D.C. Mun. Regs. tit. 12, 12-I-G3
The simulation model for calculating the proposed and baseline building performance shall be developed in accordance with the requirements in Table G3.1.
Table G3.1 Modeling Requirements for Calculating Proposed and Baseline Building Performance
No. Proposed Building Performance 1. Design Model | Baseline Building Performance |
a. The simulation model of the proposed design shall be consistent with the design documents, including proper accounting of fenestration and opaque building envelope types and areas; interior lighting power and controls; HVAC system types, sizes, and controls; and service water-heating systems and controls. All end-use load components within and associated with the building shall be modeled, including but not limited to exhaust fans, parking garage ventilation fans, snow-melt and freeze-protection equipment, facade lighting, swimming pool heaters and pumps, elevators and escalators, refrigeration, and cooking. Where the simulation program does not specifically model the functionality of the installed system, spreadsheets or other documentation of the assumptions shall be used to generate the power demand and operating schedule of the systems. b. All conditioned spaces in the proposed design shall be simulated as being both heated and cooled even if no heating or cooling system is to be installed. Exception:Spaces designed with heating only systems serving storage rooms, stairwells, vestibules, electrical/mechanical rooms, and restrooms not exhausting or transferring air from mechanically cooled thermal zones in the proposed design shall not be modeled with mechanical cooling. c. When the performance rating method is applied to buildings in which energy-related features have not yet been designed (e.g., a lighting system), those yet-to-be-designed features shall be described in the proposed design exactly as they are defined in the baseline building design. Where the space classification for a space is not known, the space shall be categorized as an office space. | The baseline building design shall be modeled with the same number of floors and identical conditioned floor area as the proposed design. The baseline building design shall be developed by modifying the proposed design as described in Section G3. Except as specifically instructed, all building systems and equipment shall be modeled identically in the proposed design and baseline building design. |
2. Additions and Alterations | |
It is acceptable to predict performance using building models that exclude parts of the existing building, provided that all of the following conditions are met: a. Work to be performed in excluded parts of the building shall meet the requirements of Sections 5 through 10. b. Excluded parts of the building are served by HVAC systems that are entirely separate from those serving parts of the building that are included in the building model. c. Design space temperature and HVAC system operating set points and schedules on either side of the boundary between included and excluded parts of the building are essentially the same. d. If a declining block or similar utility rate is being used in the analysis, and the excluded and included parts of the building are on the same utility meter, the rate shall reflect the utility block or rate for the building plus the addition. | If the proposed design excludes parts of the existing building, the baseline building design shall exclude them as well. When modeled, unmodified existing building components shall follow the same rules as new and modified building components. |
3. Space Use Classification | |
Use shall be specified using the building type or space type lighting classifications in accordance with Section 9.5.1 or 9.6.1. The user shall specify the space use classifications using either the building type or space type categories but shall not combine the two types of categories. More than one building type category may be used in a building if it is a mixed-use facility. If space type categories are used, the user may simplify the placement of the various space types within the building model, provided that building total areas for each space type are accurate. | Same as proposed design. |
4. Schedule | |
Schedules capable of modeling hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat set points, and HVAC system operation shall be used. The schedules shall be typical of the proposed building type as determined by the designer and approved by the rating authority. Temperature and Humidity Schedules. Temperature and humidity control set points and schedules as well as temperature control throttling range shall be the same for proposed design and baseline building design. HVAC Fan Schedules. Schedules for HVAC fans that provide outdoor air for ventilation shall run continuously whenever spaces are occupied and shall be cycled ON and OFF to meet heating and cooling loads during unoccupied hours. Exceptions: 1. Where no heating and/or cooling system is to be installed, and a heating or cooling system is being simulated only to meet the requirements described in this table, heating and/or cooling system fans shall not be simulated as running continuously during occupied hours but shall be cycled ON and OFF to meet heating and cooling loads during all hours. 2. HVAC fans shall remain on during occupied and unoccupied hours in spaces that have health- and safety-mandated minimum ventilation requirements during unoccupied hours. 3. HVAC fans shall remain on during occupied and unoccupied hours in systems primarily serving computer rooms. | Same as proposed design. Exceptions: 1. Set points and schedules for HVAC system s that automatically provide occupant thermal comfort via means other than directly controlling the air dry-bulb and wet-bulb temperature may be allowed to differ, provided that equivalent levels of occupant thermal comfort are demonstrated via the methodology in ASHRAE Standard 55, Section 5.3.3, "Elevated Air Speed," or Standard 55, Appendix B, "Computer Program for Calculation of PMV-PPD." 2. Schedules may be allowed to differ between proposed design and baseline building design when necessary to model nonstandard efficiency measures, provided that the revised schedules have been approved by the rating authority. Measures that may warrant use of different schedules include but are not limited to automatic lighting controls, automatic natural ventilation controls, automatic demand control ventilation controls, and automatic controls that reduce service water-heating loads. In no case shall schedules differ where the controls are manual (e.g., manual operation of light switches or manual operation of windows). |
5. Building Envelope | |
a. All components of the building envelope in the proposed design shall be modeled as shown on architectural drawings or as built for existing building envelopes per the U-value methodologies provided for in section 5.4 and associated subsections. Exceptions: The following building elements are permitted to differ from architectural drawings: 1. All uninsulated assemblies (e.g., concrete floor beams over parking garages, roof parapet) shall be separately modeled using a. either of the following techniques: a. Separate model of each of these assemblies within the energy simulation model. b. Separate calculation of the U-factor for each of these assemblies. The U-factors of these assemblies are then averaged with larger adjacent surfaces using an area-weighted average method. This average U-factor is modeled within the energy simulation model. 2. Exterior surfaces whose azimuth orientation and tilt differ by less than 45 degrees and are otherwise the same may be described as either a single surface or by using multipliers. 3. The exterior roof surface shall be modeled using the aged solar reflectance and thermal emittance determined in accordance with Section 5.5.3.1.1(a). Where aged test data are unavailable, the roof surface may be modeled with a reflectance of 0.30 and a thermal emittance of 0.90. 4. Manual fenestration shading devices, such as blinds or shades, shall be modeled or not modeled the same as in the baseline building design. Automatically controlled fenestration shades or blinds shall be modeled. Permanent shading devices, such as fins, overhangs, and light shelves shall be modeled. 5. Automatically controlled dynamic glazing may be modeled. Manually controlled dynamic glazing shall use the average of the minimum and maximum SHGC and VT. b. Infiltration shall be modeled using the same methodology, air leakage rate, and adjustments for weather and building operation in both the proposed design and the baseline building design. These adjustments shall be made for each simulation time step and must account for but not be limited to weather conditions and HVAC system operation, including strategies that are intended to positively pressurize the building. The air leakage rate of the building envelope (I75Pa) at a fixed building pressure differential of 0.3 in. of water shall be 0.4 cfm/ft2. The air leakage rate of the building envelope shall be converted to appropriate units for the simulation program using one of the methods in Section Error! Reference source not found. When whole-building air leakage testing, in accordance with ASTM E779, is specified during design and completed after construction, the proposed design air leakage rate of the building envelope shall be as measured. | Equivalent dimensions shall be assumed for each building envelope component type as in the proposed design; i.e., the total gross area of walls shall be the same in the proposed design and baseline building design. The same shall be true for the areas of roofs, floors, and doors, and the exposed perimeters of concrete slabs on grade shall also be the same in the proposed design and baseline building design. The following dditional requirements shall apply to the odeling of the baseline building design: Orientation. The baseline building performance shall be generated by simulating the building with its actual orientation and again after rotating the entire building 90, 180, and 270 degrees, then averaging the results. The building shall be modeled so that it does not shade itself. Exceptions: 1. If it can be demonstrated to the satisfaction of the rating authority that the building orientation is dictated by site considerations. 