|MINNESOTA ENERGY CODE OVERVIEW
Energy Code Requirements Effective on Permits Applied for on or after April 15, 2000
Category 1 with Appliance Upgrades or 2000 Energy Code
|ENERGY CODE FACTS
During the 2000 legislative session, the legislature passed a bill that was signed into
law giving contractors and consumers the option of using Category 1 code with upgraded
appliances, as well as the 2000 energy code.
|Both Category 1 with upgraded appliances and the 2000 energy code are high standards
and both require mechanical ventilation.
Category 2 is NOT an option.
If the contractor or owner chooses the Category 1 code, direct vent, power vent or sealed
combustion appliances for furnace, water heater, or fireplace are required.
Both Category 1 and the 2000 energy codes were written by the Department of Public Service
(no merging with the Department of Commerce). The legislature did not write the energy
code, however, they amended Category 1 requirements.
THE FOLLOWING IS A SUMMARY OF THE ENERGY CODE
|Category 1 Mechanical & Appliance Requirements (Defined by Minnesota State
Statute, Chapter 407) Requires a mechanical ventilation system which replaces, by direct
or indirect means, air from habitable rooms with outdoor air. (This allows for the use of
exhaust only ventilation, as well as an air exchanger or heat recovery ventilator.)
Requires direct vent, power vent or sealed combustion furnace, water heater, or fireplace
If any single exhaust device (eg. Kitchen fan or dryer) over 300 cubic feet per minute
(cfm) is installed, a sealed combustion furnace must be installed or an alternative
make-up source must be used.
|Category 1 Envelope Requirements (Defined by Minnesota Rule, Chapter 7670)
Category 1 incorporates air sealing and wind wash measures and requires mechanical
ventilation. A Category 1 house is built to protect the performance of installed thermal
insulation from deterioration by moisture and wind wash. This protection is provided by a
continuous vapor retarder and air barrier on the interior and a continuous barrier on the
exterior protecting against wind wash. A mechanical ventilation system is required and
additional appliance requirements as described above are required. Envelope requirements
|Interior vapor retarder on insulated ceilings, walls and floors
|Continuous air barrier at all plumbing and heating penetrations
|Fire stops must be installed to block air movement into the attic
|Penetrations in the building envelope for electrical ant telecommunications equipment
(except for electrical boxes and fan housings) must be sealed to prevent air leakage.
|Wind wash barrier required at the exterior edge of attic insulation
|Wind wash barrier required at overhangs, such as cantilevered floors and bay windows
|Window and door frames must be sealed
|All exterior joints that may be sources of air intrusion must be sealed
|Rim joist must be sealed to prevent air leakage
|Tops of interior partition walls must be sealed to prevent air leakage
|Electrical boxes and fans must be sealed to prevent air leakage
|Between wall assemblies, rim joists, and foundations must be sealed to
prevent air leakage
|(Items 1-8 were always required under Category 2.)
The 2000 energy code provisions (Minnesota Rules, Chapter 7672) apply to buildings
classified as Groug R, Division 3 Occupancies which are Detached Single-Family and
Plans and specifications must demonstrate compliance with the following: exterior envelope
component material; U-values of windows, doors and skylights; R-values of insulating
materials; location of interior air barrier, vapor retarder, and wind wash barrier; air
sealing requirements; size and type of equipment; equipment controls; and other data
needed to indicate conformance with the code.
Foundation Walls and Slabs on Grade: Foundation walls enclosing conditioned space,
including exposed edges of slabs on grade, must be insulated to an R_% minimum from top of
the wall down to the top of the footing. Slabs on grade, including heated aprons located
outside of a building, must be insulated around the perimeter. The thermal insulation must
be a minimum or R-5. If foundation wall insulation is on the exterior, the portion from
the top of the foundation wall to six inches below grade must be covered by an approved
protective coating finish. If foundation wall insulation is on the interior, a moisture
barrier must be located between the insulation and the foundation wall from floor to
Wood framed components: All buildings must provide a continuous, durable interior
air barrier on the warm side of the building envelope. Insulated ceilings must have a
vertical clearance of not less than 6 inches from the outside edge of the exterior wall
top plate to the roof sheathing, and not less than R-19 insulation at the inside edge of
the top plate. Exterior corners must be framed so that insulation can be installed after
the exterior sheathing is installed. Intersections of interior partition walls with
exterior walls must be framed so that insulation can be installed between the partition
wall and exterior sheathing after the exterior sheathing is installed. Gaps between
framing which are less than one-half inch in width must be eliminated by securing the
framing members together, or must be insulated at the time of assembly. Whenever interior
framing meets an insulated ceiling or exterior wall, a continuous interior air barrier
must be installed on the ceiling or exterior wall before installation of interior framing
to allow continuity with adjacent interior air barriers.
