Commercial Energy Codes and How They Pertain to Lighting

What´s Out There: 

IECC – 2000, 2003
The International Energy Conservation Code (IECC) is an energy efficiency code developed by the International Code Council (ICC). The IECC applies to single and multi – family residences, which are three stories in height or less. Additionally within chapter 8, provisions for simple commercial buildings are made. With more complex buildings, the IECC references ASHRAE / IESNA Standard 90.1 – 1999.

ASHRAE / IESNA Standard 90.1 – 1999, 2001
ASHRAE / IESNA 90.1 is a standard which provides minimum requirements for the energy – efficient design of commercial buildings and building systems and can be incorporated into States´ building and energy codes. ASHRAE / IESNA Standard 90.1 – 1999 has been widely adopted into State building and energy codes across the U.S. The newest version of standard 90.1 (2001) is just beginning to be adopted.

State – Developed Codes
In addition to the standards and codes written by specific organizations which are available for adoption, States also have the ability to write their own codes, which may or may not incorporate various elements from ASHRAE / IESNA Standard 90.1 or the IECC. The state of California is an example of a State that has done just this. Their commercial energy code, 2001 Energy Efficiency Standards for Residential and Non – Residential Buildings (also known as Part 6 of Title 24 - the State building code), is mandatory throughout the state and encompasses both public and private buildings.

Commercial Energy Code Adoption 
According to the Building Codes Assistance Program´s (BCAP) most recent newsletter (September / October 2003):

5 States have adopted ASHRAE / IESNA Standard 90.1 – 2001 (the most recent version of the standard) or have an equivalent State – developed code

5 States have adopted the 2000 IECC (which references ASHRAE 90.1 – 1999 for commercial buildings)

18 States have adopted ASHRAE / IESNA Standard 90.1 – 1999 or have an equivalent State – developed code;

The remaining States do not have commercial energy codes or the ones in place are not EPACT compliant. As an update to EPACT (1992), U.S. legislation was passed which mandates that States adopt a building code at least as stringent as ASHRAE 90.1-1999 by July 15th, 2004 or justify why they cannot comply. 

What ASHRAE / IESNA Standard 90.1 – 1999 says with regard to lighting:

1. Lighting Power Density requirements – Lighting power values are determined using the whole building method (Table 9.3.1.2) or the space-by-space calculation method (Table 9.3.1.2) in watts per square foot (W / SF).

2. Track Lighting / Plug – in Busway – For track lighting / plug-in busway, the code assumes 30 W / linear foot OR the total wattage of all luminaires, whichever is greater (9.2.5 c). In addition, display lighting must be on a separate circuit (9.2.1.4). 

3. Wattage Labeling – The wattage of incandescent or tungsten – halogen sources with medium screwbase sockets will be the maximum labeled wattage of the lamp. Accordingly, it is acceptable to label the socket with a lesser wattage. For instance, a tungsten halogen PAR38 fixture (LSI 290 Series, for example) with a maximum rated wattage of 250 watts could be labeled to 90 watts, thus reducing its energy consumption potential (9.2.5 a).

4. Transformer Capacity – The wattage of low – voltage lighting track, cable connector, rail connector, and other low voltage flexible lighting systems, which allows the addition or relocation of luminaires without altering the wiring of the system, shall be the specified wattage of the transformer supplying the system (9.2.5 d).

5. Additional Interior Lighting Power Allowances – The lighting power allowance for a retail sales floor is 1.8 W / SF. By using the space – by – space calculation method, an additional 1.6 W / SF is allowed for display lighting and an additional 3.9 W / SF for accent lighting of fine merchandise. In the 2001 edition of Standard 90.1, fine merchandise is furthered defined as ‘valuable merchandise´ such as fine apparel and accessories, china and silver, art, and similar items, and where detailed display and examination of merchandise is important (ASHRAE / IESNA Standard 90.1 – 2001, 9.3.1.2.1 c).

6. Exemptions – The exemptions where LSI products are often used: exhibit displays for museums, galleries, monuments and retail display windows (provided the display is enclosed by ceiling – height partitions)(9.3.1). 

Retail Example (ASHRAE / IESNA 90.1 –1999):
(See Illustration- Top- left)

Total Sales Area of a Retail Store = 1,000 Square feet

Interior Lighting Power Allowance (ILPA space-by-space method) Retail = 1.8 W / SF

General Sales Area (250 SF)
250 SF x 1.8 W / SF = 450 W    →    ILPA for Retail = 1.8 W / SF

Display Area (500 SF)
500 SF x 1.8 W / SF = 900 W    →    ILPA for Retail = 1.8 W / SF
500 SF x 1.6 W / SF = 800 W    →    Additional Allowance for
Area Wattage: 1700 W         Display Lighting

Fine Merchandise Display Area (250 SF)
250 SF x 1.8 W / SF = 450 W    →    ILPA for Retail = 1.8 W / SF
250 SF x 3.9 W / SF = 975 W    →    Additional Allowance for
Area Wattage: 1425 W        Fine Merchandise Lighting

What California´s Title 24 Part 6 (2001) says with regard to lighting:

1. Lighting Power Density requirements – The lighting power for a building must be calculated using one of the following methods: complete building method (Section 146 (b) 1), area category method (Section 146 (b) 2), or the tailored method (Section 146 (b) 3). 

