CODES

ADOPTS WITH AMENDMENTS:

International Energy Conservation Code 2012 (IECC 2012)

Important Disclaimer

2015 Minnesota Building Code Administration

2015 Minnesota Residential Energy Code

Chapter 1 [Re] Scope and Administration

Chapter 2 [Re] Definitions

Chapter 3 [Re] General Requirements

Chapter 4 [Re] Residential Energy Efficiency

Chapter 5 Referenced Standards

2015 Minnesota Commercial Energy Code

Chapter 1 [Ce] Scope and Administration

Chapter 2 [Ce] Definitions

Chapter 3 [Ce] General Requirements

Chapter 4 [Ce] Commercial Energy Efficiency

Chapter 5 Referenced Standards

Normative Appendix A

Normative Appendix B—building Envelope Climate Criteria

Normative Appendix C Methodology for Building Envelope Trade-Off Option in Subsection 5.6

Normative Appendix D Climatic Data

Informative Appendix E Informative References

Informative Appendix F Addenda Description Information

Normative Appendix G Performance Rating Method

This chapter applies to residential buildings.
Projects shall comply with Sections identified as “mandatory” and with either sections identified as “prescriptive” or the performance approach in Section R405.
A building certificate shall be completed and posted on or in the electrical distribution panel by the builder or registered design professional. The certificate shall not cover or obstruct the visibility of the circuit directory label, service disconnect label, or other required labels. The certificate shall list: the date the certificate is installed; the dwelling address; residential contractor name and contractor license number, or homeowner name, if acting as the general contractor; the predominant installed R-values, their location, and type of insulation installed in or on ceiling/roof, walls, rim/band joist, foundation, slab, basement wall, crawl space wall or floor, and ducts outside conditioned spaces; U-factors for fenestration and the solar heat gain coefficient (SHGC) of fenestration; and the results of any required duct system and building envelope air leakage testing done on the building. Where there is more than one value for each component, the certificate shall list the value covering the largest area. The certificate shall list the types, input ratings, manufacturers, model numbers and efficiencies of heating, cooling, and service water heating equipment. The certificate shall also list the structure's calculated heat loss, calculated cooling load, and calculated heat gain. Where an electric furnace or baseboard electric heater is installed in the residence, the certificate shall list “electric furnace” or “baseboard electric heater,” as appropriate. An efficiency shall not be listed for electric furnaces or electric baseboard heaters. The certificate shall list the mechanical ventilation system type, location, and capacity, and the building's designated continuous and total ventilation rates. The certificate shall also list the type, size, and location of any make-up air system installed and the location or future location of the radon fan.
The building thermal envelope shall meet the requirements of Sections R402.1.1 through R402.1.4.
The building thermal envelope shall meet the requirements of Table R402.1.1 based on the climate zone specified in Chapter 3, and the requirements contained in Section R402.2. Cast-in-place concrete and masonry block foundation walls shall be waterproofed according to IRC Section R406 and the following requirements:

1. The waterproofing shall extend from the top interior wall edge, across the top of the wall, and down the exterior wall face to the top of the footing. If a full width, closed-cell material is installed to create a seal between the sill plate and the top of the foundation wall, the installation is deemed to meet the requirements for the top of the wall waterproofing.

2. If the walls are exposed to the exterior environment, the waterproofing system shall have a rigid, opaque, and weather-resistant protective covering to prevent degradation of the waterproofing system. The protective covering shall cover the exposed waterproofing and extend a minimum of 6 inches (152 mm) below grade. The protective covering system shall be flashed in accordance with IRC Section R703.8 .

TABLE R402.1.1 INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENTa

CLIMATE
ZONE
FENESTRATI
ON
U-FACTORb
SKYLIGHTb
U-FACTOR
GLAZED
FENESTRATION
SHGCb, e
CEILINGj
R-VALUE
WOOD
FRAME
WALL
R-VALUEf
MASS WALL
R-VALUEi, g, h
FLOOR
R-VALUE
BASEMENT
WALL
R-VALUEc, i
SLAB
R-VALUE AND
DEPTHd
CRAWL
SPACE
WALL
R-VALUEc, i
60.320.55NR4920, 13+515/2030e1510, 3.5 ft15
70.320.55NR492119/2138e1510, 5 ft15
For SI: 1 foot = 304.8 mm.
a. R-values are minimums. U-factors and SHGC are maximums. When insulation is installed in a cavity that is less than the label or design thickness of the insulation, the installed R-value of the insulation shall not be less than the R-value specified in the table.
b. The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.
c. See Section R402.2.8.
d. Insulation R-values for heated slabs shall be installed to the depth indicated or to the top of the footing, whichever is less.
e. Or insulation sufficient to fill the framing cavity, R-19 minimum.
f. First value is cavity insulation, second is continuous insulation or insulated siding, so “13+5” means R-13 cavity insulation plus R-5 continuous insulation or insulated siding. If structural sheathing covers 40 percent or less of the exterior, continuous insulation R-value shall be permitted to be reduced by no more than R-3 in the locations where structural sheathing is used to maintain a consistent total sheathing thickness.
g. The second R-value applies when more than half the insulation is on the interior of the mass wall.
h. When using log-type construction for thermal mass walls the following applies:
(1) a minimum of a 7-inch diameter log shall be used; and
(2) the U-value of fenestration products shall be 0.29 overall on average or better.
i. See Section 402.2.8 . A minimum R-19 cavity insulation is required in wood foundation walls.
j. Roof/ceiling assemblies shall have a minimum 6-inch energy heel.
Any insulation assembly installed integral to the foundation walls shall be manufactured for that intended use and installed according to the manufacturer’s installation instructions.
Any insulation assembly installed on the exterior of the foundation walls and on the perimeter of slabs-on-grade that permits water drainage shall:

1. be made of water-resistant materials manufactured for that intended use;

2. be installed according to the manufacturer’s installation instructions;

3. comply with either ASTM C578, C612, or Cl029, as applicable; and

4. have a rigid, opaque, and weather-resistant protective covering to prevent the degradation of the insulation’s thermal performance. The protective covering shall cover the exposed exterior insulation and extend a minimum of 6 inches (152 mm) below grade. The insulation and protective covering system shall be flashed in accordance with IRC Section R703.8 .

Any insulation assembly installed on the exterior of the foundation walls or on the perimeter of slabs-on-grade that does not permit bulk water drainage shall:

1. be made of water-resistant materials manufactured for that intended use;

2. be installed according to the manufacturer’s installation instructions;

3. comply with either ASTM C578 or C1029, as applicable;

4. be covered with a 6-mil polyethylene slip sheet over the entire exterior surface; and

5. have a rigid, opaque, and weather-resistant protective covering to prevent degradation of the insulation’s thermal performance. The protective covering shall cover the exposed exterior insulation and extend a minimum of 6 inches (152 mm) below grade. The insulation and protective covering system shall be flashed in accordance with IRC Section R703.8 .

Any insulation assembly installed on the interior of foundation walls shall meet the following requirements:

1. Masonry foundation walls shall be drained through each masonry block core to an approved interior drainage system.

2. If a frame wall is installed, it shall not be in direct contact with the foundation wall.

3. The insulation assembly shall comply with the interior air barrier requirements of Section R402.4.

4. The insulation assembly shall comply with Section R402.1.1.5, R402.1.1.6, or R402.1.1.7, as applicable.

Rigid interior insulation shall comply with ASTM C578 or ASTM Cl289 and the following requirements:

1. For installation:

a. the insulation shall be in contact with the foundation wall surface;

b. vertical edges shall be sealed with acoustic sealant;

c. all interior joints, edges, and penetrations shall be sealed against air and water vapor penetration;

d. continuous acoustic sealant shall be applied horizontally between the foundation wall and the insulation at the top of the foundation wall; and

e. continuous acoustic sealant shall be applied horizontally between the basement floor and the bottom insulation edge.

