T5 vs. T8: How Do You Know If You Really Need T5 Lighting?
Do You Really Need T5 Lighting and Does It Matter?
Let's take a look at the differences between T8 and T5 fluorescent technology and see how they stack up. This is important because the T5 lighting could cost you 2x more than T8 Lighting. Here's why.
What Is The "T"?
The "T" is just simply a code that is used to identify the size of fluorescent bulbs. 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.
Size Of The Bulbs
A T5 bulb is roughly the same diameter as a $.10 dime. A T8 bulb is closer to the size of a $.05 Nickel. The T5 is the smaller of the 2.
Which Bulb Has The Highest Efficiency
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.
Do T5 and T8 Bulbs Cost The Same?
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. That is why you must carefully consider what is the best application so that you aren't spending 2x more than you have to.
The T5 does cost nearly 2x more, but that same margin cannot be applied to performance. The T5 does not outperform the T8 by the same margin. In fact, in many low level interior applications, the performance differences are negligible.
Both the T5 and T8 lamps have a general life expectancy of around 36,000 hrs. at 12 hrs. per day burn time.
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).
Can I Use A T5 Fixture In Area Where The Ceiling Height Is Less Than 12'?
You can use T5 in this situation, but you have to remember the extra cost involved with the T5 fluorescent bulbs. But cost shouldn't be your only factor, so you have to explore the technical aspects to understand why the T5 may not be the best fit.
Here is an average comparison of the T5 and T8.
Comparing Color Rendering Index
T8 = 85CRI
T5 = 85CRI
Comparing Lumens Per Watt (LPW)
T8 = 90LPW
T5 = 99LPW
As you can see, as far as performance, the 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....even though you are not getting any better lighting.
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 A Better Fit?
In this situation, you couldn't justify the extra expense of using the T5 technolgy. 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. T5 lighting tubes produce best at an ambient temp of 35C(95F) which would make one think that they don't do well in the cold. That's not completely true, see the ambient temperature rating that manufacturers use is that of the air against the bulb.
The temperature that T5 lighting works in depends greatly on fixture design. Be sure to do your homework before you choose.
If You Don't Have Time To Do The Homework, Hire A Professional
We recommend always using a qualified lighting consultant or designer. Guessing on the wrong kind of fixture can cost you dearly. In this case, it would cost you nearly 2-3 times more just for the t5 fluorescent tubes.
By using a lighting designer versed in energy efficiency, you can get help with lighting layout, application, and finding those pesky incentives and tax deductions your business will qualify for.
Learn More About Energy Efficiency
You can download our Free Ebook: A Business Owners Guide To Energy Efficiency to learn more about the benefits of upgrading to fluorescent lighting technologies.
Related Articles About T5 and T8 Fluorescent Technology:
T8 vs. T5: How To Determine Which Light Is The Right Light
T8 Lighting: Energy Efficient Applications And Uses For T8 Fixtures
Energy Efficient Solutions: How To Transform Existing T12 To T8
5 Reasons Why You Will Fall In Love With Fluorescent T5 Lighting