- Sections 5.2.1, 6.2.1, 7.2.1, 8.2.1, 9.2.1, and 10.2.1.
- A design energy cost, as calculated in Section 11.5, that does not exceed the energy cost budget as calculated by the simulation program described in Section 11.4.
- The energy efficiency level of installed components and systems that meets or exceeds the efficiency levels used to calculate the design energy cost.
- Verification, testing, and commissioning requirements of Section 4.2.5 shall be met.
- Proposed building systems, controls, or building envelope documented in Section 11.7.2(d) that do not have criteria in Sections 5 through 10 shall have verification or testing to document proper installation and operation in accordance with Section 4.2.5.
- 8760 hours per year
- Hourly variations in occupancy, lighting power, miscellaneous equipment power, thermostat set points, 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 mechanical cooling equipment
- Air-side economizer and fluid economizer with integrated control
- The budget building design characteristics unless otherwise specified in Section 11.5
- Theoretical and empirical information verifying the method's accuracy, and 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 that are estimated 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 energy cost budget and design energy cost calculated with and without the exceptional calculation methods.
|Proposed Design (Column A) |
Design Energy Cost (DEC)
|Budget Building Design (Column B) |
Energy Cost Budget (ECB)
|1. Design Model|
| ||The budget building design shall be developed by modifying the proposed design as described in this table. Except as specifically instructed in this table, all building systems and equipment shall be modeled identically in the budget building design and proposed design.|
|2. Additions and Alterations|
|It is acceptable to demonstrate compliance using building models that exclude parts of the existing building, provided all of the following conditions are met: ||Same as proposed design.|
|3. Space Use Classification|
|The building area type or space type classifications shall be chosen in accordance with Section 9.5.1 or 9.6.1. The user or designer shall specify the space use classifications using either the building area type or space type categories but shall not combine the two types of categories within a single permit application. More than one building area type category may be used for a building if it is a mixed-use facility.||Same as proposed design.|
|The schedule types listed in Section 126.96.36.199(b) shall be required input. The schedules shall be typical of the proposed design as determined by the designer and approved by the authority having jurisdiction. Required schedules shall be identical for the proposed design and budget building design. |
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.
|Same as proposed design.|
|5. Building Envelope|
|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. |
Exceptions: The following building elements are permitted to differ from architectural drawings.
|The budget building design shall have identical conditioned floor area and identical exterior dimensions and orientations as the proposed design, except as follows: |
Exceptions: When trade-offs are made between an addition and an existing building, as described in the exception to Section 188.8.131.52, the building envelope assumptions for the existing building in the budget building design shall reflect existing conditions prior to any revisions that are part of this permit.
|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. |
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:
|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: ||Same as proposed design.|
|9. Thermal Blocks—Multifamily Residential Buildings|
|Residential spaces shall be modeled using at least one HVAC zone per dwelling unit except for those units with the same orientations, which 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, such as equipment capacities and efficiencies, in the proposed design shall be determined as follows: ||The HVAC system type and related performance parameters for the budget building design shall be determined from Figure 11.5.2, the system descriptions in Table 11.5.2-1 and accompanying notes, and in accord with rules specified in Section 11.5.2(a) through 11.5.2(k).|
|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: ||The service water-heating system type in the budget building design shall be identical to the proposed design. The service water-heating system performance of the budget building design shall meet the requirements of Sections 7.4 and 7.5. |
Service water loads and use shall be the same for both the proposed design and baseline building design and typical of the proposed building type.
