Overview

Environment scores are assigned to lighting products by combining product-level environmental indicators (weighted at 75%) with company-level environmental indicators (weighted at 25%). Product-level scores incorporate the most significant aspects of the overall life cycle impacts of a product, but company-level scores are included to address product-level data gaps.

Product-level scores for this category are based on indicators of

• Energy use and efficacy as measured by Lumens/Watt
• Toxic waste impacts, specifically the mercury footprint of a product and its associated energy consumption
• Solid waste impacts, as measured by the rated life of each lighting product
• Certifications of efficiency or production process

Health scores are not assigned to lighting products, because this category does not typically result in significant human exposure to potentially harmful ingredients at the consumer level. Some lighting products contain mercury, which can lead to human exposure if lamps are broken. In these cases, follow the U.S. EPA’s advice on cleanup of broken CFLs and fluorescent lights.

Social scores are based on company-level research. Product-level data on social performance are
generally unavailable for this category of products, so GoodGuide relies on company-level social
scores to characterize the performance of a product on this dimension.

Background

This category includes lighting products intended for home use that utilize one of the following technologies: incandescent, halogen, light emitting diode (LED), and various types of fluorescent (including compact, T-5, T-8, and T-12 linear lamps). Other types of lighting such as high intensity discharge or sodium lamps along with ancillary equipment such as ballasts are not included in this assessment.

Here is a brief introduction to each of these bulb types:

• Incandescent: The same technology invented by Thomas Edison is still used in incandescent bulbs today. Much of the energy consumed by these lamps generates heat rather than light, which makes them the least efficient bulbs available.
• Halogen: Based on similar technology as incandescents, halogens are often used for track or spot lighting. They also waste a lot of energy by generating a lot of heat relative to light output.
• Compact Fluorescent Lightbulbs (CFL): These include the familiar “swirl” bulbs that can replace traditional incandescent bulbs. They are more efficient than incandescents or halogens when it comes to energy use, but CFLs contain small amounts of mercury vapor, a potentially hazardous substance if released to indoor or outdoor environments.
• Fluorescent Tubes: These come in a variety of sizes, and require ballasts to work properly. Ballasts are a separate component that can influence the performance of the lighting system. Commonly used in office lighting, fluorescents are efficient and long-lasting but also contain mercury vapor.
• Light Emitting Diodes (LED): These ultra-efficient bulbs contain no mercury, waste very little heat, and have extremely long lifetimes. They exhibit directional lighting, which makes them appropriate for applications such as track or spot lighting. While individual lamps are currently more expensive than CFLs or other technologies, they almost always offset their increased upfront cost over their lifetime due to low energy use.

There will be major changes to the availability of some of these bulb types over the next two years as manufacturers phase out most incandescent and halogen bulbs because they do not meet the efficiency standards of the Energy Independence and Security Act of 2007. GoodGuide provides a filter for users to identify products that will be phased out soon.

Key impacts in the environmental lifecycle of lighting products include the energy consumed by the lamp over its lifetime and environmental releases of mercury, either at the power source or at the product’s end of life. The most significant impacts are associated with generating the electricity required to operate the bulb, particularly in areas heavily reliant on fossil fuels or other non-renewable power sources. A bulb’s energy consumption is highly dependent on the amount of heat generated by the lamp. More efficient lighting products generally save money over the life of the bulb by reducing electricity bills and preventing the release of air pollutants like greenhouse gases, particulate matter and acid rain precursors.

Scoring Methods

For each of the four product attributes selected to characterize the environmental impact of lighting products, we applied the following scoring rules:

• Luminous Efficacy (50% weight): Efficacy is a good way to determine how well a lighting source converts electricity into light. Measured in Lumens/Watt, it is the ratio of the total luminous flux emitted by a light source to the electricity consumed by the source. The higher the ratio, the more effective the lighting element. The ratio uses maximum wattage values, and gives preference to mean lumens over initial lumens. LEDs and fluorescents tend to exhibit high efficacy, while incandescents and halogens tend to exhibit low efficacy.
• Mercury Footprint (30% weight): Fluorescent tubes and compact fluorescent lights contain mercury vapor. Lighting manufacturers are not currently required to disclose the mercury content in their products. Bulbs that do not contain mercury vapor may still have a significant mercury footprint associated with their energy consumption. In any region powered primarily by fossil fuels, increased electricity consumption is typically associated with increased mercury emissions from power plants. Studies have found that the mercury emitted by an incandescent or halogen bulb can be four times greater than an equivalent CFL. In our scoring system, incandescents and halogens perform poorly on this criterion, CFLs and Fluorescents are in the middle (even though they may contain mercury vapor) and LEDs perform the best.
• Rated Life (10% weight): Measured in hours, rated life as quoted by the manufacturer is scored relative to other lighting products. For fluorescent tubes, we gave preference to rated life calculated using 3-hour tests on rapid or instant start ballasts.
• Certifications (10% weight): Products that have earned an environmental qualification or certification such as ENERGY STAR are generally more energy efficient and contain less hazardous material than similar products.

Note: Other Environmental Issues

Due to data availability challenges, GoodGuide ratings do not take into account the following issues that contribute to the overall lifecycle impacts of light bulbs: use of lead and other hazardous substances during the production process and end-of-life considerations. Other attributes that may be relevant to consumer choice (bulb/base size, color rendering index, color temperature, bulb type/shape, base type) do not have a significant influence on environmental impacts.