A + B + C + D = ≤ Zero | ||||
Where: | ||||
A = | Sum of the (UA Dif) values for each distinct assembly type of the building thermal envelope, other than slabs on grade | |||
UA Dif | = | UA Proposed – UA Table | ||
UA Proposed | = | Proposed U-value x Proposed Area | ||
UA Table | = | (U-factor from Table C402.1.4 or C402.4) x Area | ||
B = | Sum of the (FL Dif) values for each distinct slab on grade perimeter condition of the building thermal envelope | |||
FL Dif | = | FL Proposed – FL Table | ||
FL Proposed | = | Proposed F-value x Proposed Perimeter length | ||
FL Table | = | (F-factor specified in Table C402.1.4) x Proposed Perimeter length |
The maximum allowed prescriptive vertical fenestration area, identified as "Vertical Fenestration Area allowed" in factor CA below, ((as a percent of))is the gross above-grade wall area ((ratio is))times either: | ||
1. | 30% | |
2. | 40% if the building complies with Section C402.4.1.1 or Section ((C402.1.4.1))C402.4.1.4; or | |
3. | 40% if the U-values used in calculating A for vertical fenestration are taken from Section C402.4.1.3 rather than Table C402.4 |
Where the proposed vertical fenestration area is less than or equal to the ((maximum allowed prescriptive))Vertical Fenestration Area allowed, the value of C (Excess Vertical Glazing Value) shall be zero. Otherwise: | |||
C = | (CA x UV) – (CA x UWall), but not less than zero | ||
CA | = | (Proposed Vertical Fenestration Area) – (Vertical Fenestration Area allowed) | |
((UA Wall | = | Sum of the (UA Proposed) values for each opaque assembly of the exterior wall)) | |
UAW | = | Sum of the (UA ((proposed))table) values for each above-grade wall assembly | |
UWall | = | UAW/(sum of proposed wall area (((excludes vertical fenestration area))+ CA) | |
UAV | = | Sum of the (UA ((Proposed))Table) values for each vertical fenestration assembly | |
UV | = | UAV/Total Vertical Fenestration Area allowed | |
Where the proposed skylight area is less than or equal to the skylight area allowed by Section C402.4.1, the value of D (Excess Skylight Value) shall be zero. Otherwise: | |||
D = | (DA x US) – (DA x URoof), but not less than zero | ||
DA | = | (Proposed Skylight Area) – (Allowable Skylight Area from Section C402.4.1) | |
UAR | = | Sum of the (UA ((Proposed))Table) values for each roof assembly | |
URoof | = | UAR/(sum of proposed roof area (((excludes skylight area))+ DA) | |
UAS | = | Sum of the (UA ((Proposed))Table) values for each skylight assembly | |
US | = | UAS/((total))the Allowable Skylight Area from Section C402.4.1 | |
Where required by other sections of the code Proposed Total Envelope UA and Allowed Total Envelope UA shall be calculated as: | |||
Proposed Total Envelope UA | = | Sum of UA Proposed and FL Proposed for each distinct envelope assembly | |
Allowed Total Envelope UA | = | Sum UA Table - C — D | |
Where: | |||
Sum UA Table | = | Sum of UA Table and FL Table for each distinct envelope assembly |
SHGCAt | SHGCogt(Aogt) + SHGCvgt (Avgt + Avgmt + Avgmot + Avgdt) | |
Where: | ||
SHGCAt | = | The target combined solar heat gain of the target fenestration area. |
SHGCogt | = | The solar heat gain coefficient for skylight fenestration found in Table C402.4. |
Aogt | = | The ((proposed))target skylight area. |
SHGCvgt | = | The solar heat gain coefficient for vertical fenestration found in Table C402.4 which corresponds to the proposed total fenestration area as a percentage of gross exterior wall. |
Avgt | = | The ((proposed))target vertical fenestration area with nonmetal framing. |
Avgmt | = | The ((proposed))target vertical fenestration area with fixed metal framing. |
Avgmot | = | The ((proposed))target vertical fenestration area with operable metal framing. |
Avgdt | = | The proposed vertical fenestration area of entrance doors. |
NOTE: | The vertical fenestration area does not include opaque doors and opaque spandrel panels. |
SHGCAp | = | SHGCogAog + SHGCvgAvg |
Where: | ||
SHGCAt | = | The combined proposed solar heat gain of the proposed fenestration area. |
SHGCog | = | The solar heat gain coefficient of the skylights. |
Aog | = | The skylight area. |
SHGCvg | = | The solar heat gain coefficient of the vertical fenestration. |
Avg | = | The vertical fenestration area. |
NOTE: | The vertical fenestration area does not include opaque doors and opaque spandrel panels. |
EXCEPTION: | Tubular pipe insulation shall not be required on the following: |
1. The tubing from the connection at the termination of the fixture supply piping to a plumbing fixture or plumbing appliance. | |
2. Valves, pumps, strainers and threaded unions in piping that is 1 inch (25 mm) or less in nominal diameter. | |