2. Buildings where the vertical fenestration area on each orientation varies by less than 5%. b. Opaque Assemblies.Opaque assemblies used for new buildings, existing buildings, or additions shall conform with assemblies detailed in Appendix A and shall match the appropriate assembly maximum U-factors in Table G3.4. * Roofs-Insulation entirely above deck (A2.2). * Above-grade walls-Steel-framed (A3.3). * Below-grade walls-Concrete block (A4). * Floors-Steel-joist (A5.3). * Slab-on-grade floors shall match the F-factor for unheated slabs from the same tables (A6). * Opaque door types shall be of the same type of construction as the proposed design and conform to the U-factor requirements from the same tables (A7). c. Vertical Fenestration Areas. For building area types included in Table G3.1.1-1, vertical fenestration areas for new buildings and additions shall equal that in Table G3.1.1-1 based on the area of gross above-grade walls that separate conditioned spaces and semiheated spaces from the exterior. Where a building has multiple building area types, each type shall use the values in the table. The vertical fenestration shall be distributed on each face of the building in the same proportion as in the proposed design. For building areas not shown in Table G3.1.1-1, vertical fenestration areas for new buildings and additions shall equal that in the proposed design or 40% of gross above-grade wall area, whichever is smaller, and shall be distributed on each face of the building in the same proportions in the proposed design. The fenestration area for an existing building shall equal the existing fenestration area prior to the proposed work and shall be distributed on each face of the building in the same proportions as the existing building. For portions of those tables where there are no SHGC requirements, the SHGC shall be equal to that determined in accordance with Section C3.6(c). The VT shall be equal to that determined in accordance with Section C3.6(c). d. Vertical Fenestration Assemblies. Fenestration for new buildings, existing buildings, and additions shall comply with the following: * Fenestration U-factors shall match the appropriate requirements in Table G3.4 for the applicable glazing percentage for Uall. * Fenestration SHGCs shall match the appropriate requirements in Table G3.4 using the value for SHGCall for the applicable vertical glazing percentage. * All vertical fenestration shall be assumed to be flush with the exterior wall, and no shading projections shall be modeled. * Manual window shading devices such as blinds or shades are not required to be modeled. e. Skylights and Glazed Smoke Vents.Skylight area shall be equal to that in the proposed design or 3%, whichever is smaller. If the skylight area of the proposed design is greater than 3%, baseline skylight area shall be decreased by an identical percentage in all roof components in which skylights are located to reach 3%. Skylight orientation and tilt shall be the same as in the proposed design. Skylight U-factor and SHGC properties shall match the appropriate requirements in Tables G3.4-1 through G3.4-8 using the value and the applicable skylight percentage. f. Roof Solar Reflectance and Thermal Emittance. The exterior roof surfaces shall be modeled using a solar reflectance of 0.30 and a thermal emittance of 0.90. g. Roof Albedo. All roof surfaces shall be modeled with a reflectivity of 0.30. |
6. Lighting | |
Lighting power in the proposed design shall be determined as follows: a. Where a complete lighting system exists, the actual lighting power for each thermal block shall be used in the model. b. Where a lighting system has been designed and submitted with design documents, lighting power shall be determined in accordance with Sections 9.1.3 and 9.1.4. c. Where lighting neither exists nor is submitted with design documents, lighting shall comply with but not exceed the requirements of Section 9. Lighting power shall be determined in accordance with the Building Area Method. d. Lighting system power shall include all lighting system components shown or provided for on the plans (including lamps and ballasts and task and furniture-mounted fixtures). Exceptions: For multifamily dwelling units, hotel/motel guest rooms, and other spaces in which lighting systems are connected via receptacles and are not shown or provided for on building plans, assume identical lighting power for the proposed design and baseline building design in the simulations. e. Lighting power for parking garages and building facades shall be modeled. f. For lighting controls, at a minimum, the proposed design shall contain the mandatory automatic lighting controls specified in Section 9.4.1 (e.g., automatic daylight responsive controls, occupancy sensors, programmable controls, etc.). These controls shall be modeled in accordance with (g) and (h). g. Automatic daylighting responsive controls shall be modeled directly in the proposed design or through schedule adjustments determined by a separate daylighting analysis approved by the rating authority. Modeling and schedule adjustments shall separately account for primary sidelighted areas, secondary sidelighted areas , and toplighted areas. d. Other automatic lighting controls included in the proposed design shall be modeled directly in the building simulation by reducing the lighting schedule each hour by the occupancy sensor reduction factors in Table G3.7 for the applicable space type. This reduction shall be taken only for lighting controlled by the occupancy sensors. Credit for other programmable lighting control in buildings less than 5000 ft2 can be taken by reducing the lighting schedule each hour by 10%. | Interior lighting power in the baseline building design shall be determined using the values in Table G3.7. Lighting shall be modeled having the automatic shutoff controls in buildings >5000 ft2 and occupancy sensors in employee lunch and break rooms, conference/meeting rooms, and classrooms (not including shop classrooms, laboratory classrooms, and preschool through 12th-grade classrooms). These controls shall be reflected in the baseline building design lighting schedules. No additional automatic lighting controls, e.g., automatic controls for daylight utilization and occupancy sensors in space types not listed above, shall be modeled in the baseline building design. Exterior lighting in areas identified as "Tradable Surfaces" in Table G3.6 shall be modeled with the baseline lighting power shown in Table G3.6. Other exterior lighting shall be modeled the same in the baseline building design as in the proposed design. |
7. Thermal Blocvks-HVAC Zones Designed | |
Where HVAC zones are defined on HVAC design drawings, each HVAC zone shall be modeled as a separate thermal block. Exceptions: Different HVAC zones may be combined to create a single thermal block or identical thermal blocks to which multipliers are applied, provided that all of the following conditions are met: 1. The space use classification is the same throughout the thermal block. 2. All HVAC zones in the thermal block that are adjacent to glazed exterior walls and glazed semiexterior walls face the same orientation or their orientations vary by less than 45 degrees. 3. All of the zones are served by the same HVAC system or by the same kind of HVAC system . | Same as proposed design. |
8. Thermal Blocks-HVAC Zones Not Designed | |
Where the HVAC zones and systems have not yet been designed, thermal blocks shall be defined based on similar internal load densities, occupancy, lighting, thermal and space temperature schedules, and in combination with the following guidelines: a. Separate thermal blocks shall be assumed for interior and perimeter spaces. Interior spaces shall be those located greater than 15 ft from an exterior wall or semiexterior wall. Perimeter spaces shall be those located within 15 ft of an exterior wall or semiexterior wall. A separate thermal zone does not need to be modeled for areas adjacent to semiexterior walls that separate semiheated space from conditioned space . b. Separate thermal blocks shall be assumed for spaces adjacent to glazed exterior walls or glazed semiexterior walls; a separate zone shall be provided for each orientation, except that orientations that differ by less than 45 degrees may be considered to be the same orientation. Each zone shall include all floor area that is 15 ft or less from a glazed perimeter wall, except that floor area within 15 ft of glazed perimeter walls having more than one orientation shall be divided proportionately between zones. c. Separate thermal blocks shall be assumed for space s having floors that are in contact with the ground or exposed to ambient conditions from zones that do not share these features. d. Separate thermal blocks shall be assumed for spaces having exterior ceiling or roof assemblies from zones that do not share these features. | Same as proposed design. |
9. Thermal Blocks-Multifamily Residential buildings | |
Residential spaces shall be modeled using at least one thermal block per dwelling unit, except that those units facing the same orientations may be combined into one thermal block. Corner units and units with roof or floor loads shall only be combined with units sharing these features. | Same as proposed design. |
10. HVAC systems | |
The HVAC system type and all related performance parameters in the proposed design, such as equipment capacities and efficiencies, shall be determined as follows: a. Where a complete HVAC system exists, the model shall reflect the actual system type using actual component capacities and efficiencies. b. Where an HVAC system has been designed and submitted with design documents, the HVAC model shall be consistent with design documents. Mechanical equipment efficiencies shall be adjusted from actual design conditions to the standard rating conditions specified in Section 6.4.1 if required by the simulation model. Where efficiency ratings include supply fan energy, the efficiency rating shall be adjusted to remove the supply fan energy from the efficiency rating in the baseline building design. The equations in Section G3.1.2.1 shall not be used in the proposed design. The proposed design HVAC system shall be modeled using manufacturers' full- and part-load data for the HVAC system without fan power. c. Where no heating system exists or no heating system has been submitted with design documents, the system type shall be the same system as modeled in the baseline building design and shall comply with but not exceed the requirements of Section 6. d. Where no cooling system exists or no cooling system has been submitted with design documents, the cooling system type shall be the same as modeled in the baseline building design and shall comply with the requirements of Section 6. Spaces using baseline HVAC system types 9 and 10. | The HVAC systems in the baseline building design shall be of the type and description specified in Section G3.1.1, shall meet the general HVAC system requirements specified in Section G3.1.2, and shall meet any system -specific requirements in Section G3.1.3 that are applicable to the baseline HVAC system types. If the proposed design includes humidification then the baseline building design shall use adiabatic humidification. Exception: If the proposed building humidification system complies with Section 6.5.2.4 then the baseline building design shall use nonadiabatic humidification. For systems serving computer rooms, the baseline building design shall not have reheat for the purpose of dehumidification. Fossil fuel systems shall be modeled using natural gas as their fuel source. Exception: For fossil fuel system s where natural gas is not available for the proposed building site as determined by the rating authority, the baseline HVAC systems shall be modeled using propane as their fuel. |
11. Service Water-Heating systems | |
