5.4 Space Uses

Each thermal zone discussed above may be subdivided into spaces. This chapter presents the building descriptors that relate to the space uses. Space uses and the defaults associated with them are listed in Appendix 5.4A. Every thermal zone shall have at least one space, as defined in this chapter. Daylit spaces should generally be separately defined by space type or orientation or both.

5.4.1 General Information

The general information is used to identify the various spaces included in each thermal zone. This information will include the area of each space as well as how the space will be used. The function of the space will inform certain standard design requirements such as lighting power density for the space.

Definition: The space function type that defines occupancy, internal load, and other characteristics, as indicated in Appendix 5.4A.

If lighting compliance is not performed, use either approach but actual LPDs cannot be entered for the spaces; the LPDs of the building match the standard design.

The allowed space function types in area category are available from Appendix 5.4A. The building or space type determines the following standard design inputs:

For unconditioned spaces, the user must enter “unconditioned” as the occupancy and ventilation; internal loads and uses are set to zero. Compliance software shall require the user to identify if lighting compliance is performed (Lighting plans are included or have already been submitted).

Definition: A unique identifier for ventilation requirements. A given space type may have different ventilation functions available, which define the design ventilation rate and minimum ventilation rates for the space, and any exhaust air requirements.

The area of the spaces that make up a thermal zone shall sum to the floor area of the thermal zone.

Input Restrictions: Area shall be measured to the outside of exterior walls and to the center line of partitions.

5.4.2 Infiltration

Infiltration of outside air into a building, and leakage of air from inside of the building will affect the space conditioning energy use of the building. There are several methods used to identify the air leakage or infiltration rate of the building. The method used to identify the air leakage rate and the inputs required are to be provided.

Definition: Energy simulation programs have a variety of methods for modeling uncontrolled air leakage or infiltration. Some procedures use the effective leakage area which is generally applicable for small residential scale buildings. The component leakage method requires the user to specify the average leakage through the building envelope per unit area (ft²). Other methods require the specification of a maximum rate, which is modified by a schedule. The flow per exterior wall area method shall be used.

Input Restrictions: The flow per exterior wall area calculation method is prescribed. A fixed infiltration rate shall be specified and calculated as a leakage per area of exterior envelope, including the gross area of exterior walls and fenestration but excluding roofs and exposed floors.

Standard Design: The infiltration method used for the standard design shall be the same as the proposed design.

Definition: Information needed to characterize the infiltration rate in buildings.

For the flow per exterior wall area calculation method, inputs are described below.

Units: Infiltration rate shall be calculated each hour using the following equation:

The infiltration is then found by multiplying the infiltration rate by the area of the exterior walls in the thermal zone.

• Infiltration Rate - zone infiltration airflow per unit wall area (m³/s-m²)

• I_design - zone infiltration airflow rate at reference conditions (m³/s-m²)

• F_schedule - fractional adjustment from a prescribed schedule, consistent with HVAC availability schedules in Appendix 5.4B(unitless)

The proposed design shall use the equation listed above, with coefficients A, B, and D set to 0. C shall be set to 0.10016 hr/mile (0.224 s/m). I_design shall be:

• 0.2016 cfm/ft2 for buildings that have air barriers verified by visual inspection as described in §140.3(a)9Cii of the Energy Code, and

• 0.1344 cfm/ft2 for buildings that have air barriers verified by whole building air leakage testing as described in §140.3(a)9Cii of the Energy Code.

For nonresidential spaces with operable windows that do not have mechanical system interlocks, the compliance software shall automatically increase the infiltration rate by 0.15 cfm/ft² whenever the outside air temperature is between 50°F and 90°F and when the HVAC system is operating. Multifamily dwelling units are exempt from mechanical system interlocks.

Standard Design: The standard design shall use the equation listed above, with coefficients A, B, and D set to 0. C shall be set to 0.10016 hr/mile (0.224 s/m). I_design shall be 0.2352 cfm/ft². For Hotel/Motel Buildings in climate zone 7 and for relocatable public school buildings I_design shall be 0.3696 cfm/ft².

Applicability: When an infiltration method is used that requires the specification of a schedule.

Definition: With the ACH method and other methods (see above), it may be necessary to specify a schedule that modifies the infiltration rate for each hour or time step of the simulation. Typically, the schedule is either on or off but can also be fractional.

Input Restrictions: For healthcare facilities, the schedule is the same as the proposed design. For all nonresidential buildings, the schedule is based on the predominant schedule group for the building story or zone. See Chapter 2.3.3: Space Use Classification Considerations for details. For multifamily buildings, see Chapter 6: Multifamily Building Descriptions. The infiltration schedule shall be set equal to 1 when the HVAC system is scheduled off and 0.25 when the HVAC system is scheduled on. This schedule is based on the assumption that when the HVAC system is on, it brings the pressure of the interior space above the pressure of the exterior, decreasing the infiltration of outside air. When the HVAC system is off, interior pressure drops below exterior pressure, and infiltration increases.

The implementation of the prescriptive requirement for interlocks for operable windows will model mixed-mode ventilation as an increased infiltration rate when outside air conditions allow for nonresidential buildings only, excluding healthcare and multifamily buildings and spaces.

The infiltration schedule for the standard design shall be scheduled the same as the proposed design.

5.4.3 Occupants

For space level information on occupancy, lighting, and plug load schedules, as well as occupant density, and allowed lighting power density.

Definition: The design egress occupant density assumed for simulation and minimum ventilation requirements of a space.

Input Restrictions: This is determined based on the specified space types defined in Appendix 5.4A and corresponding list of ventilation occupancy categories, as defined in Appendix 5.4C.

Definition: The fraction of the design egress occupant density assumed for simulation and design ventilation requirements.

