## 5.7 Prescriptive Methods for Determining Lighting Power Allowances

This section contains information on the three prescriptive approaches available for complying with the Lighting Standards:

A. Complete Building Method

B. Area Category Method

C. Tailored Method

### 5.7.1 Complete Building Method

§140.6(c)1

The Complete Building Method shall only be applied when lighting will be installed throughout the entire building under the permit is prepared. The building must consist of one type of use for a minimum of 90 percent of the floor area of the entire building.

The Allowed Indoor Lighting Power allotment for general lighting for the entire building shall be calculated as follows:

1. For a conditioned building that qualifies to use the Complete Building Method of compliance, multiply the square feet of conditioned space of the building times the applicable allotment of watts per square foot described in Table 140.6-B.

2. For an unconditioned building that qualifies to use the Complete Building Method of compliance, multiply the square feet of unconditioned space of the building times the applicable allotment of watts per square feet described in Table 140.6-B.

5.7.1.1 Requirements for Using the Complete Building Method

The Complete Building Method shall be used only for building types, as defined in §100.1, that are specifically 'listed in Table 140.6-B. (For example, retail and wholesale stores, hotel/motel, and high-rise residential buildings shall not use this method.)

The Complete Building Method shall be used only on projects involving:

A. Entire buildings with one type of use occupancy.

EXCEPTION to §140.6(c)1Bi: If a parking garage plus another type of use 'listed in Table 140.6-B are part of a single building, the parking garage portion of the building and other type of use portion of the building shall each separately use the Complete Building Method.

B. Mixed occupancy buildings where one type of use makes up at least 90 percent of the entire building (in which case, when applying the Complete Building Method, it shall be assumed that the primary use is 100 percent of the building).

C. A tenant space where one type of use makes up at least 90 percent of the entire tenant space (in which case, when applying the Complete Building Method, it shall be assumed that the primary use is 100 percent of the tenant space).

The Complete Building Method shall be used only when the applicant is applying for a lighting permit and submits plans and specifications for the entire building or the entire tenant space.

Only the lighting power allotment in Table 140.6-B is available for the entire building when using the Complete Building Method. There are no additional lighting power allowances available when using Complete Building Method. Also, there are no mounting height multipliers available when using the Complete Building Method.

5.7.1.2 Definitions of Complete Building Types

When using the Complete Building Method, qualifying building types shall be only those in which a minimum of 90 percent of the building floor area functions as one of the building types 'listed in Table 140.6-B, as defined below, which do not qualify as any other Building Occupancy Types more specifically defined in §100.1, and which do not have a combined total of more than 10 percent of the area functioning as any Nonresidential Function Areas specifically defined in §100.1:

• Auditorium Building is a public building in which a minimum of 90 percent of the building floor area are rooms with fixed seating that are primarily used for public meetings or gatherings

• Classroom Building is a building for an educational institution in which a minimum of 90 percent of the building floor area are classrooms or educational laboratories

• Commercial and Industrial Storage Building is a building for which a minimum or 90 percent of the building floor area is used for storing items

• Convention Center Building is a building in which a minimum of 90 percent of the building floor area are rooms for meetings and conventions, which have neither fixed seating nor fixed staging.

• Financial Institution Building is a building in which a minimum of 90 percent of the building floor area are rooms used for an institution which collects funds from the public and places them in financial assets, such as deposits, loans, and bonds.

• General Commercial and Industrial Work Building is a building in which a minimum of 90 percent of the building floor area are rooms for performing a craft, assembly or manufacturing operation.

• Grocery Store Building is a building in which a minimum of 90 percent of the building floor area is sales floor for the sale of foodstuffs.

• Library Building is a building which is in which a minimum of 90 percent of the building floor area are rooms use as a repository of literary materials, such as books, periodicals, newspapers, pamphlets and prints, are kept for reading or reference.

• Medical Buildings and Clinic Buildings are non “I” occupancy buildings in which a minimum of 90 percent of the building floor area are rooms where medical or clinical care is provided, does not provide overnight patient care, and is used to provide physical and mental care through medical, dental, or psychological examination and treatment.

• Office Building is a building of CBC Group B Occupancy in which a minimum of 90 percent of the building floor area are rooms in which business, clerical or professional activities are conducted.

• Parking Garage Building is a building in which a minimum of 90 percent of the building floor area is for the purpose of parking vehicles, which consists of at least a roof over the parking area enclosed with walls on all sides. The building includes areas for vehicle maneuvering to reach designated parking spaces. If the roof of a parking structure is also used for parking, the portion without an overhead roof is considered an outdoor parking lot instead of a parking garage.

• Religious Facility Building is a building in which a minimum of 90 percent of the floor area in the building floor area are rooms for assembly of people to worship.

• Restaurant Building is a building in which a minimum of 90 percent of the building floor area are rooms in which food and drink are prepared and served to customers in return for money.

• School Building is a building in which a minimum of 90 percent of the building floor area is used for an educational institution, but in which less than 90 percent of the building floor area is classrooms or educational laboratories, and may include an auditorium, gymnasium, kitchen, library, multi-purpose room, cafeteria, student union, or workroom. A maintenance or storage building is not a school building.

• Theater Building is a building in which a minimum of 90 percent of the building floor area are rooms having tiers of rising seats or steps for the viewing of motion pictures, or dramatic performances, lectures, musical events and similar live performances.

Example 5-10 Finding Lighting Power Density Allotments

Question

A 10,000-ft² medical clinic building is to be built. What is its Lighting Power Density Allotment under the complete building approach?

Answer

From Table 140.6-B, medical buildings and clinics are allowed 1.0 W/ft². The Lighting Power Density Allotment is 10,000 x 1.0 = 10,000 W.

### 5.7.2 Area Category Method

§140.6(c)2.

5.7.2.1 Area Category Method General Lighting Power Allotment

The Area Category Method is more flexible than the Complete Building Method because it can be used for multiple tenants or partially completed buildings. For purposes of the Area Category Method, an "area" is defined as all contiguous spaces that accommodate or are associated with a single primary function as 'listed in Table 140.6-C. Areas not covered by the current permit are ignored. When the lighting in these areas is completed later under a new permit, the applicant may show compliance with any of the lighting options except the Complete Building Method.

The Area Category Method divides a building into primary function areas. Each function area is defined under occupancy type in §100.1. The Lighting Power Allotment is determined by multiplying the area of each function times the lighting power density for that function. Where areas are bounded or separated by interior partitions, the floor space occupied by those interior partitions shall be included in any area. The total allowed watts is the summation of the Lighting Power Allotment for each area covered by the permit application.

When using this method, each function area in the building must be included as a separate area. Boundaries between primary function areas may or may not consist of walls or partitions. For example, kitchen and dining areas within a fast food restaurant may or may not be separated by walls. For purposes of compliance they must still be separated into two different function areas. However, it is not necessary to separate aisles or entries within primary function areas. When the Area Category Method is used to calculate the allowed total lighting power for an entire building however, the main entry lobbies, corridors, restrooms, and support functions shall each be treated as separate function areas.

A. Requirements for using the Area Category Method include all of the following:

1. The Area Category Method shall be used only for primary function areas, as defined in §100.1, that are 'listed in Table 140.6-C.

