Article #1387 - ASHRAE 90.1-2004 Lighting Requirements General Information

This article is based on questions asked during the November 2004 IESNA webcast

How do I comply with the 90.1-2004 Standard?

The 90.1-2004 standard was published in December of 2004 and this standard as well as a user's guide can be purchased from the American Society of Heating, Refrigerating and Air-Conditioning Engineers website. The user's guide contains paper forms for use in showing prescriptive compliance with the code.

States permitted to use COMcheck for energy code compliance (6/2006).

Software is available for computer or on-line compliance with national codes such as IECC (through 20030 and ASHRAE/IESNA (through 2001). The COMcheck tool is available free from the Building Energy Codes Program website. The software will be updated to include the 2004 version of 90.1.

When will the 2004 version of the ASHRAE/IESNA standard be adopted by states as the applicable energy code?

The timing of adoption of energy codes at the state level depends greatly on their legislative process and advocacy within the state. Some states adopt new codes very quickly. Others are still considering options and have not adopted a statewide energy code. You can find current information on the status of state adoption of energy codes at the Status of State Energy Codes directory.

Where are interior LPD models maintained and are they only in an Excel format?

The models are maintained by the ASHRAE Lighting subcommittee in Excel format only. An interactive version of these models representing the 1999 and 2001 versions of the standard is available at the IESNA LPD website.

Why are other technologies such as fiber optics and LEDs not included in the common fixture models?

The section of the standard that defines calculation of fixture wattage mentions some of the more common technologies only in terms of how to calculate their wattage for compliance. This same section also provides information on wattage calculation for all other (less common) technologies.

The LPD models are meant to characterize common modern lighting design to represent typical current construction. Fiber optics and LEDs are certainly used in building lighting but are not as yet common primary lighting sources for general interior illumination and therefore are not specifically represented in LPD models.

The standard does not preclude the use of any lighting system or technology. The standard only supplies power limits and controls and other mandatory requirements that can be met using any appropriate technology.

Comparision of the new ASHRAE 90.1-2004 lighting power density limits. Watts per square foot.

What are the differences in the versions of the ASHRAE standard?

For lighting, there are large differences between the 2004 and the 2001 version. The lighting power density requirements have been completely revised and a new exterior lighting section added, as well as other controls changes and updates.

What is the effective date for states to comply with the ASHRAE/IESNA 90.1-2004 energy standard?

Compliance to an energy code is mandated by a state or local jurisdiction. The federal EPACT regulation set a July 2004 deadline for states to adopt an energy code at least as efficient as 90.1-1999. Many states have done this - some have not. There is currently no effective date for compliance with the 90.1-2004 standard.

If the DOE determines that the 2004 version is more efficient than the 1999 version, then the 2004 version will likely be the reference code for adoption per EPACT and states will have a new deadline to adopt a code meeting this level of efficiency.

Who is responsible for and will be enforcing the lighting requirements and the LPD limits?

Compliance is the responsibility of the state or local building officials through plan reviews and/or inspection similar to compliance with other building codes.

What is the process for requesting an interpretation of the energy standard from ASHRAE?

An informal interpretation is typically developed by the appropriate subcommittee based on their understanding of the issue without any formal vote/approval of the full 90.1 committee. These are generally provided to the requestor in a short timeframe. If a subcommittee feels that an informal interpretation request is beyond "informal", they may choose to ask the submitter to resubmit as a formal one or simply run it through the formal process including full committee vote/approval.

A formal request is just that - more formal in process in that it requires full committee approval and becomes a listed interpretation posted on the ASHRAE website. There is no cost to the requestor for either form of interpretation, and requests chould be submitted to ASHRAE via email.

If ASHRAE provides an interpretation on its energy standard does this interpretation bind the local building official to the finding?

State and local jurisdictions are not bound by interpretations unless they decide to be. Generally, they would apply the interpretation unless there is a clash with other codes or convention in that area. Building officials are generally just as interested in a solution to code issues that they can cite as much as the user is. Therefore, interpretations are generally accepted as applicable by both building officials and builders.

How does LEED decides by what percentage a designer has gone above and beyond ASHRAE Standard 1999 to determine how many energy points a building gets?

The LEED energy credit is measured with the use of whole building energy model runs - proposed design versus base case that meets the standard. These account for all building energy systems. Therefore, it is not clear how much just lighting efficiency will affect the available LEED points.

It is likely that other energy improvements will be present in the proposed building including other lighting efficiencies such as controls that will further improve the energy points for the building.

For fluorescent fixtures, is the maximum labeled wattage of the future used for power density calculations?

For example, many manufacturers are using ballasts for fluorescent fixtures that take either a 26W, 32W, or 42W CFL. Although not specifically addressed in the standard, the general intent is that multi-watt compact fluorescent luminaires would be treated in a similar fashion to incandescent luminaires - the highest rated wattage of the ballast would be the wattage to use for compliance.

However it may not be possible to change to a different lamp given the geometry and space inside the fixture. If this is the case, the user would want the manufacturer to label their fixture for that rating to avoid a penalty for a multi-ballast rating that cannot be used. This item is currently under discussion within the ASHRAE lighting subcommittee to consider a possible modification to the standard.

What should engineers and designers of buildings say when clients do not want us to comply with ASHRAE due to the extra cost?

When a state adopts an energy code it becomes law like any other building code and must be complied with. There are always cases where a building owner will seek a waiver of some code for a specific reason but a cost element is not likely to be considered as a valid reason.

Are there any papers or other documentation on the development of the lighting models for the ASHRAE 90.1 Standard?

A paper was written and presented at the 1999 IESNA conference on the LPD methodology used in the ASHRAE/IESNA standard (at that time the 1999 version). At about the same time an interactive viewable version of the model was developed and placed on the IESNA LPD website.

The paper is also available under "Methodology" on the IESNA LPD website. While these materials are based on the 1999 version of the standard, the methodology is basically the same for the 2004 version with updates of all the inputs, which are the basis of the new 2004 LPDs.

Code citations that appear in this article are from: Copyright, 2004, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, GA. ASHRAE Standard 90.1-2004. Reproduced with permission. All rights reserved.