It's about more than choosing LED light fixtures, which provide higher-quality illumination and use less energy than other lighting types. Reduce lighting power without sacrificing functionality by decreasing total installed wattage through thoughtful design and consideration of necessary light levels.
High-efficiency LED lights have longer lifespans and can significantly reduce or even eliminate maintenance costs. No additional cost is required for disposal of hazardous materials, as is needed with fluorescents.
For a lighting power density (LPD) of 0.10 watts per square foot (W/sf), annual energy savings range up to 25% of lighting energy, depending on building operating schedule.
By using LED fixtures and light levels consistent with Illuminating Engineering Society of North America (IESNA) recommendations, a best-practice interior lighting power density may cost less than meeting the baseline with fluorescent fixtures, meaning payback is immediate.
LED lighting offers better glare control and uniformity than alternatives. LED fixtures also do not have the ballast hum that sometimes comes with fluorescent fixtures.
Specify use of LED fixtures with a target LPD of 0.10 W/sf or less and light levels consistent with IESNA (Illuminating Engineering Society of North America) recommendations. Many parking garages can achieve lighting power density values as low as 0.05 W/sf with current technology.
Target selection of fixtures meeting Design Lights Consortium Qualified Product List (DLC QPL)
A thoughtful lighting control scheme reduces energy use and increases lighting lifespan without affecting the comfort of building occupants.
Lighting controls are already required by code, so implementing a more aggressive control strategy adds little to no additional first cost.
With a control strategy targeting 50% power reduction within 5 minutes, the annual cost savings of lighting controls are up to 30% of lighting cost per year. Simple payback is usually about 2 years.
In contrast to fluorescent lights (which have a reduced lifespan with frequent switching), LED lights are not adversely affected by frequent switching, and in fact last longer with a more aggressive controls strategy due to reduced run-hours.
Designing to IESNA recommended light levels aid in improved lighting quality through reduced potential for glare. LED lights also provide better control of delivered lumens contributing to a more uniform illuminance resulting in improved lighting quality even at lower light levels.
Design lighting controls with more granular zoning to increase savings potential and to allow for short time-delay-to-off following vacancy without impact to functionality.
Alternately, implement multi-level or stepped shutoff control of light output, such as 50% reduction in 5 minutes, followed by 80% reduction in 20 minutes from vacancy.
Consider networked lighting controls which allow for advanced lighting control strategies such as task tuning to further increase savings, functionality, and ease in making changes.
As with all control measures, post-occupancy commissioning and verification is important to ensure lighting operates as designed. Consider sensor calibration and adjusting time delays.
As with interior lighting, exterior lighting efficiency is about more than just choosing LEDs. Thoughtful design addresses any security concerns strategically while not exceeding recommended light levels. Designers should incorporate high-efficacy fixtures from the array of LED products on the market.
High-efficiency LED lights have longer lifespans and can significantly reduce maintenance costs. Additionally, instant on/off control reduces the need for supplemental life safety lighting components.
Buildings that implement best-practice efficient exterior lighting can expect to save from 2% to 4% of building energy costs, with payback in one year or less due to the low initial cost.
LED lighting offers better glare control and uniformity than alternatives, contributing to improved facial and object identification. Customer satisfaction and comfort can be achieved with lower installed lighting power designs, while reducing light pollution and trespass. Safety and security concerns can be met without exceeding desired light levels. The inherent dimmability of LED fixtures provides potential for tuning light levels post-installation, providing opportunity for additional energy savings.
Compare your project's Watts per square-foot of parking and drive area and Watts per linear foot of doors to the recommended targets in this guide.
Do not exceed Illuminating Engineering Society of North America's (IESNA) recommended light levels (0.2 to 0.5 foot-candles for parking lots) for the building's exterior lighting zone.
Confirm any specific security issues requiring enhanced lighting.
Target selection of DLC QPL premium performance requirements:
· Minimum warranty of at least five years for all components
Even the most efficient lighting designs can further benefit further good lighting control strategies. Dim building mounted and pole mounted fixtures during nighttime hours with little to no activity while turning off landscape and accent lighting.
Thoughtful lighting control zoning and sequencing reduces energy use and increases lighting lifespan without affecting functionality.
Lighting controls are required by the energy code, so implementing a more aggressive control strategy does not add to the first cost of a project.
Implementing best-practice exterior lighting controls results in electric energy savings of 1 or 2%, with payback in a year or less due to the low initial cost.
Simply increasing light levels does not necessarily enhance safety or security. A U.S. Department of
Energy report (PNNL-18173) suggests that high-quality exterior lighting design contributes to safety and security.
Effective control of exterior lights can also reduce light pollution and light trespass.
Group exterior lights into at least three zones: Building-mounted fixtures, pole-mounted fixtures closest to the building, and pole-mounted fixtures farthest from the building.
When operating hours are known, implement schedule-based controls to turn off or significantly reduce all but essential dusk-to-dawn fixtures after expected use of the parking area.
When operating hours are unknown, consider motion controls to turn off or significantly reduce lighting in unoccupied areas. More granular zoning of large exterior parking areas increases savings, as sensors only activate some portion of exterior area lighting.
Enclosed parking garages require ventilation to remove automobile exhaust products and ensure a safe breathing environment. However, full ventilation is typically needed only for brief periods. Adding variable speed drives to ventilation fans controlled by carbon monoxide sensors allows the system to provide only as much ventilation air as the garage needs.
Contamination sensor-based ventilation controls are already required in enclosed parking garages by code. Incremental costs for installing and commissioning a variable speed drive range from $700 to $1,850 per horsepower.
Upgrading to variable speed fans can save 40% of ventilation and heating costs with a simple payback of 1 year or less.
Improved ventilation systems improve indoor air quality. Reducing unnecessary ventilation air reduces drafts when it’s cold outdoors, improving thermal comfort.
Specify variable frequency drives for exhaust and ventilation fan motors.
Refer to ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) Guideline 36-2018 High Performance Sequences of Operation for HVAC (Heating Ventilation and Air Conditioning) Systems for outside air control of single-zone and multi-zone variable air volume air handling units. DCV (Demand Controlled Ventilation) is only as effective as the controls installed on the system.
Many ventilated parking garages use gas-fired unit heaters to maintain a comfortable temperature. These heaters can be improved by using condensing heat exchangers in the equipment, that allow heat to be captured from water vapor in the products of combustion.
Heating fuel use is reduced by 9% or more in a typical application when using condensing unit heaters.
Condensing unit heaters cost 25% to 75% more than a standard unit heater, with a simple payback 2 to 3 years.
Condensing gas fired heating technology consists of a non-corrosive heat exchanger to capture heat from the waste vapor in the combustion process.
Properly maintaining the products of combustion is an important part of a condensing unit heater. Check with your designer to properly dispose of condensate.
Specify condensing unit heaters with a minimum gas heating efficiency of 92% per ANSI (American National Standards Institute) Z83.8. You can specify higher efficiencies for even greater savings. Condensing heating equipment has a maximum efficiency of 96%.
Incorporate high-performance energy efficiency measures into your new parking garage development. You can reduce energy costs for years to come and qualify for incentives that will offset the cost of your improvements.