plants to use in a large terrarium

[afterdark]

I found this useful when researching which lights to go with:

There are several different factors that determine levels of efficiency. Quality of light measured in CRI (Colour Rendering Index), quantity of light measured in LPW (Lumens per Watt) and CU (Co-efficiency of utilization.) The numbers being used for CU are general for those used in the low level (12 feet and under) multi-residential environment so there can be fluctuations.

CRI levels: T12 = 62CRI, T8 = 85CRI, T5 = 85CRI
LPW levels: T12 = 78LPW, T8 = 92LPW, T5 = 103LPW
CU (Generally): T12 = .46CU, T8 = .76CU, T5 = .90CU

Considering these general factors, it is obvious that T5 is the best. But, how much better? With all factors weighed equally, a general presumption can be made, that:

• a. T8 is 40% more efficient than T12.
• b. T5 is 51% more efficient than T12.

Yet, T5 in this environment is only 9% more efficient than T8. This would never justify the substantial increase in fixture, lamp and ballast costs.
Furthermore, if energy savings is an issue, you can often lower the light output by 9 or 10 percent in order to recover the efficiency without any real impact to the perceived light levels.