2. The insulation shall not be penetrated by the placement of utilities, fasteners, or connectors used to install a frame wall, with the exception of through penetrations.

3. Through penetrations shall be sealed around the penetrating products.

Spray-applied interior foam insulation shall comply with the following:

1. Closed-cell foam:

a. the foam shall comply with ASTM C1029 and have a permeance not greater than 0.8, in accordance with ASTM E96 procedure A, and a permeance of not less than 0.3, in accordance with ASTM E96 procedure B.

b. the foam shall be sprayed directly onto the foundation wall surface. There shall be a 1-inch (25.4 mm) minimum gap between the foundation wall surface and any framing.

c. the insulation surface shall not be penetrated by the placement of utilities, fasteners, or connectors used to install a frame wall, with the exception of through penetrations.

d. through penetrations shall be sealed around the penetrating products.

2. Open-cell foam:

a. The foam shall be sprayed directly onto the foundation wall surface. There shall be a 1-inch (25.4 mm) minimum gap between the foundation wall surface and any framing.

b. The insulation surface shall not be penetrated by the placement of utilities, fasteners, or connectors used to install a frame wall, with the exception of through penetrations.

c. Through penetrations shall be sealed around the penetrating product.

d. A vapor retarder and air barrier shall be applied to the warm-in-winter side of the assembly with a permeance not greater than 1.0, in accordance with ASTM E96 procedure A, and a permeance not less than 0.3, in accordance with ASTM E96 procedure B.

Fiberglass batt insulation shall comply with the following:

1. The above-grade exposed foundation wall height shall not exceed 1.5 feet (457 mm).

2. The top and bottom plates shall be air sealed to the foundation wall surface and the basement floor.

3. A vapor retarder and air barrier shall be applied to the warm in winter side of the wall with a permeance not greater than 1.0 in accordance with ASTM E96 procedure A and a permeance not less than 0.3 in accordance with ASTM E96 procedure B meeting the following requirements:

a. the vapor and air barrier shall be sealed to the framing with construction adhesive or equivalent at the top and bottom plates and where the adjacent wall is insulated;

b. the vapor and air barrier shall be sealed around utility boxes and other penetrations; and

c. all seams in the vapor and air barrier shall be overlapped at least 6 inches (152 mm) and sealed with compatible sealing tape or equivalent.

Insulated foundation systems designed and installed under the performance option shall meet the requirements of this section and the foundation, basement, or crawl space wall equivalent U-factor from Table 402.1.3.

1. Water separation plane.
The foundation shall be designed and built to have a continuous water separation plane between the interior and exterior. The interior side of the water separation plane shall:

a. have a stable annual wetting and drying cycle whereby foundation wall system water (solid, liquid, and vapor) transport processes produce no net accumulation of ice or water over a full calendar year and the foundation wall system is free of absorbed water for at least 4 months over a full calendar year;

b. prevent conditions of moisture and temperature to prevail for a time period favorable to mold growth for the material used; and

c. prevent liquid water from the foundation wall system from reaching the foundation floor system at any time during a full calendar year.

2. Documentation.
The foundation insulation system designer shall provide documentation certified by a professional engineer licensed in Minnesota demonstrating how the requirements of this section are fulfilled. The foundation insulation system designer shall also specify the design conditions for the wall and the design conditions for the interior space for which the water separation plane will meet the requirements of this section. The foundation insulation system designer shall provide a label disclosing these design conditions. The label shall be posted according to Section R401.3.

3. Installation.
The water separation plane shall be designed and installed to prevent external liquid or capillary water flow across it after the foundation is backfilled.

4. Foundation air barrier.
The foundation insulation system shall be designed and installed to have a foundation air barrier system between the interior and the exterior. The foundation air barrier system shall be a material or combination of materials that is continuous with all joints sealed and is durable for the intended application. Material used for the foundation air barrier system shall have an air permeability not to exceed 0.004 ft3/min.ft2 under a pressure differential of 0.3 inches water (l.57 psf) (0.02 L/s.m2 at 75 Pa) as determined by either commonly accepted engineering tables or by being labeled by the manufacturer as having these values when tested according to ASTM E2178.

Insulation material used in layers, such as framing cavity insulation and insulating sheathing, shall be summed to compute the component R-value. The manufacturer’s settled R-value shall be used for blown insulation. Computed R-values shall not include an R-value for other building materials or air films.
An assembly with a U-factor equal to or less than that specified in Table R402.1.3 shall be permitted as an alternative to the R-value in Table R402.1.1.

TABLE R402.1.3 EQUIVALENT U-FACTORSa

CLIMATE
ZONE
FENESTRATION
U-FACTOR
SKYLIGHT
U-FACTOR
CEILING
U-FACTOR
FRAME
WALL
U-FACTOR
MASS WALL
U-FACTORb
FLOOR
U-FACTOR
BASEMENT
WALL
U-FACTOR
CRAWL
SPACE WALL
U-FACTOR
10.500.750.0350.0820.1970.0640.3600.477
20.400.650.0300.0820.1650.0640.3600.477
30.350.550.0300.0570.0980.0470.091c0.136
4 except Marine0.350.550.0260.0570.0980.0470.0590.065
5 and Marine 40.320.550.0260.0570.0820.0330.0500.055
60.320.550.0260.0480.0600.0330.0500.055
7 and 80.320.550.0260.0480.0570.0280.0500.055
a. Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source.
b. When more than half the insulation is on the interior, the mass wall U-factors shall be a maximum of 0.17 in Climate Zone 1, 0.14 in Climate Zone 2, 0.12 in Climate Zone 3, 0.087 in Climate Zone 4 except Marine, 0.065 in Climate Zone 5 and Marine 4, and 0.057 in Climate Zones 6 through 8.
c. Basement wall U-factor of 0.360 in warm-humid locations as defined by Figure R301.1 and Table R301.1.
If the total building thermal envelope UA (sum of U-factor times assembly area) is less than or equal to the total UA resulting from using the U-factors in Table R402.1.3 (multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table R402.1.1. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The SHGC requirements shall be met in addition to UA compliance.
In addition to the requirements of Section R402.1, insulation shall meet the specific requirements of Sections R402.2.1 through R402.2.12.
When Section R402.1.1 would require R-38 in the ceiling, R-30 shall be deemed to satisfy the requirement for R-38 wherever the full height of uncompressed R-30 insulation extends over the wall top plate at the eaves. Similarly, R-38 shall be deemed to satisfy the requirement for R-49 wherever the full height of uncompressed R-38 insulation extends over the wall top plate at the eaves. This reduction shall not apply to the U-factor alternative approach in Section R402.1.3 and the total UA alternative in Section R402.1.4.
Where Section R402.1.1 would require insulation levels above R-30 and the design of the roof/ceiling assembly does not allow sufficient space for the required insulation, the minimum required insulation for such roof/ceiling assemblies shall be R-30. This reduction of insulation from the requirements of Section R402.1.1 shall be limited to 500 square feet (46 m2) or 20 percent of the total insulated ceiling area, whichever is less. This reduction shall not apply to the U-factor alternative approach in Section R402.1.3 and the total UA alternative in Section R402.1.4.
For air permeable insulations in vented attics, a baffle shall be installed adjacent to soffit and eave vents. Baffles shall maintain an opening equal or greater than the size of the vent. The baffle shall extend over the top of the attic insulation. The baffle shall be permitted to be any solid material.
Access doors from conditioned spaces to unconditioned spaces (e.g., attics and crawl spaces) shall be weatherstripped and insulated to a level equivalent to the insulation on the surrounding surfaces. Access shall be provided to all equipment that prevents damaging or compressing the insulation. A wood framed or equivalent baffle or retainer is required to be provided when loose fill insulation is installed, the purpose of which is to prevent the loose fill insulation from spilling into the living space when the attic access is opened, and to provide a permanent means of maintaining the installed R-value of the loose fill insulation.
Mass walls for the purposes of this chapter shall be considered above-grade walls of concrete block, concrete, insulated concrete form (ICF), masonry cavity, brick (other than brick veneer), earth (adobe, compressed earth block, rammed earth) and solid timber/logs.
Steel-frame ceilings, walls, and floors shall meet the insulation requirements of Table R402.2.6 or shall meet the U-factor requirements of Table R402.1.3. The calculation of the U-factor for a steel-frame envelope assembly shall use a series-parallel path calculation method.