3. Piping from user-controlled shower and bath mixing valves to the water outlets. | |
4. Cold-water piping of a demand recirculation water system. | |
5. Tubing from a hot drinking-water heating unit to the water outlet. | |
6. Piping at locations where a vertical support of the piping is installed. | |
7. Piping surrounded by building insulation with a thermal resistance (R-value) of not less than R-3. | |
8. Hot water piping that is part of the final pipe run to the plumbing fixture and is not part of the heated-water circulation system circulation path is not required to meet the minimum insulation requirements of C404.6. |
EXCEPTION: | The following alterations need not comply with the requirements for new construction provided the energy use of the building is not increased: |
1. Storm windows installed over existing fenestration. | |
2. Surface applied window film installed on existing single pane fenestration assemblies to reduce solar heat gain provided the code does not require the glazing fenestration to be replaced. | |
3. Existing ceiling, wall or floor cavities exposed during construction provided that these cavities are insulated to full depth with insulation having a minimum nominal value of R-3.0 per inch installed per Section C402. | |
4. Construction where the existing roof, wall or floor cavity is not exposed. | |
5. Roof recover. | |
6. Air barriers shall not be required for roof recover and roof replacement where the alterations or renovations to the building do not include alterations, renovations or repairs to the remainder of the building envelope. | |
7. Replacement of existing doors that separate conditioned space from the exterior shall not require the installation of a vestibule or revolving door, provided however that an existing vestibule that separates a conditioned space from the exterior shall not be removed. |
EXCEPTION: | Where the component performance building envelope option in Section C402.1.5 is used to comply with this Section, the Proposed Total Envelope UA is allowed to be up to 110 percent of the ((Target))Allowed Total Envelope UA. Where the total building performance option in Section C407 is used to comply with this section, the annual energy consumption of the proposed design is allowed to be 110 percent of the annual energy consumption otherwise allowed by Section C407.3. |
EXCEPTION: | Air leakage testing is not required for alterations and repairs, unless the project includes a change in space conditioning according to Section C503.2 or a change of occupancy or use according to Section C505.1. |
EXCEPTION: | An area-weighted average of the U-factor of replacement fenestration products being installed in the building for each fenestration product category listed in Table C402.4 shall be permitted to satisfy the U-factor requirements for each fenestration product category listed in Table C402.4. Individual fenestration products from different product categories listed in Table C402.4 shall not be combined in calculating the area-weighted average U-factor. |
EXCEPTION: | Existing mechanical systems which are altered or where parts of the systems are replaced are not required to be modified to comply with Section C403.6 as long as mechanical cooling is not added to the system. |
EXCEPTIONS: | 1. Alternate designs that are not in full compliance with this code may be approved when the code official determines that existing building constraints including, but not limited to, available mechanical space, limitations of the existing structure, or proximity to adjacent air intakes/exhausts make full compliance impractical. Alternate designs shall provide alternate energy savings strategies including, but not limited to, Demand Control Ventilation or increased mechanical cooling or heating efficiency above that required by Tables C403.2.3(1) through C403.2.3(10). |
2. Qualifying small equipment: This exception shall not be used for unitary cooling equipment installed outdoors or in a mechanical room adjacent to the outdoors. This exception is allowed to be used for other cooling units and split systems serving one zone with a total cooling capacity rated in accordance with Section C403.2.3 of less than 33,000 Btu/h (hereafter referred to as qualifying small systems) provided that these are high-efficiency cooling equipment with SEER and EER values more than 15 percent higher than minimum efficiencies listed in Tables C403.2.3 (1) through (3), in the appropriate size category, using the same test procedures. Equipment shall be listed in the appropriate certification program to qualify for this exception. The total capacity of all qualifying small equipment without economizers shall not exceed 72,000 Btu/h per building, or 5 percent of its air economizer capacity, whichever is greater. That portion of the equipment serving Group R occupancies is not included in determining the total capacity of all units without economizers in a building. Redundant units are not counted in the capacity limitations. This exception shall not be used for the shell-and-core permit or for the initial tenant improvement or for Total Building Performance. | |