The service water-heating system type and all related performance parameters, such as equipment capacities and efficiencies, in the proposed design shall be determined as follows: a. Where a complete service water-heating system exists, the proposed design shall reflect the actual system type using actual component capacities and efficiencies. b. Where a service water-heating system has been designed and submitted with design documents, the service water-heating model shall be consistent with design documents. c. Where no service water-heating system exists or has been designed and submitted with design documents but the building will have service water-heating loads, a service water-heating system shall be modeled that matches the system type in the baseline building design, serves the same water-heating loads, and shall comply with but not exceed the requirements of Section 7. d. For buildings that will have no service water-heating loads, no service water-heating system shall be modeled. Where a combined system has been specified to meet both space heating and service water-heating loads, the proposed design shall reflect the actual system type using actual component capacities and efficiencies. | The service water-heating system in the baseline building design shall be as specified in Table G3.1.1-2 and conform with the following conditions: a. Where a complete service water-heating system exists or a new service water-heating system has been specified, one service water-heating system shall be modeled for each building area type in the proposed building. Each system shall be sized according to the provisions of Section 7.4.1, and the equipment shall match the minimum efficiency requirements in Section 7.4.2. b. Where no service water-heating system exists or has been specified but the building will have service water-heating loads, one service water-heatingsystem shall be modeled for each anticipated building area type in the proposed design. Each system shall meet the minimum efficiency requirements of Section 7.4.2 and be modeled identically to the proposed design. c. For buildings that will have no service water-heating loads, no service water-heating shall be modeled. d. Where a combined system has been specified to meet both space heating and service water-heating loads, the baseline buildingsystem shall use separate systems meeting the minimum efficiency requirements applicable to each system individually. e. For large, 24-hour-per-day facilities that meet the prescriptive criteria for use of condenser heat recovery system s described in Section 6.5.6.2, a system meeting the requirements of that section shall be included in the baseline building design regardless of the exceptions to Section 6.5.6.2. Exceptions: If a condenser heat recovery system meeting the requirements described in Section 6.5.6.2 cannot be modeled, the requirement for including such a system in the actual building shall be met as a prescriptive requirement in accordance with Section 6.5.6.2, and no heat recovery system shall be included in the proposed design or baseline building design. f. Service water-heating energy consumption shall be calculated explicitly based upon the volume of service water heating required and the entering makeup water and the leaving service water-heating temperatures. Entering water temperatures shall be estimated based upon the location. Leaving temperatures shall be based upon the end-use requirements. g. Where recirculation pumps are used to ensure prompt availability of service water-heating at the end use, the energy consumption of such pumps shall be calculated explicitly. h. Service water loads and use shall be the same for both the proposed design and baseline building design and shall be documented by the calculation procedures described in Section 7.4.1. Exceptions: Service water-heating use can be demonstrated to be reduced by documented water conservation measures that reduce the physical volume of service water required. Examples include low-flow shower heads. Such reduction shall be demonstrated by calculations. Exceptions: 2. Service water-heating energy consumption can be demonstrated to be reduced by reducing the required temperature of service mixed water, by increasing the temperature, or by increasing the temperature of the entering makeup water. Examples include alternative sanitizing technologies for dishwashing and heat recovery to entering makeup water. Such reduction shall be demonstrated by calculations. 3. Service water heating use can be demonstrated to be reduced by reducing the hot fraction of mixed water to achieve required operational temperature. Examples include shower or laundry heat recovery to incoming cold-water supply, reducing the hot-water fraction required to meet required mixed-water temperature. Such reduction shall be demonstrated by calculations. i. Gas storage water heaters shall be modeled using natural gas as their fuel. Where natural gas is not available for the proposed building site, as determined by the rating authority, gas storage water heaters shall be modeled using propane as their fuel. |
12. Receptacle and Other Loads | |
Receptacle and process loads, such as those for office and other equipment, shall be estimated based on the building area type or space type category and shall be assumed to be identical in the proposed design and baseline building design, except as specifically approved by the rating authority only when quantifying performance that exceeds the requirements of Standard 90.1 but not when the Performance Rating Method is used as an alternative path for minimum standard compliance in accordance with Section 4.2.1.1. These loads shall always be included in simulations of the building. These loads shall be included when calculating the proposed building performance and the baseline building performance as required by Section G1.2.1. a. Where power and other systems covered by Sections 8 and 10 have been designed and submitted with design documents, those systems shall be determined in accordance with Sections 8 and 10. Where power and other systems covered by Sections 8 and 10 have not been submitted with design documents, those systems shall comply with but not exceed the requirements of those sections. | Motors shall have the efficiency ratings found in Table G3.9.1. Other systems covered by Section 10 and miscellaneous loads shall be modeled as identical to those in the proposed design, including schedules of operation and control of the equipment. Energy used for cooking equipment, receptacle loads, computers, medical or laboratory equipment, and manufacturing and industrial process equipment not specifically identified in the standard power and energy rating or capacity of the equipment shall be identical between the proposed building performance and the baseline building performance. When quantifying performance that exceeds the requirements of Standard 90.1 (but not when using the Performance Rating Method as an alternative path for minimum standard compliance per Section 4.2.1.1) variations of the power requirements, schedules, or control sequences of the equipment modeled in the baseline building design from those in the proposed design shall be approved by the rating authority based on documentation that the equipment installed in the proposed design represents a significant verifiable departure from documented current conventional practice. The burden of this documentation is to demonstrate that accepted conventional practice would result in baseline building equipment different from that installed in the proposed design. Occupancy and occupancy schedules shall not be changed. |
13. Modeling Limitations to the Simulation Program | |
If the simulation program cannot model a component or system included in the proposed design explicitly, substitute a thermodynamically similar component model that can approximate the expected performance of the component that cannot be modeled explicitly. | Same as proposed design. |
14. Exterior Conditions | |
Shading by Adjacent Structures and Terrain. The effect that structures and significant vegetation or topographical features have on the amount of solar radiation being received by a structure shall be adequately reflected in the computer analysis. All elements whose effective height is greater than their distance from a proposed building and whose width facing the proposed building is greater than one-third that of the proposed building shall be accounted for in the analysis. b. Ground Temperatures for Below-Grade Wall and Basement Floor Heat-Loss Calculations. It is acceptable to use either an annual average ground temperature or monthly average ground temperatures for calculation of heat loss through below-grade walls and basement floors. Water Main Temperatures for Service Water-Heating Calculations. It is acceptable to use either an annual water main supply temperature or monthly average water main supply temperatures for calculating service water heating. If annual or monthly water main supply temperatures are not available from the local water utility, annual average ground temperatures may be used. | Same as proposed design. |
15. Distribution Transformers | |
Low-voltage dry-type distribution transformers shall be modeled if the transformers in the proposed design exceed the efficiency required in Table 8.4.4. | Low-voltage dry-type distribution transformers shall be modeled only if the proposed design transformers exceed the efficiency requirements of Table 8.4.4. If modeled, the efficiency requirements from Table 8.4.4 shall be used. The ratio of the capacity to peak electrical load of the transformer shall be the same as the ratio in the proposed design. |
16. Elevators | |
Where the proposed design includes elevators, the elevator motor, ventilation fan, and light load shall be included in the model. The cab ventilation fan and lights shall be modeled with the same schedule as the elevator motor. | Where the proposed design includes elevators, the baseline building design shall be modeled to include the elevator cab motor, ventilation fans, and lighting power. The elevator peak motor power shall be calculated as follows: bhp = (Weight of Car + Rated Load - Counterweight) × Speed of Car/(33,000 × hmechanical) Pm = bhp × 746/hmotor where Weight of Car = the proposed design elevator car weight, lb Rated Load = the proposed design elevator load at which to operate, lb Counterweight of Car = the elevator car counterweight, from Table G3.9.2, lb Speed of Car = the speed of the proposed elevator, ft/min hmechanical = the mechanical efficiency of the elevator from Table G3.9.2 hmotor = the motor efficiency from Table G3.9.2 Pm = peak elevator motor power,W The elevator motor use shall be modeled with the same schedule as the proposed design. When included in the proposed design, the baseline elevator cab ventilation fan shall be 0.33 W/cfm and the lighting power density shall be 3.14 W/ft2; both operate continuously. |
17. Refrigeration | |
The proposed design shall be modeled using the actual equipment capacities and efficiencies. | Where refrigeration equipment is specified in the proposed design and listed in Tables G3.10.1 and G3.10.2, the baseline building design shall be modeled as specified in Tables G3.10.1 and G3.10.2 using the actual equipment capacities. If the refrigeration equipment is not listed in Tables G3.10.1 and G3.10.2, the baseline building design shall be modeled the same as the proposed design. |
Baseline HVAC System Type and Description
HVAC systems in the baseline building design shall comply with the following:
TABLE G3.1.1-1 BASELINE BUILDING VERTICAL FENESTRATION PERCENTAGE OF GROSS ABOVE-GRADE-WALL AREA
a Building Area Types | Baseline Building Gross Above-Grade- |
Grocery Store | Wall Area 7% |
Healthcare (outpatient) | 21 |
Hospital | 2%7 |
Hotel/motel (<=75 rooms) | 2%4 |
Hotel/motel (>75 rooms) | 3%4 |
Office (<=5000 ft 2) | 1%9 |
2 Office (5000 to 50,000 ft) | 3%1 |
2 Office (>50,000 ft) | 4%0 |
Restaurant (quick service) | 3%4 |
Restaurant (full service) | 2%4 |
Retail (stand alone) | 1%1 |
Retail (strip mall) | 2%0 |