Piping losses shall not be modeled.
|12. Miscellaneous Loads|
|Receptacle, motor, and process loads shall be modeled and estimated based on the building area type or space type category and shall be assumed to be identical in the proposed and budget building designs. These loads shall be included in simulations of the building and shall be included when calculating the energy cost budget and design energy cost. All end-use load components within and associated with the building shall be modeled, unless specifically excluded by Section 13 of Table 11.5.1, including but not limited to exhaust fans, parking garage ventilation fans, exterior building lighting, swimming pool heaters and pumps, elevators and escalators, and cooking equipment. ||Same as proposed design.|
|Where refrigeration equipment in the proposed design is rated in accordance with AHRI 1200, the rated energy use shall be modeled. Otherwise, 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 Table 6.8.1-11, the budget building design shall be modeled as specified in Table 6.8.1-11 using the actual equipment capacities. |
If the refrigeration equipment is not listed in Table 6.8.1-11, the budget building design shall be modeled the same as the proposed design.
|14. Modeling Exceptions|
|All elements of the proposed design building envelope, HVAC, service water heating, lighting, and electrical systems shall be modeled in the proposed design in accordance with the requirements of Sections 1 through 12 of Table 11.5.1. |
Exceptions: Components and systems in the proposed design may be excluded from the simulation model provided that
- Budget Building Systems Not Listed. Components and parameters not listed in Figure 11.5.2 and Table 11.5.2-2 or otherwise specifically addressed in this subsection shall be identical to those in the proposed design.
- Minimum Equipment Efficiency. All HVAC and service water-heating equipment in the budget building design shall be modeled at the minimum efficiency levels, both part load and full load, in accordance with Sections 6.4 and 7.4. Chillers shall use Path A efficiencies as shown in Table 6.8.1-3.
- Supply Fan Energy in Certain Package Equipment. Where efficiency ratings include supply fan energy, the efficiency rating shall be adjusted to remove the supply fan energy. For Budget System Types 3, 4, 6, 8, 9, 10, and 11, calculate the minimum COPnfcooling and COPnfheating using the equation for the applicable performance rating as indicated in Tables 6.8.1-1 through 6.8.1-4. Where multiple HVAC zones are combined into a single thermal block in accordance with Table 11.5.1, the efficiencies for budget System Types 6, 8, and 10 taken from Tables 6.8.1-1 through 6.8.1-4 shall be based on 9000 Btu/h equipment capacity for residential spaces; otherwise, it shall be based on the capacity of the thermal block divided by the number of HVAC zones. Budget System Types 3, 4, 9, and 11 efficiencies taken from Tables 6.8.1-1 through 6.8.1-4 shall be based on the cooling equipment capacity of a single floor when grouping identical floors in accordance with Table 11.5.1. 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: COPnfheating = 1.48E-7 × COP47 × Q + 1.062 × COP47
(applies to Systems 6 and 9 heating efficiency only)COPnfheating = —0.0296 × HSPF2 + 0.7134 × HSPFwhere COPnfcooling and COPnfheating are the packaged HVAC equipment cooling and heating energy efficiency, respectively, to be used in the budget building design, which excludes supply fan power, and Q is the AHRI-rated cooling capacity in Btu/h. If Q is greater than 760,000 Btu/h, use 760,000 Btu/h in the calculation.
- Minimum Outdoor Air Ventilation Rate. Minimum outdoor air ventilation rates shall be the same for both the budget building design and proposed design. Exhaust air heat recovery shall be modeled for the budget building design in accordance with Section 184.108.40.206.
- Economizers. Budget building systems as listed in Table 11.5.2-1 shall have air economizers or fluid economizers, the same as in the proposed design, in accordance with Section 6.5.1. The high-limit shutoff shall be in accordance with Table 11.5.2-4.
- Preheat Coils. If the proposed design system has a preheat coil, the budget building design's system shall be modeled with a preheat coil controlled in the same manner.
- Supply Airflow Rates. System design supply air rates for the budget 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 budget building design shall also be modeled with fans serving the same functions and sized for the budget system supply fan air quantity less the minimum outdoor air, or 90% of the supply fan air quantity, whichever is larger.
- Fan System Efficiency. Fan system efficiency (bhp per cfm of supply air, including the effect of belt losses but excluding motor and motor drive losses) shall be the same as the proposed design or up to the limit prescribed in Section 220.127.116.11, whichever is smaller. If this limit is reached, each fan shall be proportionally reduced in brake horsepower until the limit is met. Fan electrical power shall then be determined by adjusting the calculated fan hp by the minimum motor efficiency prescribed by Section 10.4.1 for the appropriate motor size for each fan.