Input Restrictions: Default of 0.5 as designed with a minimum value of 0.5 and a maximum value of 5.

Applicability: All projects that have a space with designed occupancy (such as a theater or auditorium).

Definition: This is a flag that indicates that the space has designed occupancy. If checked, this flag allows the user to override the default occupancy with values that comply with the California Building Code.

May not be used with multifamily living spaces, hotel/motel guest rooms, unoccupied, and unleased tenant area spaces. The default is false.

Standard Design: Existing Building: The number of occupants must be identical for both the proposed and standard design cases.

Definition: The sensible and latent heat produced by each occupant in an hour.

This depends on the activity level of the occupants and other factors. Heat produced by occupants must be removed by the air conditioning system as well as the outside air ventilation rate and can have a significant effect on energy consumption.

Input Restrictions: The occupant heat rate is prescribed by Appendix 5.4A for nonresidential buildings and by Chapter 6 of the Nonresidential ACM Reference Manual for multifamily buildings.

Standard Design: The occupant heat rate for the standard design shall be the same as the proposed design.

Definition: The occupancy schedule modifies the number of occupants to account for expected operational patterns in the building. The schedule adjusts the heat contribution from occupants to the space on an hourly basis to reflect time-dependent usage patterns. The occupancy schedule can also affect other factors such as outside air ventilation, depending on the control mechanisms specified.

Input Restrictions: For healthcare facilities, the schedule is the same as the proposed design. For all nonresidential buildings, the schedule is based on the predominant schedule group for the building story or zone. See Chapter 2.3.3: Space Use Classification Considerations for details. For multifamily buildings, see Chapter 6: Multifamily Building Descriptors Reference

Standard Design: Occupancy schedules are identical for proposed and standard design buildings.

5.4.4 Interior Lighting

The building descriptors in this chapter are provided for each lighting system. Typically, a space will have only one lighting system but, in some cases, it could have two or more. Examples include a general and task lighting system in offices, or hotel multipurpose rooms that have lighting systems for different functions. It may also be desirable to define different lighting systems for areas that are daylit and those that are not.

Definition: Indoor lighting power can be specified using the area category method or the tailored method.

Area category method can be used for all areas of the building with space types listed in Appendix 5.4A. This method can be used by itself or with the tailored lighting method.

Tailored lighting method can be used for spaces with primary function listed in Table 140.6-D of the Energy Code. The tailored lighting method is intended to accommodate special lighting applications. The tailored lighting method can be used by itself for all areas of the building or with the area category method. For a given area only one classification type can be used.

Options: Lighting Classification Method	Area Category Method	Tailored Lighting Method
Allowed combinations with other lighting classification methods	May be combined with tailored method in same building, but not in same space.	May be combined with area category method, in same building, but not in same space.
Allowed regulated lighting power types	(For all building types except multifamily buildings:) General lighting power Additional lighting power	(For all building types except multifamily buildings:) General lighting power Wall display lighting power Floor display and task lighting power Decorative/special effect lighting power Very valuable display case lighting power
Allowed regulated lighting power types	(For Multifamily Buildings:) Multifamily general lighting power Multifamily additional lighting power	(For Multifamily Buildings:) Multifamily General lighting power Multifamily Wall display lighting power Multifamily Task lighting power Multifamily Decorative/special effect lighting power
Allowed Trade-offs	General lighting between conditioned spaces using area category method General lighting between conditioned spaces using area category and tailored method	General lighting between conditioned spaces using tailored method General lighting between conditioned spaces using tailored and area category method

Exception: With the area category method, additional lighting power can be used only if the tailored lighting method is not used in any area of the building.

Definition: Total connected lighting power density for all regulated interior lighting power

This includes the loads for lamps and ballasts. The total regulated interior lighting power density is the sum of general lighting power and applicable custom lighting power per floor area in a space. Calculation of lighting power for conditioned spaces is done separately from unconditioned spaces.

Lighting in unconditioned spaces can be modeled, but total lighting power in unconditioned spaces is not enforced in the compliance software. Lighting in unconditioned spaces must follow prescriptive compliance and must be documented on appropriate compliance forms. No tradeoffs are allowed between lighting in conditioned spaces and lighting in unconditioned spaces.

a. For the area category method: the sum of the proposed general lighting power and the proposed general lighting exceptional power within a conditioned space or a user input value if no interior lighting systems are modeled.

b. For the tailored lighting method: the sum of the proposed general lighting power and the proposed custom lighting power within a conditioned space or a user input value if no interior lighting systems are modeled.

When lighting compliance is not performed, the lighting power may not be entered and is set equal to the lighting level of the standard design, which is set to the levels for the selected occupancy from Appendix 5.4A.

Standard Design: For spaces without special task lighting, wall display lighting or similar requirements, this input will be the same as the general lighting power density. See the general lighting power building descriptor for details.

With the area category and tailored method regulated interior lighting power for each space will be the sum of general lighting power and allowed custom lighting power.

Standard Design: Existing Building: For alterations where fewer than 40 luminaires have been modified the standard design is the existing lighting condition before the alteration. If 40 or more luminaires have been modified, the prescriptive requirements for newly constructed buildings apply.

Definition: General lighting power is the power used by installed electric lighting that provides a uniform level of illumination throughout an area, exclusive of any provision for special visual tasks or decorative effect, and known as ambient lighting.

For spaces without special task lighting, wall display lighting or similar requirements, this input will be the same as the regulated lighting power.

Trade-offs in general lighting power are allowed between spaces all using the area category method, between spaces all using the tailored lighting method and between spaces that use area category and tailored methods. See Table 4: Lighting Specification for details.

Standard Design: With the area category method, general lighting power is the product of the lighting power densities for the space type from Appendix 5.4A and the floor areas for the corresponding conditioned spaces.