TABLE R402.2.6 STEEL-FRAME CEILING, WALL AND FLOOR INSULATION
(R-VALUE)

WOOD FRAME
R-VALUE
REQUIREMENT
COLD-FORMED STEEL
EQUIVALENT R-VALUEa
Steel Truss Ceilingsb
R-30R-38 or R-30 + 3 or R-26 + 5
R-38R-49 or R-38 + 3
R-49R-38 + 5
Steel Joist Ceilingsb
R-30R-38 in 2 × 4 or 2 × 6 or 2 × 8 R-49
in any framing
R-38R-49 in 2 × 4 or 2 × 6 or 2 × 8 or 2 × 10
Steel-Framed Wall 16″ O.C.
R-13R-13 + 4.2 or R-19 + 2.1 or R-21 + 2.8 or
R-0 + 9.3 or R-15 + 3.8 or R-21 + 3.1
R-13 + 3R-0 + 11.2 or R-13 + 6.1 or R-15 + 5.7 or
R-19 + 5.0 or R-21 + 4.7
R-20R-0 + 14.0 or R-13 + 8.9 or R-15 + 8.5 or
R-19 + 7.8 or R-19 + 6.2 or R-21 + 7.5
R-20 + 5R-13 + 12.7 or R-15 + 12.3 or R-19 + 11.6 or
R-21 + 11.3 or R-25 + 10.9
R-21R-0 + 14.6 or R-13 + 9.5 or R-15 + 9.1 or
R-19 + 8.4 or R-21 + 8.1 or R-25 + 7.7
Steel Framed Wall, 24″ O.C
R-13R-0 + 9.3 or R-13 + 3.0 or R-15 + 2.4
R-13 + 3R-0 + 11.2 or R-13 + 4.9 or R-15 + 4.3 or
R-19 + 3.5 or R-21 + 3.1
R-20R-0 + 14.0 or R-13 + 7.7 or R-15 + 7.1 or
R-19 + 6.3 or R-21 + 5.9
R-20 + 5R-13 + 11.5 or R-15 + 10.9 or R-19 + 10.1 or
R-21 + 9.7 or R-25 + 9.1
R-21R-0 + 14.6 or R-13 + 8.3 or R-15 + 7.7 or
R-19 + 6.9 or R-21 + 6.5 or R-25 + 5.9
Steel Joist Floor
R-13R-19 in 2 × 6, or R-19 + 6 in 2 × 8 or 2 × 10
R-19R-19 + 6 in 2 × 6, or R-19 + 12 in 2 × 8 or 2 × 10
a Cavity insulation R-value is listed first, followed by continuous insulation R-value.
b. Insulation exceeding the height of the framing shall cover the framing.
Floor insulation shall be installed to maintain permanent contact with the underside of the subfloor decking.
Walls associated with conditioned basements shall be insulated from the top of the basement wall down to 10 feet (3048 mm) below grade or to the top of the footing, whichever is less. Foundation insulation shall be installed according to the manufacturer’s installation instructions. Walls associated with unconditioned basements shall meet the requirements of this section unless the floor overhead is insulated in accordance with Sections R402.1.1 and R402.2.7 and the following requirements:

a. R-15 insulation for concrete and masonry foundations shall be installed according to R402.l.l.1 to R402.l.l.8 and a minimum of a R-10 shall be installed on the exterior of the wall. Interior insulation, other than closed cell spray foam, shall not exceed R-11. Foundations shall be waterproofed in accordance with the applicable provisions of the International Residential Code (IRC).

Exception: R-10 continuous insulation on the exterior of each foundation wall shall be permitted to comply with this code if the tested air leakage rate required in Section R402.4.1.2 does not exceed 2.6 air changes per hour and the total square feet between the finished grade and the top of each foundation wall does not exceed 1.5 multiplied by the total lineal feet of each foundation wall that encloses conditioned space. Interior insulation, other than closed cell spray foam, shall not exceed R-11. See footnote c to Table R402.2.l.

b. Minimum R-19 cavity insulation is required in wood foundation walls. See footnote 1 to Table R402.2.l.

Slab-on-grade floors with a floor surface less than 12 inches (305 mm) below grade shall be insulated in accordance with Table R402.1.1. The insulation shall extend downward from the top of the slab on the outside or inside of the foundation wall. Insulation located below grade shall be extended the distance provided in Table R402.1.1 by any combination of vertical insulation, insulation extending under the slab or insulation extending out from the building. Insulation extending away from the building shall be protected by pavement or by a minimum of 10 inches (254 mm) of soil. The top edge of the insulation installed between the exterior wall and the edge of the interior slab shall be permitted to be cut at a 45-degree (0.79 rad) angle away from the exterior wall. Slab-edge insulation is not required in jurisdictions designated by the code official as having a very heavy termite infestation.
As an alternative to insulating floors over crawl spaces, crawl space walls shall be permitted to be insulated when the crawl space is not vented to the outside. Crawl space wall insulation shall be permanently fastened to the wall and extend downward from the floor to the finished grade level and then vertically and/or horizontally for at least an additional 24 inches (610 mm). Exposed earth in unvented crawl space foundations shall be covered with a continuous Class I vapor retarder in accordance with the International Building Code or International Residential Code, as applicable. All joints of the vapor retarder shall overlap by 6 inches (153 mm) and be sealed or taped. The edges of the vapor retarder shall extend at least 6 inches (153 mm) up the stem wall and shall be attached to the stem wall.
Insulation shall not be required on the horizontal portion of the foundation that supports a masonry veneer.
All sunrooms enclosing conditioned space shall meet the insulation requirements of this code.
Exception: For sunrooms with thermal isolation, and enclosing conditioned space, the following exceptions to the insulation requirements of this code shall apply:

1. The minimum ceiling insulation R-values shall be R-19 in Climate Zones 1 through 4 and R-24 in Climate Zones 5 through 8; and

2. The minimum wall R-value shall be R-13 in all climate zones. Wall(s) separating a sunroom with a thermal isolation from conditioned space shall meet the building thermal envelope requirements of this code.

