In the words of architect Luis Fernández-Galiano, "civilisation is the saving of energy". Let us now think of its opposite: the waste of energy is the end of civilisation. Our society is unaware of the Herculean effort required to produce, transport and manage energy. We can have in our mobile phone battery the electrons produced in a nuclear power station in France.

The energystatus currently being experienced by European society brings to mind a series of reflections and events that have conditioned our most recent past.

The photovoltaic effect was discovered in 1839 by the French physicist Edmond Becquerel and in 1850 a solar engine was first connected to a heat-powered refrigeration system.

The past also shows us samplehow the integration of renewable energies in building is not something that is confined to this troubled first quarter of the 21st century. It has been possible for decades, even if the support of developers, architects and politicians for their use has changed.

Thus, 1920 was the year of the highest sales of solar collectors in Los Angeles. Later they would decline because between 1920 and 1930 huge natural gas fields were discovered in the Los Angeles Valley. In 1941, "more than half of Miami's population was using solar-heated water and 80 % of the new houses built in Miami between 1937 and 1941 had solar equipment" (The Golden Thread, 1980).

Despite this negative change in energy trends, 100 years ago there were already writings that strongly advocated the use of renewable energy sources. The inventor and solar energy pioneer Frank Schuman stated that "the human race must finally use the sun's energy or go back to barbarism".

At reference letteron energy, there are two important facts to note. Firstly, in 1945, associationof Hospitals in the USA adopted on-site energy generation as the preferred option. The adoption of this technical, almost political decision would radically change our cities and the territory in which they are located.

The second event occurred in 1948, when Ghawar, the world's largest oil field, was discovered, leading to a drop in the price of crude oil supplies and a consequent increase in energy consumption.

Energy has been the driving force, the cause and the necessity of changes in history. This is not the time to present them all here, although, as a complement to the lines that follow, we might well recall Hergé's vision, when, once again anticipating the future, he expresses in the album Tintin in the land of black gold(1951) the concern about the western world's dependence on oil as the main source of energy source.

Now, I will try to recount what happened in the 1973 Yom Kippur war, and then repeat the same sentences, changing the subjects. This is neither a detailed description of those events, nor even less a clairvoyant vision of what the near future may hold, but a re-reading of the past to try to understand what may happen after the end of the current conflict in Ukraine.

In 1973, in the Yom Kippur War, a confrontation between Egypt and Syria (they wanted to regain Sinai and the Golan Heights) and Israel took place. The armed conflict began when the coalition launched a joint surprise attack on Israeli positions. 

The war had international implications beyond the political sphere: the oil embargo on the West and the lowering of production in Arab oil-producing countries triggered a dramatic rise in the price of crude oil. 

In Spain, as a result of that crisis, the first approach to the problems of energy saving took place with Decree 1490/75 of 12 July 1975 on thermal insulation in buildings, a prelude to what would become the basic ruleof BuildingNBE-CT-79, which for almost 30 years was the rules and regulationsthat marked the path of energy consumption at Building.

Now, let's do the exercise I was proposing, replacing those protagonists with the current actors.

In 2022, a war is fought between Russia (which wanted to recover territories considered to be pro-Russian) and Ukraine. The war begins when Russia launches a surprise attack on Ukrainian positions. The conflict has had international implications beyond the political sphere: the economic embargo on Russia and the decrease in gas demand from the European Union triggered a drastic rise in energy prices. 

In Spain, as a result of this crisis, it could be envisaged that, by means of a law agreed by all political parties, we could become self-sufficient in energy, taking advantage of the extraordinary conditions we have to use different renewable energies and also develop hydrogen technology at last. Although, unfortunately, no such decision has been taken, some steps have been taken in the right direction. 

The story sampletells us that energy and Economicsgo hand in hand and how their connection conditions the survival of the human species.