Comment by FooBarWidget

Just having a regular fan helps a lot. Very little energy usage, very cheap. I bought a new fan a few weeks ago, one that is nearly soundless in its lowest setting. Even the slight breeze made by the lowest setting already makes a huge difference compared to stale hot air. It also uses an order of magnitude less energy than an A/C, and costs an order of magnitude less to purchase+install (100 EUR vs 3000 EUR).