In addition to the requirements of Section R402, fenestration shall comply with Sections R402.3.1 through R402.3.6.
An area-weighted average of fenestration products shall be permitted to satisfy the U-factor requirements.
An area-weighted average of fenestration products more than 50-percent glazed shall be permitted to satisfy the SHGC requirements.
Up to 15 square feet (1.4 m2) of glazed fenestration per dwelling unit shall be permitted to be exempt from U-factor and SHGC requirements in Section R402.1.1. This exemption shall not apply to the U-factor alternative approach in Section R402.1.3 and the Total UA alternative in Section R402.1.4.
One side-hinged opaque door assembly up to 24 square feet (2.22 m2) in area is exempted from the U-factor requirement in Section R402.1.1. This exemption shall not apply to the U-factor alternative approach in Section R402.1.3 and the total UA alternative in Section R402.1.4.
All sunrooms enclosing conditioned space shall meet the fenestration requirements of this code.
Exception: For sunrooms with thermal isolation and enclosing conditioned space, in Climate Zones 4 through 8, the following exceptions to the fenestration requirements of this code shall apply:

1. The maximum fenestration U-factor shall be 0.45; and

2. The maximum skylight U-factor shall be 0.70. New fenestration separating the sunroom with thermal isolation from conditioned space shall meet the building thermal envelope requirements of this code.

Where some or all of an existing fenestration unit is replaced with a new fenestration product, including sash and glazing, the replacement fenestration unit shall meet the applicable requirements for U-factor and SHGC in Table R402.1.1.
The building thermal envelope shall be constructed to limit air leakage in accordance with the requirements of Sections R402.4.1 through R402.4.4.
The building thermal envelope shall comply with Sections R402.4.1.1 and R402.4.1.2. The sealing methods between dissimilar materials shall allow for differential expansion and contraction.
The components of the building thermal envelope as listed in Table R402.4.1.1 shall be installed in accordance with the manufacturer’s instructions and the criteria listed in Table R402.4.1.1, as applicable to the method of construction. Where required by the code official, an approved third party shall inspect all components and verify compliance.

TABLE R402.4.1.1 AIR BARRIER AND INSULATION INSTALLATION

COMPONENTCRITERIAa
Air barrier and thermal barrierA continuous air barrier shall be installed in the building envelope.
Exterior thermal envelope contains a continuous air barrier.
Breaks or joints in the air barrier shall be sealed.
Air-permeable insulation shall not be used as a sealing material.
Ceiling/atticThe air barrier in any dropped ceiling/soffit shall be aligned with the insulation and any
gaps in the air barrier sealed.
Access openings, drop down stair or knee wall doors to unconditioned attic spaces shall be sealed.
WallsCorners and headers shall be insulated and the junction of the foundation and sill plate
shall be sealed.
The junction of the top plate and top of exterior walls shall be sealed.
Exterior thermal envelope insulation for framed walls shall be installed in substantial
contact and continuous alignment with the air barrier.
Knee walls shall be sealed.
Windows, skylights and doorsThe space between window/door jambs and framing and skylights and framing shall
be sealed.
Rim joistsRim joists shall be insulated and include the air barrier.
Floors
(including above-garage and cantilevered floors)
Insulation shall be installed to maintain permanent contact with underside of subfloor
decking.
The air barrier shall be installed at any exposed edge of insulation.
Crawl space wallsWhere provided in lieu of floor insulation, insulation shall be permanently attached to
the crawlspace walls.
Exposed earth in unvented crawl spaces shall be covered with a Class I vapor retarder
with overlapping joints taped.
Shafts, penetrationsDuct shafts, utility penetrations, and flue shafts opening to exterior or unconditioned
space shall be sealed.
Narrow cavitiesBatts in narrow cavities shall be cut to fit, or narrow cavities shall be filled by insulation
that on installation readily conforms to the available cavity space.
Garage separationAir sealing shall be provided between the garage and conditioned spaces.
Recessed lightingRecessed light fixtures installed in the building thermal envelope shall be air tight, IC
rated, and sealed to the drywall.
Plumbing and wiringBatt insulation shall be cut neatly to fit around wiring and plumbing in exterior walls, or
insulation that on installation readily conforms to available space shall extend behind
piping and wiring.
Shower/tub on exterior wallExterior walls adjacent to showers and tubs shall be insulated and the air barrier installed
separating them from the showers and tubs.
Electrical/phone box on exterior wallsThe air barrier shall be installed behind electrical or communication boxes or air sealed
boxes shall be installed.
HVAC register bootsHVAC register boots that penetrate building thermal envelope shall be sealed to the
sub-floor or drywall.
FireplaceAn air barrier shall be installed on fireplace walls. Fireplaces shall have gasketed doors.
a. In addition, inspection of log walls shall be in accordance with the provisions of ICC-400.
The building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding 5 air changes per hour in Climate Zones 1 and 2, and 3 air changes per hour in Climate Zones 3 through 8. Testing shall be conducted with a blower door at a pressure of 0.2 inches w.g. (50 Pascals). Where required by the code official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. Testing shall be performed at any time after creation of all penetrations of the building thermal envelope.
During testing:

1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weatherstripping or other infiltration control measures;

2. Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures;

3. Interior doors, if installed at the time of the test, shall be open;

4. Exterior doors for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;

5. Heating and cooling systems, if installed at the time of the test, shall be turned off; and

6. Supply and return registers, if installed at the time of the test, shall be fully open.

New wood-burning fireplaces shall have tight-fitting flue dampers and outdoor combustion air.
Windows, skylights and sliding glass doors shall have an air infiltration rate of no more than 0.3 cfm per square foot (1.5 L/s/m2), and swinging doors no more than 0.5 cfm per square foot (2.6 L/s/m2), when tested according to NFRC 400 or AAMA/WDMA/CSA 101/I.S.2/A440 by an accredited, independent laboratory and listed and labeled by the manufacturer.
Exception: Site-built windows, skylights and doors.
Recessed luminaires installed in the building thermal envelope shall be sealed to limit air leakage between conditioned and unconditioned spaces. All recessed luminaires shall be IC-rated and labeled as having an air leakage rate not more than 2.0 cfm (0.944 L/s) when tested in accordance with ASTM E283 at a 1.57 psf (75 Pa) pressure differential. All recessed luminaires shall be sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.
The area-weighted average maximum fenestration U-factor permitted using tradeoffs from Section R402.1.4 or R405 shall be 0.48 in Climate Zones 4 and 5 and 0.40 in Climate Zones 6 through 8 for vertical fenestration, and 0.75 in Climate Zones 4 through 8 for skylights. The area-weighted average maximum fenestration SHGC permitted using tradeoffs from Section R405 in Climate Zones 1 through 3 shall be 0.50.
At least one thermostat shall be provided for each separate heating and cooling system.
Where the primary heating system is a forced-air furnace, at least one thermostat per dwelling unit shall be capable of controlling the heating and cooling system on a daily schedule to maintain different temperature set points at different times of the day. This thermostat shall include the capability to set back or temporarily operate the system to maintain zone temperatures down to 55°F (13°C) or up to 85°F (29°C). The thermostat shall initially be programmed with a heating temperature set point no higher than 70°F (21°C) and a cooling temperature set point no lower than 78°F (26°C).
Heat pumps having supplementary electric-resistance heat shall have controls that, except during defrost, prevent supplemental heat operation when the heat pump compressor can meet the heating load.
Ducts and air handlers shall be in accordance with Sections R403.2.1 through R403.2.3.
All exhaust, supply, and return air ducts and plenums shall be insulated according to Table R403.2.1.
For the purposes of Table R403.2.1, the following applies:

a. Insulation is only required in the conditioned space for a distance of 3 feet (914 mm) from the exterior or unconditioned space.

b. V means the vapor retarder in accordance with IMC Section 604.11 . When a vapor retarder is required, duct insulation required by this section shall be installed without respect to other building envelope insulation.

c. W means an approved weatherproof barrier.

