In the United Kingdom, 2,900 employees at 61 companies tested a four-day working week instead of five for six months at the same salary, with encouraging results. This is the largest experiment on the subject carried out anywhere in the world to date, and it confirms several hypotheses already put forward in previous studies: those who reduce their working hours achieve a better work-life balance, gain in terms of health, and produce the same output — in many cases more. At the end of the trial, which began in June and concluded in December 2022, the majority of companies said they wanted to keep this model.

Shorter week: what is the 100:80:100 model tested in the experiment

The study was coordinated by the non-profit organisation 4 Day Week Global: the non-profit NGO extended the experiment of Perpetual Guardian, a New Zealand trust company with 240 employees that has successfully adopted the four-day working week since 2018. The initiative requires that in each participating country a group of companies takes part in a six-month pilot project based on the 100:80:100 model. In practice, this means one hundred per cent of the salary for employees who, however, work 80 per cent of the standard hours (usually 32) and commit to achieving the same results that would be attained working five days a week.

Before the trial began, companies were prepared for two months through workshops, mentoring and coaching sessions, exchanges with businesses already experienced in reduced hours, and engagement with research and consultancy centres. The companies, from various sectors and of different sizes, were given the option of choosing how to reduce their total hours. The largest share opted for a free Friday.

The report's findings draw on companies' administrative data and employee survey data, together with a series of interviews conducted during the pilot period, providing measurement points at the beginning, midpoint and end of the process.

Less stress and a better work-life balance for employees

The "before and after" data show that by the end of the process 39 per cent of employees were less stressed and 71 per cent had reduced levels of burnout, the work-related stress syndrome. Similarly, levels of anxiety, fatigue and sleep problems fell, while mental and physical health improved. Those on a shorter week — the researchers at Boston College explain — tend to use the third day off for medical appointments or other errands that they would otherwise have to squeeze into a working day.

For more than half of employees, it became easier to balance work with their social and family life. A balance that in Italy is also being pursued through the new parental leave rules.

There was also a marked drop in the number of employees who left the participating companies, recording a 57 per cent decline during the trial period.

Free time is priceless

And then there are the financial savings: "You have no idea how much money we'll be able to save on childcare," commented an employee at a non-profit. This is not an isolated case: according to the Guardian, many British families have discovered that by working full-time they put aside less money than they would working part-time.

For many, the positive effects of a four-day working week were worth more than their weight in money. Fifteen per cent of employees said that no amount of money would persuade them to accept a five-day schedule on top of the four-day week they had by now grown accustomed to.

Nine out of ten companies keep the shorter week

One surprising figure among the other metrics measured in the trial concerns the companies' revenue, which remained substantially unchanged, with an average increase of 1.4 per cent. To gain a clearer picture of the impact of reduced hours on productivity, the researchers compared the revenue from the six-month trial with a similar period in previous years, finding an average revenue increase of 35 per cent.

The figure is confirmed, at least in Europe, by the latest statistics from the OECD. The western European countries that work fewer hours per year (Germany, Denmark, Austria and Switzerland) record higher productivity rates.

Partly for this reason, it is assumed, of the 61 companies that participated 56 are continuing with the four-day working week (92 per cent). For 18 of these, the change will be permanent.

CO2 emissions fall

"We also asked for information on energy consumption — the study's authors write — but since many companies were unable to provide such data, these were not included."

What we do know is that introducing the four-day working week in the United Kingdom would lead to a fall in CO2 emissions of 127 million tonnes per year by 2025. In practice, the equivalent of taking the country's entire private car fleet off the road.

Although the trial is credited with the quality of its design and the merit of including organisations from various sectors, some urge caution. It is argued that the participating companies are too small and, in general, already inclined to support shorter working schedules to be representative of a standard.

The report's authors, however, regard this experiment as a starting point. It is no longer a question of asking why shortening the working week makes sense, they write. The issue now is understanding how to export the British model to as many countries as possible.