School (primary) | 2%2 |
School (secondary and university) | 2%2 |
Warehouse (nonrefrigerated) | 6% |
Table G3.1.1-2 Baseline Service Water-Heating System
Building Area Type | Baseline Heating Method | Building Area Type | Baseline Heating Method |
Automotive facility | Gas storage water heater | Performing arts theater | Gas storage water heater |
Convenience store | Electric resistance water heater | Police station | Electric resistance storage water heater |
Convention center | Electric resistance storage water heater | Post office | Electric resistance storage water heater |
Courthouse | Electric resistance storage water heater | Religious facility | Electric resistance storage water heater |
Dining: Bar lounge/leisure | Gas storage water heater | Retail | Electric resistance storage water heater |
Dining: Cafeteria/fast food | Gas storage water heater | School/university | Gas storage water heater |
Dining: Family | Gas storage water heater | Sports arena | Gas storage water heater |
Dormitory | Gas storage water heater | Town hall | Electric resistance storage water heater |
Exercise center | Gas storage water heater | Transportation | Electric resistance storage water heater |
Fire station | Gas storage water heater | Warehouse | Electric resistance storage water heater |
Grocery store | Gas storage water heater | Workshop | Electric resistance storage water heater |
Gymnasium | Gas storage water heater | All others | Gas storage water heater |
Health-care clinic | Electric resistance storage water heater | ||
Hospital and outpatient surgery center | Gas storage water heater | ||
Hotel | Gas storage water heater | ||
Library | Electric resistance storage water heater | ||
Manufacturing facility | Gas storage water heater | ||
Motel | Gas storage water heater | ||
Motion picture theater | Electric resistance storage water heater | ||
Multifamily | Gas storage water heater | ||
Museum | Electric resistance storage water heater | ||
Office | Electric resistance storage water heater | ||
Parking garage | Electric resistance storage water heater | ||
Penitentiary | Gas storage water heater |
Table G3.1.1-3 Baseline HVAC System Types
Building Type, Number of Floors, and Gross Conditioned Floor Area | Climate Zones 3B, 3C, and 4 to 8 | Climate Zones 0 to 3A |
Residential | System 1-PTAC | System 2-PTHP |
Public assembly <120,000 ft2 | System 3-PSZ-AC | System 4-PSZ-HP |
Public assembly >120,000 ft2 | System 12-SZ-CV-HW | System 13-SZ-CV-ER |
Heated-only storage | System 9-Heating and ventilation | System 10-Heating and ventilation |
Retail and 2 floors or fewer | System 3-PSZ-AC | System 4-PSZ-HP |
Other residential and 3 floors or fewer and <25,000 ft2 | System 3-PSZ-AC | System 4-PSZ-HP |
Other residential and 4 or 5 floors and <25,000 ft2 or 5 floors or fewer and 25,000 ft2 to 150,000 ft2 | System 5-Packaged VAV with reheat | System 6-Packaged VAV with PFP boxes |
Other residential and more than 5 floors or >150,000 ft2 | System 7-VAV with reheat | System 8-VAV with PFP boxes |
Notes:
Table G3.1.1-4 Baseline System Descriptions
System No. | System Type | Fan Control | Cooling Typea | Heating Typea |
1. PTAC | Packaged terminal air conditioner | Constant volume | Direct expansion | Hot-water fossil fuel boiler |
2. PTHP | Packaged terminal heat pump | Constant volume | Direct expansion | Electric heat pump |
3. PSZ-AC | Packaged rooftop air conditioner | Constant volume | Direct expansion | Fossil fuel furnace |
4. PSZ-HP | Packaged rooftop heat pump | Constant volume | Direct expansion | Electric heat pump |
5. Packaged VAV with reheat | Packaged rooftop VAV with reheat | VAV | Direct expansion | Hot-water fossil fuel boiler |
6. Packaged VAV with PFP boxes | Packaged rooftop VAV with parallel fan power boxes and reheat | VAV | Direct expansion | Electric resistance |
7. VAV with reheat | VAV with reheat | VAV | Chilled water | Hot-water fossil fuel boiler |
8. VAV with PFP boxes | VAV with parallel fan-powered boxes and reheat | VAV | Chilled water | Electric resistance |
9. Heating and ventilation | Warm air furnace, gas fired | Constant volume | None | Fossil fuel furnace |
10. Heating and ventilation | Warm air furnace, electric | Constant volume | None | Electric resistance |
11. SZ-VAV | Single-zone VAV | VAV | Chilled water | See note (b). |
12. SZ-CV-HW | Single-zone system | Constant volume | Chilled water | Hot-water fossil fuel boiler |
13. SZ-CV-ER | Single-zone system | Constant volume | Chilled water | Electric resistance |
Purchased Heat. For systems using purchased hot water or steam, the heating source shall be modeled as purchased hot water or steam in both the proposed design and baseline building design. Hot water or steam costs shall be based on actual utility rates, and on-site boilers, electric heat, and furnaces shall not be modeled in the baseline building design.
Purchased Chilled Water. For systems using purchased chilled water, the cooling source shall be modeled as purchased chilled water in both the proposed design and baseline building design. Purchased chilled water costs shall be based on actual utility rates, and on-site chillers and direct expansion equipment shall not be modeled in the baseline building design.
Baseline HVAC System Requirements for Systems Utilizing Purchased Chilled Water and/or Purchased Heat. If the proposed design uses purchased chilled water and/or purchased heat, the following modifications to the baseline HVAC system types in Table G3.1.1-4 shall be used:
Purchased Heat Only. If the proposed design uses purchased heat, but does not use purchased chilled water, then Tables G3.1.1-3 and G3.1.1-4 shall be used to select the baseline HVAC system type and purchased heat shall be substituted for the heating type in Table G3.1.1-4. The same heating source shall be used in the proposed design and baseline building design.
Purchased Chilled Water Only. If the proposed design uses purchased chilled water but does not use purchased heat, then Tables G3.1.1-3 and G3.1.1-4 shall be used to select the baseline HVAC system type, with the modifications listed below:
Purchased Chilled Water and Purchased Heat. If the proposed design uses purchased chilled water and purchased heat, then Tables G3.1.1-3 and G3.1.1-4 shall be used to select the baseline HVAC system type, with the following modifications:
On-Site Distribution Pumps. All on-site distribution pumps shall be modeled in both the proposed design and base building design.
Modeling Building Envelope Infiltration. The air leakage rate of the buildingenvelope (I) at a pressure differential of 0.3 in. of water shall be converted to appropriate units for the simulation program using one of the following formulas:
For methods describing air leakage as a function of floor area,
IFLR = 0.112 × I75Pa × SIAFLR
For methods describing air leakage as a function of the area of above-grade walls that separate conditioned spaces and semiheated spaces from the exterior ,
IAGW = 0.112 × I75Pa × SIAAGW
When using the measured air leakage rate of the building envelope at a pressure differential of 0.3 in. of water for the proposed design, the air leakage rate shall be calculated as follows:
I75Pa = Q/S
where
I75Pa = air leakage rate of the building envelope (cfm/ft)at a fixed building pressure differential of 0.3 in. of water, or 1.57 psf
Q = volume of air in cfm flowing through the building envelope when subjected to a pressure differential of 0.3 in. of water, or 1.57 psf, in accordance with ASTM E 779
S = total area of the building envelope (ft), including the lowest floor, any below- grade walls or above-grade walls, and roof (including vertical fenestration and skylights),
IFLR = adjusted air leakage rate of the building envelope (cfm/ft2) at a reference wind speed of 10 mph and relative to the gross floor area
AFLR = gross floor area, ft
IAGW = adjusted air leakage rate of the building envelope (cfm/ft2) at a reference wind speed of 10 mph and relative to the area of the above-grade walls of the building envelope
AAGW = total area of above-grade walls of the building envelope, ft2
Exception: A multizone airflow model alternative method to modeling buildingenvelope air leakage may be used provided the following criteria are met:
General Baseline HVAC System Requirements. HVAC systems in the baseline building design shall conform with the general provisions in this section.
Equipment Efficiencies. All HVAC equipment in the baseline building design shall be modeled at the minimum efficiency levels, both part load and full load, in accordance with Tables G.3.5.1 through G.3.5.6. Chillers shall use Path A efficiencies as shown in Table 6.8.1-3. Where efficiency ratings include supply fan energy, the efficiency rating shall be adjusted to remove the supply fan energy. For Baseline HVAC Systems 1, 2, 3, 4, 5, and 6, calculate the minimum COP and COP nfcoolingnfheating using the equation for the applicable performance rating as indicated in Tables 6.8.1-1 through 6.8.1-4.
Where a full- and part-load efficiency rating is provided in Tables 6.8.1-1 through 6.8.1-4, the full-load equation below shall be used:
COPnfcooling = 7.84E-8 × EER × Q + 0.338 × EER COPnfcooling = -0.0076 × SEER + 0.3796 × SEER
COPnfheating = 1.48E-7 × COP47 × Q + 1.062 × COP47 (applies to heat-pump heating efficiency only) COP = -0.0296 × HSPF +
0.7134 × HSPF
where COPnfcooling and COPnfheating are the packaged HVAC equipment cooling and heating energy efficiency, respectively, to be used in the baseline building design, which excludes supply fan power, and Q is the AHRI-rated cooling capacity in Btu. EER, SEER, COP, and HSPF shall be at AHRI test conditions. Fan energy shall be modeled separately according to Section G3.1.2.9.
Equipment Capacities. The equipment capacities (i.e., system coil capacities) for the baseline building design shall be based on sizing runs for each orientation (per Table G3.1, No. 5a) and shall be oversized by 15% for cooling and 25% for heating, i.e., the ratio between the capacities used in the annual simulations and the capacities determined by the sizing runs shall be 1.15 for cooling and 1.25 for heating.
Sizing Runs. Weather conditions used in sizing runs to determine baseline equipment capacities shall be based either on hourly historical weather files containing typical peak conditions or on design days developed using 99.6% heating design temperatures and 1% dry-bulb and 1% wet-bulb cooling design temperatures.
Unmet Loads. Unmet load hours for the proposed design or baseline building design shall not exceed 300 (of the 8760 hours simulated). Alternatively, unmet load hours exceeding these limits shall be permitted to be accepted upon approval of the rating authority provided that sufficient justification is given indicating that the accuracy of the simulation is not significantly compromised by these unmet loads.
Fan System Operation. Supply and return fans shall operate continuously whenever spaces are occupied and shall be cycled to meet heating and cooling loads during unoccupied hours. Supply, return, and/or exhaust fans will remain on during occupied and unoccupied hours in spaces that have health and safety mandated minimum ventilation requirements during unoccupied hours.
For Systems 6 and 8, only the terminal-unit fan and reheat coil shall be energized to meet heating set point during unoccupied hours.
Ventilation. Minimum ventilation system outdoor air intake flow shall be the same for the proposed design and baseline building design.
