Some organisations found more time to plan and solidify environmental commitments, while others used more electricity and gas during the closures.
Funded arts organisations' carbon emissions nearly halved during the pandemic as much of the sector was closed.
Arts Council England's latest annual environmental impact report acknowledges the large drop was achieved under unusual circumstances and that data, provided by only 482 of 840 National Portfolio Organisations (NPOs), doesn't provide a comprehensive view of the sector's sustainability.
Mandatory monitoring was suspended in 2020 and 2021, leading to a 24% drop in emissions reporting on top of a 13% decline the year prior. Regardless, the funder says there are "valuable lessons" in its findings, which suggest the closures offered some organisations time and space to further their environmental commitments.
64% of the responding NPOs made new environmental commitments last year, sometimes to action groups like Culture Declares Emergency. Nearly half had collaborated with other sector organisations on sustainable solutions, up from two in five NPOs before the pandemic, and a third have ethical sponsorship policies.
"The overall picture is of a sector that remains engaged and committed to its environmental responsibility," ACE says.
NPOs' good intentions have not historically translated into a much smaller carbon footprint. Last year, carbon emissions among reporting NPOs fell by an average of 56.3 tonnes, 45,459 tonnes altogether - that's the equivalent of heating 16,870 UK households for a year.
There were small improvements in reducing single use plastics and in pursuing renewable energy sources. 57% now have energy efficient lighting, compared to 54% in 2019.
Roundtables held in 2020 by Julie's Bicycle, which supports NPOs' environmental ambitions, indicated sector support for absolute carbon reduction targets for large and medium-sized organisations.
Despite environmental responsibility being one of ACE's investment principles, the funder has not outlined precise carbon reduction goals, instead advising organisations to "set targets that are appropriate to your [sustainability] plan and policy".
Though reporting obligations have returned this year, there have been no consequences for chronic non-compliance among a number of NPOs since monitoring began.
While 85% of reporting NPOs said they made the same or increased progress on their environmental goals in 2021, there were "surprising" increases in energy use among some groups.
Visual arts organisations' gas consumption grew by nearly 8% during the lockdowns as they maintained environments for their collections that would satisfy insurers.
"Buildings needed to be heated for skeleton staff who were tasked with maintaining these controls, and without the physical presence of visitors, who contribute to maintaining temperature, they relied heavily on gas heating," ACE's report says.
Among the 415 organisations that reported in 2019/20 and 2020/21, 46 used more electricity last year and 78 used more gas. Overall, electricity use decreased by 45% and gas use was down nearly 38%.
Libraries' gas use fell by two thirds and theatres cut their electricity consumption by the same amount.
"Without the need to heat and light venues for audiences, staff and performers, electricity was scarcely required," the report notes.
Responsibility for sustainability appears to be concentrating among senior managers, with the number of NPOs saying it was a whole-of-organisation effort on the decline.
A third said senior managers are responsible, while fewer organisations said responsibility lies with buildings and facilities departments or belongs to all staff.
ACE says it's likely redundancies and furlough contributed to this shift, "but it remains that environmental engagement is increasingly being driven at senior management level".
88% of NPOs surveyed said environmental sustainability is part of their core business planning and 55% now formally recognise environmental responsibility in job roles, a 13 percentage point increase on 2019.
There are also encouraging signs that board members have more environmental expertise, the report said.