While high-rise buildings have unique energy-efficiency challenges relative to occupancy and ownership, there is significant evidence that energy reduction not only saves money for building owners and operators, but also increases property value.
According to the Institute for Market Transformation, lower energy costs translate to higher returns. Energy-efficient properties have higher occupancy levels, lease-up rates, and sale prices than less efficient properties. Tenants and real estate investors are demanding energy efficiency, sometimes paying a premium to lease or own space where energy costs are lower. Banks and insurance companies are beginning to reward energy efficiency with better financing and lower premiums.
Because it’s the most significant contributor to energy use, lighting also presents the most opportunity for savings.
Not only does inefficient lighting contribute to wasted energy, the by-products of poor lighting further support the need for retrofits and upgrades: excessive heat gain, low power quality, decreased occupant comfort, etc.
The following lighting measures are applicable to high-rise commercial buildings, and represent the opportunity to save up to 30 percent in energy costs:
Retrofit T12 lamps with T8s, which last longer and require less maintenance. Increased lighting quality from these lamps will decrease the number of fixtures needed per square foot. If replacement is an option, consider T5 lamps, which offer even higher performance and better optical control.
Replace magnetic ballasts with electronic ballasts to increase efficiency by as much as 30 percent. Electronic ballasts enable dimming and remote control, and have saved an estimated $15 billion in commercial buildings energy use since 2005.
Install occupancy and/or photosensor controls to dim or shut off lights when natural light or inactivity renders them unnecessary. Digital lighting controls are also gaining momentum in high-occupancy commercial settings. Their flexibility is ideally suited to spaces with occupancy churn because they enable automated management and configuration via software vs. rewiring.
Incorporate daylighting. It can be brought into a building through conventional glazing, light shelves, skylights, clerestory windows, light pipes, or specialized reflective materials. When utilizing daylighting, it’s important to also eliminate glare and put controls in place that reduce electric lighting when daylight is present.
Replace incandescent with compact fluorescent lamps (CFLs) in downlights, sconces, task lights, and wall washers. Screw-in CFLs are basic one-for-one lamp replacements, but most commercial settings utilize pin-base CFLs, which are used with a separate ballast. Pin-base systems are hardwired into the socket, which prevents the occupant from reverting back to incandescents. They’re available in a lower-power version to replace incandescent lamps, and a higher-power version to replace linear fluorescent or HID lamps.
Consider LEDs. While the initial cost of LEDs is considerably higher, they’re viable for specific applications. Due to their high efficiency, they’re particularly efficient and successful in filtered sources like exit signs. Their small size and directional nature make them a good choice for task lighting, too.
Due to the complex and comprehensive nature of high-rise facilities, as you put some of these ideas into practice, remember that a whole-system approach and proper commissioning are essential bookends to the lighting energy-efficiency process.
LED Lighting Brings Energy and Labor Savings to Marriott Headquarters
Last year, LED lighting systems were installed in several locations at Marriott International’s headquarters located in Bethesda, Md. The installations have enriched lighting quality, heightened employee security and improved energy efficiency.
Following its corporate campus-wide lighting update, Marriott now uses 860,000 fewer kilowatt hours (kWhs) of electricity and has saved more than $120,000 in combined energy and maintenance in just one year.
In an example of savings that go beyond electricty, special scaffolding was needed to reach fixtures in the high ceiling of the foyer (pictured). Marriott would change the lights, which lasted just one to two years on average, once a year at a cost close to $3,000. The maintenance savings is already adding up after Marriot replaced 12 90-watt bulbs with 20-watt LED PAR38 lamps. Rated for 50,000 hours of life, the new LEDs may keep the scaffolding away for up to seven years.
Marriott’s comprehensive LED update has decreased annual electricity use by 66 percent (680,000 kWhs outside; 180,000 kWhs inside) at its headquarters, slashing energy expense an estimated $104,000. Maintenance mitigation will yield an additional $210,000 savings over the next decade for a total return exceeding $120,000 a year. Marriott will also receive more than $130,000 in utility rebates and EPACT savings. All told, the anticipated payback period for the lighting project is slightly more than two years, based on combined electricity, maintenance and labor reductions.