- Equipment Capacities. The equipment capacities for the budget building design shall be sized proportionally to the capacities in the proposed design based on sizing runs, i.e., the ratio between the capacities used in the annual simulations and the capacities determined by the sizing runs shall be the same for both the proposed design and budget building design. Unmet load hours for the proposed design or baseline building designs shall not exceed 300 hours (of the 8760 hours simulated). The unmet load hours for the proposed design shall not exceed the unmet load hours for the budget building design. Alternatively, unmet load hours exceeding these limits may be approved by the building official, provided that sufficient justification is given indicating that the accuracy of the simulation is not significantly compromised by these unmet loads.
- Determining the HVAC System. Each HVAC system in a proposed design is mapped on a one-to-one correspondence with one of eleven HVAC systems in the budget building design. To determine the budget building system, do the following:
- Enter Figure 11.5.2 at "Water" if the proposed design system condenser is water or evaporatively cooled; enter Figure 11.5.2 at "Air/None" if the condenser is air cooled. Closed-circuit dry coolers shall be considered air cooled. Systems utilizing district cooling shall be treated as if the condenser water type were "water." If no mechanical cooling is specified or the mechanical cooling system in the proposed design does not require heat rejection, the system shall be treated as if the condenser water type were "Air." For proposed designs with ground-source or groundwater-source heat pumps, the budget system shall be water-source heat pump (System 6).
- Select the path that corresponds to the proposed design heat source: electric resistance, heat pump (including air source and water source), or fuel-fired. Systems utilizing district heating (steam or hot water) shall be treated as if the heating system type were "Fossil Fuel." Systems with no heating capability shall be treated as if the heating system type were "Fossil Fuel." For systems with mixed fuel heating sources, the system or systems that use the secondary heating source type (the one with the smallest total installed output capacity for the spaces served by the system) shall be modeled identically in the budget building design, and the primary heating source type shall be used in Figure 11.5.2 to determine budget system type.
- Select the budget building design system category. The system under "Single-Zone Residential System" shall be selected if the HVAC system in the proposed design is a single-zone system and serves a residential space. The system under "Single-Zone Nonresidential System" shall be selected if the HVAC system in the proposed design is a single-zone system and serves other than residential spaces. The system under "All Other" shall be selected for all other cases.
- Kitchen Exhaust. For kitchens with a total exhaust hood airflow rate greater than 5000 cfm, use 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 building 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 18.104.22.168.2 for the numbers and types of hoods and appliances provided in the proposed design.
|System No.||System Type||Fan Control||Cooling Type||Heating Type|
|1||VAV with parallel fan-powered boxesa||VAVd||Chilled watere||Electric resistance|
|2||VAV with reheatb||VAVd||Chilled watere||Hot-water fossil fuel boilerf|
|3||Packaged VAV with parallel fan-powered boxesa||VAVd||Direct expansionc||Electric resistance|
|4||Packaged VAV with reheatb||VAVd||Direct expansionc||Hot-water fossil fuel boilerf|
|5||Two-pipe fan coil||Single- or two-speed fan i,j||Chilled watere||Electric resistance|
|6||Water-source heat pump||Single- or two-speed fan i,j||Direct expansionc||Electric heat pump and boilerg|
|7||Four-pipe fan-coil||Single- or two-speed fan i,j||Chilled watere||Hot-water fossil fuel boilerf|
|8||Packaged terminal heat pump||Single-speed fani||Direct expansionc||Electric heat pumph|
|9||Packaged rooftop heat pump||Single- or two-speed fan i,j||Direct expansionc||Electric heat pumph|
|10||Packaged terminal air conditioner||Single-speed fani||Direct expansion||Hot-water fossil fuel boilerf|
|11||Packaged rooftop air conditioner||Single- or two-speed fan i,j||Direct expansion||Fossil fuel furnace|
- VAV with Parallel Fan-Powered Boxes: Fans in parallel VAV fan-powered boxes shall be sized for 50% of the peak design flow rate and shall be modeled with 0.35 W/cfm fan power. Minimum volume set points for fan-powered boxes shall be equal to the minimum rate for the space required for ventilation consistent with Exception 1(b) to Section 22.214.171.124. Supply air temperature set point shall be constant at the design condition (see Section 11.5.2[g]).