TABLE R403.2.1 MINIMUM REQUIRED DUCT AND PLENUM
INSULATION FOR DWELLING UNITS

DUCT TYPE/LOCATIONREQUIREMENTS
Exterior of buildingR3.3, V, and W
Attics, garages, and ventilated crawl spacesR-8 and V
Outdoor air intakes within conditioned spacesR3.3 and V
Exhaust ducts within conditioned spaces R3.3 and V
Within cement slab or within groundR3.5 and V
Within conditioned spaces and in basements
with insulated walls
None Required
Ducts, air handlers, and filter boxes shall be sealed. Joints and seams shall comply with either the International Mechanical Code or International Residential Code, as applicable.
Exceptions:

1. Air-impermeable spray foam products shall be permitted to be applied without additional joint seals.

2. Where a duct connection is made that is partially inaccessible, three screws or rivets shall be equally spaced on the exposed portion of the joint so as to prevent a hinge effect.

3. Continuously welded and locking-type longitudinal joints and seams in ducts operating at static pressures less than 2 inches of water column (500 Pa) pressure classification shall not require additional closure systems.

Duct tightness shall be verified by either of the following:

1. Postconstruction test: Total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, including the manufacturer’s air handler enclosure. All register boots shall be taped or otherwise sealed during the test.

2. Rough-in test: Total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 square feet (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the system, including the manufacturer’s air handler enclosure. All registers shall be taped or otherwise sealed during the test. If the air handler is not installed at the time of the test, total leakage shall be less than or equal to 3 cfm (85 L/min) per 100 square feet (9.29 m2) of conditioned floor area.

Exception: The total leakage test is not required for ducts and air handlers located entirely within the building thermal envelope.
Air handlers shall have a manufacturer’s designation for an air leakage of no more than 2 percent of the design air flow rate when tested in accordance with ASHRAE 193.
Building framing cavities shall not be used as ducts or plenums.
Mechanical system piping capable of carrying fluids above 105°F (41°C) or below 55°F (13°C) shall be insulated to a minimum of R-3.
Piping insulation exposed to weather shall be protected from damage, including that caused by sunlight, moisture, equipment maintenance, and wind, and shall provide shielding from solar radiation that can cause degradation of the material. Adhesive tape shall not be permitted.
Energy conservation measures for service hot water systems shall be in accordance with Sections R403.4.1 and R403.4.2.
Circulating hot water systems shall be provided with an automatic or readily accessible manual switch that can turn off the hot-water circulating pump when the system is not in use.
).
Insulation for hot water pipe with a minimum thermal resistance (R-value) of R-3 shall be applied to the following:

1. Piping larger than 3/4 inch nominal diameter.

2. Piping serving more than one dwelling unit.

3. Piping from the water heater to kitchen outlets.

4. Piping located outside the conditioned space.

5. Piping from the water heater to a distribution manifold.

6. Piping located under a floor slab.

7. Buried piping.

8. Supply and return piping in recirculation systems other than demand recirculation systems.

9. Piping with run lengths greater than the maximum run lengths for the nominal pipe diameter given in Table R403.4.2.

All remaining piping shall be insulated to at least R-3 or meet the run length requirements of Table R403.4.2.

TABLE R403.4.2 MAXIMUM RUN LENGTH (feet)a

Nominal Pipe Diameter of Largest
Diameter Pipe in the Run (inch)
3/81/23/4> 3/4
Maximum Run Length3020105
For SI: 1 inch = 25.4 mm, 1 foot 304.8 mm.
a. Total length of all piping from the distribution manifold or the recirculation loop to a point of use.
The building shall be provided with a balanced mechanical ventilation system that is +/-10 percent of the system’s design capacity and meets the requirements of Section R403.5.5, which establishes the continuous and total mechanical ventilation requirements for dwelling unit ventilation. All conditioned unfinished basements, conditioned crawl spaces, and conditioned levels shall be provided with a minimum ventilation rate of 0.02 cfm (0.000566 m3/m) per square foot or a minimum of 1 supply duct and 1 return duct. The supply and return ducts shall be separated by 1/2 the diagonal dimension of the basement to avoid a short circuit of the air circulation. Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating.
Exception: Kitchen and bath fans that are not included as part of the mechanical ventilation system are exempt from these requirements.
Alterations to existing buildings are exempt from meeting the requirements of Section R403.5.

TABLE R403.5.1 MECHANICAL VENTILATION SYSTEM FAN EFFICACY

FAN LOCATIONAIR FLOW RATE MINIMUM
(CFM)
MINIMUM EFFICACY
(CFM/WATT)
AIR FLOW RATE MAXIMUM
(CFM)
Range hoodsAny2.8 cfm/wattAny
In-line fanAny2.8 cfm/wattAny
Bathroom, utility room101.4 cfm/watt< 90
Bathroom, utility room902.8 cfm/wattAny
For SI: 1 cfm = 28.3 L/min.
The mechanical ventilation system shall provide sufficient outdoor air to equal the total ventilation rate average for each 1-hour period in accordance with Table R403.5.2, or Equation R403.5.2, based on the number of bedrooms and square footage of conditioned space, including the basement and conditioned crawl spaces.
For the purposes of Table R403.5.2 and Section R403.5.3, the following applies:

a. Equation R403.5.2 Total ventilation rate: Total ventilation rate (cfm) = (0.02 × square feet of conditioned space) + [15 × (number of bedrooms + 1)].

b. Equation R403.5.2.1 Continuous ventilation rate: Continuous ventilation rate (cfm) = Total ventilation rate/2.

TABLE R403.5.2 NUMBER OF BEDROOMS

1234562
Conditioned space1 (in sq. ft.) Total/
Continuous
Total/
Continuous
Total/
Continuous
Total/
Continuous
Total/
Continuous
Total/
Continuous
1000-150060/4075/4090/45105/53120/60135/68
1501-200070/4085/43100/50115/58130/65145/73
2001-250080/4095/48110/55125/63140/70155/78
2501-300090/45105/53120/60135/68150/75165/83
3001-3500100/50115/58130/65145/73160/80175/88
3501-4000110/55125/63140/70155/78170/85185/93
4001-4500120/60135/68150/75165/83180/90195/98
4501-5000130/65145/73160/80175/88190/95205/103
5001-5500140/70155/78170/85185/93200/100215/108
5501-60002150/75165/83180/90195/98210/105225/113
1. Conditioned space includes the basement and conditioned crawl spaces.
2. If conditioned space exceeds 6,000 sq. ft. or there are more than 6 bedrooms, use Equation R403.5.2.
Continuous ventilation rate (CVR) is a minimum of 50 percent of the total ventilation rate (TVR). The CVR shall not be less than 40 cfm (1.13 m3/m) and shall provide a continuous average cfm rate according to Table R403.5.2 or according to Equation R403.5.2 for every 1-hour period. The portion of the ventilation system that is intended to be continuous may have automatic cycling controls to provide the average flow rate for each hour.
All balanced systems shall be balanced so that the air intake is within 10 percent of the exhaust output. A heat recovery ventilator (HRV) or energy recovery ventilator (ERV) shall meet either:

1. The requirements of HVI Standard 920, 72 hours minus 13°F (-l0°C) cold weather test; or

2. Certified by a registered professional engineer and installed per manufacturer’s installation instructions.

An HRV or ERV intended to comply with both the continuous and total ventilation rate requirements shall meet the rated design capacity of the continuous ventilation rate specified in Section R403.5.3 under low capacity and meet the total ventilation rate specified in Section R403.5.2 under high capacity.
Exception: The balanced system and HRV/ERV system may include exhaust fans to meet the intermittent ventilation rate. Surface mounted fans shall have a maximum 1.0 sone per HVI Standard 915.
All mechanical systems shall meet the requirements of Section R403.5.6. The mechanical ventilation system and its components shall also be installed according to the Minnesota Mechanical Code, Minnesota Rules, Chapter 1346, and the equipment manufacturer’s installation instructions.
Outdoor air shall be delivered to each habitable space by a forced air circulation system, separate duct system, or individual inlets.
When outdoor air is supplied directly through a forced air circulation system, the requirements of this section shall be met using one of the following methods:

a. When an outdoor air supply is not ducted to the forced air system, controls shall be installed to allow the forced air system to provide an average circulation flow rate each hour of not less than 0.15 cfm (0.00425 m3/m) per square foot of the conditioned floor area; or

b. When the outdoor air supply is ducted to the forced air system, the mixed air temperature shall not be less than the heating equipment manufacturer's installation instructions. The controls shall be installed to allow the forced air circulation system to provide an average flow rate not less than 0.075 cfm (0.00212 m3/m) per square foot of conditioned floor area.

When outdoor air is supplied directly to habitable spaces with an airflow of 20 cfm (0.57 m3/m) or greater, the system shall be designed and installed to temper incoming air to not less than 40°F (4°C) measured at the point of distribution into the space.
All mechanical ventilation system airflows greater than 30 cfm (0.85 m3/m) at the building exhaust or intake shall be tested and verified. The airflow verification results shall be made available to the building official upon request.
When used as part of the mechanical ventilation system, fans shall be capable of delivering the designed air flow at the point of air discharge or intake as determined by Section R403.5.2 and according to HVI Standard 916. Fans shall be designed and certified by the equipment manufacturer to be capable of continuous operation at the maximum fan-rated cfm. Surface mounted fans used to comply with the continuous ventilation requirement of the mechanical ventilation system shall have a maximum 1.0 sone, according to HVI Standard 915. Fans used to comply with the intermittent ventilation requirement of the mechanical ventilation system shall have a maximum 2.5 sone, according to HVI Standard 915. Mechanical ventilation system fans shall meet the efficacy requirements of Table R403.5.l .
Exception to sone requirements: Sone requirements do not apply to forced air circulation systems and remotely mounted fans. If the remotely mounted fan is not in a habitable space and there are at least 4 feet (1219 mm) of ductwork between the fan and grille, then the fan sone rating shall be 2.5 sone or less. Where mechanical ventilation fans are integral to tested and listed HVAC equipment, the fans shall be powered by an electronically commutated motor.
When two or more fans in a dwelling unit share a common duct, each fan shall be equipped with a backdraft damper to prevent recirculation of exhaust air into another room.
When air ducts are directly connected to the forced air circulation system, the outdoor air shall be supplied directly to the forced air circulation system, or the exhaust air shall be drawn directly from the forced air circulation system, but not both. To meet the mechanical ventilation system requirements, the air duct shall be installed according to the manufacturer’s installation instructions.
Exception: Both outdoor air and exhaust air may be connected to the forced air circulation system only if controls are installed to operate the forced air circulation system when the mechanical ventilation system is operating or other means are provided to prevent short circuiting of ventilation air in accordance with the manufacturer’s recommendations.
The mechanical ventilation system supply and exhaust ducts shall be provided with accessible backflow dampers to minimize flow to or from the outdoors when the ventilation system is off.
Exterior air intake openings shall be accessible for inspection and maintenance. Intake openings shall be located according to the Minnesota Mechanical Code, Minnesota Rules, Chapter 1346, and shall be covered with a corrosion-resistant screen of not less than 1/4-inch (6.4 mm) mesh. Intake openings shall be located at least 12 inches (305 mm) above adjoining grade level.
Exception: Combination air intake and exhaust hoods may be approved by the building official when specifically allowed by the equipment manufacturer’s installation instructions.
All mechanically supplied outdoor air shall have a filter with a designated minimum efficiency of MERV 4 as defined by ASHRAE Standard 52.2. The filter location shall be prior to the air entering the thermal conditioning components, blower, or habitable space. The filter shall be installed so it is readily accessible and facilitates regular service.
Mechanical ventilation system components shall be installed to minimize transmission of noise and vibration. The equipment manufacturer’s installation instructions shall be followed and any materials provided by the equipment manufacturer for installation shall be used. In the absence of specific materials or instructions, vibration dampening materials, such as rubber grommets and flexible straps, shall be used when connecting fans and heat exchangers to the building structure. Isolation duct connectors shall be used to mitigate noise transmission.
Balanced mechanical ventilation system controls shall comply with all the following:

1. When the mechanical ventilation system is not designed to operate whenever the forced air circulation system is operating, the mechanical ventilation system shall incorporate an accessible backflow damper to prevent flow from the outside when the mechanical ventilation system is off.

2. Controls shall be compatible with the mechanical ventilation system, its components, and the manufacturer’s installation and operating instructions.

3. Controls shall be installed to operate the mechanical ventilation system as designed.

4. Each control shall be readily accessible to occupants and shall be labeled to indicate the control’s function.

All ventilation intake and exhaust outlets shall include permanent, weather-resistant identification labels on the building’s exterior.
Documentation, which includes proper operation and maintenance instructions, shall accompany all mechanical ventilation systems. The documentation shall be in a conspicuous and readily accessible location.

A. HVAC equipment shall be sized according to the ACCA Manual S or an equivalent method, based on the building’s heating and cooling load calculations by using ASHRAE Handbook of Fundamentals or the ACCA Manual J. Oversizing of heating equipment shall not exceed 40 percent of the calculated load requirements and oversizing of cooling equipment shall not exceed 15 percent of the calculated load requirements.

B. Design conditions shall be determined according to Table 403.5.17. Design condition adjustments may be determined by the building official if local climates differ from the tabulated temperatures based on local climate data.

TABLE R403.5.17 CLIMATIC DATA DESIGN CONDITIONS

CITYSUMMER Db/Wb °FWINTER Db °F
Aitkin82/72-24
Albert Lea85/72-15
Alexandria86/70-21
Bemidji84/68-24
Cloquet82/68-20
Crookston84/70-27
Duluth81/67-20
Ely82/68-29
Eveleth82/68-26
Faribault86/73-16
Fergus Falls86/71-21
Grand Rapids81/67-23
Hibbing82/68-19
International Falls83/67-28
Litchfield85/71-18
Little Falls86/71-20
Mankato86/72-15
Minneapolis/St. Paul88/72-15
Montevideo86/72-17
Mora84/70-21
Morris84/72-21
New Ulm87/73-15
Owatonna86/73-16
Pequot Lakes84/68-23
Pipestone85/73-15
Redwood Falls89/73-17
Rochester85/72-17
Roseau82/70-29
St. Cloud86/71-20
Thief River Falls82/68-25
Tofte75/61-14
Warroad83/67-29
Wheaton84/71-20
Willmar85/71-20
Winona88/74-13
Worthington84/71-14
For SI: °C = [(°F)-32]/1.8.
Db = dry bulb temperature, degrees Fahrenheit.
Wb = wet bulb temperature, degrees Fahrenheit.
Heating and cooling equipment shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies.
Systems serving multiple dwelling units shall comply with Sections C403 and C404 of the IECC—Commercial Provisions in lieu of Section R403.
Snow- and ice-melting systems, supplied through energy service to the building, shall include automatic controls capable of shutting off the system when the pavement temperature is above 50°F, and no precipitation is falling and an automatic or manual control that will allow shutoff when the outdoor temperature is above 40°F.
Pools and inground permanently installed spas shall comply with Sections R403.9.1 through R403.9.3.
All heaters shall be equipped with a readily accessible on-off switch that is mounted outside of the heater to allow shutting off the heater without adjusting the thermostat setting. Gas-fired heaters shall not be equipped with constant burning pilot lights.
Time switches or other control method that can automatically turn off and on heaters and pumps according to a preset schedule shall be installed on all heaters and pumps. Heaters, pumps and motors that have built in timers shall be deemed in compliance with this requirement.
Exceptions:

1. Where public health standards require 24-hour pump operation.

2. Where pumps are required to operate solar- and waste-heat-recovery pool heating systems.

Heated pools and inground permanently installed spas shall be provided with a vapor-retardant cover.
Exception: Pools deriving over 70 percent of the energy for heating from site-recovered energy, such as a heat pump or solar energy source computed over an operating season.
Installation of photovoltaic modules and systems shall meet the requirements of Minnesota Rules, Chapter 1315.
A minimum of 75 percent of the lamps in permanently installed lighting fixtures shall be high-efficacy lamps or a minimum of 75 percent of the permanently installed lighting fixtures shall contain only high efficacy lamps.
Exception: Low-voltage lighting shall not be required to utilize high-efficiency lamps.
Fuel gas lighting systems shall not have continuously burning pilot lights.
This section establishes criteria for compliance using simulated energy performance analysis. Such analysis shall include heating, cooling, and service water heating energy only.
Compliance with this section requires that the mandatory provisions identified in Section R401.2 be met. All supply and return ducts not completely inside the building thermal envelope shall be insulated to a minimum of R-6.
Compliance based on simulated energy performance requires that a proposed residence (proposed design) be shown to have an annual energy cost that is less than or equal to the annual energy cost of the standard reference design. Energy prices shall be taken from a source approved by the code official, such as the Department of Energy, Energy Information Administration’s State Energy Price and Expenditure Report. Code officials shall be permitted to require time-of-use pricing in energy cost calculations.
Exception: The energy use based on source energy expressed in Btu or Btu per square foot of conditioned floor area shall be permitted to be substituted for the energy cost. The source energy multiplier for electricity shall be 3.16. The source energy multiplier for fuels other than electricity shall be 1.1.
Documentation of the software used for the performance design and the parameters for the building shall be in accordance with Sections R405.4.1 through R405.4.3.
Documentation verifying that the methods and accuracy of the compliance software tools conform to the provisions of this section shall be provided to the code official.
Compliance software tools shall generate a report that documents that the proposed design complies with Section R405.3. The compliance documentation shall include the following information:

1. Address or other identification of the residence;

2. An inspection checklist documenting the building component characteristics of the proposed design as listed in Table R405.5.2(1). The inspection checklist shall show results for both the standard reference design and the proposed design, and shall document all inputs entered by the user necessary to reproduce the results;

3. Name of individual completing the compliance report; and

4. Name and version of the compliance software tool.

Exception: Multiple orientations. When an otherwise identical building model is offered in multiple orientations, compliance for any orientation shall be permitted by documenting that the building meets the performance requirements in each of the four cardinal (north, east, south and west) orientations.
The code official shall be permitted to require the following documents:

1. Documentation of the building component characteristics of the standard reference design.

2. A certification signed by the builder providing the building component characteristics of the proposed design as given in Table R405.5.2(1).

3. Documentation of the actual values used in the software calculations for the proposed design.

Calculations of the performance design shall be in accordance with Sections R405.5.1 and R405.5.2.
Except as specified by this section, the standard reference design and proposed design shall be configured and analyzed using identical methods and techniques.
The standard reference design and proposed design shall be configured and analyzed as specified by Table R405.5.2(1). Table R405.5.2(1) shall include by reference all notes contained in Table R402.1.1.

TABLE R405.5.2(1) SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS

BUILDING COMPONENT STANDARD REFERENCE DESIGN PROPOSED DESIGN
Above-grade wallsType: mass wall if proposed wall is mass; otherwise wood frame.
Gross area: same as proposed
U-factor: from Table R402.1.3
Solar absorptance = 0.75
Remittance = 0.90
As proposed
As proposed
As proposed
As proposed
As proposed
Basement and crawl space wallsType: same as proposed
Gross area: same as proposed
U-factor: from Table R402.1.3, with insulation layer on interior side of walls.
As proposed
As proposed
As proposed
Above-grade floorsType: wood frame
Gross area: same as proposed
U-factor: from Table R402.1.3
As proposed
As proposed
As proposed
CeilingsType: wood frame
Gross area: same as proposed
U-factor: from Table R402.1.3
As proposed
As proposed
As proposed
RoofsType: composition shingle on wood sheathing
Gross area: same as proposed
Solar absorptance = 0.75
Emittance = 0.90
As proposed
As proposed
As proposed
As proposed
AtticsType: vented with aperture = 1 ft2 per 300 ft2 ceiling areaAs proposed
FoundationsType: same as proposed foundation wall area above and below grade and soil characteristics: same as proposed.As proposed
As proposed
DoorsArea: 40 ft2
Orientation: North
U-factor: same as fenestration from Table R402.1.3.
As proposed
As proposed
As proposed
GlazingaTotal areab =
(a) The proposed glazing area; where proposed glazing area is less than
15% of the conditioned floor area.
(b) 15% of the conditioned floor area; where the proposed glazing area is
15% or more of the conditioned floor area.
As proposed
Orientation: equally distributed to four cardinal compass orientations
(N, E, S & W).
As proposed
U-factor: from Table R402.1.3 As proposed
SHGC: From Table R402.1.1 except that for climates with no requirement (NR) SHGC = 0.40 shall be used.
Interior shade fraction: 0.92-(0.21 × SHGC for the standard reference design)
External shading: none
As proposed
0.92-(0.21 × SHGC as proposed)
As proposed
SkylightsNoneAs proposed
Thermally isolated sunroomsNoneAs proposed

(continued)

TABLE R405.5.2(1)—continued
SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS

BUILDING COMPONENTSTANDARD REFERENCE DESIGNPROPOSED DESIGN
Air exchange rateAir leakage rate of 5 air changes per hour in Climate Zones 1 and 2,
and 3 air changes per hour in Climate Zones 3 through 8 at a pressure
of 0.2 inches w.g (50 Pa). The mechanical ventilation rate shall be in
addition to the air leakage rate and the same as in the proposed design,
but no greater than 0.01 × CFA + 7.5 × (Nbr + 1)
where:
CFA = conditioned floor area
Nbr = number of bedrooms
Energy recovery shall not be assumed for mechanical ventilation.
For residences that are not
tested, the same air leakage rate
as the standard reference design.
For tested residences, the measured air exchange ratec.
The mechanical ventilation rated
shall be in addition to the air
leakage rate and shall be as proposed.
Mechanical ventilationNone, except where mechanical ventilation is specified by the proposed design, in which case:
Annual vent fan energy use:
kWh/yr = 0.03942 × CFA + 29.565 × (Nbr +1)
where:
CFA = conditioned floor area
Nbr = number of bedrooms
As proposed
Internal gainsIGain = 17,900 + 23.8 × CFA + 4104 × Nbr (Btu/day per dwelling unit)Same as standard reference design.
Internal massAn internal mass for furniture and contents of 8 pounds per square foot
of floor area.
Same as standard reference
design, plus any additional mass
specifically designed as a thermal
storage elemente but not
integral to the building envelope
or structure.
Structural massFor masonry floor slabs, 80% of floor area covered by R-2 carpet and
pad, and 20% of floor directly exposed to room air.