Exception to G3.1.2.5:
Economizers. Air economizers shall not be included in baseline HVAC Systems 1, 2, 9, and 10. Air economizers shall be included in baseline HVAC Systems 3 through 8, and 11, 12, and 13 based on climate as specified in Table G3.1.2.6.
Table G3.1.2.6 Climate Conditions under which Economizers are Included for Comfort Cooling for Baseline Systems 3 through 8 and 11, 12, and 13
Climate Zone 0A, 0B, 1A, 1B, 2A, 3A, 4A | Conditions NR |
Others | Economizer Included |
Note: NR means that there is no conditioned building floor area for which economizers are included for the type of zone and climate.
Exception to G3.1.2.6: Economizers shall not be included for systems meeting one or more of the exceptions listed below.
Computer Room Economizers. Systems that serve computer rooms that are HVAC System 3 or 4 shall not have an economizer. Systems that serve computer rooms that are HVAC System 11 shall include an integrated fluid economizer meeting the requirements of Section 6.5.1.2 in the baseline building design.
Economizer High-Limit Shutoff. The high- limit shutoff shall be a dry-bulb fixed switch with setpoint temperatures in accordance with the values in Table G3.1.2.7.
Table G3.1.2.7 Economizer High-Limit Shutoff Temperature
Climate Zone 2B, 3B, 3C, 4B, 4C, 5B, 5C, 6B, 7, 8 | Dry-Bulb Temperature Set Point 75°F |
5A, 6A | 70°F |
Design Airflow Rates
Baseline All System Types Except System Types 9 and 10. System design supply airflow rates for the baseline building design shall be based on a supply-air-to- room- temperature set-point difference of 20°F or the minimum outdoor airflow rate, or the airflow rate required to comply with applicable codes or accreditation standards, whichever is greater. For systems with multiple zone thermostat set-points, use the design set point that will result in the lowest supply air cooling set point or highest supply air heating set point. If return or relief fans are specified in the proposed design, the baseline building design shall also be modeled with fans serving the same functions and sized for the baseline system supply fan air quantity less the minimum outdoor air, or 90% of the supply fan air quantity, whichever is larger.
Exception to G3.1.2.8.1:
Baseline System Types 9 and 10. System design supply airflow rates for the baseline building design shall be based on the temperature difference between a supply air temperature setpoint of 105°F and the design space heating temperature setpoint, the minimum outdoor airflow rate, or the airflow rate required to comply with applicable codes or accreditation standards, whichever is greater. If the proposed design includes a fan sized and controlled to provide non-mechanical cooling, the baseline building design shall include a separate fan to provide non-mechanical cooling, sized and controlled the same as the proposed design.
System Fan Power. System fan electrical power for supply, return, exhaust, and relief (excluding power to fan-powered VAV boxes) shall be calculated using the following formulas:
For Systems 1 and 2,
Pfan = CFMs × 0.3
For Systems 3 through 8, and 11, 12, and 13,
Pfan = bhp × 746/fan motor efficiency
For Systems 9 and 10 (supply fan),
Pfan = CFMs × 0.3
For Systems 9 and 10 (nonmechanical cooling fan if required by Section G3.1.2.8.2)
where
Pfan = electric power to fan motor, W
bhp = brake horsepower of baseline fan motor from Table G3.1.2.9
fan motor efficiency = the efficiency from Table G3.9.1 for the next motor size greater than the bhp using a totally enclosed fan cooled motor at 1800 rpm
CFMs = the baseline system maximum design supply fan airflow rate, cfm
CFMnmc = the baseline non-mechanicalcooling fan air flow, cfm
Table G3.1.2.9 Baseline Fan Brake Horsepower
Baseline Fan Motor Brake Horsepower | ||
Constant-Volume Systems 3 to 4 | Variable-Volume Systems 5 to 8 | Variable-Volume System 11 |
CFMs × 0.00094 + A | CFMs × 0.0013 + A | CFMs × 0.00062 + A |
Notes:
Exhaust Air Energy Recovery. Individual fan systems that have both a design supply air capacity of 5000 cfm or greater and have a minimum design outdoor air supply of 70% or greater shall have an energy recovery system with at least 50% enthalpy recovery ratio. Fifty percent enthalpy recovery ratio shall mean a change in the enthalpy of the outdoor air supply equal to 50% of the difference between the outdoor air and return air at design conditions. Provision shall be made to bypass or control the heat recovery system to permit air economizer operation, where applicable.
Exceptions to G3.1.2.10: If any of these exceptions apply, exhaust air energy recovery shall not be included in the baseline building design.
proposed design.
System-Specific Baseline HVAC System Requirements. Baseline HVAC systems shall conform with provisions in this section, where applicable, to the specified baseline system types as indicated in section headings.
Heat Pumps (Systems 2 and 4). Electric air- source heat pumps shall be modeled with electric auxiliary heat and an outdoor air thermostat. The systems shall be controlled to energize auxiliary heat only when the outdoor air temperature is less than 40°F. The air-source heat pump shall be modeled to continue to operate while auxiliary heat is energized.
Type and Number of Boilers (Systems 1, 5, and 7). The boiler plant shall use the same fuel as the proposed design and shall be natural draft, except as noted in Section G3.1.1.1. The baseline building design boiler plant shall be modeled as having a single boiler if the baseline building design plant serves a conditioned floor area of 15,000 ft or less and as having two equally sized boilers for plants serving more than 15,000 ft . Boilers shall be staged as required by the load.
Hot-Water Supply Temperature (Systems 1, 5, 7, and 12). Hot-water design supply temperature shall be modeled as 180°F and design return temperature as 130°F.
Hot-Water Supply Temperature Reset (Systems 1, 5, 7, 11, and 12). Hot-water supply temperature shall be reset based on outdoor dry-bulb temperature using the following schedule: 180°F at 20°F and below, 150°F at 50°F and above, and ramped linearly between 180°F and 150°F at temperatures between 20°F and 50°F.
Exception to G3.1.3.4
Systems served by purchased heat.
Hot-Water Pumps. The baseline building design hot-water pump power shall be 19 W/gpm. The pumping system shall be modeled as primary-only with continuous variable flow and a minimum of 25% of the design flow rate. Hot-water systems serving 120,000 ft or more shall be modeled with variable-speed drives, and systems serving less than 120,000 ft shall be modeled as riding the pump curve.
Exception to G3.1.3.5: The pump power for systems using purchased heat shall be 14 W/gpm.
Piping Losses (Systems 1, 5, 7, 8, and 11). Piping losses shall not be modeled in either the proposed design or baseline building design for hot-water, chilled-water, or steam piping.
Type and Number of Chillers (Systems 7, 8, 11, 12, and 13). Electric chillers shall be used in the baseline building design regardless of the cooling energy source, e.g., direct fired absorption or absorption from purchased steam. The baseline building design's chiller plant shall be modeled with chillers having the number and type as indicated in Table G3.1.3.7 as a function of building peak cooling load.
Table G3.1.3.7 Type and Number of Chillers
Building Peak Cooling Load | Number and Type of Chillers |
<300 tons | 1 water-cooled screw chiller |
>300 tons, <600 tons | 2 water-cooled screw chillers sized equally |
>600 tons | 2 water-cooled centrifugal chillers minimum with chillers added so that no chiller is larger than 800 tons, all sized equally |
Exception: Systems using purchased chilled water shall be modeled in accordance with Section G3.1.1.3.
Chilled-Water Supply Temperature Reset (Systems 7, 8, 11, 12, and 13).
Chilled-water supply temperature shall be reset based on outdoor dry-bulb temperature using the following schedule: 44°F at 80°F and above, 54°F at 60°F and below, and ramped linearly between 44°F and 54°F at temperatures between 80°F and 60°F.
Exception to G3.1.3.9:
If the baseline chilled-water system serves a computer room HVAC system, the supply chilled- water temperature shall be reset higher based on the HVAC system requiring the most cooling; i.e., the chilled-water setpoint is reset higher until one cooling-coil valve is nearly wide open. The maximum reset chilled-water supply temperature shall be 54°F.
Systems served by purchased chilled water.
Chilled-Water Pumps (Systems 7, 8, and 11). Chilled-water systems shall be modeled as primary/secondary systems with constant-flow primary loop and variable-flow secondary loop. For systems with cooling capacity of 300 tons or more, the secondary pump shall be modeled with variable-speed drives and a minimum flow of 25% of the design flow rate. For systems with less than 300 tons cooling capacity, the secondary pump shall be modeled as riding the pump curve. The baseline building constant-volume primary pump power shall be modeled as 9 W/gpm, and the variable-flow secondary pump power shall be modeled as 210 W/gpm at design conditions. For computer room systems using System 11 with an integrated fluid economizer, the baseline building design primary chilled-water pump power shall be increased by 3 W/gpm for flow associated with the fluid economizer.
Exception to G3.1.3.10
For systems using purchased chilled water, the building distribution pump shall be modeled with variable-speed drive, a minimum flow of 25% of the design flow rate, and a pump power of 16 W/gpm.
Heat Rejection (Systems 7, 8, 9, 12, and 13). The heat rejection device shall be an axial fan open circuit cooling tower with variable-speed fan control and shall have an efficiency of 38.2 gpm/hp at the conditions specified in Table 6.8.1-7. Condenser water design supply temperature shall be calculated using the cooling tower approach to the 0.4% evaporation design wet- bulb temperature as generated by the formula below, with a design temperature rise of 5.6°C.
