If your outdoor power test goes well, and it does look like indoor temperature is affecting ability to perform high intensity intervals, you can (if you already haven’t) look into Lasko fans.
A quick search of the forum should find links - and if you’re in the UK, this thread has a useful alternative.
That said, I’ve found that during summer, the air-blower still isn’t enough to get what I need to out of vo2 max sessions. So I’d also look into hills and loops for doing these outdoors.