Comments on: LEDs Beat Incandescents in Lifecycle Assessment Energy Use

By: Isabel Santis

Isabel Santis — Thu, 03 Dec 2009 19:18:45 +0000

Larry, I find the argument that heat loss from incandescent lighting should be factored into the equation to be short sighted. Yes, you should consider LEDs and CFLs to be neutral in terms of heat release. And during winter, you could argue that the incremental heating needed to bring a building up to comfortable temperature would be higher. The flip side is that incandescent lighting releases heat regardless of wether conditions, and during the summer months, additional AC would have to be used to offset the heat generated by the lightbulbs. Soyour argument is not valid unless you are willing to consider both sides of the equation.

By: Paul

Paul — Thu, 03 Dec 2009 00:09:00 +0000

Larry – While I agree that these items are not accounted for in the study, I don’t understand why you seem to be bashing CFL’s instead of LED’s? Isn’t the article discussing the benefits of LED’s? Sure, they don’t produce heat, but I would rather control where the heat is directed and control both heating and cooling through the system meant to maintain it: HVAC. Why complicate things? As far as the volt amp-hour argument…..really….remember we are talking LED’s? Power factors aside, which is more efficient during use and manufacturing?…..LED’s or incandescents? I really don’t understand why you would argue against LEDs….they are most definitely the future.

You stick with Edison and I’ll stick to Tesla. Let’s move forward and not battle new technologies that improve both the environment and the pocketbook.

Paul

By: Larry Spielvogel, PE, FSLL

Larry Spielvogel, PE, FSLL — Wed, 02 Dec 2009 01:03:51 +0000

This “study” is not “comprehensive” or complete because it omits to consider (1) the heat replacement effect, and (2) the effect on electricity generation and pollution. They deliberately do not tell the whole story.

In any buildings that require heating, lower wattage lighting or any other “more efficient” electric appliances use less electricity, but also produce less heat. This heat then comes from the building heating system. Where electric heat is used, the building owner saves zero energy and money. Where less expensive heat is used, such as gas, the savings are the difference between the cost of electricity and the cost of gas. Therefore, the “advertised” energy cost savings are never achieved.

Electric generating plants do not produce watt-hours. They make volt ampere-hours. Energy Star CFLs must have a 0.5 power factor. This means that utilities must produce and supply 50-volt ampere-hours for a 25-watt CFL. Unless the utility meters for these, which some do for commercial buildings, they only meter and charge for watt-hours. Thus, with CFLs, utilities must generate, pollute, and produce twice the carbon emissions than the wattage indicates. In the end, consumers pay for this in the form of higher electric rates.

In summer months, less heat from lighting also means less cooling. However, much of that cooling (1) is not simultaneous with lighting, and (2) is achieved without using energy by using economy cycle, as required by building codes.