Resources Category

Lighting Retrofits

Many commercial office buildings in New York City have old, technologically outdated lighting systems. Local Law 88 required that larger buildings bring these systems up to the energy code by 2025. 

Upgrades to commercial lighting systems can be implemented at different levels of complexity and cost, from simple upgrades installing new components, such as lamps, ballasts, and occupancy or vacancy sensors, to total relighting and redesign scopes. 

THE BETTER THE UPGRADE, THE GREATER THE BENEFIT
The primary motivation for lighting upgrades may often become economic (realizing savings through reduced energy consumption and available incentives), but benefits extend to improved aesthetics and lighting quality, elevated productivity, and increased property values and rents. Too often we focus only on the energy aspect, but these other more intangible benefits may be of equal or even greater value. 

3.0 The diagram above illustrates an important fundamental concept: As the significance, scope, and investment cost of a lighting retrofit increase (shown in green), the hard and soft benefits (shown in yellow) will increase as well. Furthermore, there is compelling evidence that the ratio of upgrade cost to aggregated benefits is most advantageous for the more involved upgrade scenarios. 

WHEN & WHERE TO UPGRADE?
The following trigger conditions indicate which commercial spaces quality as good candidates for lighting system upgrades. 

  • Spaces currently using old, inefficient technology such as T12 fluorescent fixtures or screw-based incandescent bulbs.
  • Spaces currently using inefficient luminaire types, such as parabolic recessed troffers or recessed downlights.
  • Spaces whose poor lighting quality renders them dark, depressed, dreary, boring, and generally unwelcoming.
Upgrading these spaces to the current energy code with new technology while using better design approaches can dramatically improve their marketability, rents, and occupant satisfaction.

Local Law 88 mandates that large buildings upgrade their lighting systems by 2025, but there are compelling reasons for owners and property managers to consider upgrading sooner:
  • The energy code is becoming more stringent. If a building upgrades now by bringing its lighting system in compliance with the current City Energy Code it will be in early compliance with LL 88. By waiting for a later date or even 2025 to implement the upgrade, compliance with the more stringent energy code in effect at that time will make the upgrade commensurately more involved and costly.
  • Waiting is costly. Sooner the upgrade is completed, the sooner the benefits will start accumulating - including cost savings from lower energy use as well as increased income from improved marketability and rents. 
  • Tenant changes offer cost-efficient opportunities for upgrades. With changes in tenancy the commercial interiors are typically remodeled (known as tenant improvements or tenant fit-outs). Since there will already be a capital budget in place for such tenant fit-outs, the incremental cost of upgrading the lighting system in accordance with LL 88 will be lower than if it was funded as a stand-alone project. 
  • Financial incentives are available now, but may not be in the future. Current financial incentives for lighting upgrades (by Con Edison, NYPA, and NYSERDA) are typically only funded for a limited period, and the incentives landscape of the future is essentially unknowable. Therefore, project teams may want to take advantage of those incentives while they are available. 

THREE APPROACHES TO LIGHTING RETROFITS
The diagram shows three tiers of upgrade: Good, Better, and Better Yet. Good is perhaps the most common and involves simple component replacements, such as relamping/reballasting existing luminaires. Better involves replacing whole luminaires and controls. Better Yet involves total relighting and redesign using new products and current best design practices. The following paragraphs explore these three approaches based on their presumed implementation in a hypothetical generic office suite. 

The office suite shown below is a rectangular corner suite with windows along the east and north sides, a row of enclosed private offices along the north side, and a large open office area in the remainder of the space. The pre-retrofit lighting system consists of 3-lamp T12 parabolic recessed troffers for the entire suite, controlled by three on/off switches for the open office area, and individual on/off switches in the private offices. 

Good - Component Replacement
Per the current energy code, office spaces need to stay below a lighting power allowance of 1 Watt per square foot. To achieve this, all luminaires will be relamped and reballasted from T12 to high-performance T8 lighting. Inefficient T12 fixtures are often found in older office environments featuring parabolic recessed troffers as shown below. To comply with the energy code's automatic lighting shutoff requirement, a schedule-based lighting control system for all lighting circuits will be installed, as well as new vacancy sensors in the private offices per the requirements of Local Law 48. While this approach will yield substantial lighting energy reductions, the space will retain its somewhat outdated design aesthetic which may continue to limit its marketability. 


