Objective
The massive footprint of mostly old building stock in the Department of Defense’s (DoD) inventory offers significant opportunities for reducing energy consumption, carbon emissions, and operating costs. Existing lighting systems in many DoD facilities consume excessive electrical energy because they are often outdated, inefficient, and lack automated controls. These factors result in increased energy consumption, higher operational, maintenance, and lifecycle costs, and reduced workforce productivity. The objective of this project was to retrofit buildings with advanced lighting control systems that combine dimmable light sources, occupancy and daylight sensors, and intelligent controls to significantly lower the lighting energy consumption as well as reduce cooling loads due to the thermal effects of lighting. Furthermore, appropriate control and monitoring systems can lower maintenance cost and improve occupant satisfaction.
Technology Description
A team consisting of Philips and Lawrence Berkeley National Laboratory (LBNL) studied the performance of advanced lighting control systems in DoD buildings. Philips developed and deployed the lighting control systems in three buildings in Fort Irwin, California, and LBNL carried out the evaluation of energy savings and occupant surveys by collecting pre- and post-retrofit data and performing all the data analysis.
In this study, three lighting control systems were deployed:
- OccuSwitch Wireless is a room-based lighting control system employing dimmable light sources, occupancy and daylight sensors, wireless interconnection, and modular control to provide energy savings through occupancy sensing, dimming, and daylight harvesting.
- Dynalite is a distributed control-based, wired networked building-wide lighting control system offering scene settings, personalized dimming, scheduling, occupancy sensing, and daylight harvesting to provide energy savings as well as ambience for different activities.
- Hybrid Integrated Lighting and Daylight Control (ILDC) is a combination wireless and wired control solution for building-wide networked system that maximizes the use of daylight while improving visual comfort through integrated control of electric lights and motorized blinds.
Demonstration Results
This project studied the energy, environmental, economic, and user benefits of the three lighting control systems in DoD buildings. The systems’ performance against the objectives and success criteria are summarized in the table below. Most of the objectives were met during the demonstration, with the exception of two that are discussed below.
The three systems performed differently with respect to energy savings as expressed in energy use intensity (EUI)/carbon footprint reduction, peak lighting power density, and cost effectiveness. This is partly due to the differences in the characteristics of the buildings they were deployed in and partly due to the energy savings features of the systems. For instance, the size of the buildings is an important parameter that determines the system cost per unit area as fixed hardware cost, such as servers and controllers that are amortized over the entire area. To provide a more generalized picture that can be applied across DoD facilities, three different building size scenarios have been considered—small, medium, and large. With this classification, payback in less than 7 years is met in most cases with the exception of the small area category for the Dynalite system. The savings to investment ratio (SIR) objective (more than 2) is met in the large buildings for all three systems and in medium buildings for the Hybrid ILDC and OccuSwitch systems. In small buildings, the SIR objective is not met.
Performance Results
| Performance Objective | Success Criteria | Results | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Hybrid ILDC | OccuSwitch | Dynalite | ||||||||
| Reduce electrical energy consumption for lighting | >45% reduction in EUI compared with code baseline lighting energy | 79% | 62% | 43% | ||||||
| Yes | Yes | Yes in 80% of space | ||||||||
| Reduce lighting demand by better lighting design | >25% reduction in peak lighting power density (LPD) compared with code baseline LPD | 60% | 47% | 52% | ||||||
| Yes | Yes | Yes | ||||||||
| Reduce carbon footprint of the lighting system | >45% reduction in carbon footprint compared to a building with code baseline lighting energy in the same region | 79% | 62% | 43% | ||||||
| Yes | Yes | Yes in 80% of space | ||||||||
| Cost effectiveness | Building size | Sm | Md | Lg | Sm | Md | Lg | Sm | Md | Lg |
| >2 SIR over a 20 year period | 1.6 | 2.8 | 3.4 | 1.8 | 2.8 | 4.4 | 1.2 | 1.6 | 2.4 | |
| No | Yes | Yes | No | Yes | Yes | No | No | Yes | ||
| <7 years payback | 6.25 | 3.89 | 3.09 | 5.37 | 3.56 | 2.28 | 8.67 | 6.47 | 4.29 | |
| Yes | Yes | Yes | Yes | Yes | Yes | No | Yes | Yes | ||
With respect to system reliability, system maintainability, work plane illuminance, and ease of installation and commissioning, all three systems met the objectives with significant margin. Systems integration performance—or the effect of the lighting control systems on the HVAC load—as computed from Energy Plus model-based simulations met the project objectives.
Implementation Issues
This demonstration project has shown that advanced lighting control systems deployed in existing DoD buildings can provide significant energy cost and carbon footprint reduction ranging from 43% to 79% depending on the building geometry, legacy system deployed, and usage pattern. For large buildings (over 100,000 square feet), networked systems such as the Dynalite or Hybrid ILDC, are expected to provide the best results; whereas, for medium to small sized buildings, standalone room-based systems such as the OccuSwitch Wireless system would be more appropriate. The Dynalite and the OccuSwitch wireless systems were introduced as commercial products in the U.S. market in 2010 and 2012, respectively.
