New, dual pane energy efficient windows is the way to go. Not only is it a sound barrier it will keep the heat/cold in. We replaced our windows..twice..now, I can't hear the phone ring when sitting on the patio and our heating/cooling bills have decreased significantly as well.

The energy efficient bulbs shown in the above photo suck the light is awful and they butn out quite often, if you want real energy savings go with LEDs they come in warm or cool light and you probably never have to chang a bulb as long as you live. They come in all kinds of wattages and can be retrofitted in almost any fixture.

Hello Mr.Ankit Pandey, The Glider (Gliding , Sliding) window is a reliable choice for simple operation and energy efficiency. Cathrinfrancis URBELITE Bangalore

I feel partitions are not needed. You already have too much for the space. Adding a partition will shrink the space further. The simplistic solution, you do not wish to discard any furniture would be to paint all the walls in lighter pastles. And use some wall painting frames to highlight certain walls.