- VAV with Reheat: Minimum volume set points for VAV reheat boxes shall be the larger of the following: (1) the minimum primary outdoor airflow rate required to meet the Simplified Procedure ventilation requirements of ASHRAE Standard 62.1 for the zone or (2) the airflow rate required to comply with applicable codes or accreditation standards, including, but not limited to, pressure relationships or minimum air change rates. The supply air temperature for cooling shall be reset higher by 5°F under the minimum cooling load conditions.
- Direct Expansion: The fuel type for the cooling system shall match that of the cooling system in the proposed design.
- VAV: The supply, return, or relief fan motor shall be modeled assuming a variable-speed drive and shall meet the VAV fan part-load performance requirements of Section G126.96.36.199. If the proposed design's system has a DDC system at the zone level, static pressure set-point reset based on zone requirements in accordance with Section 188.8.131.52.3 shall be modeled.
- Chilled Water: For systems using purchased chilled water, the chillers are not explicitly modeled, and chilled-water costs shall be based as determined in Section 11.4.3. Otherwise, the budget building design's chiller plant shall be modeled with chillers having the number as indicated in Table 11.5.2-2 as a function of budget building design chiller plant load and type as indicated in Table 11.5.2-3 as a function of individual chiller load. Where chiller fuel source is mixed, the system in the budget building design shall have chillers with the same fuel types and with capacities having the same proportional capacity as the proposed design's chillers for each fuel type. Chilled-water supply temperature shall be modeled at 44°F design supply temperature and 56°F return temperature. Piping losses shall not be modeled in either building model. Chilled-water supply water temperature shall be reset in accordance with Section 184.108.40.206. Pump system power for each pumping system shall be the same as for the proposed design; if the proposed design has no chilled-water pumps, the budget building design pump power shall be 22 W/gpm (equal to a pump operating against a 75 ft head, 65% combined impeller and motor efficiency). The chilled-water system shall be modeled as primary-only variable flow with flow maintained at the design rate through each chiller using a bypass. Chilled-water pumps shall be modeled as riding the pump curve or with variable-speed drives when required in Section 220.127.116.11. The heat-rejection device shall be an open-circuit axial-fan cooling tower with variable-speed fan control, if required in Section 6.5.5, and shall meet the performance requirements of 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 10°F: Approach10°FRange = 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.Except during economizer operation, the tower shall be controlled to maintain a cooling tower leaving water temperature, where weather permits, per Table 11.5.2-5, floating up to the design leaving water temperature for the cooling tower. Pump system power for each pumping system shall be the same as the proposed design; if the proposed design has no condenser water pumps, the budget building design pump power shall be 19 W/gpm (equal to a pump operating against a 60 ft head, 60% combined impeller and motor efficiency). Each chiller shall be modeled with separate condenser water and chilled-water pumps interlocked to operate with the associated chiller.
- Fossil Fuel Boiler: For systems using purchased hot water or steam, the boilers are not explicitly modeled and hot-water or steam costs shall be based on actual utility rates. Otherwise, the boiler plant shall use the same fuel as the proposed design and shall be natural draft. The budget building design boiler plant shall be modeled with a single boiler if the budget building design plant load is 600,000 Btu/h or less and with two equally sized boilers for plant capacities exceeding 600,000 Btu/h. Boilers shall be staged as required by the load. Hot-water supply temperature shall be modeled at 180°F design supply temperature and 130°F return temperature. Piping losses shall not be modeled in either building model. Hot-water supply water temperature shall be reset in accordance with Section 18.104.22.168. Pump system power for each pumping system shall be the same as for the proposed design; if the proposed design has no hot-water pumps, the budget building design pump power shall be 19 W/gpm (equal to a pump operating against a 60 ft head, 60% combined impeller and motor efficiency). The hot-water system shall be modeled as primary-only with continuous variable flow. Hot-water pumps shall be modeled as riding the pump curve or with variable-speed drives when required by Section 22.214.171.124.