Approach 10°F Range = 25.72 - (0.24 × WB) where WB is the 0.4% evaporation design wet-bulb temperature in °F; valid for wet bulbs from 55°F to 90°F. The tower shall be controlled to maintain a leaving water temperature, where weather permits, per Table G3.1.3.11, floating up to the design leaving water temperature for the cooling tower. The baseline building design condenser-water pump power shall be 19 W/gpm and modeled as constant volume. For computer room systems using System 11 with an integrated water-side economizer, the baseline building design condenser water-pump power shall be increased by 3 W/gpm for flow associated with the water-side economizer. Each chiller shall be modeled with separate condenser water and chilled-water pumps interlocked to operate with the associated chiller.
Table G3.1.3.11 Heat-Rejection Leaving Water Temperature
Climate Zone | Leaving Water Temperature |
5B, 5C, 6B, 8 | 65°F |
0B, 1B, 2B, 3B, 3C, 4B, 4C, 5A, 6A, 7 | 70°F |
3A,4A | 75°F |
0A, 1A, 2A | S0°F |
Supply Air Temperature Reset (Systems 5 through 8). The air temperature for cooling shall be reset higher by 5°F under the minimum cooling load conditions.
VAV Minimum Flow Setpoints (Systems 5 and 7). Minimum volume setpoints for VAV reheat boxes shall be 30% of zone peak airflow, the minimum outdoor air- flow rate or the airflow rate required to comply with applicable codes or accreditation standards, whichever is larger.
Exception to G3.1.3.13: Systems serving laboratory spaces shall reduce the exhaust and makeup air volume during unoccupied periods to the largest of 50% of zone peak airflow, the minimum outdoor airflow rate, or the airflow rate required to comply with applicable codes or accreditation standards.
Fan Power (Systems 6 and 8). Fans in parallel VAV fan-powered boxes shall run as the first stage of heating before the reheat coil is energized. Fans in parallel VAV fan-powered boxes shall be sized for 50% of the peak design primary air (from the VAV air-handling unit) flow rate and shall be modeled with 0.35 W/cfm fan power. Minimum volume setpoints for fan-powered boxes shall be equal to 30% of peak design primary airflow rate or the rate required to meet the minimum outdoor air ventilation requirement, whichever is larger. The supply air temperature setpoint shall be constant at the design condition.
VAV Fan Part-Load Performance (Systems 5 through 8 and 11). VAV system supply fans shall have variable-speed drives, and their part-load performance characteristics shall be modeled using either Method 1 or Method 2 specified in Table G3.1.3.15.
Table G3.1.3.15 Part-Load Performance for VAV Fan Systems Method 1-Part-Load Fan Power Data
Fan Part-Load Ratio | Fraction of Full-Load Power |
0.00 | 0.00 |
0.10 | 0.03 |
0.20 | 0.07 |
0.30 | 0.13 |
0.40 | 0.21 |
0.50 | 0.30 |
0.60 | 0.41 |
0.70 | 0.54 |
0.80 | 0.68 |
0.90 | 0.83 |
1.00 | 1.00 |
Method 2 Part-Load Fan Power Equationl
Pfan = 0.0013 + 0.1470 X PLRfan + 0.9506 X (PLRfan)2 - 0.0998 X (PLRfan)3
where
Pfan = fraction of full-load fan power and
PLRfan = fan part-load ratio (current cfm/design cfm).
Computer Room Equipment Schedules. Computer room equipment schedules shall be modeled as a constant fraction of the peak design load per the following monthly schedule:
Month 1, 5, 9-25%
Month 2, 6, 10-50%
Month 3, 7, 11-75%
Month 4, 8, 12-100%
System 11 Supply Air Temperature and Fan Control. Minimum volume setpoint shall be 50% of the maximum design airflow rate, the minimum ventilation outdoor airflow rate, or the airflow rate required to comply with applicable codes or accreditation standards, whichever is larger.
Fan volume shall be reset from 100% airflow at 100% cooling load to minimum airflow at 50% cooling load. Supply air temperature setpoint shall be reset from minimum supply air temperature at 50% cooling load and above to space temperature at 0% cooling load. In heating mode supply air temperature shall be modulated to maintain space temperature, and fan volume shall be fixed at the minimum airflow.
Dehumidification (Systems 3 through 8 and 11, 12, and 13). If the proposed design HVAC system(s) have humidistatic controls, then the baseline building design shall use mechanical cooling for dehumidification and shall have reheat available to avoid overcooling. When the baseline building design HVAC system does not comply with any of the exceptions in Section 6.5.2.3, then only 25% of the system reheat energy shall be included in the baseline building performance. The reheat type shall be the same as the system heating type.
Preheat Coils (Systems 5 through 8). The baseline system shall be modeled with a preheat coil controlled to a fixed setpoint 20°F less than the design room heating temperature setpoint.
Table G3.4 Performance Rating Method Building Envelope Requirements for Climate Zone 4 (A,B,C)*
Opaque Elements | Nonresidential Assembly Maximum | Residential Assembly Maximum | Semiheated Assembly Maximum |
Insulation entirely above deck | U-0.063 | U-0.063 | U-0.218 |
Walls, Above-Grade | |||
Steel-framed | U-0.124 | U-0.064 | U-0.124 |
Wall, Below-Grade | |||
Below-grade wall | C-1.140 | C-1.140 | C-1.140 |
Floors | |||
Steel-joist | U-0.052 | U-0.038 | U-0.069 |
Slab-on-Grade Floors | |||
Unheated | F-0.730 | F-0.730 | F-0.730 |
Opaque Doors | |||
Swinging | U-0.700 | U-0.700 | U-0.700 |
Nonswinging | U-1.450 | U-0.500 | U-1.450 |
Fenestration | Assembly Max. U | Assembly Max. SHGC | Assembly Max. U | Assembly Max. SHGC | Assembly Max. U | Assembly Max. SHGC |
Vertical Glazing, % of Wall | ||||||
0% to 10.0% | Uall-0.57 | SHGCall-0.39 | Uall-0.57 | SHGCall-0.39 | Uall-1.22 | SHGCall-NR |
10.1% to 20.0% | Uall-0.57 | SHGCall-0.39 | Uall-0.57 | SHGCall-0.39 | Uall-1.22 | SHGCall-NR |
20.1% to 30.0% | Uall-0.57 | SHGCall-0.39 | Uall-0.57 | SHGCall-0.39 | Uall-1.22 | SHGCall-NR |
30.1% to 40.0% | Uall-0.57 | SHGCall-0.39 | Uall-0.57 | SHGCall-0.39 | Uall-1.22 | SHGCall-NR |
Skylight All, % of Roof | ||||||
0% to 2.0% | Uall-0.69 | SHGCall-0.49 | Uall-0.58 | SHGCall-0.36 | Uall-1.36 | SHGCall-NR |
2.1%+ | Uall-0.69 | SHGCall-0.39 | Uall-0.58 | SHGCall-0.19 | Uall-1.36 | SHGCall-NR |
*The following definitions apply: c.i. = continuous insulation (see Section 3.2), NR = no (insulation) requirement. a. Exception to Section A3.1.3.1 applies.
