Lighting Power Density Tool

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Maximize the energy efficiency of your design, with our Lighting Power Density (LPD) Tool —a downloadable Excel-based tool managed and provided by Efficiency Vermont. With all of the options from the Vermont Commercial Building Energy Standards, we hope that it’s simple, straightforward, and useful.

You may use this tool as an alternative to COMcheck for Lighting, and to receive financial incentives for a completed Efficiency Vermont project.

Calculating Lighting Power

For both interior and exterior lighting, the Vermont Commercial Building Energy Standards (“Energy Code”) require that a Lighting Power calculation be completed to show compliance. For interior lighting, either the “building area” or “space-by-space” method can be used. Different maximum power-densities, measured in watts per square foot, are allowed for different building or space types.

For example, using the building area method, an office building is allowed 0.82 w/sq. ft., while a warehouse is allowed 0.60 w/sq. ft. To complete the calculation, the total allowed power is first determined by multiplying the total building area by the maximum allowed power density. Next, the total lighting power of all installed fixtures is calculated. Finally, the installed power is compared to the allowed power, and must be less to meet Code.

Some special lighting applications are exempt from the calculation, such as exit lights, and some are allowed more power than the standard calculation, such as sales display lighting. There are no lighting fixture requirements for commercial buildings; any technology can be used (ex. incandescent, fluorescent, LED), as long as the installed lighting power is less than the maximum allowed.

While either the building area or space-by-space method can be used to show compliance with Code, the space-by-space method is required to receive financial incentives from Efficiency Vermont. Rather than simply a calculation to show compliance, the Lighting Power calculation is useful during design to determine the effects of different lighting fixture selections and layout.

Code Compliance

The U.S. Department of Energy’s free program called COMcheck is used to show code compliance for all requirements including building envelope, mechanical equipment and systems, and lighting. The Lighting Power calculation in particular is completed in COMcheck. While there are options other than COMcheck to demonstrate compliance, such as energy modeling, it is the simplest and most appropriate for the majority of projects in Vermont. An alternative to COMcheck for the Lighting Power calculation is Efficiency Vermont’s LPD Tool. This Tool has been approved by the Vermont Department of Public Service for the lighting power portion of compliance. A designer can submit the inputs and outputs of the completed Tool to the Code Official as part of their COMcheck submittal, and then to Efficiency Vermont’s assigned Energy Consultant for review and financial incentive consideration. Efficiency Vermont highly recommends the use of this Tool, and that it be used for design in addition to simply compliance.

Using the Tool

Efficiency Vermont’s LPD Tool is automated as much as possible, and includes all of the space types, exemptions, requirements, etc. from the CBES. It is designed to be simple and straightforward to use, while providing accurate and useful information for projects. The LPD Tool is a 2010 Excel based spreadsheet which has four distinct tabs:

  1. Project Info – Basic project information is provided.
  2. Fixture Schedule – Light fixtures and associated power inputs are identified. A default power input is calculated automatically, aside from LED fixtures since the products vary so greatly.
  3. Space by Space – Space types, floor areas, and fixture quantities are identified. Baseline and designed power density and total power for each space are calculated.
  4. Summary – Total building baseline and designed power are calculated.

There are also 2 “modes” that can be used across the tool:

  • Compliance Only – Similar to COMcheck. Cannot be used for EVT incentives.
  • Compliance + Controls + Energy – Same as compliance, but with controls inputs/requirements, and energy calculations as well. Required to receive EVT incentives.

To download the tool, simply submit the following form and you will be directed to the most recent version. By providing your email, you agree to receive future updates about new versions of the tool.

Last revised date: January 01, 2019

Version: 9a

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