If you use the booster, the power is conserved irw. input and output. So you have effectively 2xAA capacity (~5400 mAh) minus losses, as I noted earlier, fixing the presumption of not using a booster. It could still do better with a single Si7021. The 225 ms is excessive. Radio wakeup is around 0.5 ms IIRC. Waiting for 100 ms when you know the TX finishes in 4 ms is not a good idea either, IMO. Though, realistically speaking, after 2 years people forget when they swapped the batteries the last time 