2. Primary Function Areas in Table 140.6-C shall not apply to a complete building. Each primary function area shall be determined as a separate area.

3. For purposes of compliance with §140.6(c)2, an "area" shall be defined as all contiguous areas which accommodate or are associated with a single primary function area 'listed in TABLE 140.6-C.

4. Where areas are bounded or separated by interior partitions, the floor area occupied by those interior partitions may be included in a Primary Function Area.

5. If at the time of permitting for a newly constructed building, a tenant is not identified for a multi-tenant area, a maximum of 0.6 watts per square foot shall be allowed for the lighting in each area in which a tenant has not been identified. The area shall be classified as Unleased Tenant Area.

6. Under the Area Category Method, the allowed indoor Lighting Power Density for each primary area is the Lighting Power Density value in Table 140.6-C times the square feet of the primary function. The total allowed indoor Lighting Power Density for the building is the sum of all allowed indoor Lighting Power Densities for all areas in the building.

5.7.2.2 Additional Lighting Power - Area Category Method

'In 'addition to the allowed indoor Lighting Power calculated according to §140.6(c)2, additional lighting power allowances for specialized task work, ornamental, precision, accent, display, decorative, and white boards and chalk boards, may be added in accordance with the footnotes in Table 140.6-C under the following conditions:

1. Only primary function areas having a footnote next to the allowed Lighting Power Density allotments in Table 140.6-C shall qualify for the added lighting power allowances in accordance with the correlated footnote 'listed at the bottom of the table.

2. The additional lighting power allowances shall be used only if the plans clearly identify all applicable task areas and the lighting equipment designed to illuminate these tasks.

3. Tasks that are performed less than two hours per day or poor quality tasks that can be improved are not eligible for the additional lighting power allowances.

4. The additional lighting power allowances shall not utilize any type of luminaires that are used for general lighting in the building.

5. The additional lighting power allowances shall not be used when using the Complete Building Method, or when the Tailored Method is used for any area in the building.

6. The additional lighting power allowed is the smaller of lighting power 'listed in the applicable footnote in Table 140.6-C, or the actual design wattage.

7. 'In 'addition to the lighting power allowed under §140.6(c)2G(i through vi), up to 1.5 watts per square foot of additional lighting power shall be allowed in a videoconferencing studio, as defined in §100.1, provided the following conditions are met:

a. Before the Additional Videoconference Studio Lighting power allotment will be allowed for compliance with §140.6 of the Energy Standards, the person who is eligible under Division 3 of the Business and Professions Code to accept responsibility for the construction or installation of features, materials, components, or manufactured devices shall sign and submit the Certificate of Installation.

If any of the requirements in this Certificate of Installation fail the Additional Videoconference Studio Lighting installation tests, the installation shall not be eligible for the additional lighting power allotment.

b. The Videoconferencing Studio is a room with permanently installed videoconferencing cameras, audio equipment, and playback equipment for both audio-based and video-based two-way communication between local and remote sites.

c. General lighting is controlled in accordance with Table 130.1-A.

d. Wall wash lighting is separately switched from the general lighting system.

e. All of the lighting in the studio, including general lighting and additional lighting power allowed by §140.6(c)2Gvii is controlled by a multiscene programmable control system (also known as a scene preset control system).

Example 5-11 Calculating allowed lighting power

Question

A small bank building has the following area distribution:

Corridors 800 ft²

Main Entry Lobby 200 ft²

Financial Transactions 1,200 ft²

Manager’s Office 200 ft²

What is the allowed lighting power for this building under the Area Category Method?

Answer

The following Lighting Power Densities apply (from Table 140.6-C):

Space LPD Area Allowed Watts

Corridors 0.6 W 800 ft² 480

Main Entry 0.95 W 200 ft² 190

Financial Transactions 1.0 W 1,200 ft² 1,200

Manager’s Office 1.0 W 200 ft² 200

Total 2,070 W

Financial Transactions in this example are assumed to include all the spaces in which financial transactions for the public are taking place. The allowed lighting power for this building is 2,070 W

Example 5-12 Allowed lighting power including decorative lighting

Question:

What is the allowed maximum lighting power if the small bank in example 5-11 above incorporates decorative chandeliers and wall sconces as part of their lighting design?

Answer:

Provided the decorative lighting occurs in either the Financial Transaction area or Main Lobby and is, in addition to the general lighting, up to 0.5W/ft² added power is allowed for these areas. Therefore the added maximum power is as follows:

Main Entry 0.5 W X 200 ft² = 100 W

Financial Transactions 0.5 W X 1,200 ft² = 600 W

The maximum total of added watts allowed for the ornamental lighting (Chandeliers and sconces) is 100 + 600 = 700 W.

With the addition of these 700 W is revised allowed maximum watts for the small bank is 2,770 W (2,070 + 700 = 2,770).

Note that ornament lighting is “use-it–loose” therefore actual allowed maximum watts for the small bank is the base 2,070 W + the smaller of the actual power of the ornamental lighting or 700W. Therefore if the ornamental lighting uses 300 W the total allowed maximum is 2,370 W for the bank not 2,770 W. (2,070 + 300 = 2,370)

Example 5-13 Allowed lighting power for multi-use spaces

Question

A 10,000-ft² multi-use building is to be built consisting of:

A) 500 ft² main entry lobby,

B) 2,000 ft² corridors and restroom,

C) 3,000 ft² grocery store,

D) 2,500 ft² retail, and

E) 2,000 ft² future development.

What is the allowed lighting power under the area category method?

Answer

Space LPD Area Allowed Watts

A) Main Entry 0.95 W/ft² 500 ft² 475

B) Corridors and Restrooms 0.6 W/ft² 2,000 ft² 1,200

C) Grocery Sales 1.2 W/ft² 3,000 ft² 3,600

D) Retail Store 1.2 W/ft² 2,500 ft² 3,000

TOTAL 8,000 ft² 8,275

With 2,000 ft² for future development

Example 5-14 Maximum allowed wattage for spaces within a multiuse building

Question

What if in the multi-use building (example 5-13), the retail store is planning floor displays and wall displays, as well as decorative chandeliers. How do you determine the allowed maximum watts for this store?

Answer

A) As in the above example, determine the total square feet of the retails store (2,500 feet)

B) As in the above example multiply the allowed LPD (1.2 W/ft²) X 2,500 = 3,000 W (base allowance)

C) Determine the maximum allowed display and accent allowance by multiplying the retail stores 2,500 feet by 0.3 W/ft² (Footnote 6 from Table 140.6-C) = 750 W

D) Determine the maximum allowed ornamental lighting allowance (for chandeliers) by multiplying the retail stores 2,500 feet by 0.2 W/ft² (Footnote 7 from Table 140.6-C) = 500 W

E) Add the 3,000 W base plus 750 W for display and 500 W for ornamental = 4,250 W

The maximum allowed watts for this retail store, under the area method, is therefore 4,250W or 1.7 W/ft²

Note: The allowed maximum is usually somewhat less than the theoretical maximum of 1.7 W/ft² as the display/accent lighting and ornamental lighting components are “use-it-lose it” with the lower luminaire lighting power becoming the allowed power. Also for the added power to be allowed, it must be in addition to general lighting and must use the appropriate luminaires for the task as defined the luminaires

Example 5-15 Decorative lighting

Question

What is the wattage allowance for a 10 ft3 chandelier with five 50 W lamps in a 300 ft² bank entry lobby?

