(This is a normative appendix and is part of this standard).
All requirements of Sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4 are met. These sections contain the mandatory provisions of the standard and are prerequisites for this rating method. The improved performance of the proposed building design is calculated in accordance with provisions of this appendix using the following formula:
- A brief description of the project, the key energy efficiency improvements, the simulation program used, the version of the simulation program, and the results of the energy analysis. This summary shall contain the calculated values for the baseline building performance, the proposed building performance, and the percentage improvement.
- An overview of the project that includes: the number of stories (above and below grade), the typical floor size, the uses in the building (e.g., office, cafeteria, retail, parking, etc.), the gross area of each use, and whether each use is conditioned space.
- A list of the energy-related features that are included in the design and on which the performance rating is based. This list shall document all energy features that differ between the models used in the baseline building performance and proposed building performance calculations.
- A list showing compliance for the proposed design with all the requirements of 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4 (mandatory provisions).
- A list identifying those aspects of the proposed design that are less stringent than the requirements of 5.5, 6.5, 7.5, 9.5, and 9.6 (prescriptive provisions).
- A table with a summary by end use of the energy cost savings in the proposed building performance.
- A site plan showing all adjacent buildings and topography which may shade the proposed building (with estimated height or number of stories).
- Building elevations and floor plans (schematic is acceptable).
- A diagram showing the thermal blocks used in the computer simulation.
- An explanation of any significant modeling assumptions.
- Backup calculations and material to support data inputs (e.g., U-factors for envelope assemblies, NFRC ratings for fenestration, end-uses identified in 1. Design Model, paragraph [a], in Table G3.1).
- Input and output report(s) from the simulation program or compliance software including a breakdown of energy usage by at least the following components: lights, internal equipment loads, service water heating equipment, space heating equipment, space cooling and heat rejection equipment, fans, and other HVAC equipment (such as pumps). The output reports shall also show the amount of unmet load hours for both the proposed design and baseline building design.
- Purchased energy rates used in the simulations.
- An explanation of any error messages noted in the simulation program output.
- For any exceptional calculation method(s) employed, document the predicted energy savings by energy type, the energy cost savings, a narrative explaining the exceptional calculation method performed, and theoretical or empirical information supporting the accuracy of the method.
- The reduction in proposed building performance associated with on-site renewable energy.
- 8760 hours per year
- hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat setpoints, and HVAC system operation, defined separately for each day of the week and holidays
- thermal mass effects
- ten or more thermal zones
- part-load performance curves for mechanical equipment
- capacity and efficiency correction curves for mechanical heating and cooling equipment
- air-side economizers with integrated control
- baseline building design characteristics specified in Section G3
- Step-by-step documentation of the Exceptional Calculation Method performed detailed enough to reproduce the results;
- Copies of all spreadsheets used to perform the calculations;
- A sensitivity analysis of energy consumption when each of the input parameters is varied from half to double the value assumed;
- The calculations shall be performed on a time step basis consistent with the simulation program used;
- The Performance Rating calculated with and without the Exceptional Calculation Method.
|No.||Proposed Building Performance||Baseline Building Performance|
|1. Design Model|
||The baseline building design shall be modeled with the same number of floors and identical conditioned floor area as the proposed 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:
||Same as proposed building design|
|3. Space Use Classification|
|Usage 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 building design|
|Schedules capable of modeling hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat setpoints, 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 setpoints and schedules as well as temperature control throttling range shall be the same for proposed and baseline building designs.
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.
|Same as proposed building design
|5. Building Envelope|
||Equivalent dimensions shall be assumed for each exterior envelope component type as in the proposed design; i.e., the total gross area of exterior walls shall be the same in the proposed and baseline building designs. 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 and baseline building designs. The following additional requirements shall apply to the modeling of the baseline building design:
|Lighting power in the proposed design shall be determined as follows:
|7. Thermal Blocks—HVAC Zones Designed|
|Where HVAC zones are defined on HVAC design drawings, each HVAC zone shall be modeled as a separate thermal block.
||Same as proposed building 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:
||Same as proposed building 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 building 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:
||The HVAC system(s) 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 type(s).
If the proposed design includes computer room humidification then the computer room humidification system, schedules, and setpoints in the baseline building design shall be the same as in the proposed design.
