T8 vs. T5: How To Determine Which Light Is The Right Light

Shouldn't It Be T12 vs. T8 vs. T5?

Your Kids Won't Even Know What A T-12 Was

T-12 technology is going away and will soon be history.  Your kids won't even know what a T12 was (okay...fair enough...energy efficiency geeks are likely the only ones who talk to their kids about lighting...).  But anyhow, by today's standards, the T12 is considered inefficient compared to the newer more modern fluorescent standards. 

Let's take a look at the differences between T8 and T5 fluorescent technology and see how they stack up.

What's Up With "T"?

The "T" is just simply a code.  As focus on energy saving technologies has grown and become popularized, these codes have come to designate levels of energy efficiency, as well as indicate lamp tube diameter.

Assumptions of Efficiency:

• T12 = old and inefficient
• T8 = higher efficiency
• T5 = highest efficiency

While the chart above is generally true, it is important to evaluate the application and determine the cost benefit of T5 over T8.  By doing so, you will be able to determine if the increased efficiency of T5 justifies the increase in initial and long term maintenance costs.

Costs of T5 and T8 Lighting

With a standard 4 foot T8 lamp costs between $3.00 and $5.00, and a standard T5 lamp costs between $5.50 and $12.00.

T5 costs significantly more than T8 but does not outperform it by the same margin. In fact, in many low level interior applications, the performance differences are negligible.

All lamps have a general life expectancy of around 36,000 hrs. at 12 hrs. per day burn time.

General Assumptions of Cost:

• T8 = roughly 20% more expensive than T12
• T5 = 2-3 times the cost of T8

Brightness Levels T8 vs. T5

There are several different factors that determine levels of efficiency. The quality of light, often referred to as lumen output(also called "brightness" by the Department of Energy) is an important factor to consider. 

Quality of light measured is measured in CRI (Color Rendering Index), and quantity of light measured in LPW (Lumens per Watt).

So, What Makes Sense In A Low Level Scenario Of Less Thank 12'?

Here is an average comparision;

CRI levels:       

T12 = 62CRI    
T8 = 85CRI     
T5 = 85CRI      

LPW levels:

T12 = 78LPW 
T8 = 90LPW 
T5 = 99LPW

T5 in this setting barely beats T8 as far as CRI and LPW values.  If you didn't understand the numbers and compare all of the variables, you could get stuck with lighting that costs much more.....and you wouldn't need it.

With the numbers being this close, you could never justify the substantial increase in fixture, lamp and ballast costs which is what you would get with the T5 in this case.

Where is T5 Better?

While it obviously isn't a good idea to switch from T8 to T5 in the above scenario, it would be very good if it were a switch from T12 to T5 standard output lighting.

T5 standard output lamps have their place, it's just understanding the applications and the desired results. We recommend always using a qualified lighting consultant or designer.  Guessing on the right kind of fixture can cost you dearly.  .

Their experience can help in lighting layout, application, and help with knowing what incentives and rebates your business will qualify for.

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