Spain started imposing new energy-saving rules in public spaces on Wednesday as part of the European Union's efforts to reduce reliance on Russia amid its ongoing invasion of Ukraine.
Under the government decree, air conditioning must be turned down and set at no lower than 27 degrees Celsius (80.6 degrees Fahrenheit) during the warmest months of the year, in rules affecting everything from public transport to shops, offices, theatres and cinemas.
During the summer months, temperatures across Spain often hit 40 degrees or higher.
The legislation also affects heating in winter, when temperatures can be set no higher than 19 degrees Celsius.
"The plan's aim is to save gas for the winter in case (Russian President Vladimir) Putin decides to cut off gas supplies to Europe as a result of sanctions," said Joan Groizard, head of the Energy Savings and Diversification Institute at Spain's ecology ministry.
That scenario "could make this winter very difficult," he told public television.
Adopted last week, the legislation also requires that from 10 p.m. (8 p.m. GMT), shops switch off window-display lighting in a move that also affects the illumination of public buildings.
By the end of September, any air-conditioned or heated premises must have an automatic door-closing mechanism installed to avoid energy waste.
However, the law does not lay out any specific penalties and has left the task of monitoring compliance to Spain's 17 regions, some of which have been highly critical of the move, notably those run by the right-wing opposition People's Party.
Among the most critical has been Madrid's regional leader Isabel Diaz Ayuso, who has vowed to take the measure to Spain's Constitutional Court.
The government unveiled details of the plan in May as part of an EU-wide effort to cut dependence on Russia for oil and gas following its February invasion of Ukraine.
The European Commission is planning to cut EU dependency on Russian gas by two-thirds this year and end its reliance on Russian fuel supplies before 2030.
An EU-wide plan to cut gas consumption came into effect on Tuesday with the aim of member states cutting back by "at least 15%" between August and March 2023 based on their average use over the past five years.
Given the unique position of Spain and Portugal and their limited connection with the European energy market, Brussels has allowed both countries to adopt a reduced target of 7%.
The overriding aim is to bolster gas reserves in time for what is likely to be a very tough winter, with European households and businesses already squeezed by skyrocketing energy prices.
Groizard said the new rules "would not (on their own) enable Spain to reach its 7% target," saying further energy-saving measures would be unveiled in due course.
Spain's energy supplies were assured, he recalled, saying the country had "very low dependence on Russian gas" compared with other European nations.
The United States is currently Spain's biggest gas supplier, providing 29.6% of its supplies in June.
Deliveries from Algeria, which had long been Spain's top supplier, dropped to 21.6% in the same month following a diplomatic spat with Madrid, with Russia moving into second place with 24.4%, figures from gas network operator Enagas show.