By Stan Walercyzk
In lighting, it can be relatively easy for distributors and contractors to do a reality check on manufacturers’ claims. Some manufacturers provide very credible claims on certain products, and others may not. What applies to lighting can also apply to other products.
One example is an email that I received in response to my column regarding LED T8s. This person wanted my opinion regarding one manufacturer’s LED T8s. The cut-sheet stated that at least 40% energy savings could be achieved compared to fluorescent T8s. So I did some math.
A 3100 lumen 32W fluorescent F32T8 with 1-lamp high performance 1.18 BF electronic ballast provides 3658 lumens and consumes 38W, which is 96.3 lumens per watt.
This 20W LED T8 with the same ballast provides 2000 lumens and consumes 22W, which is 90.9 lumens per watt.
You can see that the fluorescent T8 is actually comparable to the LED T8. Plus some fluorescent T8s last considerably longer than most LED T8s.
Another example is that some manufacturers claim that their LED MR16s can provide as much light as 50W standard halogen MR16s. If you look in a GE, Philips or Osram – Sylvania lamp catalog, you can see that the 50W standard halogen MR16s provide 600 – 950 lumens. You can also see that the manufacturers that are making these claims only have 600 – 620 lumens out of their LED MR16s. So these LED MR16s could provide as much light as the lousy halogen MR16s, but not as much as the good halogen ones. In its recent report, the DOE only tested one LED MR16, which can really replace 50W standard halogen MR16s.
Lastly, the major lighting companies usually state that their exterior LED products can reduce wattage by 50% – 75% compared to existing HPS or MH fixtures. However, a number of the smaller and newer companies state that their exterior LED products can save 80% – 90% of wattage. If you do some calculations or run some photometric programs, you will see that the 50% – 75% is usually much more realistic.
This issue also applies to controls companies. I keep seeing claims that certain controls will save up to 70%, and even up to 80%, of energy. Yes, in some isolated instances, those numbers may be correct. But in most typical applications, the savings are much less, often as low as 15%, which is what Database for Energy Efficient Resources (DEER) approve for occupancy sensors. Plus with LED and high performance incumbent technology lighting being so efficient, controls are often not cost effective, because the electric bill is so low. For example a 120 square foot office may be lit with two 25W LED troffers or troffer kits, which totals 50W. If the lights are on 2500 hours per year and if the electric rate is $.15/KWH, the annual electric cost is $18.75. Let’s be very optimistic and say that a wall occupancy sensor will save 30% of that, which is $5.63. Parts and labor for a basic grade occupancy senor may be $90, which after a $10 rebate, may be $80. So the payback would be 14 years. Who wants a 14 year payback?
If you would like more guidance on the subject of lighting, my lighting book is now available. It contains useful tools on how to evaluate and purchase products in the future. I hope it can be helpful to you. http://www.aeeprograms.com/store/detail.cfm?id=1143&category_id=6
As mentioned at the end of all of my columns, contractors, please send me feedback and input for new columns. My email is firstname.lastname@example.org.Tagged with tED