Light is precious and you will want to maximise usable light from your grow lights. One excellent way of doing this is to use reflective sheeting.
Investment in reflective sheeting allows stray light to be redirected towards your plants. This is especially important in a small grow room. Plant growth is nearly linear in relation to light intensity, so the installation of reflective sheeting will increase the light intensity and save money in the long term and in some cases, it may also reduce initial costs.