Exception: For fossil fuel systems where natural gas is not available for the proposed building site as determined by the rating authority, the baseline HVAC system(s) shall be modeled using propane as their fuel source.
|11. Service Hot-Water Systems|
|The service hot-water system type and all related performance parameters, such as equipment capacities and efficiencies, in the proposed design shall be determined as follows:
||The service hot-water system in the baseline building design shall conform with the following conditions:
|12. Receptacle and Other Loads|
|Receptacle and process loads, such as those for office and other equipment, shall be estimated based on the building type or space type category and shall be assumed to be identical in the proposed and baseline building designs, except as specifically authorized by the rating authority. These loads shall be included in simulations of the building and shall be included when calculating the baseline building performance and proposed building performance.||Other systems, such as motors 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. Where there are specific efficiency requirements listed in Sections 5 through 10, these systems or components shall be modeled as having the lowest efficiency allowed by those requirements. Where no efficiency requirements exist, power and energy rating or capacity of the equipment shall be identical between the baseline building and the proposed design with the following exception: variations of the power requirements, schedules, or control sequences of the equipment modeled in the baseline building from those in the proposed design shall be allowed by the rating authority based upon documentation that the equipment installed in the proposed design represents a significant verifiable departure from documented 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 building design|
|14. Exterior Conditions|
||Same as proposed building 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 building 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.|
- Use additional system type(s) for nonpredominant conditions (i.e., residential/nonresidential or heating source) if those conditions apply to more than 20,000 ft2 of conditioned floor area.
- If the baseline HVAC system type is 5, 6, 7, 8, 9, 10, 11, 12, or 13 use separate single-zone systems conforming with the requirements of System 3 or System 4 (depending on building heating source) for any spaces that have occupancy or process loads or schedules that differ significantly from the rest of the building. Peak thermal loads that differ by 10 Btu/h•ft2 or more from the average of other spaces served by the system or schedules that differ by more than 40 equivalent full-load hours per week from other spaces served by the system are considered to differ significantly. Examples where this exception may be applicable include, but are not limited to, natatoriums and continually occupied security areas. This exception does not apply to computer rooms.
- For laboratory spaces in a building having a total laboratory exhaust rate greater than 5000 cfm, use a single system of type 5 or 7 serving only those spaces. The lab exhaust fan shall be modeled as constant horsepower reflecting constant-volume stack discharge with outdoor air bypass.
- For kitchens with a total exhaust hood airflow rate greater than 5,000 cfm, use system type 5 or 7 with a demand ventilation system on 75% of the exhaust air. The system shall reduce exhaust and replacement air system airflow rates by 50% for one half of the kitchen occupied hours in the baseline design. If the proposed design uses demand ventilation the same airflow rate schedule shall be used. The maximum exhaust flow rate allowed for the hood or hood section shall meet the requirements of Section 188.8.131.52.3 for the numbers and types of hoods and appliances provided for the in the proposed design.
- Thermal zones designed with heating only systems in the proposed design, 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 use System type 9 or 10 in the baseline building design.
- If the baseline HVAC system type is 9 or 10, all spaces that are mechanically cooled in the proposed building design shall be assigned to a separate baseline system determined by using the area and heating source of the mechanically cooled spaces.
- Computer rooms in buildings with a total computer room peak cooling load >3,000,000 Btu/h kW or a total computer room peak cooling load >600,000 Btu/h where the baseline HVAC system type is 7 or 8 shall use System 11. All other computer rooms shall use System 3 or 4.
- For hospitals, depending on building type, use System 5 or 7 in all climate zones.
|Building Area Typesa||Baseline Building Gross Above-Grade-Wall Area|
|Hotel/motel (≤75 rooms)||24%|
|Hotel/motel (>75 rooms)||34%|
|Office (≤5000 ft2)||19%|
|Office (5000 to 50,000 ft2)||31%|
|Office (>50,000 ft2)||40%|
|Restaurant (quick service)||34%|
|Restaurant (full service)||24%|
|Retail (stand alone)||11%|
|Retail (strip mall)||20%|
|School (secondary and university)||22%|
a. In cases where both a general building area type and a specific building area type are listed, the specific building area type shall apply.
