D.C. Mun. Regs. tit. 12, 12-I5.4

Current through Register Vol. 71, No. 49, December 6, 2024

Section 12-I5.4 - MANDATORY PROVISIONS

Insert a new Section 5.4.1.1 in the Energy Conservation Code-Commercial Provisions to read as follows:

5.4.1.1

Accounting for Thermal Conduction Components. Where a component of the building envelope assembly reduces the overall U-value of the rest of the assembly, that component shall be thermally represented and integrated into the area-weighted U-value as described by the following default methodology. This default methodology shall be used in all energy compliance pathways including: Prescriptive U-value compliance, Section 5.6 Trade-off, and Appendix G energy model. Prescriptive R-value compliance with Table 5.5 and the energy model baseline shall assume Default Cladding Attachment Coefficients = 1 from Table 5.4.1.1(1) and no Linear Anomalies as described in Table 5.4.1.1(2). Tables 5.4.1.1(1) and 5.4.1.1(2) shall be used in conjunction with Equation 5.4.1.1 and associated default calculation methodology to account for common thermal conduction situations not currently described in Appendix A. In lieu of the equation and methodology the project team may demonstrate to the authority having jurisdiction two dimensional heat flow modeling, three dimensional heat flow modeling, linear transmission calculations per ASHRAE D RP-1365, or hot box-testing results showing the resultant area-weighted U-value as acceptable to the authority having jurisdiction. If using this alternate methodology, all thermal bridges described by ASHRAE D RP-1365 shall be represented.

Exceptions:

1. Electrical wiring used for transmission of energy.

2. Plumbing penetrations complying with prescriptive insulation requirements of Section 7.

3. Mechanical penetrations complying with prescriptive insulation requirements of Section 6.

4. Non-metal flashing for moisture management.

Where

Ubw = "Overall U-Factor for Entire Base Wall Assembly" (such as from ASHRAE

90.1 , Normative Appendix A, Table A3.3, A3.4 - Insulation in stud cavity, plus gypsum, thermal boundary layers)

Re = Nominal Exterior insulation R-value (From Project Design)

Cac = Cladding Attachment Coefficient (from Table 5.4.1.1(1))

Wac = Wall Anomaly Coefficient (from Table 5.4.1.1(2))

Default Methodologies:

Option A - Specification Approach:

1) If complying with the Prescriptive R-value requirements per Table 5.5-4 the building project must have:

a. No Linear Anomalies for Vertical Assemblies as described in Table 5.4.1.1

b. For projects using exterior insulation "Materials and/or Orientations" identified in Table 5.4.1.1(1) with Cladding Attachment Coefficients (Cac) of 1 shall be explicitly specified in the drawings and/or specifications.

Option B - Simplified Approach:

1) Find the lowest Default Linear Anomaly for Vertical Assembly applicable to the proposed design. Use this value to include in Equation 5.4.1.1

2) Determine the Default Cladding Attachment Coefficient for the proposed design

3) Use equation 5.4.1.1 to determine U-value_(Overall_including_Thermal_Bridges) for vertical walls

4) Use the calculated U-value_(Overall_including_Thermal_Bridges) for compliance with prescriptive U-value compliance per Table 5.5-4, Trade off method section 5.6 (via COMCheck), or the proposed energy model via Appendix G.

5) Calculations and assumptions shall be presented to the authority having jurisdiction

Option C - Detailed Approach:

1) Define a new rectangular vertical wall area associated with one Default Linear Anomaly per story, or part of a story (includes stories below grade)

2) If there is more than one Default Linear Anomaly per vertical, rectangular wall section (for example such as a wall with both a concrete balcony and a parapet), select the lowest Default Linear Anomaly Coefficient for Vertical Assembly and use that for Equation 5.4.1.1

3) Determine the Default Cladding Attachment Coefficient for the proposed design wall section.

4) Use equation 5.4.1.1 to determine U-value_(Overall_including_Thermal_Bridges)

5) Use the calculated U-value_(Overall_including_Thermal_Bridges) for compliance with prescriptive U-value compliance per Table 5.5-4, Trade off method section 5.6 (via COMCheck), or the proposed energy model via Appendix G.