With the tailored lighting method, general lighting power is the product of the lighting power density for the primary function type in Table 140.6-D of the Energy Code and the floor area of the space. The lighting power density is given as a function of room cavity ratio (RCR) and interior illumination level in Table 140.6-G. No interpolation is allowed for this table.

The general lighting power in the tailored method is calculated by the following steps:

Step 1: Determine illumination level from Table 140.6-D by matching the primary function area in Table 140.6-D with the space type in Appendix 5.4A.

Step 2: Calculate the room cavity ratio (RCR) by using the applicable equation in Table 140.6-F.

Where: L = length of room; W = width of room; H = vertical distance from the work plane to the centerline of the lighting fixture; P = perimeter of room, and A = area of room

Step 3. Determine the general lighting power density in the space(s) using the tailored method by a look-up in Table 140.6-G, where the general lighting power density is a function of illuminance level and RCR. No interpolation is allowed for this table. A space between two illuminance levels (for example, 150 lux) uses the applicable LPD from the next lower illuminance level (100 lux).

The standard design uses the irregular room RCR equation for simplified and detailed geometry models.

The standard design lighting power is modified by a factor of 1/1.20 (0.833) if the simplified geometry approach is used and if the visible transmittance of any fenestration in the space does not meet the prescriptive requirements established in §140.3 of the Energy Code.

Standard Design: Existing Building: When the lighting status is “existing” (and unaltered) for the space, the standard design is the same as the existing, proposed design.

When the lighting status is “altered” for the space, and at least 10 percent of existing luminaires have been altered:

a) If the lighting status is “existing”, then the standard design LPD is the same as the proposed design.

b) If the lighting status is “new”, then the standard design LPD is same as newly constructed buildings.

c) If the lighting status is “altered”, then the standard design LPD is the same as newly constructed buildings.

Applicability: Spaces that use the area category method – for all building types except multifamily buildings. Some additional lighting power allowances are applicable only to certain space types. See Table 140.6-C of the Energy Code.

Definition: The Energy Code provide an additional lighting power allowance for qualified lighting systems. The additional lighting power allowance for qualified lighting systems is treated separately as “use-it-or-lose-it” lighting--the user receives no credit (standard design matches proposed) but there is a maximum power allowance for each item. The qualified lighting systems and the respective allowed additional lighting power allowance values are listed in the two rightmost columns in Table 140.6-C of the Energy Code.

Units: Data structure. This input has the following data elements – each data element corresponds to the additional lighting allowance of the functional area types listed in Table 140.6-C of the Energy Code

3. Transition lighting OFF at night, aging eye/low-vision – main entry lobby (W/ft²)

Standard Design: The standard design additional lighting power (ALP) is given by the following equation:

The proposed ALP of the allowance is in the data structure above. If there is no proposed lighting system in the proposed design serving as the qualified lighting system, the ALP_prop,ishould be assigned with a zero value (no allowance permitted and given). If there is a proposed lighting system serving as the qualified lighting system, the ALP_prop,i should be assigned a value of one (1).

The additional lighting power allowance (ALPA), which is the maximum allowed additional lighting power indicated in the two rightmost columns in Table 140.6-C of the Energy Code.

The additional lighting power task quantity (ALPTQ) for the i^th allowance, where the task area corresponds to the functional area with the additional lighting power allowance in Table 140.6-C of the Energy Code.

Standard Design: Existing Building: When the lighting status is “existing” (and unaltered) for the space, the standard design is the same as the existing, proposed design.

When the lighting status is “altered” for the space and at least 10 percent of existing luminaires have been altered:

• If the lighting status is “existing,” then the standard design LPD is the same as the proposed design.

• If the lighting status is “new,” then the standard design LPD is the same as for newly constructed buildings.

• If the lighting status is “altered,” then the standard design LPD is the same as for newly constructed buildings.

Definition: The area, length, or quantity associated with each of the additional lighting allowances in the ALP building descriptor.

Units: ft2., number of ATM(s), or number of illuminated mirror(s).Input Restrictions: As designed but cannot exceed the floor area of the space.

Definition: Custom lighting power covers lighting sources that are not included as general lighting, including qualified lighting systems specified in Table 140.6-C and lighting systems in Table 140.6-D of the Energy Code. This lighting must be entered separately from the general lighting because it is not subject to trade-offs.

Compliance software shall allow the user to input a custom lighting input for the allowed lighting system.

Standard Design: Same as proposed but subject to the maximum limits specified in Table 140.6-C and Table 140.6-D of the Energy Code. For spaces using the tailored method, the maximum allowed custom power is defined by the following procedure:

The standard design custom lighting power is calculated by the sum of the following four terms:

• The product of the standard design wall display power and the standard design wall display length.

• The product of the standard design floor and task lighting power and the standard design floor and task lighting area.

• The product of the standard design decorative and special effect lighting power, and the standard design ornamental and special effect lighting area.

• The product of the standard design very valuable display case power and the standard design very valuable display case area, subject to prescriptive limits in Table 140.6-D.

Standard Design: Existing Building: For alterations where fewer than 10 percent of existing luminaires have been modified, the standard design is the existing lighting condition before the alteration. If 10 percent or more luminaires have been altered, the custom lighting power for the standard design is the same as proposed, but subject to the maximum limits specified in Table 140.6-D of the Energy Code.

Applicability: All spaces that use the tailored method. This is applicable to all building types except multifamily buildings.

Definition: The lighting power allowed for wall display, as specified in the Energy Code Table 140.6-D, column 3.

Standard Design: The standard design lighting power is the lesser of the proposed design wall display power or the limit specified in Table 140.6-D for the applicable space type.

Definition: The horizontal length of the wall display lighting area using the tailored method for the space.

Input Restrictions: As designed but this value cannot exceed the floor area of the space.

