It’s a little too hot for bunny comfort indeed (~25 °C for our non-American members). It’s smart that they’re in the basement now, that has the most stable temperature of any place in the house 🙂
Besides cold water and fresh veg you could also offer them bunny-safe cool packs or let them lay against soda bottles filled with a mix of ice and water.
Giving them a fan can also help, just direct it to one side of their space so they can choose whether they want to be in the air flow. Our previous bun loved his fan and would spend entire afternoons napping with his back towards the fan, fur rippling in the breeze. Oh, and sometimes he stood high on all fours to air out the family jewels, preferably when I had visitors 🙄🤣
It’s a temporary measure, but you can keep the temperature of the house a bit lower by putting alu foil on the windows that face the sun. That can easily save a couple of degrees. True, it makes the place look like a crackhouse, but it’s a handy trick when you’re in a pinch 😉
I just put the foil over our living room window. It’s hard to get rid of the heat in my apartment because all the windows are on one side. This trick helped me to keep things cool during the record-breaking heat wave that we had a couple of years ago. We had 40 °C temperatures for almost a week. It was a nasty mix of extreme heat and high humidity. The Netherlands is a sea climate country, so our summers are always sticky. Blegh…
If you’re in an area with low humidity you could also hang wet laundry or wet blankets in rooms at night, while you keep windows open. When water evaporates it picks up heat from its environment, and the night air can get rid of the moisture.
Fingers crossed that the new AC will arrive soon!