Answer

The wattage based on the task space is 0.5 W/ft² x 300 ft² = 150 W (0.5 W/ft² is based on Footnote 3 of Table 140.6-C.)

The wattage based on actual design watts is 250 W.

The wattage allowance for the chandelier is the smaller of the two values, or 150 W

Example 5-16 Decorative LED lighting

Question

What is the wattage allowance for a LED chandelier with five 10 W LED lamps in a 300 ft² bank entry lobby?

Answer

The wattage based on the task space is 0.5 W/ft² x 300 ft² = 150 W

The wattage based on actual design watts is 50 W.

The wattage allowance for the chandelier is the smaller of the two values, or 50 W

### 5.7.3 Tailored Method

§140.6(c)3.

5.7.3.1 Tailored Method Application

The Tailored Method is a lighting compliance approach which establishes an allowed lighting power budget on a room-by-room or area-by-area basis. 'In 'addition to providing a lighting power budget for general illumination, this compliance approach provides additional lighting power budgets for illuminating wall displays, floor displays, task lighting, and ornamental/special effects lighting.

These additional layers of lighting power have been informally referred to as “use-it or lose-it” lighting power allowances because these additional allowances cannot be traded-off to other areas or applications. If a lighting design does not include these additional layers of lighting power, the total lighting power budget using the Tailored Method may be less than if the Area Category Method or Whole Building Method of compliance is used.

Use of Tailored Method may also be helpful when a function area has a high room cavity ratio (RCR).

The Energy Standards allow the Tailored Method to be used for only a limited number of primary function areas. The primary function area shall only be one of the following:

1. As specifically 'listed in Table 140.6-D.

2. As specifically 'listed in §140.6(c)3H.

5.7.3.2 Tailored Method General Rules

1. There shall be no lighting power allotment trade-offs between the separate conditioned and unconditioned indoor function areas. Indoor conditioned and indoor unconditioned lighting power allotments must each be separately determined on compliance documentation

2. There shall be no lighting power allotment trade-offs between the separate indoor and outdoor function areas. Indoor and outdoor lighting power allotments must each be separately determined on compliance documentation.

3. Some areas of a building may use the Tailored Method, while other areas of the same building may use the Area Category Method. However, no single area in a building shall be allowed to use both the Tailored Method and the Area Category Method.

4. The Tailored Method shall not be used in any building using the Complete Building method for compliance.

5.7.3.3 Room Cavity Ratio (RCR)

1. The room cavity ratio must be determined for any primary function area using the Tailored Lighting Method.

2. The lighting level in a room is affected in part by the configuration of the room, expressed as the room cavity ratio (RCR). Rooms with relatively high ceilings typically are more difficult to light and have a high RCR. Because luminaires are not as effective in a room with a high RCR, §140.6 allows a greater LPD to compensate for this effect.

3. The RCR is based on the entire space bounded by floor-to-ceiling partitions. If a task area within a larger space is not bounded by floor to ceiling partitions, the RCR of the entire space must be used for the task area. The exception to this rule allows for imaginary or virtual walls when the boundaries are established by “high stack” elements (close to the ceiling structure and high storage shelves) or high partial walls defined as “permanent full height partitions” described in §140.6(c)3Iiv wall display. These permanent full height partitions are only applicable when claiming additional lighting power for wall display lighting.

Note: For use in calculating the RCR of the space, the walls are not required to be display walls as is required under §140.6(c)3Iiv.

The RCR is calculated from one of the following formulas:

Equation 5-3 (Table 140.6-F) Rectangular Shaped Rooms

Where:

RCR = The room cavity ratio

H = The room cavity height, vertical distance measured from the work plane to the center line of the luminaire

L = The room length using interior dimensions

W = The room width using interior dimensions

A = The room area

Equation 5-4 (Table 140.6-F) Non-Rectangular Shaped Rooms

Where:

RCR = The room cavity ratio

H = The room cavity height (see equation above)

A = The room area

P = The room perimeter

4. For rectangular rooms, these two methods yield the same result and the second more general form of calculating RCR may be used in all instances, if desirable.

5. It is not necessary to document RCR values for rooms with an RCR less than 2.0. Rooms with a RCR higher than 2.0 are allowed higher LPDs under the Tailored Method.The figure below gives example RCR values calculated for rooms with the task surface at desk height (2.5 ft above the floor). This is useful in assessing whether or not a room is likely to have an RCR greater than 2.0.

6. A special situation occurs when illuminating stacks of shelves in libraries, warehouses, and similar spaces. In this situation, the lighting requirements are to illuminate the vertical stack rather than the horizontal floor area. In stack areas the RCR is assumed to be greater than seven. The non-stack areas are treated normally.

#### Table 5-3: Typical RCRs based on Equation 5-1

Room Length (ft) | Room Height (ft)
8 | 12 | 16 | 20 | 24 | 30 | 36 | 40 | 8 | 12 | 16 | 20 | 24 | 30 | 36 | 40
8 feet from floor to ceiling and task is 2.5 ft above floor, so H=5.5 (8 – 2.5) | 10 feet from floor to ceiling and task is 2.5 ft above floor, so H=7.5 (10 – 2.5)
5 | 8.9 | 7.8 | 7.2 | 6.9 | 6.6 | 6.4 | 6.3 | 6.2 | 12.2 | 10.6 | 9.8 | 9.4 | 9.1 | 8.8 | 8.5 | 8.4
8 | 6.9 | 5.7 | 5.2 | 4.8 | 4.6 | 4.4 | 4.2 | 4.1 | 9.4 | 7.8 | 7.0 | 6.6 | 6.3 | 5.9 | 5.7 | 5.6
12 | 5.7 | 4.6 | 4.0 | 3.7 | 3.4 | 3.2 | 3.1 | 3.0 | 7.8 | 6.3 | 5.5 | 5.0 | 4.7 | 4.4 | 4.2 | 4.1
16 | 5.2 | 4.0 | 3.4 | 3.1 | 2.9 | 2.6 | 2.5 | 2.4 | 7.0 | 5.5 | 4.7 | 4.2 | 3.9 | 3.6 | 3.4 | 3.3
20 | 4.8 | 3.7 | 3.1 | 2.8 | 2.5 | 2.3 | 2.1 | 2.1 | 6.6 | 5.0 | 4.2 | 3.8 | 3.4 | 3.1 | 2.9 | 2.8
24 | 4.6 | 3.4 | 2.9 | 2.5 | 2.3 | 2.1 | 1.9 | 1.8 | 6.3 | 4.7 | 3.9 | 3.4 | 3.1 | 2.8 | 2.6 | 2.5
30 | 4.4 | 3.2 | 2.6 | 2.3 | 2.1 | 1.8 | 1.7 | 1.6 | 5.9 | 4.4 | 3.6 | 3.1 | 2.8 | 2.5 | 2.3 | 2.2
36 | 4.2 | 3.1 | 2.5 | 2.1 | 1.9 | 1.7 | 1.5 | 1.5 | 5.7 | 4.2 | 3.4 | 2.9 | 2.6 | 2.3 | 2.1 | 2.0
40 | 4.1 | 3.0 | 2.4 | 2.1 | 1.8 | 1.6 | 1.5 | 1.4 | 5.6 | 4.1 | 3.3 | 2.8 | 2.5 | 2.2 | 2.0 | 1.9

5.7.3.4 Determining Allowed General Lighting Power for Tailored Method

§140-6(c)3G, 140.6(c)3H

A. Tailored Method Trade-Off Allowances

Compliance forms shall be used to document trading-off Tailored Method Lighting Power allotments. Trade-offs are available only for general lighting, and only under the following circumstances:

1. From one conditioned primary function area using the Tailored Method, to another conditioned primary function area using the Tailored Method.

