Buildings are minimally heated and cooled over holiday periods to further save energy.
https://etown.edu/about/sustainability/effect...

Year-round, we grow hundreds of varieties of vegetables, fruits, flowers and herbs in 7.5 acres of outdoor fields and gardens and a 22,000-square-foot minimally heated greenhouse.
https://www.stonebarnscenter.org/the-farm/agr...

Museum hours are limited to the milder months of the year as our cabins are minimally heated and snow removal is difficult.
https://www.rootbeerlady.com/visit/hours-admi...

Just a guess. Something like 'lightly heated' or 'conservatively heated' would probably also work.

(~54°–68°F, if my web search was correct)