Better - Luminaire / Control Replacement
The Better approach goes a step further by replacing whole luminaires (not only luminaire components), thus allowing the project to take advantage of the improved efficiency and distribution of state-of-the-art luminaires. In addition to the schedule-based lighting control system, new vacancy sensors will be installed to control the lightings in both the open office area and the private offices. The added advantage of this approach is the improved quality of the light and updated aesthetic of the luminaires themselves which may benefit the space's marketability.


Better Yet - Relighting / Redesign
This "from scratch" approach involves complete relighting and redesign of the lighting system, optimizing the lighting and controls specifically for the space. A task/ambient strategy is selected to stay significantly below the energy code's lighting power allowance. The ambient lighting system will provide sufficient illuminance for computer tasks, and the task lighting will provide the supplemental illuminance for reading and writing small print.

The ambient lighting system will consist of 1-lamp HPT8 pendant direct/indirect luminaires mounted at a height of seven feet above the floor in both the open and private offices. The task lighting will consist of LED lights at each work station. An advanced control system will provide scheduling and occupancy controls in both private offices and the open office area as well as daylight dimming controls in daylit zones. In addition, bi-level vacancy controls will be installed in the private offices. The Better Yet approach, in particular if coupled with a broader tenant improvement scope, allows a space to maximize its marketability and to command high rents and/or sale prices. 


Comparison
The following chart compares the three approaches in economic terms. Keep in mind however, that the non-economic benefits and potentially increased property valuation and rents are not reflected in these numbers. 

We notice that the Good and Better approaches have the same simple payback of 6.8 years, but with its higher annual energy cost savings the Better approach is a more attractive long-term investment. The Better Yet approach, as one would expect, has a longer simple payback. 

As illustrated in the following chart, all three approaches comply with the energy code, but the Better Yet approach exceeds the minimum code requirements by the largest margins - translating into greater savings and potentially higher rebates from energy efficiency incentive programs. 

The quantitative analysis of the three approaches, however, fails to convey a very important maxim: Lighting is ultimately for the benefit of the people inhabiting a space. A study by the Rocky Mountain Institute demonstrates that businesses on average spend 85% of their expenditures on people (salaries & benefits) and only 1% on lighting. It becomes apparent that even an incremental in employee productivity can dwarf the entire electric bill of a business. 

The key conclusion from this comparison are that simple payback is ultimately not a good metric for evaluating efficiency investments, and that when all the benefits - hard and soft - are considered, the Better Yet approach wins. 

MINIMIZING LIGHTING POWER DENSITY
The lighting power density (LPD), measured in watts per square foot (W/sf), refers to the amount of energy used by the lighting systems per square foot. The lower the LPD, the more efficient the lighting system. Keep in mind, however, that strategies to minimize LPD should never be implemented at the expense of lighting quality.

The real-life challenge to implementing holistic low-LPD strategies is the separation of responsibilities among the members of the design team. Many of the design decisions affecting LPD are not within the scope of the lighting designer. Instead, the architect or interior designer is typically responsible for factors such as interior layout and colors and materials for partitions, ceilings, and furniture. Therefore, an integrative design process is critical for driving down LPD while realizing high lighting quality. 

The following five fundamental steps can guide design teams toward the achievement of low-LPD outcomes:
  1. Optimize the space layout and partition heights. Generally, open offices will have lower LPDs than private offices, and lower partition heights in open areas with high ceilings can further lower LPD.
  2. Specify high reflectance finishes with bright, matte colors. Finishes for interior partitions, floors, ceilings, and furniture should avoid grays, browns, reds, and darker greens that create dark spaces. This strategy has the greatest impact in smaller spaces with lots of vertical surfaces. 
  3. Employ a task/ambient lighting strategy. Install an ambient lighting system to meet the lower illuminance criteria for one set of tasks coupled with adjustable task lights for tasks requiring higher illuminance.
  4. Use high-efficiency luminaires. The best luminaires are those that maximize luminaires are those that maximize luminaire efficiency and distribute the light where it is needed (as opposed to losing it in the luminaire housing) without introducing problematic glare.
  5. Use high-efficiency technologies. For interior spaces, fluorescent and LED are the preferred technologies. Selecting the most efficient version from a technology family can substantially reduce LPD. 

The chart below shows ranges of LPD for common lighting technologies. 

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