A happy school can be achieved when there is cooperation between all colleagues and when they work as one team to achieve the goals set for the success of the educational process. Happiness can be arrived at when the best teaching and learning is provided to the learners regardless of their ethnic, race, religion or political backgrounds.
I salute raising this question since it admits that there are "unhappy" schools and we need to rectify things in order to achieve the noble goal of having "happy" schools everywhere.
Schools cannot be separated from the wider frame that encircles them & they are not insulated at all . There is continuous exchange between the school & the "engulfing" frame in the world of today.
What harms any school is the external intervention in its affairs starting with imposing "big brothers" & ending up with interference in many details. This has meant that schools have been politicized. Well, politicians are the most miserable persons on earth so their leverage will surely "ripple" sending waves of depression, upsetting, anger, dissatisfaction, racism, dishonesty, apprehension and all the wrong attitudes that you may think of.
When there are the "right" persons at the top, they will give schools the freedom of speech, thinking, actions, and progress. The intellectuals, inside a school, can manage by themselves to create a happy atmosphere provided that unnecessary outer intrusion is eliminated entirely.
The core of Sukhomlynsky's system of education was his approach to moral education, which involved sensitising his students to beauty in nature, in art and in human relations, and encouraging students to take responsibility for the living environment which surrounded them.
Sukhomlynsky sought to prolong children's childhood, to keep them optimistic and open to the world, to preserve the freshness of their emotional responses to the world.
A school will be happy where learning becomes automatic and fun. The school should have state of the art infrastructure and highly dedicated and qualified faculty members.