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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 (gas).

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 are:
1. Interior vapor retarder on insulated ceilings, walls and floors
2. Continuous air barrier at all plumbing and heating penetrations
3. Fire stops must be installed to block air movement into the attic
4. Penetrations in the building envelope for electrical ant telecommunications equipment (except for electrical boxes and fan housings) must be sealed to prevent air leakage.
5. Wind wash barrier required at the exterior edge of attic insulation
6. Wind wash barrier required at overhangs, such as cantilevered floors and bay windows
7. Window and door frames must be sealed
8. All exterior joints that may be sources of air intrusion must be sealed
9. Rim joist must be sealed to prevent air leakage
10. Tops of interior partition walls must be sealed to prevent air leakage
11. Electrical boxes and fans must be sealed to prevent air leakage
12. 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 Two-Family Dwellings.

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.


ENVELOPE
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 grade.

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 continuity.

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.


WINDOWS
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.


MECHANICAL SYSTEMS
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 insulation.


MECHANICAL VENTILATION
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 design conditions.

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

1991 The Legislature mandated the Minnesota have the most stringent energy code in the nation.
1993 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.
1997 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.
1998 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 1999.
1999 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.
2000 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.

APPLIANCE REQUIREMENTS
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 appliances.

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 that site.