2. From one conditioned primary function area using the Tailored Method, to another conditioned primary function area using the Area Category Method.

3. From one unconditioned primary function area using the Tailored Method, to another unconditioned primary function area using the Tailored Method.

4. From one unconditioned primary function area using the Tailored Method, to another unconditioned primary function area using the Area Category Method.

B. Determine Lighting Power Allotments for Conditioned and Unconditioned Primary Function Areas

The allowed Tailored Method Indoor Lighting Power allotment for general lighting shall be separately calculated for conditioned and unconditioned primary functions are as follows:

1. For a conditioned primary function area, multiply the conditioned square feet of that area times the applicable allotment of watts per square feet for the area shown in Table 140.6-D.

2. For an unconditioned primary function area, multiply the unconditioned square feet of that area times the applicable allotment of watts per square feet for the area shown in Table 140.6-D.

An "area" is defined as all contiguous areas which accommodate or are associated with a single primary function area. Where areas are bounded or separated by interior partitions, the floor area occupied by those interior partitions may be included in a primary function area.

C. Calculating Tailored Method General Lighting Power Allotments

The Energy Standards define general lighting as installed electric lighting that provides a uniform level of illumination throughout an area, exclusive of any provision for special visual tasks or decorative effect, exclusive of daylighting. To qualify as general lighting for the Tailored Method, the lighting system shall NOT use narrow beam direction lamps, wall-washers, valance, direct cove or perimeter linear slot types of lighting systems.

Table 140.6-D or §140.6(c)3H. shall be used to determine the general lighting power density allotments as follows:

1. Using Table 140.6-D to Determine General Lighting Power Allotments:

a. Find the appropriate Primary Function Area in column 1 that fits one of the Nonresidential Function Area definitions in §100.1.

b. Find the corresponding General Illumination Level (Lux) in column 2;

c. Determine the room cavity ratio (RCR) for that primary function area, according to the applicable equation in Table 140.6-F. Use the RCR compliance form to document the RCR calculation.

d. Refer to Table 140.6-G, using the General Illumination Level (Lux, determined according to item ii), and the RCR (determined according to item iii),to determine the allowed Power Density Value;

e. Multiply the allowed Lighting Power Density Value times the square feet of the primary function areas. The product is the Allowed Indoor Lighting Power allotment for general lighting for that primary function area.

2. Using §140.6(c)3H. to Determine General Lighting Power Allotments:

a. This section shall be used to determine general lighting power allotments ONLY for the following primary function areas, as defined in §100.1:

1. Exercise Center, Gymnasium

2. Medical and Clinical Care

3. Police Stations and Fire Stations

4. Public rest areas along state and federal roadways

5. Other primary function areas that are 'listed in neither TABLE140.6-C nor TABLE140.6-D

b. Determine the illuminance values (Lux) for one of the primary function areas 'listed above as found in the Tenth Edition IES Lighting Handbook (IES HB), using the IES Recommended Horizontal Maintained Illuminance Targets for Observers 25-65 years old for illuminance;

c. Determine the room cavity ratio (RCR) for that primary function area, according to the applicable equation in Table 140.6-F. Use the RCR compliance form to document the RCR calculation;

d. Refer to Table 140.6-G, using the General Illumination Level (Lux, determined according to item b), and the RCR (determined according to item c), to determine the allowed Power Density Value;

e. Multiply the allowed Lighting Power Density Value times the square feet of the primary function areas. The product is the Allowed Indoor Lighting Power Density allotment for general lighting for that primary function area.

5.7.3.5 Determine Additional Allowed Power for Tailored Method

§140.6(c)3I thru §140.6(c)3L: Table|topic=(c) Calculation of Allowed Indoor Lighting Power\: Specific Methodologies. 140.6-D.

When using the Tailored Method for lighting compliance, 'in 'addition to the general lighting power allowance determined in accordance with Table 140.6-D, F, and G, additional allowed lighting power is available for wall display, floor display, task, ornamental/special effects, and very valuable display case lighting.

These additional layers of lighting power are not available when using §140.6(c)3H to determine the general Lighting Power allotment, and are not available for any primary function areas using the Complete Building or Area Category methods of compliance.

All of the additional lighting power allowances are “use it or lose it” allowances that cannot be traded-off. That is, if the installed watts are less than the allowed watts, the difference in watts is not available to trade-off anywhere else in the building.

A. Additional Wall Display Lighting Power:

1. Wall display lighting is defined by the §100.1 as supplementary lighting required to highlight features such as merchandise on a shelf, which is displayed on perimeter walls; and that provides a higher level of illuminance to a specific area than the level of surrounding ambient illuminance.

1. Additional allowed power for wall display lighting is available only for lighting that illuminates walls having wall displays, only when there is a watt per linear foot allowance in column 3 of Table 140.6-D for the primary function area.

1. The wall display lighting power is NOT available for the following:

a. When using §140.6(c)3H for determining the Allowed Indoor Lighting Power Density allotment for general lighting for the area.

b. For any function areas using the Complete Building or Area Category methods of compliance.

c. Floor displays shall not qualify for wall display lighting power allowances.

2. To qualify for the additional wall display lighting power, the lighting system shall be a type that is appropriate for creating a higher level of illuminance on the wall display.

a. Lighting systems appropriate for wall lighting are lighting track adjacent to the wall, wall-washer luminaires, luminaires behind a wall valance or wall cove, or accent light. (Accent luminaires are adjustable or fixed luminaires with PAR, R, MR, AR, or other directional lamp types.)

b. General lighting systems shall not qualify for this allowance.

3. Qualifying wall display lighting shall be mounted within 10 feet of the wall having the wall display.

a. When track lighting is used for wall display, and where portions of that lighting track are more than 10 feet from the wall and other portions are within 10 feet of the wall, only those portions of track within 10 feet from the wall shall qualify for the wall display allowance.

4. The length of display walls shall include the length of the perimeter walls, including but not limited to closable openings, and permanent full height interior partitions.

a. Permanent full height interior partitions are those that meet the following conditions:

i. Extend from the floor to no more than two feet below the ceiling or are taller than ten feet.

ii. Are permanently anchored to the floor, provided that neither commercial industrial stacks nor industrial storage stacks are permanent full height interior partitions.

5. Column 3 of Table 140.6-D shall be used to determine the additional allowed power for wall display lighting as follows:

a. Use the same Primary Function Area Category row in column 1 that was used to determine the general lighting power density allotments for the area.

b. Find the corresponding Wall Display Power (W/linear ft) in column 3.

c. Determine the length of qualifying display walls in a single room or area.

d. Multiply the Wall Display Power times the length of qualifying display walls, to calculate Wall Display lighting power allowance.

