three.js Box3.min and max localToWorld

I am just stuck right now. i have several Vectors (Vertices) which are parts of bigger objects and i am generating two Box3's with it:

    obj1box = new THREE.Box3().setFromPoints(buffer1); //buffer 1 and 2 are arrays of vectors
    obj2box = new THREE.Box3().setFromPoints(buffer2); //vectors were part of a huge object

With these Boxes i want to compute distances between these boxes, but both boxes are in localspace. So with console.log(obj1box), the box.max and min parameters are in local space but i need them in world space. How can i convert the boxes into worldspace?