|Building Area Type||Baseline Heating Method|
|Automotive facility||Gas storage water heater|
|Convention center||Electric resistance storage water heater|
|Courthouse||Electric resistance storage water heater|
|Dining: Bar lounge/leisure||Gas storage water heater|
|Dining: Cafeteria/fast food||Gas storage water heater|
|Dining: Family||Gas storage water heater|
|Dormitory||Gas storage water heater|
|Exercise center||Gas storage water heater|
|Fire station||Gas storage water heater|
|Gymnasium||Gas storage water heater|
|Health-care clinic||Gas storage water heater|
|Hospital||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|
|Performing arts theater||Gas storage water heater|
|Police station||Electric resistance storage water heater|
|Post office||Electric resistance storage water heater|
|Religious building||Electric resistance storage water heater|
|Retail||Electric resistance storage water heater|
|School/university||Gas storage water heater|
|Sports arena||Gas storage water heater|
|Town hall||Electric resistance storage water heater|
|Transportation||Electric resistance storage water heater|
|Warehouse||Electric resistance storage water heater|
|Workshop||Gas storage water heater|
|All Others||Gas storage water heater|
|Building Type||Climate Zones 3b, 3c, and 4—8||Climate Zones 1—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|
|Nonresidential and 3 floors or fewer and <25,000 ft2||System 3—PSZ-AC||System 4—PSZ-HP|
|Nonresidential 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|
|Nonresidential and more than 5 floors or >150,000 ft2||System 7—VAV with reheat||System 8—VAV with PFP boxes|
|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|
1. Residential building types include dormitory, hotel, motel, and multifamily. Residential space types include guest rooms, living quarters, private living space, and sleeping quarters. Other building and space types are considered nonresidential.
2. Where attributes make a building eligible for more than one baseline system type, use the predominant condition to determine the system type for the entire building except as noted in Exception (1) to Section G3.1.1.
4. For hospitals, depending on building type, use System 5 or 7 in all climate zones.
5. Public assembly building types include houses of worship, auditoriums, movie theaters, performance theaters, concert halls, arenas, enclosed stadiums, ice rinks, gymnasiums, convention centers, exhibition centers, and natatoriums.
G3.1.1-4 Baseline System Descriptions
|System No.||System Type||Fan Control||Cooling Type||Heating Type|
|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.|
|12. SZ-CV-HW||Single zone||Constant volume||Chilled water||Hot-water fossil fuel boiler|
|13. SZ-CV-ER||Single zone||Constant volume||Chilled water||Electric resistance|
1. For purchased chilled water and purchased heat, see G184.108.40.206.
2. Where the proposed design heating source is electric or other, the heating type shall be electric resistance. Where the proposed design heating source is fossil fuel, fossil/electric hybrid, or purchased heat, the heating type shall be hot-water fossil fuel boiler.
G220.127.116.11 Baseline HVAC System Requirements for Systems Utilizing Purchased Chilled Water and/or Purchased Heat
- Purchased chilled water shall be substituted for the Cooling Types in Table G3.1.1-4.
- System 1 and 2 shall be constant-volume fan-coil units with fossil fuel boiler(s).
- System 3 and 4 shall be constant-volume single-zone air handlers with fossil fuel furnace(s).
- System 7 shall be used in place of System 5.
- System 8 shall be used in place of System 6.
IFLR = 0.112 × I75Pa × S/AFLR
IEW = 0.112 × I75Pa × S/AEW
I75Pa = Q/S
|I75Pa||=||air leakage rate of the building envelope expressed in cfm/ft2 at a fixed building pressure differential of 0.3 in. H2O, or 1.57 psf|
|Q||=||volume of air in cfm flowing through the whole-building envelope when subjected to an indoor/ outdoor pressure differential of 0.3 in. H2O, or 1.57 psf, in accordance with ASTM E 779|
|S||=||total area of the envelope air pressure boundary (expressed in ft2), including the lowest floor, any below- or above-grade walls, and roof (or ceiling) (including windows and skylights), separating the interior conditioned space from the unconditioned environment measured|
|IFLR||=||adjusted air leakage rate (expressed in cfm/ft2) of the building envelope at a reference wind speed of 10 mph and the total gross floor area|
|AFLR||=||total gross floor area, ft2|
|IEW||=||adjusted air leakage rate (expressed in cfm/ft2) of the building envelope at a reference wind speed of 10 mph and the above ground exterior wall area|
|AEW||=||total above-grade exterior wall area, ft2|
- If the calculations are made independently of the energy simulation program, the proposed method must comply with Section G2.5.
- The method for converting the air infiltration rate of the building envelope at 0.3 in. H2O, or 1.57 psf, to the appropriate units for the simulation program is fully documented and submitted to the rating authority for approval.
where COPnfcooling and COPnfheating are the packaged HVAC equipment cooling and heating energy efficiency, respectively, to be used in the baseline building, which excludes supply fan power, and Q is the AHRI-rated cooling capacity in Btu/h.
- When modeling demand-control ventilation in the proposed design when its use is not required by Section 6.3.2(q) or Section 18.104.22.168.