6) Each unique vertical wall assembly shall be evaluated and/or included for the compliance Options C step 5

7) Calculations and assumptions shall be presented to the authority having jurisdiction

See following Tables:

Table 5.4.1.1(1)	- Default Cladding Attachment Coefficient
Attachment type through Rigid Insulation	Material and/or Orientation	Cladding Attachment Coefficient, Cac
Girts	Metal Vertical girt (Detail 1*)	53%
	Horizontal Metal girt (Detail 2*)	62%
	Horizontal Non-Metal girt	100%
Clips	Metal Clips	75%
	Stainless Steel Clips	85%
	Thermal Stop Clips	90%
	Fiberglass Clip	100%
Brick Ties	Steel Brick Ties	78%
	Stainless Steel Brick Ties	90%
	Thermal Break Brick Ties	100%
Long Screws	Galvanized Long Screws	80%
Long Screws	Stainless Long Screws	100%

*Detail Associated with ASHRAE D RP-1365

Table 5.4.1.1(2) - Default Linear Anomaly Coefficient for Vertical Assembly
Construction Type	Wall Linear Anomaly	Insulation Placement	ASHRAE D RP -1365 Detail #	Wall Anomaly Coefficient, Wac
All Wall Facades	Concrete Balcony or Concrete Floor	Uninsulated at top and bottom, exterior and in stud cavity insulation	5	36%
	Concrete Balcony or Concrete Floor	Insulated at top of slab, exterior and in stud cavity insulation	5	39%
	Concrete Balcony or Concrete Floor	insulated at top and bottom of slab, exterior and in stud cavity insulation	5a	42%
All Facades with Structural Steel	Steel Support for Floor	Interior Insulated Wall	16	64%
	Steel Support for Floor	Exterior & Interior Insulated	17	80%
	Metal or Masonry Parapet	Exterior Rigid and Interior Framed	10	72%
Brick Facade	Concrete Slab with Standard Metal Shelf Angle or Metal Flashing	Exterior Rigid and Interior Framed	14	54%
	Concrete Slab with Reduced-Contact Metal Shelf Angle	Exterior Rigid and Interior Framed	15	65%
	Metal or Masonry Parapet	Both sides insulated with rigid, with Roof insulation	9	100%
	Metal or Masonry Parapet	Interior wall metal framed insulation with roof insulation	20	65%
Spandrel Panels	Slab Intersection	No Stud Insulation and Back Pan Insulation	22	34%
	Slab Intersection	Stud Insulation and Back Pan Insulation	23	44%
	Metal or Masonry Parapet	Stud Insulation and Back Pan Insulation	25	41%
Precast Walls	Slab Intersection Metal or Masonry Parapet	Interior Metal Framed Insulation Exterior Metal Framed Insulation	29 30	73% 76%
	Slab Intersection	Sandwich Panel, at slab intersection	32	63%
	Metal or Masonry Parapet	Sandwich Panel, at roof intersection	33	65%
Concrete Block With Exterior Rigid Insulation	Metal Shelf Angle	Exterior Rigid and Metal Shelf Angle	35	62%
	Reduced Contact Shelf Angle	Exterior Rigid and Reduced Contact Shelf Angle	36	70%
	Metal or Masonry Parapet	Brick Ties at Parapet and Roof	37	69%
No Linear Anomalies as Described Above	All	All	-	100%

Strike Exception 2 to Section 5.4.3.2 of ASHRAE 90.1 in its entirety without substitution:

Strike Section 5.4.3.4 of ASHRAE 90.1 in its entirety and insert a new Section 5.4.3.4 in its place in the Energy Conservation Code-Commercial Provisions to read as follows:

5.4.3.4

Vestibules.Building entrances that separate conditioned space from the exterior shall be protected with an enclosed vestibule, with all doors opening into and out of the vestibule equipped with self-closing devices. Vestibules shall be designed so that in passing through the vestibule it is not necessary for the interior and exterior doors to open at the same time. Interior and exterior doors shall have a minimum distance between them of not less than 7 ft when in the closed position. The floor area of each vestibule shall not exceed the greater of 50 ft² or 2% of the gross conditioned floor area for that level of the building. The exterior envelope of conditioned vestibules shall comply with the requirements for a conditioned space. The interior and exterior envelope of unconditioned vestibules shall comply with the requirements for a semiheated space.

Exceptions:

1. Revolving doors;

2. Doors not intended to be used as a building entrance, including service entrance doors;

3. Doors opening directly from a dwelling unit;

4. Doors that open directly from a space that is less than 3,000 ft² in area;

5. Semiheated spaces;

6. Enclosed elevator lobbies for building entrances directly from parking garages.

[No change to Section 5.4.3.4.1 ]

Insert a new Section 5.4.4 in ASHRAE 90.1 to read as follows:

5.4.4

On-Site Renewable Energy Systems.Building project design shall show allocated space and pathways for future installation of on-site renewable energy systems and associated infrastructure to cover no less than 25% of horizontal projection of the gross roof area.

Exceptions:

1.Building projects that have an annual daily average incident solar radiation available to a flat plate collector oriented due south at an angle from horizontal equal to the latitude of the collector location less than 1.2 kBtu/ft²·day (4.0 kWh/m²·day), accounting for existing buildings, permanent infrastructure that is not part of the building project, topography, or trees.

2.Building projects that comply with Section 13.1.

D.C. Mun. Regs. tit. 12, 12-I5.4

Final Rulemaking published at 67 DCR 5679 (5/29/2020)