Definition: The lighting power allowed for floor display and task lighting, as specified in Table 140.6-D, column 4 of the Energy Code.

Standard Design: The standard design floor and task lighting power is the lesser of the proposed design floor and task lighting power or the limit specified in Table 140.6-D, column 4, for the applicable space type.

Definition: The lighting area that is served by the floor and task lighting defined using the tailored method for the space.

Input Restrictions: As designed but this value cannot exceed the floor area of the space.

Definition: The lighting power allowed for decorative and special effect lighting, as specified in Table 140.6-D, column 5 of the Energy Code.

Standard Design: The standard design decorative and special effect lighting power is the lesser of the proposed design decorative and special effect lighting power or the limit specified in Table 140.6-D, column 5, for the applicable space type.

Definition: The lighting area that is served by the decorative and special effect lighting defined using the tailored method for the space.

Input Restrictions: As designed but this value cannot exceed the floor area of the space.

Applicability: All spaces that use the tailored method. This is applicable to all building types except multifamily buildings.

Definition: The lighting power allowed for very valuable display case lighting, as specified in the Energy Code Section 140.6(c)3J.

Standard Design: The standard design very valuable display case lighting power is the lesser of the following:

Input Restrictions: As designed but this value cannot exceed the floor area of the space.

Definition: For California, §140.6(a)3 of the Energy Code identifies nonregulated (exempted) lighting.

The nonregulated lighting power should be cross-referenced to the type of exception and to the construction documents. The default for nonregulated lighting power is zero.

Standard Design: The nonregulated interior lighting in the standard design shall be the same as the proposed design.

Definition: Schedule of operation for interior lighting power used to adjust the energy use of lighting systems on an hourly basis to reflect time-dependent patterns of lighting usage.

Input Restrictions: For healthcare facilities, the schedule is the same as the proposed design. For all nonresidential buildings, the schedule is based on the predominant schedule group of the building story or zone. See Chapter 2.3.3: Space Use Classification Considerations for details. For multifamily buildings, see Chapter 6: Multifamily Building Descriptors Referenced.

Standard Design: The nonregulated interior lighting in the standard design shall be the same as the proposed design.

Definition: The illumination height is the vertical distance from the work plane which is 3 feet, to the centerline of the luminaire. This distance is used in the room cavity ratio (RCR) calculation which determines the allowed general lighting power density for a tailored lighting space.

The illumination height, H, is used to calculate the RCR and therefore the standard design general lighting power. See general lighting power for details.

Applicability: Spaces that have wall display or floor display lighting and tailored lighting power allowances.

Definition: The mounting height of wall display or floor display lighting above the floor.

The entered value corresponds to Table 140.6-E of the Energy Code, that provides an adjustment multiplier for the tailored lighting wall power allowance in Table 140.6-D. The multiplier is 1.00 if the mounting height is equal to or less than 10 ft, 6 inches, 1/0.85 if the mounting height is greater than 10 feet, 6 inches and equal to or less than 14 feet, 1/0.75 if the mounting height is greater than 14 feet up and equal to or less than 18 feet, and 1/0.70 if the mounting height is greater than 18 feet. The compliance software uses this adjustment multiplier to set the standard design lighting power.

Definition: The type of lighting fixture, which is used to determine light heat gain distribution.

Definition: The type of lighting luminaire used to determine the light heat gain distribution

The dominant luminaire type determines the daylight dimming characteristics when there is more than one type of luminaire in the space.

Definition: The distribution of the heat generated by the lighting system that is directed to the space, the plenum, the HVAC return air, or to other locations

This input is a function of the luminaire type, fixture type and location. Luminaires recessed into a return air plenum contribute more heat to the plenum or the return air stream if the plenum is used for return air, while pendant mounted fixtures hanging in the space contribute more heat to the space. Common luminaire type/space configurations are listed in Table 3, Chapter 18, 2009 ASHRAE Handbook of Fundamentals, summarized in Table 5: Light Heat Gain Parameters for Typical Operating Conditions . Typically, the data will be linked to a list of common luminaire configurations similar to Table 5: Light Heat Gain Parameters for Typical Operating Conditions so that the user chooses a luminaire type category and heat gain is automatically distributed to the appropriate locations.

Units: List (of luminaire types) or data structure consisting of a series of decimal fractions that assign heat gain to various locations.

Input Restrictions: Heat gain distribution is fixed to Table 5: Light Heat Gain Parameters for Typical Operating Conditions values based on the luminaire, fixture, and distribution type.

Where lighting fixtures having different heat venting characteristics are used within a single space, the wattage weighted average heat-to-return-air fraction shall be used.

Standard Design: The standard design shall use the values in Table 5: Light Heat Gain Parameters for Typical Operating Conditions for recessed/downlight LED luminaires.

Table 5: Light Heat Gain Parameters for Typical Operating Conditions
Based on Table 3, Chapter 18, 2009 ASHRAE Handbook - Fundamentals