- When designing systems in accordance with Standard 62.1, Section 6.2, "Ventilation Rate Procedure," reduced ventilation airflow rates may be calculated for each HVAC zone in the proposed design with a zone air distribution effectiveness (Ez) > 1.0 as defined by Table 6-2 in Standard 62.1. Baseline ventilation airflow rates in those zones shall be calculated using the proposed design Ventilation Rate Procedure calculation with the following change only. Zone air distribution effectiveness shall be changed to (Ez) = 1.0 in each zone having a zone air distribution effectiveness (Ez) > 1.0. Proposed design and baseline design Ventilation Rate Procedure calculations, as described in Standard 62.1, shall be submitted to the rating authority to claim credit for this exception.
- If the minimum outdoor air intake flow in the proposed design is provided in excess of the amount required by the rating authority or building official then the baseline building design shall be modeled to reflect the greater of that required by the rating authority or building official and will be less than the proposed design.
- For baseline systems serving only laboratory spaces that are prohibited from recirculating return air by code or accreditation standards, the baseline system shall be modeled as 100% outdoor air.
Exceptions: Economizers shall not be included for systems meeting one or more of the exceptions listed below.
- Systems that include gas-phase air cleaning to meet the requirements of Section 6.1.2 in Standard 62.1. This exception shall be used only if the system in the proposed design does not match the building design.
- Where the use of outdoor air for cooling will affect supermarket open refrigerated casework systems. This exception shall only be used if the system in the proposed design does not use an economizer. If the exception is used, an economizer shall not be included in the baseline building design.
- Systems that serve computer rooms complying with Section G22.214.171.124.1.
|1a, 1b, 2a, 3a, 4a||NR|
Note: NR means that there is no conditioned building floor area for which economizers are included for the type of zone and climate.
TABLE G126.96.36.199 Economizer High-Limit Shutoff
|Climate Zone||High-Limit Shutoff|
|1b, 2b, 3b, 3c, 4b, 4c, 5b, 5c, 6b, 7, 8||75°F|
|2a, 3a, 4a||28 Btu/lb|
|5a, 6a, 7a||70°F|
- For systems serving laboratory spaces, use a supply-air-to-room-air temperature difference of 17°F or the required ventilation air or makeup air, whichever is greater.
- If the proposed design HVAC design airflow rate based on latent loads is greater than the design airflow rate based on sensible loads, then the same supply-air-to-room-air humidity ratio difference (gr/lb) used to calculate the proposed design airflow shall be used to calculate design airflow rates for the baseline building design.
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
Pfan = CFMnmc × 0.054
|Pfan||=||electric power to fan motor (watts)|
|bhp||=||brake horsepower of baseline fan motor from Table G188.8.131.52|
|fan motor efficiency||=||the efficiency from Table 10.8-2 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 in cfm|
|CFMnmc||=||the baseline nonmechanical cooling fan airflow in cfm|
|Baseline Fan Motor Brake Horsepower|
|CFMs • 0.00094 + A||CFMs • 0.0013 + A||CFMs • 0.00062 + A|
- Where A is calculated according to Section 184.108.40.206.1 using the pressure drop adjustment from the proposed building design and the design flow rate of the baseline building system.
- Do not include pressure drop adjustments for evaporative coolers or heat recovery devices that are not required in the baseline building system by Section G220.127.116.11.
Exception: The pump power for systems using purchased heat shall be 14 W/gpm.
TABLE G18.104.22.168 Type and Number of Chillers
|Building Peak Cooling Load||Number and Type of Chiller(s)|
|≤300 tons||1 water-cooled screw chiller|
|>300 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: 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.
Exception: The pump power for systems using purchased chilled water shall be 16 W/gpm.
Approach10°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 70°F leaving water temperature where weather permits, floating up to leaving water temperature at design conditions. The baseline building design condenser-water pump power shall be 19 W/gpm. For computer room systems using System 11 with an integrated water-side economizer, the baseline building design condenser water-pump power shall be increased 5 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.
Exception: 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.
|Method 1—Part-Load Fan Power Data|
|Fan Part-Load Ratio||Fraction of Full-Load Power|
|Method 2—Part-Load Fan Power Equation|
|Pfan = 0.0013 + 0.1470 × PLRfan + 0.9506 × (PLRfan)2 — 0.0998 × (PLRfan)3|
Pfan = fraction of full-load fan power and
PLRfan = fan part-load ratio (current L/s/design L/s).
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.