Retail:
Complete building method - 1.7 W / SF
Area category method - 2.0 W / SF

The Tailored Method allows 2.0 W / SF + additional wattage for Sales Feature Displays:

Gross Sales floor area: The gross sales floor area shall be no more than 2.0 watts per square foot, plus the allocation for sales feature displays (Section 146 (b) 3D, i)

Sales Feature Floor Displays: Illuminance category G (Table 1-S) may be used for no more than 10 percent of the gross sales floor area of the building. (Section 146 (b) 3D, ii)

Gross Sales Wall Area: Gross sales wall area shall be no more than 2.0 watts per square foot, plus the allocation for sales feature wall displays (Section 146 (b) 3D, iii)

Sales Feature Wall Displays: Illuminance category G (Table 1-S) may be used for no more than 10 percent of the gross sales wall area. (Section 146 (b) 3D, iv)

Very valuable merchandise: For lighting of very valuable merchandise the smaller of the two: (1) 20 watts per square foot times the area of lighted case top; or (2) The actual design wattage of the lighting equipment for the merchandise (Section 146 (b) 3H, i)

Mounting Height Multipliers: Multiply the lighting power density value of each task for Illuminance categories E through I multiplied by the area of the task space. For tasks where luminaires must be at or above 15- foot mounting height, the result may be multiplied by the applicable figure from Table 1-R (Section 146 (b) 3F).

2. Track Lighting / Plug – in Busway – Calculating actual lighting power can be done through: 
a. 45 W / linear foot (wattage assumed by the code);
b. The total wattage of the luminaires;
c. The rating of an integral current limiter (Section 130 (d) 3&4)

Display lighting must be on separately switched circuits of no more than a 20 Amp capacity. (Section 131 (e))

3. Wattage Labeling – The wattage of incandescent or tungsten – halogen sources with medium screwbase sockets will be the maximum labeled wattage of the lamp. Accordingly, it is acceptable to label the socket with a lesser wattage. For instance, a tungsten halogen PAR38 fixture (LSI 290 Series) with a maximum rated wattage of 250 watts could be labeled to 90 watts (Section 130 (d) 1).

4. Transformer Capacity – The wattage of low – voltage lighting track, cable connector, rail connector, and other low voltage flexible lighting systems, which allows the addition or relocation of luminaires without altering the wiring of the system, shall be the specified wattage of the transformer supplying the system (Section 130 (d) 4).

For a 10´ run of track, you would have the following options (examples courtesy of the CA Energy Commission) (Section 130 (d) 3&4):

Example 1
1. Lighting power density for track lighting: 45 watts / foot = 450 watts
2. Actual wattage used - 500 watts
In this example, 500 watts must be used

Example 2
1. 45 watts / foot = 450 watts
2. Actual wattage - 300 watts
In this example, 450 watts must be used

Example 3
1. 45 watts / foot = 450 watts
2. Actual wattage - 300 watts
3. The maximum electrical capacity of an integral current limiter (2.5A@120V) - 300 watts
In this example, 300 watts can be used

5. Exemptions – The exemptions for applications where LSI products are used:
(1) display or accent lighting essential for galleries, museums, and monuments; 
(2) special effects lighting at theme parks (Section 146 (a) 5). Lighting within retail windows enclosed by partitions is non – exempt as it is in ASHRAE / IESNA 90.1.

Conclusions / Summary:

In the U.S., energy codes within the States are constantly changing as older versions are replaced with newer ones. In 2005, California will adopt a more stringent version of Title 24. Even within a State, local jurisdictions may adopt different versions of the energy code adopted by the State itself.

For the most up-to-date information, please visit these websites:

Building Codes Assistance Program (BCAP):
www.bcap-energy.org

Department of Energy (DOE):
www.energycodes.gov 

California Energy Commission (CEC):
www.energy.ca.gov/title24/index.html

American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE):
www.ashrae.org

International Energy Conservation Code (IECC):
www.iccsafe.org/index.html 

This publication is designed to provide accurate and authoritative information in regard to the subject matter, which is covered herein. While we endeavor to provide accurate and timely information, inaccuracies may occur from time to time. The information contained herein is accurate to the best of our knowledge at this time. 1/29/04