The Commercial Buildings Energy Consumption Survey (CBECS) reports “17% of all electricity consumed in U.S. commercial buildings is for lighting.” As a result, lighting is a category where improvements in energy efficiency are often sought. Recent new lighting technologies and changes to lighting efficiency have achieved reductions in the amount of electricity consumed by commercial buildings.
Types of Lighting
Each of these lighting categories has features and qualities that make them best suited to specific lighting needs.
- Standard fluorescent
- Compact fluorescent (CFL)
- Incandescent
- Halogen
- High-intensity discharge (HID)
- Light-emitting diode (LED)
- Other lighting types
Fluorescent and compact fluorescent lamps have longer lifespans than incandescent and are more energy efficient. Incandescent bulbs generally produce light that renders colors near to how they appear in daylight making them preferable in certain situations. Halogen lamps are a category of incandescent light that generates high-quality light with increased energy efficiency but with high heat output. High-intensity lamps discharge very bright light, suitable for lighting large areas such as sports arenas, warehouse areas, industrial spaces, and big-box retail stores. LEDs are a highly efficient and durable type of lighting that is rapidly evolving to produce the quality of light consumers expect. The Other lighting category includes less common bulb types that generally have particular uses, such as germicidal lights, neon lights, and laser lights.
Common Commercial Building Lighting Terms*
Ambient Lighting – General lighting providing visibility in a building environment including both artificial and natural light.
Foot-Candle – Equal to one lumen per square foot
Lumen (lm) – Unit of measure for the total lighting output of a lamp or fixture.
Task Lighting – Lighting fixtures with the objective to improve visibility in an area where specific tasks are performed.
Total Cost of Ownership (TCO) – The total cost of owning a light produces over its lifetime including sales price, installation cost, energy consumption, maintenance, and disposal.
Watt – Measurement unit for the electric power consumption of lighting fixtures, or any other appliance that runs with electricity.
Design Considerations
The principal purpose for a commercial building is to be a space for the occupants or visitors to accomplish a task or to conduct an activity. To accomplish this purpose, both ambient and task lighting are generally necessary. To achieve either is why the amount of light is essential. Under-illuminating impedes most types of activities, but over-illuminating also causes problems.
The current energy codes will often indirectly dictate the type of lighting to be used. Usually, the code limitation on the design building energy performance factor narrows the list of possible lighting to LEDs with maybe some large projects allowing other types. Incandescent and halogen are generally out while the more efficient bulbs of standard fluorescent (T5, T8, and T12) and CFL, are possible.
Calculation of the foot-candle level is required to determine the number of lights needed in a space. Typically, Electrical Engineers use software programs such as DIALux or AGi32 for foot-candle level calculations. Then codes will usually require that a COMcheck report is generated that demonstrates the building’s design complying with all commercial energy code requirements for envelope, lighting, and mechanical systems.
Based on just the upfront cost, incandescent and CFL bulbs appear to be the most economical choices when compared to LED bulbs, but sticker price doesn’t tell the whole story. Utility companies don’t seem to have any grand plan of slashing energy costs anytime soon so the cost of energy consumption must be factored in. And each time you replace a light bulb, there is not only the cost of the replacement bulb but also labor. Ideally, you would want light of sufficient brightness, in the correct light temperature, that was inexpensive to operate and own that also produces little waste heat and has a long life.
LEDs seem to fit the bill. Many calculations show that the TCO of CFL bulbs is 70% less than incandescent while the TCO of LEDs is 80% less than incandescent. Overall, the TCO of LEDs is 30% less than CFLs. LEDs produce far less heat than incandescent – allowing the HVAC systems to be smaller and work less.
The closest TCO to LEDs is the CFL and the higher efficient fluorescents. But the fluorescents have inherent problems to consider – they contain mercury (complicates disposal and has a chance of exposure is the bulb breaks), they have a shorter life-span, a delayed startup time especially when cold, most are not dimmable, their ballasts can buzz audibly, and some people are sensitive to their “flickering”.
Lighting may seem like a minor and unusual concern when creating or improving a commercial building or space. But, it’s the concern that has quite an impact on both employees and clients. A well-lit office will send the right message to your customers and make them feel comfortable and welcome within your space.
For your employees, a poorly-lit workspace can seriously hinder their work productivity and possibly be unsafe. Employees spend about one-third of their lives in their workspace and if the lighting is not bright enough, the day can feel drab and can make it challenging to stay focused.
Although increased awareness of the available options is always a good idea, a discussion with a trusted contractor to determine what type of lighting will be best for a project is appropriate. Your contractor can assist in determining the options and the most appropriate features for your tenants, customers, and employees.