Paul Walitsky CHMM President
The Industrial Ecology Co LLC
The LEED for Existing Buildings (LEED-EB) Rating System is fundamentally different from LEED applications for new construction or commercial interiors. LEED for existing buildings is focused on the operation and maintenance of buildings that in some cases were constructed more than 100 years ago.
Various existing structures built in the early 1900s have earned LEED Gold and Platinum status. They have special challenges compared with new construction. The opportunities open to designers and architects presented by a new building are in many cases closed to those working on existing buildings. One cannot reorient a building to take advantage of southern exposures. Roof structures may not be amenable to greening. Day-lighting poses challenges for an existing building which may be relatively easy to implement in a new building.
The Materials and Resources Prerequisite 1.2 offers a challenge in an opposite direction. The mercury issue does not arise in LEED for new construction but here it is in LEED for existing buildings. How to handle this prerequisite and the accompanying credit (6.1)? We will spend some time exploring this prerequisite, its ramifications for lighting design and the environment. In later articles we will look at the other areas of LEED for existing buildings where lighting choices comes into play
First, a little background, Mercury is essential to the operation fluorescent lamps, most High Intensity Discharge lamps and many specialty lamps (projection, UV germicidal and the long life induction lamps.) It is the engine that drives the light output of the lamp. While phosphors in fluorescent lamps and optical designs in fixtures give the designer the choices needed for modern efficient lighting, it is the mercury that generates the ultraviolet needed to excite the phosphors and generate the light.
However, mercury itself is a potent neurotoxin. Fish advisories in more than forty states limit fish consumption especially for those pregnant or of child bearing age. Many advisories ban consumption for everyone depending on the fish and its source. Concern about mercury reaches the press almost everyday. If one puts Google Alert search on Toxic mercury, four to ten hits a day are recorded. Does this concern about mercury affect lighting choices?
Mercury containing lamps have come under State scrutiny across the country. A nationwide labeling scheme is also in place. Nine States now ban solid waste disposal of mercury containing lamps and insist on lamp recycling.(part of prerequisite in Materials and Resources) Some of these bans on disposal now include households as well as commercial establishments. The Europeans limit the mercury dose in fluorescent lamps.
Where does the mercury in fish come from? Mercury is put into the air by nature (volcanoes), and by man (power plants burning coal and by things that break which contain mercury such as mercury thermometers, lamps, and switches). The mercury in the air settles to the bottom of rivers and lakes and converts via bacteria to methyl mercury. The methyl mercury gets into plankton and algae. The little fish eat the plankton and algae, big fish eat the little fish and who eats the big fish? We do.
About 1/3 of the mercury in the air is from nature, the other two thirds from man. In the US, power plants put about 48 tons of mercury into the air every year. The last industry numbers I had indicated that the lamp industry uses about 13 tons of mercury per year with about seven tons ending up in lamps. When lamps break some amount of this mercury is emitted to the air.
The aim of the prerequisite in LEED for existing buildings is to have building operators recognize that they are responsible for what they bring into their buildings. Their choice for a “green” building should be to minimize the amount of toxic material brought into the building. Indeed this is the theme of many other sections of LEED including the Indoor Air Quality Section.
The prerequisite does this by developing a new measurement, the picogram per lumen hour. To generate this measure you need three basic pieces of data; the mercury content of the lamp, the rated life and the mean or design lumen output. The mercury content is divided by the product of life and output resulting (after moving zeros and decimal points) in picograms per lumen hour. You also need a lamp inventory (how many of what kinds of lamps).
The prerequisite sets out a maximum level. To achieve the prerequisite the building weighted average of all the mercury containing lamps must be below 100 picograms per lumen hour if you get the weighted average below 80 picograms per lumen hour the building gains the credit found in Credit 6 of this section.
How does this work out in real life. Is it hard to achieve? Does it cost more? How will this affect my design? Do I have to re-lamp the building?
The design criteria generated from this prerequisite is elegant and depending on your viewpoint, easy to achieve. The designer or specifier needs to aim for the lowest mercury, highest output and longest life lamps available for the task at hand. Because this is a weighted average, you can have some lamps above the prerequisite level as long as there are enough lamps below the criteria level to balance those above.
The rated life is defined, for fluorescent lamps as the life using the ANSI specification of 3 hours on twenty minutes off on an instant start ballast (program start for T-5) and is found in all of the lamp manufacturers catalogs. For HID lamps the standard 11 hours per start is used. The lumen output is the design lumens also found in all manufacturers catalogs (For HID lamps the mean lumens).
The mercury content is more elusive but getting less so. The web sites of the lamp manufacturers are excellent sources of information. OsramSylania and Philips Lighting both have picogram per lumen hour calculators in their environmental sections. These calculators not only have the mercury content of their lamps but also do the calculations for you. (You do have to know how many of what lamps you have). MaxLight lists the mercury content on the Material Safety Data Sheets (assuming you know the lamp weight you can convert the parts per million to milligrams). An independent environmental group called INFORM INC also has an older listing of mercury content by manufacturer and lamp type.
Some strategic examples:
A lamp with 3.5 milligrams of mercury, 20,000 hours rated life and 2800 lumens achieves (3,500,000,000/divided by 20,000 x 2800) 60 picograms per lumen hour meeting the prerequisite and earning credit 6,1
A lamp 6.0 milligrams, 20,000 hours and 2800 lumens gets 107 picograms per lumen hour and does not meet the prerequisite. However, if one chooses the same lamp type rated at 24,000 hours the result is 89 picograms per lumen hour, meeting the Prerequisite.
Unfortunately low wattage CFLs get very high picogram numbers. If you are specifying the 5 watt or 7 watt CFL you might want to consider LEDs, this avoids the mercury altogether, gives you very long life and saves energy. However, because this is a weighted average you could still use low wattage CFL as long as there are enough lamps with lower numbers to bring the weighted average within criteria limits.
On the HID side, ceramic pulse start lamps generally have significantly lower mercury than quartz arc tubes, they save energy and allow for control devices that might not be available for standard quartz lamps. Again as with the CFLs, you can still use the higher picogram HID lamps as long as your weighted average meets the criteria.
In a small installation you might have 5 150 watt Quartz HID lamps which in one configuration has a picogram number of 507 and in the office area 30 T-5 lamps with a picogram number of 27.The weighted average of these two lamps gives a number below 100.
The question was raised concerning lamps in the ceiling with expected lives of two or three more years. Do I have to remove them and re-lamp. The answer is a resounding no! All you need to do is have a policy in place that says when the lamps burn out you will replace them with low mercury lamps. Low mercury lamps are competitively priced so there should not be a significant price differential.
This prerequisite brings home the message that toxic materials need to be minimized in a building that aspires to listed among the best green buildings under the US GBC LEED for existing buildings criteria.
Paul Walitsky is president of The Industrial Ecology Co. LLC in Parsippany, NJ. Previously, he worked at Philips Lighting, where he was responsible for environmental compliance for all Philips Lighting facilities in North America.