Fixture Type	Luminaire Type	Return Type	Space Fraction	Radiative Fraction
Recessed with Lens	Linear Fluorescent	Ducted/Direct	1.00	0.67
Recessed with Lens	Linear Fluorescent	Plenum	0.45	0.67
Recessed/Downlight	Linear Fluorescent	Ducted/Direct	1.00	0.58
Recessed/Downlight	Linear Fluorescent	Plenum	0.69	0.58
Recessed/Downlight	CFL	Ducted/Direct	1.00	0.97
Recessed/Downlight	CFL	Plenum	0.20	0.97
Recessed/Downlight	Incandescent	Ducted/Direct	1.00	0.97
Recessed/Downlight	Incandescent	Plenum	0.75	0.97
Recessed/Downlight	LED	Ducted/Direct	1.00	0.97
Recessed/Downlight	LED	Plenum	0.20	0.97
Recessed/Downlight	Metal Halide	Ducted/Direct	1.00	0.97
Recessed/Downlight	Metal Halide	Plenum	0.75	0.97
Non in Ceiling	Linear Fluorescent	Ducted/Direct	1.00	0.54
Non in Ceiling	Linear Fluorescent	Plenum	1.00	0.54
Non in Ceiling	CFL	Ducted/Direct	1.00	0.54
Non in Ceiling	CFL	Plenum	1.00	0.54
Non in Ceiling	Incandescent	Ducted/Direct	1.00	0.54
Non in Ceiling	Incandescent	Plenum	1.00	0.54
Non in Ceiling	LED	Ducted/Direct	1.00	0.54
Non in Ceiling	LED	Plenum	1.00	0.54
Non in Ceiling	Metal Halide	Ducted/Direct	1.00	0.54
Non in Ceiling	Metal Halide	Plenum	1.00	0.54
Non in Ceiling	Mercury Vapor	Ducted/Direct	1.00	0.54
Non in Ceiling		Plenum	1.00	0.54
Non in Ceiling	High Pressure Sodium	Ducted/Direct	1.00	0.54
Non in Ceiling		Plenum	1.00	0.54

In this table, the space fraction is the fraction of the lighting heat gain that goes to the space; the radiative fraction is the fraction of the heat gain to the space that is due to radiation, with the remaining heat gain to the space due to convection.

Definition: Automatic controls that are not already required by the Energy Code and which reduce lighting power uniformly over the day can be modeled as power adjustment factors. Power adjustment factors represent the percentage reduction in lighting power that will approximate the effect of the control. Models account for such controls by multiplying the controlled watts by (1–PAF).

Eligible California power adjustment factors are defined in Table 140.6-A. Reduction in lighting power using the PAF method can be used only for nonresidential controlled general lights. Only one PAF can be used for a qualifying lighting system unless multiple adjustment factors are allowed in Table 140.6-A of the Energy Code. Controls for which PAFs are eligible are listed in Table 140.6-A of the Energy Code and include:

• Institutional tuning – lighting tuned to not use more than 85 percent of rated power, per §140.6 of the Energy Code.

• Daylight dimming plus off controls – daylight dimming controls that automatically shut off luminaires when natural lighting provides an illuminance level of at least 150 percent of the space requirement.

• Horizontal slats – interior or exterior horizontal slats on fenestration adjacent to daylit areas

• Light shelves – interior or exterior light shelves adjacent to daylit areas

Clerestories are modeled as power adjustment factors and are not modeled directly by compliance software. Compliance software shall have a means of disregarding daylight through clerestory windows when using the PAF. If handled with a PAF, daylight controls in zones with clerestory windows should be disabled.

5.4.5 Daylighting Control

This group of building descriptors is applicable for spaces that have daylighting controls or daylighting control requirements.

California prescribes a modified version of the split flux daylighting methods to be used for compliance. This is an internal daylighting method because the calculations are automatically performed by the simulation engine. For skylit daylit areas (aka top-lighted areas) or sidelit daylit areas, California compliance prescribes an internal daylighting model consistent with the split flux algorithms used in many simulation programs. With this method the simulation model has the capability to model the daylighting contribution for each hour of the simulation and make an adjustment to the lighting power for each hour, considering factors such as daylighting availability, geometry of the space, daylighting aperture, control type, and the lighting system. The assumption is that the geometry of the space, the reflectance of surfaces, the size and configuration of the daylight apertures, and the light transmission of the glazing are taken from other building descriptors.

For daylight control using a simplified geometry approach, daylight control for both the primary daylit zone and secondary daylit zone (mandatory) must be indicated on the compliance forms. If the simplified geometry approach is used and the visible transmittance of fenestration does not meet prescriptive requirements, the standard design lighting power is reduced by 20 percent as a penalty. See Chapter 5.4.4 Interior Lighting

Definition: The extent of daylighting controls in skylit and sidelit areas of the space.

Input Restrictions: When the installed general lighting power in the primary daylit zone exceeds 120W, daylighting controls are required, per the Title 24 mandatory requirements.

Standard Design: For nonresidential spaces, when the installed general lighting power in the skylit, primary sidelit, or secondary sidelit daylit zone exceeds 120W, daylighting controls are required, per the Title 24 mandatory requirements. Controls are not required if total glazing area is less than 24 ft² or for luminaires in sidelit daylit zones in retail merchandise sales and wholesale showroom areas.

For parking garages, when the installed general lighting power in the primary sidelit and secondary sidelit daylit zone exceeds 60W, daylighting controls are required, per the Title 24 mandatory requirements. Luminaires located in daylit transition zones or dedicated ramps are exempt from this requirement. Controls are not required if total glazing and openings are less than 36 ft².

Standard Design: Existing Buildings: When lighting systems in an existing altered building are not modified as part of the alteration, daylighting controls are the same as the proposed design.

When an alteration increases the area of a lighted space, increases lighting power in a space, or when luminaires are modified in a space where proposed design lighting power density is greater than 85 percent of the standard design LPD, daylighting control requirements are the same as for newly constructed buildings.

The skylit area is the portion of the floor area that gets daylighting from a skylight. Two types of sidelit daylit areas are recognized. The primary daylit area is the portion that is closest to the daylighting source and receives the most illumination. The secondary daylit area is an area farther from the daylighting source, which still receives useful daylight.

The primary daylit area for side lighting is a band near the window with a depth equal to the distance from the floor to the top of the window and width equal to window width plus 0.5 times window head height wide on each side of the window opening. The secondary daylit area for side lighting is a band beyond the primary daylit area that extends a distance double the distance from the floor to the top of the window and width equal to window width plus 0.5 times window head height wide on each side of the window opening. Area beyond a permanent obstruction taller than 6 feet should not be included in the primary and secondary daylight area calculation.