3. Chilled water terminal units connected to systems with chilled water generation equipment with IPLV values more than 25 percent higher than minimum part load efficiencies listed in Table C403.2.3(7), in the appropriate size category, using the same test procedures. Equipment shall be listed in the appropriate certification program to qualify for this exception. The total capacity of all systems without economizers shall not exceed 480,000 Btu/h per building, or 20 percent of its air economizer capacity, whichever is greater. That portion of the equipment serving Group R occupancy is not included in determining the total capacity of all units without economizers in a building. This exception shall not be used for the initial permit (this includes any initial permit for the space including, but not limited to, the shell-and-core permit, built-to-suit permit, and tenant improvement permit) or for Total Building Performance Method. |
Option A | Option B (alternate to A) | Option C (alternate to A) | Option D (alternate to A) | |
Unit Type | Any alteration with new or replacement equipment | Replacement unit of the same type with the same or smaller output capacity | Replacement unit of the same type with a larger output capacity | New equipment added to existing system or replacement unit of a different type |
1. Packaged Units | Efficiency: min.1 Economizer: C403.32 | Efficiency: min.1 Economizer: C403.32,3 | Efficiency: min.1 Economizer: C403.32,3 | Efficiency: min.1 Economizer: C403.32,4 |
2. Split Systems | Efficiency: min.1 Economizer: C403.32 | Efficiency: + 10/5%5 Economizer: shall not decrease existing economizer capability | Only for new units < 54,000 Btuh replacing unit installed prior to 1991 (one of two): Efficiency: + 10/5%5 Economizer: 50%6 | Efficiency: min.1 Economizer: C403.32,4 |
For units > 54,000 Btuh or any units installed after 1991: Option A | ||||
3. Water Source Heat Pump | Efficiency: min.1 Economizer: C403.32 | (two of three): Efficiency: + 10/5%5 Flow control valve7 Economizer: 50%6 | (three of three): Efficiency: + 10/5%5 Flow control valve7 Economizer: 50%6 (except for certain pre-1991 systems8) | Efficiency: min.1 Economizer: C403.32,4 (except for certain pre-1991 systems8) |
4. Hydronic Economizer using Air-Cooled Heat Rejection Equipment (Dry Cooler) | Efficiency: min.1 Economizer: 14332 | Efficiency: + 10/5%5 Economizer: shall not decrease existing economizer capacity | Option A | Efficiency: min.1 Economizer: C403.32,4 |
5. Air-Handling Unit (including fan coil units) where the system has an air-cooled chiller | Efficiency: min.1 Economizer: C403.32 | Economizer: shall not decrease existing economizer capacity | Option A (except for certain pre-1991 systems8) | Option A (except for certain pre-1991 systems8) |
6. Air-Handling Unit (including fan coil units) and Water-cooled Process Equipment, where the system has a water-cooled chiller10 | Efficiency: min.1 Economizer: C403.32 | Economizer: shall not decrease existing economizer capacity | Option A (except for certain pre-1991 systems8 and certain 1991-2004 systems9) | Efficiency: min.1 Economizer: C403.32,4 (except for certain pre-1991 systems8 and certain 1991-2015 systems9) |
7. Cooling Tower | Efficiency: min.1 Economizer: C403.32 | No requirements | Option A | Option A |
8. Air-Cooled Chiller | Efficiency: min.1 Economizer: C403.32 | Efficiency: + 5%11 Economizer: shall not decrease existing economizer capacity | Efficiency (two of two): (1) + 10%12 and (2) multistage Economizer: shall not decrease existing economizer capacity | Efficiency: min.1 Economizer: C403.32,4 |
9. Water-Cooled Chiller | Efficiency: min.1 Economizer: C403.32 | Efficiency (one of two): (1) + 10%13 or (2) plate frame heat exchanger15 Economizer: shall not decrease existing economizer capacity | Efficiency (two of two): (1) + 15%14 and (2) plate-frame heat exchanger15 Economizer: shall not decrease existing economizer capacity | Efficiency: min.1 Economizer: C403.32,4 |
10. Boiler | Efficiency: min.1 Economizer: C403.32 | Efficiency: + 8%16 Economizer: shall not decrease existing economizer capacity | Efficiency: + 8%16 Economizer: shall not decrease existing economizer capacity | Efficiency: min.1 Economizer: C403.32,4 |
