honeybee_ph_utils.aisi_s250_21 module

AISI S250-21 | “North American Standard for Thermal Transmittance of Building Envelopes With Cold-Formed Steel Framing, 2021 Edition”

https://www.steel.org/2021/09/aisi-publishes-aisi-s250-21-north-american-standard-for-thermal-transmittance-of-building-envelopes-with-cold-formed-steel-framing-2021-edition/

Thermal transmittance (U-factors) of above-grade wall assemblies constructed with standard Cshape studs and track, where the framing spacing is 6, 12, 16 or 24 inches on-center, shall be determined in accordance with Equation B3.1.8-1 using Sections B3.1.1 through B3.1.8 or shall be determined in accordance with Appendix 1. Where a non-standard designation thickness for the cold-formed steel framing member is applicable, values for the OTZ coefficients from Table B3.1.11 and thermal conductivity from Table B3.1.3-1 shall be based on linear interpolation for the intermediate value of designation thickness or shall be based on the next larger standard designation thickness. Extrapolation is not permitted.

NOTE: AISI does not provide an ‘SI’ version of the coefficients in Table B3.1.11. therefor ALL values in this module are in imperial units. This includes R-Values, U-Values, and dimensions.

class honeybee_ph_utils.aisi_s250_21.StudSpacingInches(_value: str | int = 1)[source]

Bases: CustomEnum

ToString()
classmethod from_dict(_dict: dict[str, Any]) → CustomEnum
to_dict() → dict[str, Any]
allowed: list[str] = ['6', '12', '16', '24']
property allowed_upper: list[str]
property number: int

Returns the index pos of self.value (usually 1-based)

property value: str
class honeybee_ph_utils.aisi_s250_21.StudThicknessMil(_value: str | int = 1)[source]

Bases: CustomEnum

ToString()
classmethod from_dict(_dict: dict[str, Any]) → CustomEnum
to_dict() → dict[str, Any]
allowed: list[str] = ['33', '43', '54', '68']
property allowed_upper: list[str]
property number: int

Returns the index pos of self.value (usually 1-based)

property value: str
honeybee_ph_utils.aisi_s250_21.calculate_stud_cavity_effective_u_value(_r_ext_cladding: float, _r_ext_insulation: float, _r_ext_sheathing: float, _r_cavity_insulation: float, _stud_spacing_inch: StudSpacingInches, _stud_thickness_mil: StudThicknessMil, _stud_flange_width_inch: float, _stud_depth_inch: float, _steel_conductivity: float, _r_int_sheathing: float, _r_se: float = 0.17, _r_si: float = 0.68) → float[source]
honeybee_ph_utils.aisi_s250_21.framing_factor(stud_flange_width_inch: float, stud_thickness_mils: float) → float[source]

[AISI S250-21w/S1-22] B3.1.2 C-Shape Framing Factor.

The C-shape framing factor (FFcs) for the cold-formed steel framing shall be determined in accordance with Equation B3.1.2-1:

Eq. B3.1.2-1: FF_cs = (CFS_t / 1000) / CFS_flange

Parameters:

  • stud_thickness_mils (CFS_t) – Designation thickness of cold-formed steel framing member (mils)

  • stud_flange_width_inch (CFS_flange) – Flange width of cold-formed steel framing member (inches)

Returns:

(FF_cs) C-shape framing factor (unitless)

Return type:

float

honeybee_ph_utils.aisi_s250_21.overall_thermal_zone(c_0: float, c_1: float, c_2: float, c_3: float, c_4: float, c_5: float, r_cavity: float, r_ext_insulation: float) → float[source]

[AISI S250-21w/S1-22] B3.1.1 Overall Thermal Zone.

The overall thermal zone (OTZ) shall be determined in accordance with Equation B3.1.1-1. The appropriate coefficients for use in Equation B3.1.1-1 shall be obtained from Table B3.1.11 with the given on-center spacing of framing members and C-shape designation thickness.