The skylit area is a band around the skylight well that has a depth equal to 70 percent of the ceiling height from the edge of the skylight well. The geometry of the skylit daylit area will be the same as the geometry of the skylight. Area beyond a permanent obstruction taller than 50 percent of the height of the skylight from the floor should not be included in the skylit area calculation.

Double counting due to overlaps is not permitted. If there is an overlap between secondary and primary or skylit areas, the effective daylit area used for determining reference position shall be the area minus the overlap.

Input Restrictions: The daylit areas in a space are derived using other modeling inputs like dimensions of the fenestration and ceiling height of the space.

Standard Design: The daylit areas in the standard design are derived from other modeling inputs, including the dimensions of the fenestration and ceiling height of the space. Daylit area calculation in the standard design is done after window to wall ratio and skylight to roof ratio rules in Chapter 5.5.7 Fenestration of this manual are applied.

Standard Design: Existing Buildings: Same as newly constructed buildings when skylights are added/replaced and general lighting altered.

Definition: The installed lighting power of general lighting in the primary and skylit daylit zone.

The primary and skylit daylit zone shall be defined on the plans and be consistent with the definition of the primary and skylit daylit zone in the Energy Code. Note that a separate building descriptor, fraction of controlled lighting, defines the fraction of the lighting power in the space that is controlled by daylighting.

Standard Design: The installed lighting power for the standard design is the product of the primary daylit area and the LPD for general lighting in the space.

Standard Design: Existing Buildings: Same as newly constructed buildings when skylights are added/replaced and general lights are altered.

Definition: The installed lighting power of general lighting in the secondary daylit zone.

The secondary daylit zone shall be defined on the plans and be consistent with the definition of the secondary daylit zone in the Energy Code. Note that a separate building descriptor, fraction of controlled lighting, defines the fraction of the lighting power in the space that is controlled by daylighting.

Standard Design: The installed lighting power for the standard design is the product of the secondary daylit area and the LPD for general lighting in the space.

Standard Design: Existing Buildings: Same as newly constructed buildings when skylights are added/replaced and general lights are altered.

Applicability: All spaces or thermal zones, depending on which object is the primary container for daylighting controls.

Definition: The position of the two daylight reference points within the daylit space.

Lighting controls are simulated so that the illuminance at the reference position is always maintained at or above the illuminance setpoint. For step switching controls, the combined daylight illuminance plus uncontrolled electric light illuminance at the reference position must be greater than the setpoint illuminance before the controlled lighting can be dimmed or tuned off for stepped controls. Similarly, dimming controls will be dimmed so that the combination of the daylight illuminance plus the controlled lighting illuminance is equal to the setpoint illuminance.

Preliminary reference points for primary and secondary daylit areas are located at the farthest end of the daylit area aligned with the center of each window. For skylit area, the preliminary reference point is located at the center of the edge of the skylit area closest to the centroid of the space. In each case, the Z – coordinate of the reference position (elevation) shall be located 2.5 feet above the floor.

Up to two final reference positions can be selected from among the preliminary reference positions identified in for each space.

Input Restrictions: The user does not specify the reference position locations; reference positions are automatically calculated by the compliance software based on the procedure outlined below. Preliminary reference positions are each assigned a relative daylight potential (RDP) which estimates the available illuminance at each position, and the final reference position selection is made based on the RDP.

Relative Daylight Potential: An estimate of daylight potential at a specific reference position. This is NOT used directly in the energy simulation, but it used to determine precedence for selecting the final reference points. The relative daylight potential is calculated as a function of effective aperture, azimuth, illuminance setpoint and the type (skylit, primary sidelit, or secondary sidelit) of the associated daylit zone. RDP is defined as:

Illuminance Setpoint: This is defined by the user, subject to the limits specified in Appendix 5.4A, determined from the space type.

Source Orientation (SO): The angle of the outward facing normal of the daylight source’s parent surface projected onto a horizontal plane, expressed as degrees from south. This is not a user input but is calculated from the geometry of the parent surface. For skylights, the source orientation is not applicable. For vertical fenestration, it is defined:

Where: Azimuth is defined as the azimuth of the parent object containing the fenestration associated with the preliminary reference point.

Effective Aperture (EA): For this calculation, effective aperture represents the effectiveness of all sources which illuminate a specific reference position in contributing to the daylight available to the associated daylit zone. In cases where daylit zones from multiple fenestration objects intersect, the effective aperture of an individual daylit zone is adjusted to account for those intersections according to the following rules:

For skylit and primary sidelit daylit zones, intersections with other skylit or primary sidelit daylit zones are considered.

For secondary sidelit daylit zones, intersections with any toplit or sidelit (primary or secondary) daylit zones are considered.

EA_dz - Is the combined effective aperture of all daylight sources illuminating a specific daylit zone.

VT_fdz - Is the user specified visible transmittance of the fenestration object directly associated with the daylit zone.

A_fdz - Is the area of the fenestration object directly associated with the daylit zone.

VT_i - Is the user specified visible transmittance of the fenestration object associated with each intersecting daylit zone.

A_i - Is the area of the fenestration object directly associated with each intersecting daylit zone.

F_i - Is the fraction of intersecting area between the daylit zone in question and each intersecting daylit zone:

A_dzi - Is the area of each intersecting daylit zone (including area that might fall outside a space or exterior boundary).

A_dz- Is the area of the daylit zone (including area that might fall outside a space or exterior boundary).

First Reference Position: Select the preliminary reference point with the highest relative daylight potential (RDP) from among all preliminary reference points located within either top or primary sidelit daylit zones. If multiple reference points have identical RDPs, select the reference point geometrically closest to the centroid of the space.