6. A mounting height multiplier is available in Table 140.6-E for wall display luminaires mounted 12 feet or higher, where mounting height is the distance from the finished floor to the bottom of the luminaire.

a. The mounting height multiplier is NOT available for the general lighting power density allotment.

b. The mounting height multiplier in Table 140.6-E shall be used to reduce the input wattage of luminaires (adjusted input wattage).

c. Wall display lighting with varying mounting heights shall be separately determined.

2. In a single room, or single area having wall display lighting, using §130.0(c)to determine luminaire classification and input wattage, do the following:

• Separately add together the input wattage of all wall display luminaires mounted lower than 12 feet. These luminaires do not qualify for a height multiplier.

• Separately add together the input wattage of all wall display luminaires mounted between 12 feet to 16 feet. Multiply the total input wattage of these luminaires times 0.87. This will be your adjusted input wattage for these luminaires.

• Separately add together the input wattage of all wall display luminaires mounted higher than 16 feet. Multiply the total input wattage of these luminaires times 0.77. This will be your adjusted input wattage for these luminaires.

7. The additional allowed power for wall display lighting shall be the smaller of the calculated Wall Display Power allowance, or the sum total of the adjusted input wattage of all luminaires used for the wall display lighting systems in that room or area. Use the smaller of the two calculated allowances as follows:

a. The additional allowed power for wall display lighting determined in accordance with Column 3 of Table 140.6-D, or

b. The sum total of:

i. Sum total input wattage of all wall display luminaires mounted lower than 12 feet, plus

ii. Sum total adjusted input wattage of all wall display luminaires mounted 12 feet to lower than 16 feet, plus

iii. Sum total adjusted input wattage of all wall display luminaires mounted higher than 16 feet.

8. Use the appropriate compliance form, NRCC-LTI-04-E, to document the additional allowed power for wall display lighting.

B. Additional Floor Display and Task Lighting Power:

1. Floor display lighting is defined by §100.1 as supplementary lighting required to highlight features, such as merchandise on a clothing rack, which is not displayed against a wall; and provides a higher level of illuminance to this specific area than the level of surrounding ambient illuminance.

2. Task Lighting is defined by §100.1 as lighting that is not general lighting and that specifically illuminates a location where a task is performed.

3. Additional allowed power for floor display lighting and additional allowed power for task lighting, may be used only for qualifying floor display lighting systems, qualifying task lighting systems, or a combination of both, only when there is a watt per square foot allowance in column 4 of Table 140.6-D for the primary function area.

4. For floor areas qualifying for both floor display and task lighting power allowances, the additional allowed power shall be used only once for the same floor area, so that the allowance shall not be additive.

5. Additional allowed power for a combination of floor display lighting and task lighting shall be available only for:

a. Floors having floor displays; or

b. Floors not having floor displays but having tasks having illuminance recommendations that appear in the Tenth Edition of the IES Lighting Handbook and that are higher than the general lighting level in column 2 of Table 140.6-D.

6. Floor display and task lighting shall be separately switched from the general lighting system.

7. The additional power for floor display and task lighting are NOT available for the following:

a. When using §140.6(c)3H for determining the Allowed Indoor Lighting Power Density allotment for general lighting for the area.

b. For any function areas using the Complete Building or Area Category methods of compliance.

c. Displays that are installed against a wall shall not qualify for the floor display lighting power allowances.

d. Any floor area designed to not have floor displays or tasks, such as floor areas designated as a path of egress, shall not be included for the floor display allowance.

8. Lighting internal to display cases shall be counted either as floor display lighting in accordance with §140.6(c)3J; or as very valuable display case lighting in accordance with §140.6(c)3Liii and iv.

9. To qualify for the additional power for floor display and task lighting, the lighting system shall be a type that is appropriate for creating a higher level of illuminance on the floor display or task. Floor display and task lighting shall be of a type different from the general lighting system.

a. Lighting systems appropriate for floor display and task lighting consist of only directional lighting types, such as PAR, R, MR, AR; or of lighting employing optics providing directional display light from non-directional lamps.

b. If track lighting is used, only track heads that are classified as directional lighting types qualify

10. Qualifying floor display lighting shall be mounted no closer than 2 feet to a wall, and shall be located immediately adjacent to and capable of illuminating the task for which it is installed.

a. When track lighting is used for floor or task lighting, and where portions of that lighting track are more than 2 feet from the wall and other portions are within 2 feet of the wall, only those portions of track more than 2 feet from the wall shall qualify for the floor display and task lighting power allowance.

11. Column 4 of Table 140.6-D shall be used to determine the additional allowed power for floor display and task lighting as follows:

a. Use the same Primary Function Area Category row in column 1 that was used to determine the general lighting power density allotments for the area;

b. Find the corresponding Allowed Combined Floor Display Power and Task Lighting Power (W/ft2) in column 4.

c. Determine the square feet of the qualifying area.

d. Multiply the Allowed Combined Floor Display Power and Task Lighting Power Floor Display/Task Lighting Power allowance.

12. A mounting height multiplier is available in Table 140.6-E for floor display and task luminaires mounted 12 feet or higher, where mounting height is the distance from the finished floor to the bottom of the luminaire.

a. The mounting height multiplier is NOT available for the general lighting power density allotment.

b. The mounting height multiplier in Table 140.6-E shall be used to reduce the input wattage of luminaires (adjusted input wattage),

c. Floor display lighting and task lighting luminaires with varying mounting heights shall be separately determined.

3. In a single room having floor display lighting and/or task lighting luminaires, using § 130.0(c) to determine luminaire classification and input wattage, do the following:

• Separately add together the input wattage of all floor display lighting and task lighting luminaires mounted lower than 12 feet. These luminaires do not qualify for a height multiplier.

• Separately add together the input wattage of all floor display lighting and task lighting luminaires mounted between 12 feet to 16 feet. Multiply the total input wattage of these luminaires times 0.87. This will be your adjusted input wattage for these luminaires.

• Separately add together the input wattage of all floor display lighting and task lighting luminaires mounted higher than 16 feet. Multiply the total input wattage of these luminaires times 0.77. This will be your adjusted input wattage for these luminaires.

13. The additional allowed power for all floor display lighting and task lighting luminaires lighting shall be the smaller of the calculated Floor Display/Task Lighting Power allowance, or the sum total of the adjusted input wattage of all luminaires used for floor display and task lighting systems in that room or area. Use the smaller of the two calculated allowances:

a. The additional allowed power for wall display lighting determined in accordance with Column 4 of Table 140.6-D, or

b. The sum total of:

i. Sum total input wattage of all floor display luminaires and task lighting luminaires mounted lower than 12 feet, plus

ii. Sum total of adjusted input wattage of all floor display luminaires and task lighting luminaires mounted from 12 feet to 16 feet, plus

iii. Sum total adjusted input wattage of all floor display luminaires and task lighting luminaires mounted higher than16 feet.

14. Use the appropriate compliance form, NRCC-LTI-04-E to document the additional allowed power for Floor Display/Task Lighting Power lighting.