Eq. B3.1.1-1: OTZ = C_0 + C_1 * R_cav + C_2 * R_she + C_3 * R_cav^2 + C_4 * R_she^2 + C_5 * R_cav * R_she

r_cavity (r_cav) = R_air + R_ins
  • R_ins: Thermal resistance (R-value) of cavity insulation (h-ft2-F/Btu)

    • = 0 where wall cavity contains no insulation

  • R_air: Thermal resistance (R-value) of the cavity air space (h-ft2-F/Btu)

    • = 0.91 where wall cavity contains an air space

    • = 0 where wall cavity contains no air space

Parameters:

  • C_0 – Coefficient from Table B3.1.1-1

  • C_1 – Coefficient from Table B3.1.1-1

  • C_2 – Coefficient from Table B3.1.1-1

  • C_3 – Coefficient from Table B3.1.1-1

  • C_4 – Coefficient from Table B3.1.1-1

  • C-5 – Coefficient from Table B3.1.1-1

  • r_cavity (R_cav) – Total thermal resistance (R-value) of the wall cavity (h-ft2-F/Btu)

  • r_ext_insulation (R_she) – Thermal resistance (R-value) of exterior continuous insulation (hr-ft2-F/Btu). R_she does not include wood or gypsum panels.

Returns:

Overall thermal zone (inch)

Return type:

OTZ

honeybee_ph_utils.aisi_s250_21.overall_thermal_zone_framing_factor(_overall_thermal_zone: float, _stud_spacing_inch: float) → float[source]

[AISI S250-21w/S1-22] B3.1.7 OTZ Framing Factor.

The OTZ Framing Factor (FF_otz) shall be determined using Equation B3.1.7-1:

  • FF_otz = OTZ / FS

Parameters:

  • _overall_thermal_zone (OTZ) – Overall thermal zone (inch)

  • _stud_spacing_inch (fs) – Spacing of cold-formed steel framing members (inches)

Returns:

(FF_otz) OTZ Framing Factor (unitless)

Return type:

float

honeybee_ph_utils.aisi_s250_21.r_value_series_cavity_path(r_ext_cladding: float, r_ext_insulation: float, r_ext_sheathing: float, r_cavity_insulation: float, r_int_sheathing: float, r_se: float = 0.17, r_si: float = 0.68) → float[source]

[AISI S250-21w/S1-22] B3.1.6.1 Thermal Resistance (R-value) of Series Paths | Cavity Path.

B3.1.6.2 Cavity Path The thermal resistance (R-value) of all materials in the design assembly in series for the path containing only cavity insulation (R_spc), illustrated as the cavity path in Figure B3.1.31 or Figure B3.1.3-2, shall be determined using Equation B3.1.6-2:

  • R_spc = R_o + Side_ext + R_she + Sheath_ext + R_ins + R_air + Sheath_int + R_i

Parameters:

  • R_o – Thermal resistance (R-value) of outside air film (h-ft2F/Btu)

  • r_ext_cladding (Side_ext) – Thermal resistance (R-value) of exterior siding (h-ft2F/Btu)

  • r_ext_insulation (R_she) – Thermal resistance (R-value) of exterior continuous insulation (h-ft2F/Btu)

  • r_ext_sheathing (Sheath_ext) – Thermal resistance (R-value) of all exterior sheathing(s) (h-ft2F/Btu)

  • r_cavity_insulation (R_ins) – Thermal resistance (R-value) of cavity insulation (h-ft2F/Btu)

  • R_air – Thermal resistance (R-value) of the cavity air space (h-ft2F/Btu) : 0.91 where wall cavity contains an air space : 0.00 where wall cavity contains no air space

  • r_int_sheathing (Sheath_int) – Thermal resistance (R-value) of all interior sheathing(s) (h-ft2F/Btu)

  • R_i – Thermal resistance (R-value) of inside air film (h-ft2F/Btu)

Returns:

(R_spc) Effective thermal resistance (R-value) of all materials in the design assembly

in series for the path containing only cavity insulation (h-ft2-F/Btu)

Return type:

float

honeybee_ph_utils.aisi_s250_21.r_value_series_stud_path(r_ext_cladding: float, r_ext_insulation: float, r_ext_sheathing: float, r_3: float, r_int_sheathing: float, r_se: float = 0.17, r_si: float = 0.68) → float[source]

[AISI S250-21w/S1-22] B3.1.6.1 Thermal Resistance (R-value) of Series Paths | C-Shape Path.

