5.4. MANDATORY PROVISIONS

SECTION 5 BUILDING ENVELOPE 5.4 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: Electrical wiring used for transmission of energy. Plumbing penetrations complying with prescriptive insulation requirements of Section 7. Mechanical penetrations complying with prescriptive insulation requirements of Section 6. 4. Non-metal flashing for moisture management. Equation 5.4.1.1: U-value(Overall including Thermal Bridges) = 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: If complying with the Prescriptive R-value requirements per Table 5.5-4 the building project must have: No Linear Anomalies for Vertical Assemblies as described in Table 5.4.1.1 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: 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 Determine the Default Cladding Attachment Coefficient for the proposed design Use equation 5.4.1.1 to determine U-value(Overall including Thermal Bridges) for vertical walls 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. Calculations and assumptions shall be presented to the authority having jurisdiction Option C – Detailed Approach: Define a new rectangular vertical wall area associated with one Default Linear Anomaly per story, or part of a story (includes stories below grade) 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 Determine the Default Cladding Attachment Coefficient for the proposed design wall section. Use equation 5.4.1.1 to determine U-value(Overall including Thermal Bridges) 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. Each unique vertical wall assembly shall be evaluated and/or included for the compliance Options C step 5 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% 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 Interior Metal Framed Insulation 29 73% Metal or Masonry Parapet Exterior Metal Framed Insulation 30 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: Revolving doors; Doors not intended to be used as a building entrance, including service entrance doors; Doors opening directly from a dwelling unit; Doors that open directly from a space that is less than 3,000 ft2 in area; Semiheated spaces; 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: 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. Building projects that comply with Section 13.1. SOURCE: Final Rulemaking published at 67 DCR 6326 (May 29, 2020 – Part 2). The District of Columbia Energy Conservation Code (2017), referred to as the “Energy Conservation Code,” consists of ANSI/ASHRAE/IES 90.1-2013, Energy Standard for Buildings Except Low-Rise Residential Buildings (ASHRAE 90.1) and substantial portions of Chapter 7 of ANSI/ASHREA/IES 189.1-2014, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings (ASHRAE 189.1), published by the American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE), and the Residential Provisions of the 2015 edition of the International Energy Conservation Code (International Energy Conservation Code), published by the International Code Council (ICC), as amended by the Energy Conservation Code Supplement of 2017 – Commercial Provisions (12-I[CE] DCMR) and the Energy Conservation Code Supplement of 2017 – Residential Provisions (12-I[RE] DCMR). The International Energy Conservation Code is copyrighted by the ICC and therefore is not republished here. However, a copy of the text may be obtained at: https://codes.iccsafe.org/public/document/IECC2015. ASHRAE 90.1 is copyrighted by ASHRAE and therefore is not republished here. However, the text of ASHRAE 90.1 may be reviewed at: https://www.ashrae.org/standards-research--technology. Portions of Chapter 7 of ASHRAE 189.1 are reprinted in the District of Columbia Energy Conservation Code Supplement by permission of ASHRAE and ICC. District of Columbia Municipal Regulations Energy Conservation Code Supplement of 2017 – Commercial Provisions 12-I[CE] DCMR § 5.4