C. Additional Ornamental/Special Effects Lighting Power:

1. §140.6(c)3K(ii) defines qualifying ornamental lighting to include luminaires such as chandeliers, sconces, lanterns, neon and cold cathode, light emitting diodes, theatrical projectors, moving lights, and light color panels when any of those lights are used in a decorative manner that does not serve as display lighting or general lighting.

2. Special effects lighting is defined as lighting installed to give off luminance instead of providing illuminance.

3. Additional allowed power for ornamental/special effects lighting may be used only for qualifying ornamental lighting systems, qualifying special effects lighting systems, or a combination of both, only when there is a watts per square foot allowance in column 5 of Table 140.6-D for the primary function area.

4. Additional ornamental and special effects lighting power is NOT available for the following:

a. When using §140.6(c)3H for determining the Allowed Indoor Lighting Power Density allotment for general lighting for the area.

b. For any function areas using the Complete Building or Area Category methods of compliance.

5. For floor areas qualifying for both ornamental and special effects lighting power allowances, the additional allowed power shall be used only once for the same floor area, so that the allowance shall not be additive.

6. Any floor area not designed to have ornamental or special effects lighting shall not be included for the ornamental/special effects lighting allowance.

7. Column 5 of Table 140.6-D shall be used to determine the additional allowed power for ornamental/special effects lighting as follows:

a. Use the same Primary Function Area Category row in column 1 that was used to determine the general lighting power density allotments for the area;

b. Find the corresponding Allowed Ornamental/Special Effects Lighting Power (W/ft2) in column 5;

c. Determine the square feet of the qualifying area:

d. Multiply the Allowed Ornamental/Special Effects Lighting Power, times the square feet of the qualifying area, to determine calculated Allowed Ornamental/Special Effects Lighting Power allowance.

8. A mounting height multiplier is NOT available for ornamental/special effects lighting.

9. The additional allowed power for Ornamental/Special Effects Lighting shall be the smaller of the calculated Allowed Ornamental/Special Effects Lighting Power allowance, or the actual power used for the Allowed Ornamental/Special Effects Lighting systems;

10. Use the appropriate compliance form, NRCC-LTI-04-E to document the additional allowed power for Ornamental/Special Effects Lighting.

D. Additional Very Valuable Display Case Lighting Power:

1. Case lighting is defined in §100.1 as lighting of small art objects, artifacts, or valuable collections which involves customer inspection of very fine detail from outside of a glass enclosed display case.

2. To qualify for additional allowed power for very valuable display case lighting, a case shall contain jewelry, coins, fine china, fine crystal, precious stones, silver, small art objects and artifacts, and/or valuable collections the display of which involves customer inspection of very fine detail from outside of a locked case.

3. Additional allowed power for very valuable display case lighting shall be available only for display cases in retail merchandise sales, museum, and religious worship areas.

4. Qualifying lighting includes internal display case lighting or external lighting employing highly directional luminaires specifically designed to illuminate the case or inspection area without spill light, and shall not be fluorescent lighting unless installed inside of a display case.

5. Any floor area designed to not have very valuable display case lighting shall not be included for the very valuable display case lighting allowance.

6. The valuable display case lighting power is NOT available for the following:

a. When using §140.6(c)3H for determining the Allowed Indoor Lighting Power Density allotment for general lighting for the area.

b. For any function areas using the Complete Building or Area Category methods of compliance.

7. A mounting height multiplier is NOT available for very valuable display case lighting.

8. The very valuable display case lighting allowance shall be the smallest of the following:

a. The product of the area of the primary function and 0.8 watt per square foot.

b. The product of the area of the display case and 12 watts per square foot.

c. The actual power of lighting for very valuable displays.

9. Use the appropriate compliance f orm, NRCC-LTI-04-E to document the additional allowed power for valuable display case lighting.

Example 5 17 Room Cavity Ratio

Question

A small retail shop “Personal Shopper” room is 14 ft wide by 20 ft long by 8 ft high. The lighting system uses recessed ceiling fixtures. The task surface is at desk height (2.5 ft above the floor). What is the room cavity ratio?

Answer

The room cavity height is the distance from the ceiling (center line of luminaires) to the task surface (desk height). This is 8 ft -2.5 ft = 5.5 ft

RCR = 5 x H x (L + W) / Area

RCR = 5 x 5.5 (14+20) / (14 x 20) = 3.34

Example 5-18 Retail space lighting allocation

Question

A large retail store with a sales area that has a 14 ft high ceiling and full height perimeter wall also has several other walls and a high fixture element in the space. Based on the definition of “full-height” partitions (per §140.6(c)3Iiv), which components qualify for the wall display allocation?

Answer

Example 5-19 Wall display lighting – Tailored Method

Question

In this question, condition A has 2X4 troffers placed 3 ft from a perimeter sales wall as well as fluorescent wall-washers 5 ft from the sales wall. Condition B has fluorescent wall-washers 3 ft from the wall and PAR adjustable accent lights 5 ft from the wall. Which luminaires qualify for the wall display lighting allocation?

Answers

Per §140.6(c)3Iiia, qualifying lighting must be mounted within 10 ft of the wall and appropriate wall lighting luminaires. (Luminaires with asymmetric distribution toward the wall or adjustable –directed toward the wall)

CONDITION A

While both luminaires are within ten feet of the wall only the wall-washer qualifies for the wall display allocation. The 2X4 is a general lighting luminaire with symmetric versus asymmetric distribution and does not qualify for the allocation.

CONDITION B

Both luminaires are within ten feet of the wall and both qualify for the wall display allocation. The fluorescent wall-washer has an asymmetric distribution and the PAR accent light at 5 ft from the wall is directional and is lamped with a projetor lamp.

Example 5-20 Museum lighting – Tailored Method

Question

A museum space has directional accent lighting luminaires on a track mounted to the ceiling. The first track is three feet from the perimeter wall of the exhibit space and the second track is nine feet from the wall. There is a third track (not shown) that is fifteen feet into the space. To what display category should these luminaires be assigned under §140.6(c) 3I and 3J

Answers

Per §140.6(c)3Iiv& 3Jv wall display luminaires must be within 10 ft of the wall and directional and floor displays must be at least two feet away from the wall and also directional. Using these criteria, the allocations for the two conditions shown are as follows:

CONDITION A

Both sets of luminaires shown are at least 2 ft away from the wall and are directed onto a floor exhibit (display) therefore they both qualify for the floor display allocation. The third track with directional luminaires also qualifies as floor display.

CONDITION B

Both sets of luminaires shown are also closer than 10 ft to the wall and are directed onto a wall exhibit (display) therefore they both, when directed toward the wall qualify for the wall display allocation. The third track with directional luminaire (15 ft from the wall) does not qualify for wall display, only floor display.

Note: Luminaires within a 2 ft to 10 ft zone may be assigned to either wall or floor display depending on the focus direction of the luminaires. However only one classification, either wall or floor can be used for luminaire compliance, not both.

Example 5-21 Adjustments for luminaire mounting height – Tailored Method

Question

A high ceiling space with allowed display lighting has wall-washers mounted on the ceiling near the wall and accent lights mounted on suspended track in the center of the space. Because of the 18 ft high ceiling, does the display lighting qualify for a mounting height factor adjustment?

