Go back to article: Visualising electricity demand: use and users of a 3D chart from the 1950s

Trends and rhythms of demand

The chart provides information on the timing of demand, especially when the demand peaks take place and how high they reach, but also on the seasonal changes. Most importantly, perhaps, the object vividly suggests a distinctive rhythmic patterning of daily load, as each day follows a roughly similar demand profile, with public holidays and seasonal changes providing the most distinctive alterations (see Figure 11). The chart includes both domestic and commercial/industrial demand, but does not give clues to puzzles such as what is the base load during night time, what makes the afternoon peak, and how is domestic work stretched over the day? In this section, we elaborate on these questions, before speculating on whether these were the kinds of questions the users of the model at the time were interested in.  

Figure 11

Colour photograph of a 1950s three dimensional chart showing electricity demand over time

View of the model showing the rhythmic pattern of daily load

Each load curve is characterised by a period of low night-time demand. The night-time base load most likely consists of activities that were either in constant demand for electricity, such as the functioning of the cold chain; or activities that mostly took place in the night time, such as street lighting, night-time storage heating, or some commercial activities such as the working of press office machines, newspaper printing, or bakeries. Even though the object does not give us clues about what electricity was used for, some cards are an exception. For example, the death of Queen Mary on 25 March 1953 was marked down on one of the cards as a special event causing a peak at 03:00 due to a sudden press load from newspaper printing (see Figure 12).

Figure 12

Colour photograph of an individual chart card from a 1950s three dimensional chart showing electricity demand over time

The death of Queen Mary on 25 March 1953 is marked by a spike in demand at 03:00 as the press respond to the news

After the relatively constant night-time load, demand doubles or more for the morning hours from 06:30 onwards. Unlike today, factories, shops and offices in the 1950s did not routinely function around the clock (Agger, 2015), but were run on weekdays from 08:00–17:00, and this partially explains the steep increase. Studies of domestic demand in the 1950s suggested that much of domestic work – which was at that time electrifying fast – took place in the mornings (BEA, 1950a). The mass market for energy intensive home appliances was not yet mature, and until the 1960s, most British families spent discretionary income on furniture, clothes and home entertainment, such as a radio and television, rather than on labour-saving devices such as washers or fridges; with the vacuum cleaner as an exception (Trentmann and Carlsson-Hyslop, 2017). However, the use of space heaters such as electric fires, water heaters, and wash boilers (that were more often rented than owned) did accentuate the weekday morning load.

The morning hours were followed by a lunch break at noon, with a dip in demand of 60–90 megawatts (see Figure 13). The regular reduction in electricity demand during the lunch hour suggests that some machines, appliances or lighting were either switched off for that time, or used in a different, less consuming, mode. The synchronisation of commercial and industrial activity around the lunch hour is remarkable compared to today (Durand-Daubin, 2015).

Figure 13

Colour photograph of an individual chart card from a 1950s three dimensional chart showing electricity demand over time

Card showing the lunchtime dip in demand, here to a value of 70 MW

Another peak, often the steepest of the day especially in the winter months, takes place in the afternoon around 16:00–17:00. This afternoon peak is interesting in many respects. The peak could be made from demand for lighting during the darker office hours, and heating and cooking when many people start to return home. When domestic rhythms overlap with industrial and commercial patterns of demand, consequences on peak demand can be significant. In a Manchester Guardian article on 11 December 1954 it was stated that, ‘If the B.B.C. would alter the Children’s Hour programme on television by half an hour it would save the Eastern Electricity Board a full power station on peak demand’ (The Manchester Guardian, 1954). According to the article, the nearly four million television sets in the UK in 1954 were a major contributor in shifting the peak demand from 08:00 to the time of broadcast: 17:00. A three-peak pattern emerges in the month of August, when the demand for lighting occurs later in the day and becomes separate from the ‘teatime’ peak (see Figure 14).

Figure 14

Colour photograph of an individual chart card from a 1950s three dimensional chart showing electricity demand over time

A load curve with three distinct peaks is most noticeable during August, when the ‘teatime’ peak is separated from the switching on of lights

In addition to a clear daily profile, the chart illustrates a distinctive seasonal variation in electricity demand. There is growth in demand in the winter months due to increased need for heating and lighting. On national holidays, most notably during Christmas and Easter, and the holiday season in July and August, demand plunged significantly, as Figures 15 and 16 illustrate. The load on national holidays was primarily domestic demand, corroborated by statistical reports, according to which domestic demand accounted for one third of electricity consumption in the early 1950s in the UK (Office for National Statistics, 2017).

Figure 15

Colour photograph of a 1950s three dimensional chart showing electricity demand over time

View of the model showing the distinctive seasonal variation

Figure 16

Colour photograph of three individual chart cards from a 1950s three dimensional chart showing electricity demand over time

Load curves on Easter Friday 11 April 1952 and the preceding and following Fridays. The minimum demand across the whole model was 30 MW on Monday 4 August 1952

Our analysis of the trends demonstrated how the data could have been used at the time. Factors such as peaks in demand, their maximum values, and the seasonal variations were made manifest – materialised – in the object. Was it this data, and the daily activities of which it was constituted, that was of interest to the users? 

Component DOI: http://dx.doi.org/10.15180/180905/003