1 | Minimum equipment efficiency shall comply with Section C403.2.3 and Tables C403.2.3(1) through C403.2.3(10). | |
2 | System and building shall comply with Section C403.3 (including both the individual unit size limits and the total building capacity limits on units without economizer). It is acceptable to comply using one of the exceptions to Section C403.3 or C504.3.4. | |
3 | All equipment replaced in an existing building shall have air economizer complying with Section C403.3 unless both the individual unit size and the total capacity of units without air economizer in the building is less than that allowed in Exception 2 to Section C503.4. | |
4 | All separate new equipment added to an existing building shall have air economizer complying with Section C403.3 unless both the individual unit size and the total capacity of units without air economizer in the building is less than that allowed in Exception 3 to Section C503.4. | |
5 | Equipment shall have a capacity-weighted average cooling system efficiency: | |
a. | For units with a cooling capacity below 54,000 Btuh, a minimum of 10% greater than the requirements in Tables C403.2.3(1) and C403.2.3(2). | |
b. | For units with a cooling capacity of 54,000 Btuh and greater, a minimum of 5% greater than the requirements in Tables C403.2.3(1) and C403.2.3(2). | |
6 | Minimum of 50% air economizer that is ducted in a fully enclosed path directly to every heat pump unit in each zone, except that ducts may terminate within 12 inches of the intake to an HVAC unit provided that they are physically fastened so that the outside air duct is directed into the unit intake. If this is an increase in the amount of outside air supplied to this unit, the outside air supply system shall be configured to provide this additional outside air and equipped with economizer control. | |
7 | Have flow control valve to eliminate flow through the heat pumps that are not in operation with variable speed pumping control complying with Section C403.4.2 for that heat pump. | |
- When the total capacity of all units with flow control valves exceeds 15% of the total system capacity, a variable frequency drive shall be installed on the main loop pump. | ||
- As an alternate to this requirement, have a capacity-weighted average cooling system efficiency that is 5% greater than the requirements in note 5 (i.e., a minimum of 15%/10% greater than the requirements in Tables C403.2.3(1) and C403.2.3(2)). | ||
8 | Systems installed prior to 1991 without fully utilized capacity are allowed to comply with Option B, provided that the individual unit cooling capacity does not exceed 90,000 Btuh. | |
9 | Economizer not required for systems installed with water economizer plate and frame heat exchanger complying with previous codes between 1991 and June 2016, provided that the total fan coil load does not exceed the existing or added capacity of the heat exchangers. | |
10 | For water-cooled process equipment where the manufacturers specifications require colder temperatures than available with waterside economizer, that portion of the load is exempt from the economizer requirements. | |
11 | The air-cooled chiller shall have an IPLV efficiency that is a minimum of 5% greater than the IPLV requirements in Table C403.2.3(7). | |
12 | The air-cooled chiller shall: | |
a. | Have an IPLV efficiency that is a minimum of 10% greater than the IPLV requirements in Table C403.2.3(7); and | |
b. | Be multistage with a minimum of two compressors. | |
13 | The water-cooled chiller shall have an IPLV efficiency that is a minimum of 10% greater than the IPLV requirements in Table C403.2.3(7). | |
14 | The water-cooled chiller shall have an IPLV efficiency that is a minimum of 15% greater than the IPLV requirements in Table C403.2.3(7). | |
15 | Economizer cooling shall be provided by adding a plate-frame heat exchanger on the waterside with a capacity that is a minimum of 20% of the chiller capacity at standard AHRI rating conditions. | |
16 | The replacement boiler shall have an efficiency that is a minimum of 8% higher than the value in Table C403.2.3(5), except for electric boilers. |
EXCEPTION: | Where the component performance alternative in Section C402.1.5 is used to comply with this section, the Proposed Total Envelope UA is allowed to be up to 110 percent of the ((target))Allowed Total Envelope UA. Where the total building performance option in Section C407 is used to comply with this section, the annual energy consumption of the proposed design is allowed to be 110 percent of the annual energy consumption otherwise allowed by Section C407.3. |