As proposed
For masonry basement walls, as proposed, but with insulation required
by Table R402.1.3 located on the interior side of the walls
As proposed
For other walls, for ceilings, floors, and interior walls, wood frame
construction
As proposed
Heating systemsf, gAs proposed for other than electric heating without a heat pump.
Where the proposed design utilizes electric heating without a heat
pump the standard reference design shall be an air source heat pump
meeting the requirements of Section R403 of the IECC—Commercial
Provisions.
Capacity: sized in accordance with Section R403.6.
As proposed
Cooling systemsf, hAs proposed
Capacity: sized in accordance with Section R403.6.
As proposed
Service water Heatingf, g, h, iAs proposed
Use: same as proposed design
As proposed
gal/day = 30 + (10 × Nbr)
Thermal distribution systemsThermal distribution system
efficiency shall be as tested or as
specified in Table R405.5.2(2) if
not tested. Duct insulation shall
be as proposed.
ThermostatType: Manual, cooling temperature setpoint = 75°F;
Heating temperature setpoint = 72°F
Same as standard reference
For SI: 1 square foot = 0.93 m2, 1 British thermal unit = 1055 J, 1 pound per square foot = 4.88 kg/m2, 1 gallon (U.S.) = 3.785 L, °C = (°F-3)/1.8, 1 degree = 0.79 rad.
a. Glazing shall be defined as sunlight-transmitting fenestration, including the area of sash, curbing or other framing elements, that enclose conditioned space. Glazing includes the area of sunlight-transmitting fenestration assemblies in walls bounding conditioned basements. For doors where the sunlight-transmitting opening is less than 50 percent of the door area, the glazing area is the sunlight transmitting opening area. For all other doors, the glazing area is the rough frame opening area for the door including the door and the frame.
b. For residences with conditioned basements, R-2 and R-4 residences and townhouses, the following formula shall be used to determine glazing area:
AF = As × FA × F
where:
AF = Total glazing area.
As = Standard reference design total glazing area.
FA = (Above-grade thermal boundary gross wall area)/(above-grade boundary wall area + 0.5 × below-grade boundary wall area).
F = (Above-grade thermal boundary wall area)/(above-grade thermal boundary wall area + common wall area) or 0.56, whichever is greater.
and where:
Thermal boundary wall is any wall that separates conditioned space from unconditioned space or ambient conditions.
Above-grade thermal boundary wall is any thermal boundary wall component not in contact with soil.
Below-grade boundary wall is any thermal boundary wall in soil contact.
Common wall area is the area of walls shared with an adjoining dwelling unit.
L and CFA are in the same units.
c. Where required by the code official, testing shall be conducted by an approved party. Hourly calculations as specified in the ASHRAE Handbook of Fundamentals, or the equivalent shall be used to determine the energy loads resulting from infiltration.
d. The combined air exchange rate for infiltration and mechanical ventilation shall be determined in accordance with Equation 43 of 2001 ASHRAE Handbook of Fundamentals, page 26.24 and the “Whole-house Ventilation” provisions of 2001 ASHRAE Handbook of Fundamentals, page 26.19 for intermittent mechanical ventilation.
e. Thermal storage element shall mean a component not part of the floors, walls or ceilings that is part of a passive solar system, and that provides thermal storage such as enclosed water columns, rock beds, or phase-change containers. A thermal storage element must be in the same room as fenestration that faces within 15 degrees (0.26 rad) of true south, or must be connected to such a room with pipes or ducts that allow the element to be actively charged.
f. For a proposed design with multiple heating, cooling or water heating systems using different fuel types, the applicable standard reference design system capacities and fuel types shall be weighted in accordance with their respective loads as calculated by accepted engineering practice for each equipment and fuel type present.
g. For a proposed design without a proposed heating system, a heating system with the prevailing federal minimum efficiency shall be assumed for both the standard reference design and proposed design.
h. For a proposed design home without a proposed cooling system, an electric air conditioner with the prevailing federal minimum efficiency shall be assumed for both the standard reference design and the proposed design.
i. For a proposed design with a nonstorage-type water heater, a 40-gallon storage-type water heater with the prevailing federal minimum energy factor for the same fuel as the predominant heating fuel type shall be assumed. For the case of a proposed design without a proposed water heater, a 40-gallon storage-type water heater with the prevailing federal minimum efficiency for the same fuel as the predominant heating fuel type shall be assumed for both the proposed design and standard reference design.

TABLE R405.5.2(2) DEFAULT DISTRIBUTION SYSTEM EFFICIENCIES FOR PROPOSED DESIGNSa

DISTRIBUTION SYSTEM CONFIGURATION AND CONDITIONFORCED AIR SYSTEMSHYDRONIC SYSTEMSb
Distribution system components located in unconditioned space0.95
Untested distribution systems entirely located in conditioned spacec0.881
“Ductless“ systemsd1
For SI: 1 cubic foot per minute = 0.47 L/s, 1 square foot = 0.093m2, 1 pound per square inch = 6895 Pa, 1 inch water gauge = 1250 Pa.
a. Default values given by this table are for untested distribution systems, which must still meet minimum requirements for duct system insulation.
b. Hydronic systems shall mean those systems that distribute heating and cooling energy directly to individual spaces using liquids pumped through closed-loop piping and that do not depend on ducted, forced airflow to maintain space temperatures.
c. Entire system in conditioned space shall mean that no component of the distribution system, including the air-handler unit, is located outside of the conditioned space.
d. Ductless systems shall be allowed to have forced airflow across a coil but shall not have any ducted airflow external to the manufacturer’s air-handler enclosure.
Calculation software, where used, shall be in accordance with Sections R405.6.1 through R405.6.3.
Calculation procedures used to comply with this section shall be software tools capable of calculating the annual energy consumption of all building elements that differ between the standard reference design and the proposed design and shall include the following capabilities:

1. Computer generation of the standard reference design using only the input for the proposed design. The calculation procedure shall not allow the user to directly modify the building component characteristics of the standard reference design.

2. Calculation of whole-building (as a single zone) sizing for the heating and cooling equipment in the standard reference design residence in accordance with Section R403.6.

3. Calculations that account for the effects of indoor and outdoor temperatures and part-load ratios on the performance of heating, ventilating and air-conditioning equipment based on climate and equipment sizing.

4. Printed code official inspection checklist listing each of the proposed design component characteristics from Table R405.5.2(1) determined by the analysis to provide compliance, along with their respective performance ratings (e.g., R-value, U-factor, SHGC, HSPF, AFUE, SEER, EF, etc.).

Performance analysis tools meeting the applicable sections of Section R405 shall be permitted to be approved. Tools are permitted to be approved based on meeting a specified threshold for a jurisdiction. The code official shall be permitted to approve tools for a specified application or limited scope.
When calculations require input values not specified by Sections R402, R403, R404 and R405, those input values shall be taken from an approved source.
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