Table G3.5.1 Performance Rating Method Air Conditioners
Equipment Type | Size Category | Heating Section Type | Subcategory or Rating Condition | Minimum Efficiency | Test Procedure |
Air conditioners, | <65,000 Btu/h | All | Single-package | 9.7 SEER | ARI 210/240 |
air-cooled | >65,000 Btu/h and <135,000 Btu/h | Split-system and single-package | 10.1 EER | ARI 340/360 | |
>135,000 Btu/h and <240,000 Btu/h | 9.5 EER | ||||
>240,000 Btu/h and <760,000 Btu/h | 9.3 EER 9.4 IEER | ||||
>760,000 Btu/h | 9.0 EER 9.1 IEER |
Table G3.5.2 Performance Rating Method Electrically Operated Unitary and Applied Heat Pumps- Minimum Efficiency Requirements
Equipment Type | Size Category | Heating Section Type | Subcategory or Rating Condition | Minimum Efficiency | Test Procedure |
Air-cooled | <65,000 Btu/h | All | Single package | 9.7 SEER | ARI 210/240 |
(cooling mode) | >65,000 Btu/h and < 135,000 Btu/h >135,000 Btu/h and <240,000 Btu/h >240,000 Btu/h | Split-system and single-package | 9.9 EER 9.1 EER 8.8 EER 8.9 IEER | ARI 340/360 | |
Air-cooled (heating mode) | <65,000 Btu/h (cooling capacity) | Single-package | 6.6 HSPF | ARI 210/240 | |
>65,000 Btu/h and < 135,000 Btu/h (cooling capacity) | 47°F db/43°F wb outdoor air 17°F db/15°F wb outdoor air | 3.2 COPH 2.2 COPH | ARI 340/360 | ||
>135,000 Btu/h (cooling capacity) | 47°F db/43°F wb outdoor air 17°F db/15°F wb outdoor air | 3.1 COPH 2.0 COPH |
Table G3.5.3 Performance Rating Method Water Chilling Packages-Minimum Efficiency Requirements
Equipment Type | Size Category | Subcategory or Rating Condition | Minimum Efficiency | Test Procedure |
Water-cooled, electrically operated, positive | <150 tons k | W/ton | 0.790 FL 0.676 IPLV.IP | ARI 550/590 |
displacement (rotary screw and scroll) | >150 tons and <300 tons | 0.718 FL 0.629 IPLV.IP | ||
Water-cooled, electrically operated, centrifugal | >300 tons <150 tons A | W/ton | 0.639 FL 0.572 IPLV.IP 0.703 FL 0.670 IPLV.IP | ARI 550/590 |
>150 tons and <300 tons | 0.634 FL 0.596 IPLV.IP | |||
>300 tons | 0.576 FL 0.549 IPLV.IP |
Table G3.5.4 Performance Rating Method Electrically Operated Packaged Terminal Air Conditioners and Packaged Terminal Heat Pumps
Equipment Type | Size Category (Input) | Subcategory or Rating Condition | Minimum Efficiency | Test Procedure |
PTAC (Cooling Mode) | All Capacities | 95°F db Outdoor air | 12.5 - (0.213 × Cap/1000)EER | ARI 310/380 |
PTHP (Cooling Mode) | All Capacities | 95°F db Outdoor air | 12.3 - (0.213 × Cap/1000)EER | ARI 310/380 |
PTHP (Heating Mode) | All Capacities | 3.2 - (0.026 × Cap/1000)COP | ARI 310/380 |
Table G3.5.5 Warm-Air Furnaces and Unit Heaters
Equipment Type | Size Category | Subcategory or Rating Condition | Minimum Efficiency | Test Procedure |
Warm Air Furnace, Gas-Fired | <225,000 Btu/h | 1 | 78% AFUE or 80% Et | DOE 10 CFR Part 430 or ANSI Z21.47 |
>=225,000 Btu/h | Maximum Capacity | 80% Ec | ANSI Z21.47 | |
Warm Air Unit Heaters, Gas-Fired | All Capacities | Maximum Capacity | 80% Ec | ANSI Z83.8 |
Table G3.5.6 Gas-Fired Boilers-Minimum Efficiency Requirements
Equipment Type | Size Category | Subcategory or Rating Condition | Minimum Efficiency | Test Procedure |
Boilers, gas-fired | <300,000 Btu/h | Hot water | 80% AFUE | DOE 10 CFR Part 430 |
>300,000 Btu/h and <2,500,000 Btu/h | Maximum capacity | 75% Et | DOE 10 CFR Part 431 | |
>2,500,000 Btu/h | Hot water | 80% Ec |
Table G3.6 Lighting Power Densities for Building Exteriors
Tradable Surfaces (Lighting power densities for uncovered parking areas, building grounds, building entrances and exits, canopies and overhangs and outdoor sales areas may be traded.) | Uncovered Parking Areas | |
Parking Lots and drives | 0.15W/ft2 | |
Building Grounds | ||
Walkways less than 10 feet wide | 1.0W/linear foot | |
Walkways 10 feet wide or greater Plaza areas Special Feature Areas | 0.2W/ft2 | |
Stairways | 1.0 W/ft2 | |
Building Entrances and Exits | ||
Main entries | 30W/linear foot of door width | |
Other doors | 20W/linear foot of door width | |
Canopies and Overhangs | ||
Canopies (free standing and attached and overhangs) | 1.25W/ft2 | |
Outdoor Sales | ||
Open areas (including vehicle sales lots) | 0.5W/ft2 | |
Street frontage for vehicle sales lots in addition to "open area" allowance | 20W/linear foot | |
Non-Tradable Surfaces (Lighting power density calculations for the following applications can be used only for the specific application and cannot be traded between surfaces or with other exterior lighting. The following allowances are in addition to any allowance otherwise permitted in the "tradable Surfaces" section of this table.) | Building Facades | 0.2 W/ft2 for each illuminated wall or surface or 5.0W/linear foot for each illuminated wall or surface length |
Automated teller machines and night depositories | 270W per location plus 90W per additional ATM per location | |
Entrances and gatehouse inspection stations at guarded facilities | 1.25W/ft2of uncovered area (covered areas are included in the "Canopies and Overhangs" section of "Tradable Surfaces") | |
Loading areas for law enforcement, fire, ambulance and other emergency service vehicles | 0.5 W/ft2of uncovered area (covered areas are included in the "Canopies and Overhangs" section of "Tradable Surfaces") | |
Drive-up windows at fast food restaurants | 400W per drive-through | |
Parking near 24-hour retail entrances | 800 W per main entry | |
Table G3.7 Performance Rating Method Lighting Power Density Allowances and Occupancy Sensor Reductions Using the Space-by-Space Method
Common Space Typesa Audience Seating Area | Lighting Power Density, W/ft2 | Occupancy Sensor Reductionb |
Auditorium | 0.90 | 10% |
Convention center | 0.70 | 10% |
Exercise center | 0.30 | 10% |
Gymnasium | 0.40 | 10% |
Motion picture theater | 1.20 | 10% |
Penitentiary | 0.70 | 10% |
Performing arts theater | 2.60 | 10% |
Religious facility | 1.70 | 10% |
In a sports arena | 0.40 | 10% |
Transportation facility | 0.50 | 10% |
All other audience seating area | 0.90 | 10% |
Atrium | ||
<40 ft in height | 0.0375 per foot in total height | 10% |
>40 ft in height | 0.50 + 0.025 per foot in total height | 10% |
Banking Activity Area | 1.50 | 10% |
Breakroom (See Lounge/Breakroom) | ||
Classroom/Lecture Hall/Training Room | ||
Penitentiary | 1.30 | None |
Preschool through 12th grade, laboratory, and shop classrooms | 1.40 | 30% |
All other classroom/lecture hall/training room | 1.40 | None |
Conference/Meeting/Multipurpose Room | 1.30 | None |
Confinement Cells | 0.90 | 10% |
Copy/Print Room | 0.90 | 10% |
Corridor | ||
Facility for the visually impaired (and used primarily by residents) | 1.15 | 25% |
Hospital | 1.00 | 25% |
Manufacturing facility | 0.50 | 25% |
All other corridor | 0.50 | 25% |
Courtroom | 1.90 | 10% |
Computer Room | 2.14 | 35% |
Dining Area | ||
Penitentiary | 1.30 | 35% |
Facility for the visually impaired (and used primarily by residents) | 3.32 | 35% |
Bar/lounge or leisure dining | 1.40 | 35% |
Cafeteria or fast food dining | 0.90 | 35% |
Family dining | 2.10 | 35% |
All other dining area | 0.90 | 35% |
Electrical/Mechanical Room | 1.50 | 30% |
Emergency Vehicle Garage | 0.80 | 10% |
Food Preparation Area | 1.20 | 30% |
Guest Room | 1.14 | 45% |
Judges Chambers | 1.30 | 30% |
Common Space Typesa | Lighting Power Density, W/ft2 | Occupancy Sensor Reductionb |
Laboratory | ||
In or as a classroom All other laboratory | 1.40 1.40 | None 10% |
Laundry/Washing Area | 0.60 | 10% |
Loading Dock, Interior | 0.59 | 10% |
Lobby | ||
Facility for the visually impaired (and used primarily by residents) | 2.26 | 25% |
Elevator | 0.80 | 25% |
Hotel | 1.10 | 25% |
Motion picture theater | 1.10 | 25% |
Performing arts theater | 3.30 | 25% |
All other lobby | 1.30 | 25% |
Locker Room | 0.60 | 25% |
Lounge/Breakroom | ||
Healthcare facility | 0.80 | None |
All other lounge/breakroom | 1.20 | None |
Office | ||
Enclosed | 1.10 | 30% |
Open plan | 1.10 | 15%c |
Parking Area, Interior | 0.20 | 15% |
Pharmacy Area | 1.20 | 10% |
Restroom | ||
Facility for the visually impaired (and used primarily by residents) | 1.52 | 45% |
All other restroom | 0.90 | 45% |
Sales Area | 1.70 | 15% |
Seating Area, General | 0.68 | 10% |
Stairwell | 0.60 | 75% |
Storage Room | ||
Hospital | 0.90 | 45% |
>50 ft2 | 0.80 | 45% |
<50 ft2 | 0.80 | 45% |