Prior to installing a tub, shower or spa located at an exterior wall, insulation and a
continuously sealed interior air barrier must be installed on the exterior wall to allow
continuity with adjacent interior air barriers. Exterior wall intersections of wood,
masonry and other dissimilar materials must be sealed to maintain interior air barrier
Vapor Retarder: A vapor retarder, also known as a vapor barrier, must be installed
on the warm side of all walls and on all ceilings, rim joist areas and earth floors of
unvented crawl spaces. Polyethylene vapor retarders which are not cross-laminated must be
4-mils or thicker.
Wind Wash Barrier: Install barriers in specified locations to resist wind wash.
Wind wash barriers may be either rigid or flexible. Flexible wind wash material must meet
ASTM Standard E1677. The code does not require house wrap over the entire house. When a
sealed wind wash barrier is required, install caulk, gasketing, or exterior house wrap
material to prevent entry of wind and wind-driven rain. Install a rigid wind wash barrier
at the exterior edge of the exterior wall top plate. Extend the rigid barrier vertically
to the underside of the truss top chord, or for non-truss wood framing to within 3-1/2
inches of the roof deck, or to the top of the required ceiling insulation. A sealed wind
wash barrier must be installed at floors, overhangs, and floor rim joist areas separating
conditioned from unconditioned spaces. Sheathing joints which are not supported by framing
and framing joints which are not covered by sheathing must be sealed at the exterior side
of the joint. Sheathing penetrations must be sealed. A sealed wind wash barrier must be
installed between an attached garage and interior conditioned spaces.
Average U-value is 0.37 maximum for windows and glass doors except foundation windows 5.6
square feet and less. U-0.55 for skylights. U-0.51 for foundation windows 5.6 square feet
and less. U-values of windows, doors and skylights must be determined according to the
National Fenestration rating Council (NFRC). A durable exterior side infiltration and
weather seal and insulation must be installed at the time of fenestration product
installation around the perimeter of the product frame. In the new energy code summary
sheets, there is the cookbook table as well in the Mncheck computer software.
Heating Equipment and Ducts: Insulate ducts within concrete or in contact with the
ground to R-5 minimum. Insulate ducts from unconditioned spaces with R-8 minimum. Seal
ducts outside of the interior air barrier with a foil tape or mastic product meeting UL181
or equivalent. Use of cloth backed duct tape with rubber adhesive is specifically
prohibited for this application.
Service Water Heating: For water heaters without integral heat traps, insulate the
first three feet of both inlet and outlet pipe with 1/2 inch thick pipe insulation. Don't
install pipe insulation closer to a draft diverter than is recommended by the manufacturer
or safety codes. Insulate pipes in contact with concrete or earth with 1-inch minimum
A residential mechanical ventilation system is required in all new homes.
Ventilation requirements: Calculate the size (in cfm) of the required mechanical
ventilation system by multiplying the house conditioned square footage area (which
normally would include the basement) by 0.05. Calculate the people ventilation as 15 cfm
for each bedroom plus an additional 15 cfm (the people ventilation rate should not be less
than 45 cfm). The supplemental ventilation is simply the total ventilation computed as
above minus the people ventilation rate.
