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.
Either the building area or space-by-space method can be used to show compliance with Code and receive financial incentives from Efficiency Vermont. The space-by-space method, recommended for most projects, is useful during design to determine the effects of different lighting fixture selections and layout.
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/building 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 2 "modes" that can be used across the tool, either of which can be used to show compliance and receive EVT incentives:
- Building Area Method – Building area type and fixture quantities are identified. Controls must be entered manually.
- Space by Space Method – Space types, floor areas, and fixture quantities are identified. Automatically shows required controls.
Both modes have four input tabs and a summary tab:
- Project Info – Basic project information is provided.
- 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.
- Building Area Method/Space by Space Method – Baseline and designed power density and total power for each building area type or space type are calculated, based on the mode selected.
- Exterior Lighting – Exterior fixtures and associated power inputs are identified.
- Summary – Total building baseline and designed power are calculated.
Check out this video that demonstrates how to use the tool.
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: April 02, 2021