The effective thermal resistance (R-value) of all materials in the design assembly in series for the path containing cold-formed steel (R_sps), illustrated as the C-shape path in Figure B3.1.3-1 or Figure B3.1.3-2, shall be determined using Equation B3.1.6-1:

  • R_sps = R_o + Side_ext + R_she + Sheath_ext + R_3 + Sheath_int + R_i

Parameters:

  • r_ext_cladding (Side_ext) – Thermal resistance (R-value) of exterior siding (h-ft2-F/Btu)

  • r_ext_insulation (R_she) – Thermal resistance (R-value) of exterior continuous insulation (h-ft2-F/Btu)

  • r_ext_sheathing (Sheath_ext) – Thermal resistance (R-value) of all exterior sheathing(s) (h-ft2-F/Btu)

  • R_3 – Thermal resistance (R-value) determined from Equation B3.1.5-1 (h-ft2-F/Btu)

  • r_int_sheathing (Sheath_int) – Thermal resistance (R-value) of all interior sheathing(s) (h-ft2-F/Btu)

  • r_se (R_o) – [Default=0.17] Thermal resistance (R-value) of outside air film (h-ft2-F/Btu)

  • r_si (R_i) – [Default=0.68] Thermal resistance (R-value) of inside air film (h-ft2-F/Btu)

Returns:

(R_sps) Effective thermal resistance (R-value) of all materials in the design assembly

in series for the path containing cold-formed steel (h-ft2-F/Btu)

Return type:

float

honeybee_ph_utils.aisi_s250_21.stud_web_r_value(stud_depth_inch: float, conductivity: float) → float[source]

[AISI S250-21w/S1-22] B3.1.3.1 Thermal Resistance of C-Shape Web.

The thermal resistance (R-value) of the web of the cold-formed steel framing member (Rs- wall ) shall be determined in accordance with Equation B3.1.3-1:

  • R_s-wall = CFS_depth / k

Parameters:

  • stud_depth (CFS_depth) – Web depth of cold-formed steel framing member that is in contact with cavity insulation (inches) as illustrated by Figure B3.1.3-1 without cavity air space and Figure B3.1.3-2 with cavity air space

  • conductivity (k) – Thermal conductivity of cold-formed steel as selected from Table B3.1.3-1 (Btu/h-ft2-F)

Returns:

(R_s-wall) Thermal resistance (R-value) of the web of the cold-formed steel framing member (h-ft2-F/Btu)

Return type:

float

honeybee_ph_utils.aisi_s250_21.u_value_at_stud(framing_factor: float, r_value_cavity_insulation: float, r_value_stud_web: float) → float[source]

[AISI S250-21w/S1-22] B3.1.3.2 Thermal Transmittance of Cavity with Insulation.

The parallel path thermal transmittance (U-factor) of the assembly where insulation(s) are in contact with cold-formed steel framing member (U1 ) shall be determined in accordance with Equation B3.1.3-2. Where there is no insulation in the wall cavity, Equation B3.1.3-2 shall not be used and the resultant value of R 1 in Equation B3.1.3-3 shall be “zero” (0).

  • U_1 = (1 - FFcs) / R_ins + FFcs / Rs-wall

Parameters:

  • framing_factor (FF_cs) – C-shape framing factor determined from Equation B3.1.2-1

  • r_value_cavity_insulation (R_ins) – Thermal resistance (R-value) of cavity insulation (h-ft2-F/Btu)

  • r_value_stud_web (R_s-wall) – Thermal resistance (R-value) of the wall assembly at the web of the cold-formed steel framing member determined from Equation B3.1.3-1 (h-ft2-F/Btu)

Returns:

(U_1) Parallel path thermal transmittance (U-factor) of the assembly where insulation(s) are

in contact with cold-formed steel framing member (Btu/hr-ft2-F)

Return type:

float

honeybee_ph_utils.aisi_s250_21.u_value_total(_overall_thermal_zone_framing_factor: float, _r_value_series_cavity_path: float, _r_value_series_stud_path: float) → float[source]

[AISI S250-21w/S1-22] B3.1.8 Overall Thermal Transmittance (U-Factor).

The overall thermal transmittance (U-factor) of the above-grade wall assembly (U_o) shall be determined using Equation B3.1.8-1:

  • U_o = (1 - FF_otz) / R_spc + FF_otz / R_sps

Parameters:

  • _overall_thermal_zone_framing_factor (FF_otz) – OTZ Framing Factor determined from Equation B3.1.7-1 (dimensionless)

  • _r_value_series_cavity_path (R_spc) – Thermal resistance (R-value) of all materials in the design assembly in series for the cavity path determined from Equation B3.1.6-2 (h-ft2-F/Btu)

  • _r_value_series_stud_path (R_sps) – Thermal resistance (R-value) of all materials in the design assembly in series for the C-shape path determined from Equation B3.1.6-1 (h-ft2-F/Btu)

Returns:

(U_o) Overall thermal transmittance (U-factor) of the above-grade wall assembly (Btu/hr-ft2-F)

Return type:

float