Many orchid growers, lacking the space and are wanting to expand their collection go to growing their orchids under lights. There's a number of ways they can accomplish this. One is to get a high density sodium lamp which irradiates the plants at a level equivalent to sunlight. And you can see that when this starts glowing that it's almost like regular sunlight. In addition, they may actually enclose their whole group of plants in a plastic arrangement which helps control the moisture. But the primary source of light becomes the artificial lighting that is available through the products that are available today. High pressure sodium will help generate some heat so it will keep the plants warmer and if you want to keep plants cooler, there are newer models that generate little heat at all.