Equipment requirements: Fans providing the people ventilation (or all ventilation
fans if people ventilation is not separately identified) must be listed for continuous
operation, and their sound rating must not exceed 1.0 sones for surface mounted fans
(non-surface mounted fans may be 1.5 sones). Ventilation may be provided by systems using
a heat recovery ventilator (HRV), a mixing box, or individual fans. If an HRV is
installed, it must be tested and rated according to the Canadian standard CSA-439. There
is an exception for the cold weather performance part of this standard, and UL standard
1812 or equivalent. All HRVs must have a permanent label indicating the net air flow and
sensible recovery efficiency at outdoor conditions of both 32 degrees F and at ventilation
Distribution, installation, and certification requirements: The residential
mechanical ventilation system fans and ducts must be sized to provide the required
airflow. Seal all ducts outside the interior air barrier with a product meeting UL181 or
equivalent. If either the ventilation exhaust and supply ducts connect to furnace ductwork
then the furnace blower must provide an hourly average minimum flow rate of 0.15 cfm per
square foot of house area whenever the residential ventilation system is running. If both
exhaust and supply ventilation system ducts connect to furnace ductwork then the furnace
blower must run whenever the residential ventilation system is running.
PRESCRIPTIVE VS. PERFORMANCE
De-pressurization: The 2000 energy code requires that provision be made to limit
excessive depressurization of new homes with fuel burning appliances. Exception: No
specific provisions to limit depressurization are needed, if the dwelling contains only
sealed combustion appliances and the exhaust from the dryer, kitchen exhaust and larger
remaining exhaust does not exceed 425 cfm. However, ventilation must still be provided.
MINNESOTA ENERGY CODE DEVELOPMENT BACKGROUND
|The Legislature mandated the Minnesota have the most stringent energy code in the
|Department of Public Service adopts new energy code that tightens homes to save energy
in response to legislative mandate. Category 1 and Category 2 code goes into effect in
1994. The primary difference is that Category 1 requires mechanical ventilation. The
intent is to adopt Category 1 only in 1998.
|Department of Public Service starts rewriting rules and requests that the code
implementation be delayed until 1999 so new language can be developed. Department of
Public Service publishes new rules in October. BAM and other groups oppose the new code
due to complexity and conflicts with the mechanical code. As a result of opposition,
contested rulemaking hearings begin on December 19, 1997.
|Five administrative hearings on the code were completed on February 20, 1998. On May
12, the Administrative Law Judge ruled in favor of adopting the new rules. The
Commissioner of Public Service established the effective date of July 20, 1999.
In September, the Department of Administration began rewriting the mechanical code. As a
result of this process, they requested the Department of Public Service reopen rulemaking
on the new code in the mechanical requirement sections to eliminate conflicts between the
energy code and the mechanical code. These changes to the energy code passed in January
|BAM supported legislation that delayed the new energy code to April 15, 2000; removed
the 1991 mandate that Minnesota have the most stringent energy code in the nation; and
transferred the adoption process of the energy code from the Department of Public Service
to the Department of Administration. However, the development of the energy code remained
in the Department of Public Service. The Builders Association of Minnesota indicated that
we would not request another delay in the 2000 legislative session and would start to
develop training for the industry on the new code.
There was no action taken by the Department of Public Service or the Department of
Administration to address the change in law that Minnesota no longer is required to have
the most stringent energy code in the nation.
|The legislature passes two bills that affect the energy code in Minnesota. The Senator
Wiener/Representative Boudreau bill moves the development of the energy code from the
Department of Commerce (Public Service) to the Department of Administration. This is
critical since the Department of Administration is responsible for adoption and
enforcement of the energy code.
The Senator Limmer/Representative Bradley legislation allows both Category 1 with upgraded
appliances as well as the 2000 energy code. The legislation also requires the Department
of Administration to study the current and new energy code and report back to the
legislature by December 2001 with a cost benefit analysis.
Both the Category 1 and the 2000 energy code have appliance requirements. In the Category
1 option, fuel-burning equipment using non-solid fuels or space heating, service water
heating, or hearth products must be direct vent, power vent, or sealed combustion
In the 2000 energy code, there are 4 prescriptive paths that a contractor can follow. Path
0 is the least restrictive path, but also requires that all vented combustion appliances
be "sealed combustion". Not all direct vent furnaces and water heaters may meet
the definition of sealed combustion. On the Department of Commerce (Public Service) web site, there are letters from
manufacturers that indicate which appliances meet the definition of sealed combustion.
ENERGY CODE INFORMATION
For additional information, or to receive a Request for Interpretation forms, contact the
Energy Information Center at 651-296-5175 or 800-657-3710 or the Building Codes and
Standards Division at 651-205-4707.
Request for Interpretation forms may also be downloaded at www.commerce.state.mn.us.
Responses to current interpretations on the Minnesota Energy Code may also be obtained at