- Electric Heat Pump and Boiler: Water-source heat pumps shall be connected to a common heat pump water loop controlled to maintain temperatures between 60°F and 90°F. Heat rejection from the loop shall be provided by an closed-circuit axial-fan evaporative fluid cooler with fan-speed control as required in Section 126.96.36.199. Heat addition to the loop shall be provided by a boiler that uses the same fuel as the proposed design and shall be natural draft. If no boilers exist in the proposed design, the budget building boilers shall be fossil fuel. The budget building design boiler plant shall be modeled with a single boiler if the budget building design plant load is 600,000 Btu/h or less and with two equally sized boilers for plant capacities exceeding 600,000 Btu/h. Boilers shall be staged as required by the load. Piping losses shall not be modeled in either building model. Pump system power shall be the same as for the proposed design; if the proposed design has no pumps, the budget building design pump power shall be 22 W/gpm, which is equal to a pump operating against a 75 ft head, with a 65% combined impeller and motor efficiency. Loop flow shall be variable with flow shutoff at each heat pump when its compressor cycles OFF as required by Section 188.8.131.52 Loop pumps shall be modeled as riding the pump curve or with variable-speed drives when required by Section 184.108.40.206.
- Electric Heat Pump: Electric air-source heat pumps shall be modeled with electric auxiliary heat. The system shall be controlled with a multistage space thermostat and an outdoor air thermostat wired to energize auxiliary heat only on the last thermostat stage and when outdoor air temperature is less than 40°F.
- Fan System Operation: Fans shall be controlled in the same manner as in the proposed design; i.e., fan operation whenever the space is occupied or fan operation cycled ON calls for heating and cooling.
- Fan Speed Control: Fans shall operate as one or two speed as required by Section 220.127.116.11, regardless of the fan speed control used in the proposed design.
|Total Chiller Plant Capacity||Number of Chillers|
|>300 tons, <600 tons||Two sized equally|
|≥600 tons||Two minimum with chillers added so that no chiller is larger than 800 tons, all sized equally|
|Individual Chiller Plant Capacity||Electric Chiller Type||Fossil Fuel Chiller Type|
|≤ 100 tons||Scroll||Single-effect absorption, direct fired|
|>100 tons, <600 tons||Screw||Double-effect absorption, direct fired|
|≥600 tons||Centrifugal||Double-effect absorption, direct fired|
|Economizer Type||High-Limit Shutoff|
|Fluid (integrated)||When its operation will no longer reduce HVAC system energy|
|Climate Zone||Leaving Water Temperature|
|5B, 5C, 6B, 8||65°F|
|0B, 1B, 2B, 3B, 3C, 4B, 4C, 5A, 6A, 7||70°F|
|0A, 1A, 2A||80°F|
- The energy cost budget for the budget building design and the design energy cost for the proposed design.
- The simulation program used and the version of the simulation program.
- 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.
- A list of the energy-related features that are included in the design and on which compliance with the provisions of Section 11 is based. This list shall document all energy features that differ between the models used in the energy cost budget and the design energy cost calculations.
- A list showing compliance for the proposed design with all the requirements of Sections 5.4, 6.4, 7.4, 8.4, 9.4, and 10.4 (mandatory provisions).
- Building elevations and floor plans.
- 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 building envelope assemblies, NFRC ratings for fenestration, end uses identified in Table 11.5.1, "1. Design Model," paragraph [a]).
- The input and output reports from the simulation program, 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 time any loads are not met by the HVAC system for both the proposed design and budget 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 methods 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 design energy cost associated with on-site renewable energy.
- The version of the software and the link to the website that contains the ASHRAE Standard 140 results for the version used in accordance with Section 18.104.22.168.