by the government. There is a huge amount of detailed information in these tables, including energy consumption from different household appliances, the number of appliances in the UK, percentage of households with double glazing or cavity wall insulation and how much energy is used for manufacturing different types of goods. The data is produced from many different sources, which are referenced at the end of the spreadsheet. So you can delve deep into analysis of all kinds of things if you’re so inclined!

When do we use energy?

The time that we use energy is important for planning storage.storage.  Storage in the energy system comes in many forms and timescales, as discussed in the section on energy storage and transportation infrastructure.  Patterns of energy use include moments of high and low use through the day, week and year. Seasonal changes in energy needs are particularly important for heat. Daily patterns are particularly important for electricity.

Electricity

The amount of electricity used varies throughout the day, the week, and the year, as shown in the image below:

Daily

Weekly

Yearly

Illustrative sketch of minute-by-minute, daily, weekly and yearly electricity consumption profiles

Note in particular the daily peaks in the morning and evening, when people get up and have breakfasts and showers, and come home in the evening and cook, watch TV and relax.

Elexon, who run the electricity market, produce ‘load profiles‘ for different types of electricity customers. These are used to make predictions and estimations, and as part of the balancing of the electricity market while we don’t have smart meters (as discussed in section on money flows). As an example, the daily and annual load profiles for the most ‘standard’ type of domestic energy user are shown below. This shows the general shape of electricity consumption over the day and the year.

Images from elexon guidance Load Profiles and their use in Electricity Settlement.

The Energy Consumption in the UK statistics used for the pie charts at the start of this page also provide some information on electricity consumption in households over the course of the day, from the Household Electricity Use Survey 2010-11.  This is shown in the graph below. Please note that this is electricity only – a lot of these use types are provided by gas in most houses (e.g. cooking, water heating, heating).

Graph created from data from Energy Consumption in the UK.

This graph shows the average electricity use profiles for 250 households, monitored over 12 months using meters on total electricity use and most appliances.

For non-domestic users, the usage patterns vary a lot depending on the type of industry or commercial entity.  Non-domestic users with high consumption are usually metered half-hourly, but smaller users have their usage estimated.  The ‘demand profiles’ are primarily used for commercial and market purposes, discussed in the section on money flows, but the images below give a sense of how the daily consumption pattern can be different to household consumption. Note that the numbers at the bottom refer to a half-hourly ‘settlement period’ – i.e. there are 48 settlement periods in a 24 hour period.

Images from elexon guidance Load Profiles and their use in Electricity Settlement.

Heat and gas

In the UK we need to heat buildings in winter, and this seasonal pattern is one of the biggest challenges for the energy system. Homes also use heat year-round for hot water, and industrial processes need high temperatures.

Daily

Yearly

Figure 7: daily, weekly and annual variations in heat consumption in the UK

Most of the UK’s space heat and hot water is provided via the gas network, so gas consumption over time gives a good indication of the heat consumption.

If we were to shift this gas consumption onto the electricity network, to make use of renewable electricity, this would make a big shift in electricity consumption, and cause challenges for the electricity network.

The biggest heating demand is in  January. The graph below shows the power supplied by the gas grid and by the electricity grid for one week in January. Note the magnitude of the additional energy that would need to be supplied through the electricity network to meet winter heating demand.

The graph below shows how electricity demand would change if gas demand is reduced by 30%, then transferred to the electrical network, with heat pumps that have a coefficient of performance (COP of 1 or 3).

Potential to change our patterns of consumption

The rhetoric of “keeping the lights on” denotes a fixation with meeting demand for energy. But the quickest and simplest way to adapt the energy system is by reducing consumption.

Reduction in energy use can be achieved through:

• [bullets to be green]
• Technological improvements, eg making appliances more efficient (but beware of rebound effects)
• System improvements, ie by doing things more effectively
• Behaviour change, ie doing things differently
• Re-evaluating ie re-assessing whether an activity or service is needed, and what value it really provides

In addition to reducing total energy use, the cost and climate impact of the system as a whole can be managed by reducing peak energy demands. This is analogous to reducing peak hour travel to reduce the amount of road space needed.

Flexibility through consumption infrastructure

One approach to this is flexibility in when we use energy. This has implications for energy transportation and generation infrastructure. Most sources of flexibility are actually forms of energy storage. For example:

• Switching off freezers and fridges for short periods while the door is kept closed, which results in minimal temperature changes – this is effectively storage of ‘coolth’ in an insulated box. [green]
• Electrical storage heaters. These are electric heaters with a big lump of concrete which provides thermal mass for heat storage.  In practice, people with houses heated in this way may report feeling cold. [black]
• Charging of electric vehicles off-peak This makes use of the battery storage in the car. [green]
• Avoiding heating or cooling buildings during peak electricity periods – this makes use of the thermal mass in the building. It requires well-insulated, well draught-proofed and high thermal mass buildings. [green]

Some ‘demand side’ flexibility is changing when the energy service is accessed: 

• Dishwashers, washing machines or tumble dryers on a timer so they operate at night or at off peak times. [green]

Other approaches involve people actively choosing to change when they use energy, or to manage peaks:

• Not putting the kettle on at peak electricity times (if this was combined with using a thermos, it would involve storage!)
• Not using high-power appliances simultaneously – e.g. using toaster, kettle, oven, tumble-dryer one after another, rather than simultaneously.

Metering

The consumption of electricity and gas by different users is measured through metering. Meters are therefore a part of the energy consumption infrastructure.

Traditional ‘dumb’ meters

Historically, household energy meters have a rolling count of the amount of energy that has been used to date. Electricity meters show kWh (energy) and gas meters show m3 (volume). They are usually located at the entrance to the house and often make a quiet ticking sound as they turn. These meters have to be read manually, and energy supply companies request customer readings or come to the house to read the meter.

 Half-hourly meters

Users of large amounts of energy are metered half-hourly.  This makes it possible to charge different rates for energy at different times of day (see section on money flows).

Smart meters

The flows of energy in the electricity system were historically relatively easy to calculate and estimate, as they moved in one direction. Now, solar panels on people’s roofs are being connected to the system, and patterns of usage are becoming more unpredictable and variable due to electric cars, heat pumps and home batteries. Electricity network operators need more data to understand what is going on. Distribution networks are also closer to capacity, and knowing how close to the limit we are becomes more important.

Smart meters, which measure minute-by-minute household electricity consumption, could provide this information. They are being installed in homes as UK government policy, in line with EU policy.

Smart meters:

• [green bullets]
• send live information to an ‘in home display’ which shows you how much energy you are using and how much it costs
• send monthly consumption data directly to your energy supplier, so they will no longer need to estimate bills or send someone to look at the meter

They could also help domestic flexibility, and play a role in controlling the time of use of different appliances. This would require additional control devices, but smart meters would provide data to support this function.

The UK government, unlike most EU countries, decided that the supply companies rather than distribution companies (DNOs) should be responsible for the roll-out of the smart meters. This is more expensive to roll-out, because suppliers serve houses that are dotted around, whereas DNOs have the potential to roll out installations street by street. The reason the government took this decision was that the financial benefits of smart meters were thought to primarily accrue to suppliers rather than DNOs. 

CSE have published some useful guidance on smart meters here.