Answer

Per §140.6(c) 3Iv and 3Jix, some but not all of the display lighting qualifies for the mounting height adjustment. The wall directional lighting that mounted at the ceiling is above 12 ft which then qualifies it for an adjustment factor of 0.87 in accordance with Table 140.6-E. However the track that is suspended at 11 ft is excluded from an adjustment factor. It must use the default factor of 1 with the allowed LPD as shown in column 4 in Table 140.6-E.

Example 5-22 Tailored Method lighting power allowance

Question

The customer area of a bank building includes financial transaction counters, wall displays and seating. The size of the space is 20 ft wide by 50 ft long and 11 ft high. Transaction counters are 3-feet off the floor and there is 75 ft of wall display. Proposed luminaires used for general illumination are recessed down lights and for wall display lighting are wall-washer luminaires. Under the Tailored Method, what is the maximum allowed Lighting Power Density (LPD) (excluding any control credits)?

Answer

From Table 140.6-D in the EnergyStandards, target general illumination of 300 lux is recommended for financial transaction area. Using the dimensions given (20 ft x 50 ft x 11 ft and a task height of 3-feet), the room cavity ratio (RCR) is calculated to be 2.8. Using Table 140.6-G, 0.82 W/ft2 of LPD is allowed for the 300 lux target and RCR of 2.8 . Therefore, the general lighting allowance is 820 W (= 20 ft x 50 ft x 0.82 W/ft2).

For the wall display lighting, 3.15 W/ft of LPD is allowed (per Table 140.6-D Column 3) . The wall display lighting power allowance is 236 W (=75 ft X 3.15 W/ft).

For floor display and task lighting, 0.2 W/ft2 of LPD is allowed (per Table 140.6-D Column 4). The combined floor display and task lighting power allowance is 200 W (= 20 ft x 50 ft x 0.2 W/ft2).

Total allowed lighting power for this financial transaction area is 1,256 W (= 820 W + 236 W + 20.0W).

Example 5-23 Tailored Method lighting power allowance

Question

If, in the previous question, the design used only down lights or 2X2 fluorescent troffers, what is the maximum allowed power (excluding any control credits)?

Answer

Since the proposed downlights or 2X2 fluorescent troffers provide general illumination only and there are no luminaires providing wall display lighting, the wall display lighting power allowance cannot be applied here as there are no qualifying luminaires in the design. Display lighting is a use-it-loose-it component and the lighting equipment used must meet the optical characteristics of display and focal lighting.

The maximum allowed power 1,020 W (= 820W + 200W).

The 1,020 W comprises 820W for the allowed general lighting and 200 watts for the task lighting.

Example 5-24 Decorative lighting - Tailored Method

Question

The bank from the previous question wants to add chandeliers in addition to down lights and wall-washers. What is the maximum allowed power under Tailored Method (excluding any control credits)?

Answer

1,756W (=1256W + 500W) is the maximum allowed lighting power. See below for details..

In addition to the 1,256 W allowed for the combination of general lighting display lighting and task lighting, a maximum of 500 W (per Table 140.6-D column 5) of Ornamental/Special effects lighting is allowed. Note: for this wattage to be allowed the decorative lighting must be in addition to general lighting and the luminaire must meet the ornamental lighting criteria. The actual allowed Ornamental lighting power will be the lower of the maximum allowed or total ornamental lighting power.

Example 5-25 Ornamental lighting and very valuable display lighting - Tailored Method

Question

A 5,500-ft² retail store has:

5,000 ft² of gross sales floor area with a RCR of 2.5

200 ft² of restrooms (with a RCR of 6.0)

300 ft² of corridors (with a RCR of 6.5)

100 ft² of very valuable merchandise case top with 1,200 W of actual lighting

There are 300 linear ft of perimeter wall including closeable openings and Ornamental/special effects lighting is being used as part of the retail scheme.

What are the allowed lighting power for general lighting, wall display, floor display, ornamental/special effect, and very valuable display lighting in this store using the Tailored Method?

Answer

The general illumination for retail is 400 Lux per Standards Table 140.6-D. The Lighting Power Density (LPD) is 0.98 W/ft² for a 400 Lux space with an RCR of 2.5 per Table 140.6-G. Therefore, the allowed general lighting power for the retail store is 0.98 W/ft² X 5,000 ft² = 4,900 W.

Corridors and restrooms are not included in the Tailored Method tables and therefore must comply under the area category method. Look up Table 140.6-C for the allowed LPD for these spaces. Table 140.6-C contains LPD values for primary functional areas and it allows 0.6 W/ft2 of LPD for corridors and restrooms. (RCR is not relevant in looking up LPD values in Table 140.6-C. This is different from how to look up values from Table 140.6-G)

The allowed power for the restrooms is 200 ft² x 0.6 W/ft² = 120 W. The allowed power for the corridors is 300 ft² x 0.6 W/ft² = 180 W.

The wall display lighting is computed from the entire wall perimeter, including all closeable openings, times the wall display power allowance. Therefore, the allowed wattage is 300 ft x 14 W/ft = 4,200 W. The allowance is taken from column three of Standards Table 140.6-D.

The floor display allowance is computed from the area of the entire space with floor displays times the floor display lighting power density. Therefore, the allowed wattage is 5,000 ft² x 1.0 W/ft² = 5,000 W. The allowance is taken from column four of Table 140.6-D.

The ornamental/special effect allowance is computed from the area of the entire space with floor displays times the ornamental/special effect lighting power density. Therefore, the allowed wattage is 5,000 ft² x 0.5 W/ft² = 2,500 W. The allowance is taken from column five of Table 140.6-D.

The allowed wattage for very valuable display case top is smaller of the product of 0.8 W/ft² and the gross sales area (5,000 ft²) or the product of 14 W/ft² and the actual area of the case tops (100 ft²). The maximum allowed power is the smaller of 0.8 W/ft² X 5,000 ft² = 4,000 watts, or 14 W/ft² X 100 ft² = 1,200 watts. 0.8 W/ft² for very valuable display case lighting, is allowed per §140.6(c)3Lv. Therefore, the maximum allowed power is 1,200 W.

Therefore, the total allowed lighting power is 4,900 + 120 + 180 + 4,200 + 5,000 + 2,500 + 1,200
= 18,100 W. Note that in the Tailored Method, the allowed wattage for each lighting task other than general lighting is of the use-it-or-lose-it variety, which prohibits trade-offs among these wattages and different tasks or areas. Only the General Lighting component of the Tailored Method is tradable between areas using tailored compliance or areas using Area compliance.

Example 5-26 Very valuable display lighting – Tailored method

Question

If in the question above, the actual design wattages for floor display and very valuable display are 4,500 W and 1,000 W respectively, what are the maximum allowed floor display and very valuable display power allowances?

Answer

Because the floor display and very valuable display allowances are use-it-or-lose-it allowances, the maximum power allowed is the smaller of allowed watts for floor display (5,000 W) and very valuable display (1,200 W) or the actual design watts for floor display (4,500 W) and very valuable display (1,000 W). Therefore, the maximum allowed watts for floor display and very valuable display lighting are 4,500 W and 1,000 W actual design watts, not 5,000 W and 1,400 W maximum allowed watts.

