they've even been found (accompanied by batteries in the seat tube and/or down tube, presumably) built into bikes' bottom brackets, where they connect to the crank arms and supplement the rider's own pedaling efforts.
That’s easier said than done in extreme heat, but as a first step, close your windows and pull the drapes or lower your blinds, especially on south-facing windows, in the daytime. Open them back up at night to allow warm inside air to escape and cooler nighttime air to enter.</...