As a greenhouse grower, light is very important. And unfortunately, sometimes during our builds we can block out too much of the free stuff and end up having to rely on more power to make up the difference. Issue with most fixtures, is they either take up too much space or don't produce enough light. Take for example, a single ended HPS reflector called the "Magnum" The reflector almost takes up and entire 1200 inches in surface area. Requiring more reflectors to make up the difference. Which results in more sun shading.
Not very efficient
So let's not talk about some bad ideas, and instead lets compare just a few ideas that are considered good. Below is a chart that lists a few fixtures, and how much space they take up.
As you can see, even the worst is considerably better than the magnum. But it's still taking up a fair amount of space. So that leads us to one important question.
How bad is that?
We can actually get a decent idea of how much free light we're blocking.