Second Reference Position: Select the preliminary reference point with the highest RDP from amongst all remaining preliminary reference points located within either top or primary sidelit daylit zones. If multiple reference points have identical RDPs, select the reference point geometrically closest to the centroid of the space.

Standard Design: Reference positions for the standard design shall be selected using the same procedure as those selected for the proposed design.

Standard Design: Existing Buildings: Additions or alternations of lighting in spaces trigger the daylighting control requirements whenever the total installed lighting in the daylit zone is 120 W or greater, and the reference positions shall be determined in the same manner as with newly constructed buildings. This only applies when alterations or additions to the lighting in an existing building trigger daylighting control requirements.

Definition: Recent studies have shown that the split flux interreflection component model used in many simulation programs overestimates the energy savings due to daylighting, particularly deep in the space. A set of two adjustment factors is provided, one for the primary daylit zone and one for the secondary daylit zone.

For simulation purposes, the input daylight illuminance setpoint will be modified by the illuminance adjustment factor as follows:

Standard Design: The standard design illumination adjustment factors shall match the proposed.

Standard Design: Existing Buildings: Same as newly constructed buildings when skylights are added/replaced and general light is altered.

Definition: The fraction of the general lighting power in the primary and skylit daylit zone, or secondary sidelit daylit zone that is controlled by daylighting controls.

Units: Numeric: fraction for primary and skylit daylit zone, and fraction for secondary zone

Input Restrictions: As designed for secondary daylit areas. Primary, secondary and skylit daylit area fraction of controlled general lighting shall be as designed when the daylight control requirements building descriptor indicates that they are not required and shall be 1 when controls are required.

Standard Design: When daylight controls are required according to the daylight control requirements building descriptor in either the primary daylit and skylit zone, or the secondary daylit zone, or both, the fraction of controlled lighting shall be 1.

Standard Design: Existing Buildings: Same as for newly constructed buildings when skylights are added/replaced, and general light is altered.

Definition: The type of control that is used to control the electric lighting in response to daylight available at the reference point.

Stepped switching controls: The electric power input and light output vary in discrete, equally spaced steps.

Continuous dimming controls: The fraction to rated power to fraction of rated output that is a linear interpolation of the minimum power fraction at the minimum dimming light fraction to rated power at full light output. See Figure 8: Example of Lighting Power Fraction Continuous Dimming and Continuous Dimming Plus OFF Daylighting Controls (with Minimum Dimming Fraction of 10 Percent).

Continuous dimming + off controls: Same as continuous dimming controls except that these controls can turn all the way off when none of the controlled light output is needed. The OFF stage is implemented at a daylight illuminance of 150% or higher than design illuminance.

Figure 8: Example of Lighting Power Fraction Continuous Dimming and Continuous Dimming Plus OFF Daylighting Controls (with Minimum Dimming Fraction of 10 Percent)

Input Restrictions: Daylighting control type must be specified when daylighting control is required. For parking garage with daylighting control, the users must use continuous dimming plus off control or stepped switching control to meet the mandatory requirement.

Standard Design: Parking garage in standard design uses continuous plus off daylighting control. All other spaces in standard design use continuous daylighting control.

Standard Design: Existing Buildings: Same as for newly constructed buildings when skylights are added/replaced, and general light is altered.

Definition: The minimum power fraction when controlled lighting is fully dimmed. Minimum power fraction = minimum power / full rated power.

Input Restrictions: In proposed design if continuous daylighting control is used, the dimming fraction must be 0.1 or lower. No restriction if other control types are used.

Standard Design: Standard design uses a minimum dimming power fraction of 0.1.

Standard Design: Existing Buildings: Same as for newly constructed buildings when skylights are added/replaced, and general light is altered.

Definition: The minimum light output when controlled lighting is fully dimmed. Minimum light fraction = minimum light output / rated light output.

Standard Design: Standard design uses a minimum dimming light fraction of 0.1.

Standard Design: Existing Buildings: Same as for newly constructed buildings when skylights are added/replaced, and general light is altered.

5.4.6 Receptacle Loads

Definition: Receptacle power is power for typical general service loads in the building. Receptacle power includes equipment loads normally served through electrical receptacles, such as office equipment and printers, but does not include either task lighting or equipment used for HVAC purposes. Receptacle power values are slightly higher than the largest hourly receptacle load that is actually modeled because the receptacle power values are modified by the receptacle schedule, which approaches but does not exceed 1.0.

Compliance software shall also use the following prescribed values to specify the latent heat gain fraction and the radiative/convective heat gain split.

For compliance software that specifies the fraction of the heat gain that is lost from the space, this fraction shall be prescribed at 0.

Input Restrictions: Prescribed to values from Appendix 5.4A for nonresidential buildings.

For multifamily buildings, the rules established in Chapter 6 Multifamily Building Descriptors Reference of the Nonresidential ACM Reference Manual apply.

Definition: Schedule for receptacle power loads used to adjust the intensity on an hourly basis to reflect time-dependent patterns of usage.

Input Restrictions: For healthcare facilities, the schedule is the same as the proposed design. For all nonresidential buildings, the schedule is based on the predominant schedule group of the building story or zone. See Chapter 2.3.3 Space Use Classification Considerations. for details. For multifamily buildings, see Chapter 6 Multifamily Building Descriptors Reference.

Definition: The efficiency of the Uninterruptible Power Supply (UPS) systems in a computer room. This only applies with computer room process loads with a minimum power density of 20 W/sf.

Input Restrictions: For healthcare facilities, same as the proposed design. For all nonresidential buildings, the schedule is based on the predominant schedule group of the building story or zone. See Chapter 2.3.3 Space Use Classification Considerations. for details. For multifamily buildings, see Chapter 6 Multifamily Building Descriptors Reference

Standard Design: The UPS Efficiency shall match the requirements in Table 140.9-B.