Vehicular Maintenance Area | 0.70 | 10% |
Workshop | 1.90 | 10% |
Building Type Specific Space Types a | Lighting Power Density, W/ft2 | Occupancy Sensor Reduction b |
Assisted Living Facility | ||
Chapel (used primarily by residents) | 2.77 | 10% |
Recreation room (used primarily by residents) | 3.02 | 10% |
Automotive (See "Vehicular Maintenance Area") | 10% | |
Convention Center-Exhibit Space | 1.30 | 35% |
Dormitory-Living Quarters | 1.11 | 10% |
Fire Station-Sleeping Quarters | 0.30 | 10% |
Building Type Specific Space Types a Gymnasium/Fitness Center | Lighting Power Density, W/ft2 | Occupancy Sensor Reduction b |
Exercise area | 0.90 | 35% |
Playing area | 1.40 | 35% |
Healthcare Facility | ||
Emergency room | 2.70 | 10% |
Exam/treatment room | 1.50 | 10% |
Medical supply room | 1.40 | 45% |
Nursery | 0.60 | 10% |
Nurse's station | 1.00 | 10% |
Operating room | 2.20 | 10% |
Patient room | 0.70 | 10% |
Physical therapy room | 0.90 | 10% |
Recovery room | 0.80 | 10% |
Library | ||
Reading area | 1.20 | 15% |
Stacks | 1.70 | 15% |
Manufacturing Facility | ||
Detailed manufacturing area | 2.10 | 10% |
Equipment room | 1.20 | 10% |
Extra-high bay area (>50 ft floor-to-ceiling height) | 1.32 | 10% |
High bay area (25 to 50 ft floor-to-ceiling height) | 1.70 | 10% |
Low bay area (<25 ft floor-to-ceiling height) | 1.20 | 10% |
Museum | ||
General exhibition area | 1.00 | 10% |
Restoration room | 1.70 | 10% |
Post Office-Sorting Area | 1.20 | 10% |
Religious Facility | ||
Fellowship hall | 0.90 | 10% |
Worship/pulpit/choir area | 2.40 | 10% |
Retail Facilities | ||
Dressing/fitting room | 0.89 | 10% |
Mall concourse | 1.70 | 10% |
Sports Arena-Playing Area | ||
Class I facility | 4.61 | 10% |
Class II facility | 3.01 | 10% |
Class III facility | 2.26 | 10% |
Class IV facility | 1.50 | 10% |
Transportation Facility | ||
Baggage/carousel area | 1.00 | 10% |
Airport concourse | 0.60 | 10% |
Terminal ticket counter | 1.50 | 10% |
Warehouse-Storage Area | ||
Medium to bulky, palletized items | 0.90 | 45% |
Smaller, hand-carried items | 1.40 | 45% |
space type shall apply
Add new Table G.3.8
Table G3.8 Performance Rating Method Lighting Power Densities Using the Building Area Method
Building Area Type | LPD (W/ft2) |
Automotive facility | 0.90 |
Convention center | 1.20 |
Courthouse | 1.20 |
Dining: bar lounge/leisure | 1.30 |
Dining: cafeteria/fast food | 1.40 |
Dining: family | 1.60 |
Dormitory | 1.00 |
Exercise center | 1.00 |
Fire station | 1.00 |
Gymnasium | 1.10 |
Health-care clinic | 1.00 |
Hospital | 1.20 |
Hotel | 1.09 |
Library | 1.30 |
Manufacturing facility | 1.17 |
Motion picture theater | 1.20 |
Multifamily | 0.70 |
Museum | 1.10 |
Office | 1.00 |
Parking garage | 0.30 |
Penitentiary | 1.00 |
Performing arts theater | 1.60 |
Police station | 1.00 |
Post office | 1.10 |
Religious building | 1.30 |
Retail | 1.50 |
School/university | 1.20 |
Sports arena | 1.10 |
Town hall | 1.10 |
Transportation | 1.00 |
Warehouse | 0.80 |
Workshop | 1.40 |
Table G3.9.1 Performance Rating Method Motor Efficiency Requirements
Motor Horsepower | Minimum Nominal Full-Load Efficiency, % |
1.0 | 82.5 |
1.5 | 84.0 |
2.0 | 84.0 |
3.0 | 87.5 |
5.0 | 87.5 |
7.5 | 89.5 |
10.0 | 89.5 |
15.0 | 91.0 |
20.0 | 91.0 |
25.0 | 92.4 |
30.0 | 92.4 |
40.0 | 93.0 |
50.0 | 93.0 |
60.0 | 93.6 |
75.0 | 94.1 |
100.0 | 94.5 |
125.0 | 94.5 |
150.0 | 95.0 |
200.0 | 95.0 |
Table G3.9.2 Performance Rating Method Baseline Elevator Motor
Number of Stories (Including Basement) | Motor Type | Counterweight | Mechanical Efficiency | Motor Efficiencya |
<4 | Hydraulic | None | 58% | Table G3.9.3 |
>4 | Traction | Proposed design counterweight, if not specified use weight of the car plus 40% of the rated load | 64% | Table G3.9.1 |
Table G3.9.3 Performance Rating Method Hydraulic Elevator Motor Efficiency
Horsepower | Full-Load Efficiency |
10 | 72% |
20 | 75% |
30 | 78% |
40 | 78% |
100 | 80% |
Table G3.10.1 Performance Rating Method Commercial Refrigerators and Freezers
Equipment Type | Application | Energy Use Limits, kWh/day | Test Procedure |
Refrigerator with solid doors | Holding temperature | 0.125 × V + 2.76 | AHRI 1200 |
Refrigerator with transparent doors | 0.172 × V + 4.77 | ||
Freezers with solid doors | 0.398 × V + 2.28 | ||
Freezers with transparent doors | 0.94 × V + 5.10 | ||
Refrigerators/freezers with solid doors | 0.12 × V + 4.77 | ||
Commercial refrigerators | Pulldown | 0.181 × V + 5.01 |
Note:V is the chiller or frozen compartment volume (ft3) as defined in Association of Home Appliance Manufacturers Standard HRF-1.
Table G3.10.2 Performance Rating Method Commercial Refrigeration
EquipmentType | |||||
Equipment Classa | Family Code | Operating Mode | Rating Temperature | Energy Use Limits,b,c kWh/day | Test Procedure |
VOP.RC.M | Vertical open | Remote condensing | Medium temperature | 1.01 × TDA + 4.07 | AHRI 1200 |
SVO.RC.M | Semivertical open | Remote condensing | Medium temperature | 1.01 × TDA + 3.18 | |
HZO.RC.M | Horizontal open | Remote condensing | Medium temperature | 0.51 × TDA + 2.88 | |
VOP.RC.L | Vertical open | Remote condensing | Low temperature | 2.84 × TDA + 6.85 | |
HZO.RC.L | Horizontal open | Remote condensing | Low temperature | 0.68 × TDA + 6.88 | |
VCT.RC.M | Vertical transparent door | Remote condensing | Medium temperature | 0.48 × TDA + 1.95 | |
VCT.RC.L | Vertical transparent door | Remote condensing | Low temperature | 1.03 × TDA + 2.61 | |
SOC.RC.M | Service over counter | Remote condensing | Medium temperature | 0.62 × TDA + 0.11 | |
VOP.SC.M | Vertical open | Self-contained | Medium temperature | 2.34 × TDA + 4.71 | |
SVO.SC.M | Semivertical open | Self-contained | Medium temperature | 2.23 × TDA + 4.59 | |
HZO.SC.M | Horizontal open | Self-contained | Medium temperature | 1.14 × TDA + 5.55 | |
HZO.SC.L | Horizontal open | Self-contained | Low temperature | 2.63 × TDA + 7.08 | |
VCT.SC.I | Vertical transparent door | Self-contained | Ice cream | 1.63 × TDA + 3.29 | |
VCS.SC.I | Vertical solid door | Self-contained | Ice cream | 0.55 × V + 0.88 | |
HCT.SC.I | Horizontal transparent door | Self-contained | Ice cream | 1.33 × TDA + 0.43 | |
SVO.RC.L | Semivertical open | Remote condensing | Low temperature | 2.84 × TDA + 6.85 | |
VOP.RC.I | Vertical open | Remote condensing | Ice cream | 3.6 × TDA + 8.7 | |
SVO.RC.I | Semivertical open | Remote condensing | Ice cream | 3.6 × TDA + 8.7 | |
HZO.RC.I | Horizontal open | Remote condensing | Ice cream | 0.87 × TDA + 8.74 | |
VCT.RC.I | Vertical transparent door | Remote condensing | Ice cream | 1.2 × TDA + 3.05 | |
HCT.RC.M | Horizontal transparent door | Remote condensing | Medium temperature | 0.39 × TDA + 0.13 | AHRI 1200 |
HCT.RC.L | Horizontal transparent door | Remote condensing | Low temperature | 0.81 × TDA + 0.26 | |
HCT.RC.I | Horizontal transparent door | Remote condensing | Ice cream | 0.95 × TDA + 0.31 | |
VCS.RC.M | Vertical solid door | Remote condensing | Medium temperature | 0.16 × V + 0.26 | |
VCS.RC.L | Vertical solid door | Remote condensing | Low temperature | 0.33 × V + 0.54 | |
VCS.RC.I | Vertical solid door | Remote condensing | Ice cream | 0.39 × V + 0.63 | |
HCS.RC.M | Horizontal solid door | Remote condensing | Medium temperature | 0.16 × V + 0.26 | |
HCS.RC.L | Horizontal solid door | Remote condensing | Low temperature | 0.33 × V + 0.54 | |
HCS.RC.I | Horizontal solid door | Remote condensing | Ice cream | 0.39 × V + 0.63 | |
SOC.RC.L | Service over counter | Remote condensing | Low temperature | 1.3 × TDA + 0.22 | |
SOC.RC.I | Service over counter | Remote condensing | Ice cream | 1.52 × TDA + 0.26 | |
VOP.SC.L | Vertical open | Self contained | Low temperature | 5.87 × TDA + 11.82 | |
VOP.SC.I | Vertical open | Self-contained | Ice cream | 7.45 × TDA + 15.02 | |
SVO.SC.L | Semivertical open | Self-contained | Low temperature | 5.59 × TDA + 11.51 | |
SVO.SC.I | Semivertical open | Self-contained | Ice cream | 7.11 × TDA + 14.63 | |
HZO.SC.I | Horizontal open | Self-contained | Ice cream | 3.35 × TDA + 9.0 | |
SOC.SC.I | Service over counter | Self-contained | Ice cream | 2.13 × TDA + 0.36 | |
HCS.SC.I | Horizontal solid door | Self-contained | Ice cream | 0.55 × V + 0.88 | |
Insert a new Appendix Z in the Energy Conservation Code-Commercial Provisions to read as follows:
D.C. Mun. Regs. tit. 12, 12-I-G3