Unless you're doing one of the alphas, the fastest way to do act 1 glitchless is to use a trash can to jump up onto the roof from the scaffold next to the porch, then jump to the invisible ledge next to the red window, break the window, grab the key, then run and unlock the door to the basement
Once down there you can use one of the giant panels to jump over and click the generator button, then you can climb back over and go through the final door.
Trust me, I'm a speedrunner