Example 5-27 Retail store lighting - Tailored Method

Question (Two Parts – Part 1 and 2)

Owners of a retail store want to use track lights for all the sales floor lighting. The sales floor is 50 ft x 100 ft with 10 ft high ceilings. There are 125 ft of sales wall and decorative pendants for ornamental effect lighting also mounted on track. All the merchandise is on open sell racks, tables or on wall shelves and hangers. There will be no casework or high-end valuable merchandise lighting required in the design.

Part 1: using tailored compliance, what is the maximum allowed lighting power?

Part 2: based on the design description, what other compliance requirements are unique to this approach?

Single circuit, dual circuit or mono-point for Ornamental lighting

Dual Circuit tracks for general and wall accent lighting

Separate tracks for general and wall accent lighting

Dual circuit track with one circuit for general and the other floor display lighting

Separate tracks for general and floor display lighting

Answer – Part 1

The allowed maximum wattage is 13,150 W which is determined as follows:

From Standards Table140.6-D, Column 2, the general illumination for retail is 400 lux. From Standards Table 141.0-G, the LPD for 400 lux in a space with the RCR determined as <2.0 is 0.78W/ft². Therefore, the allowed general lighting power is 0.78 W/ft² X 5,000 ft² = 3,900 W along with the allowed floor display lighting from Table 140.6-D column 4 which is 1.0W/ft² X 5,000 ft² = 5,000 W and the allowed wall display lighting from the same table column 3 which is 14 W/ft X 125 ft = 1,750 W. Plus an ornamental lighting adder from column 5 of 0.5 W/ft² X 5,000 ft² = 2,500 W. [3900 + 5000 +1750 + 2500 =13,150]

Answer – Part 2

Dual circuit track, multiple independently circuited tracks or combination of both will be required for an all track design to conform to Title 24-2016 Tailored Method lighting compliance.

Retail stores or other spaces using the Tailored Method that use track lighting exclusively for the layered lighting approach as defined in the Tailored Method must provide a system for separately switching and controlling the layered lighting components (general, floor display, wall display and ornamental lighting). One solution is the use of dual circuit track with one circuit dedicated to general lighting and the other to wall display or floor display, based on where the track is located and on its assigned function. If/when ornamental lighting is also powered by track; it must also be separately circuited using dual circuit track or a separate dedicated track.

Another solution is to use multiple, single circuit tracks, as needed, with each track circuited for its specific task (general, display or ornamental lighting).

Note: each lighting task; general, display and/or ornamental lighting must be separately circuited and controlled. Therefore, in an application that has an area with general lighting, wall and floor display and ornamental lighting all occurring multiple adjacent dual circuit tracks or a combination of tracks and other power connections (such as mono-points) may be needed.

Example 5-28 Retail store lighting - Tailored Method

Question

How are the task spaces and allowed LPD’s determined for a 27,000 square foot retail store with sales areas, stockrooms and offices using Tailored Method?

Answer

Determine square footage allowances by space type, as well as allowed maximum watts, for each area as follows:

1) First, identify spaces allowed to use the Tailored Method and those requiring the Area Category Method. Only the sales area can use the Tailored Method (per Table 140.6-D of the standards). Stock rooms and offices are not in the Tailored table and therefore must comply under the Area Category Method (Table 140.6-C).

2). The area of offices and stockrooms are determined by multiplying the length and width of each space (25 X 30 = 750 ft² for offices) (30 X 125 = 3,750 ft² for stockrooms). The allowed maximum watts for offices and stockrooms are then determined by multiplying the allowed LPD of the space (Table 140.6-C) by the area of the space.

3) The area of the sales floor is also determined by multiplying the length and width of the space. However the gross sales area also includes major circulation paths that are required by code (evacuation egress). Therefore these egress areas must be deducted from the total sales floor footprint to determine allowed sales area when using the Tailored Method. Note: the same is also true for a sales area complying under the Area Category Method. The allowed sales floor square footage is therefore 19,980 ft² (150 X 150 = 22,500 minus 2,520 total egress area shown in pale blue on the plan).

To determine maximum allowed lighting power for the sales floor it is also necessary to identify the lineal foot of qualifying walls eligible for wall display. Total maximum watts for the sales floor is then determined by using the allowed LPD (from Table 140.6-G) for general lighting based on the RCR of the space and the LPD for allowed floor display, wall display and ornamental effect lighting (columns 2, 3, 4 from Table 140.6-D).

4) LPD for the 2,520 ft² of egress space is determined by using the Area Category Method, as egress space is not in the Tailored table (Table 140.6-D). Table 140.6-C of the Area Category Method will determine the allowed LPD as egress space falls under the category of corridor. Multiply the LPD for corridor by the egress area for the allowed maximum watts.

Example 5-29 Exercise center lighting – Tailored method

Question

Using provisions as defined under §140.6(c)3H Tailored Compliance, what is the Allowed Lighting Power for an exercise center with two separate rooms? One room is 40 ft wide X 60 ft long with a 16 ft ceiling. The other room is 16 ft wide X 30 ft long with a 12 ft ceiling. The luminaires are mounted at the ceiling for both rooms.

Answer

2,995 W total for the two room Exercise Center. This allowed wattage is determined by:

1) Illuminance values (Lux) for an Exercise Center according to the IESNA Lighting Handbook Tenth Edition using the horizontal illuminance targets for observers in the 25-65 age bracket. From the handbook, the horizontal illumination target is determined to be a maximum of 400 lux measured at 4 to 5 ft above the floor.

2) The RCR in accordance with Table 140.6-F. Because there are two different rooms, each will need to have its RCR determined.

a) The RCR for the 40’ X 60’ with 16‘ ceiling has an RCR of 2.4 (5 X 12 X 100 ÷ 2400 =2.4)

b) The RCR for the 16’ X 30’ with 12‘ ceiling has an RCR of 3.83 (5 X 8 X 46 ÷ 480 = 3.83)

3) The allowed lighting power density (LPD) in Table 140.6-G.

a) The first room with an RCR of 2.4 and a lux target of 400 is allowed 0.98 W/ft²

b) The second room with an RCR of 3.83 and a lux target of 400 is allowed 1.34 W/ft²

4) The square feet of the areas; One room is 40 ft wide X 60 ft long = 2,400 feet and the other 16 ft wide X 30 ft long = 480 feet. Therefore the allowed watts are as follows:

a) 2,400 X 0.98 = 2,352 W

b) 480 X 1.34 = 643 W

5) The total allowed lighting power in watts is 2352 W + 643 W or a total of 2,995 W for the two room exercise center.

Example 5-30 Decorative lighting in exercise center - Tailored Method

Question

Using provisions as defined under §140.6(c)3H, what is the Allowed Lighting Power for the exercise center if a portion of the lighting will use decorative chandeliers?

Answer

2,995 W total for the two room exercise center using the same procedure as outlined in Example 5-29 above.

Although some of the lighting is being created with use of decorative chandeliers, Table 140.6-D column 5 doesn’t apply when using §140.6(c)3H.

A provision of §140.6(c)3Hii requires that when calculating allowed indoor Lighting Power Density allotments for general lighting using §140.6(c)3H, the building shall not add additional lighting power allowances for any other use, including but not limited to wall display, floor display and task, ornamental/special effects, and very valuable display case lighting.