5.4.7 Commercial Refrigeration Equipment

Refrigeration equipment is modeled as neutral plug loads, with the standard design power matching the proposed design and no heat added to or removed from the space where the equipment is located.

Applicability: All buildings that have commercial refrigeration for cold storage or display

Definition: The method used to estimate refrigeration energy and to model the thermal interaction with the space where casework is located.

• Title 24 defaults. With this method, the power density values provided in Appendix 5.4A are used; schedules are assumed to be continuous operation.

Applicability: All buildings that have commercial refrigeration for cold storage or display.

Definition: Commercial refrigeration power is the average power for all commercial refrigeration equipment, assuming constant year-round operation. Equipment includes walk-in refrigerators and freezers, open refrigerated casework, and closed refrigerated casework. It does not include residential type refrigerators used in kitchenettes or refrigerated vending machines. These are covered under receptacle power.

Input Restrictions: With the Title 24 defaults method, the values in Appendix 5.4A are prescribed. These values are multiplied times the floor area of the rated building to estimate the refrigeration power.

Standard Design: Refrigeration power is the same as the proposed design when the Title 24 defaults are used.

5.4.8 Elevators, Escalators and Moving Walkways

Elevators, escalators and moving walkways account for 3 percent to 5 percent of electric energy use in buildings.1F1F Buildings up to about five to seven stories typically use hydraulic elevators because of their lower initial cost. Mid-rise buildings commonly use traction elevators with geared motors, while multifamily buildings typically use gearless systems where the motor directly drives the sheave. The energy-using components include the motors and controls as well as the lighting and ventilation systems for the cabs.

Elevators, escalators, and moving walkways are modeled as a plug loads, with the standard design power matching the proposed design.

Applicability: All buildings that have commercial elevators, escalators, or moving walkways.

Definition: The power for elevators, escalators and moving walkways are modeled as plug loads.

Applicability: All buildings that have commercial elevators, escalators, or moving walkways.

Definition: The schedule of operation for elevators, escalators, and moving walkways. This is used to convert elevator/escalator power to energy use.

Input Restrictions: For healthcare facilities, the schedule is the same as the proposed design. For all nonresidential buildings, the schedule is based on the predominant schedule group of the building story or zone. See Chapter 2.3.3 Space Use Classification Considerations for details. For multifamily buildings, see Chapter 6 Multifamily Building Descriptors Reference.

5.4.9`Process Loads

The majority of gas equipment is located in the space and may contribute both sensible and latent heat. Gas equipment is modeled by specifying the rate of average gas consumption or a fractional schedule that is prescribed in Appendix 5.4B which represents full load hours. The procedure consists of prescribed power and energy values for use with both the proposed and standard design buildings. No credit for commercial gas energy efficiency features is offered.

The prescribed average load values are provided in Appendix 5.4A. The full load schedules in Appendix 5.4B are used as the default.

Definition: Commercial gas power is the average power for all commercial gas equipment, assuming constant year-round operation.

Compliance software shall also use the following prescribed values to specify the latent heat gain fraction and the radiative/convective heat gain split.

For compliance software that specifies the fraction of the heat gain that is lost from the space, this fraction shall be prescribed at 0.

Input Restrictions: The values in Appendix 5.4A are prescribed. However, these values may be overridden with a “0” value for buildings that are designed to use only electricity as the source.

Definition: The schedule of operation for commercial gas equipment. This is used to convert gas power to energy use.

Definition: Process load is the gas energy consumption in the conditioned space of a building resulting from an activity or treatment not related to the space conditioning, lighting, service water heating, or ventilating of a building as it relates to human occupancy. Process load may include sensible and/or latent components.

Units: Data structure: Total load (Btu/h), radiant fraction, latent fraction, and loss fraction.

Input Restrictions: Compliance software shall receive input for total load, radiant fraction, latent fraction, and loss fraction for each zone in the proposed design. The radiant, latent, and loss fraction are defaulted to zero. The process load input shall be the annual average of the process load (Btu/h-ft2) and the thermal zone where the process equipment is located. The modeled information shall be consistent with the plans and specifications of the building.Standard Design: The standard design shall use the same gas process loads and sensible and latent contribution and radiative/convective split for each zone as the proposed design.

Definition: The schedule of process load operation. Used to convert gas power to energy use.

Definition: Process load is the electrical energy consumption in the conditioned space of a building resulting from an activity or treatment not related to the space conditioning, lighting, service water heating, or ventilating of a building as it relates to human occupancy.

Data center loads including transformers, uninterruptible power supplies, power delivery units, server fans and power supplies are considered receptacle loads, not process loads, and the equipment schedules are given in Appendix 5.4B.

Compliance software shall model and simulate process loads only if the amount of the process energy and the location and type of process equipment are specified in the construction documents. This information shall correspond to specific special equipment shown on the building plans and detailed in the specifications. The compliance software shall inform the user that the compliance software will output process loads including the types of process equipment and locations on the compliance forms.

For electric process loads, the radiative latent, and loss fractions shall be defaulted by the compliance software to 0.0 resulting in a convective fraction of 1.0. The user may enter other values for the radiative/convective split, but the compliance software shall verify that the values add to 1.

Input Restrictions: Compliance software shall receive input for sensible and/or latent process load for each zone in the proposed design. The process load input shall be the annual average of the process load (W/h-ft2) and the thermal zone where the process equipment is located. The modeled information shall be consistent with the plans and specifications of the building.

Standard Design: The standard design shall use the same process loads and radiative/convective split for each zone as the proposed design.

5.4.10 Water Heating Use

This chapter defines the water heating load (use rate) and system requirements on a space level.

Definition: A mapping that defines the standard design water heating fuel type for a space.