Official Nebraska Government Web site
Nebraska Energy Building Code
KNOX COUNTY
ENERGY BUILDING CODES


Cities and counties may adopt codes that differ from the Nebraska Energy Code, however, state law requires the adopted code to be equivalent to the Nebraska Energy Code.

Bloomfield
 
Energy Codes in Other Areas of Knox County

The Nebraska Energy Code applies in other areas of Knox County.
Copies of the Nebraska Energy Code (2009 International Energy Conservation Code) can be purchased through the International Code Council’s website and bookstore.

Options for Meeting the Residential Building Envelope Requirements of the Nebraska Energy Code

A. The Prescriptive Package Option - outlined in the table below may be used to ensure compliance with the Building Envelope requirements of the Nebraska Energy Code.

Windows

Insulation

Foundation

Fenestration U-Factor

Skylight U-factor

Glazed Fenestration SHGC

Ceiling R-Value

Wood Frame Wall
R-Value

Mass Wall
R-Value

Floor
R-Value

Basement Wall
R-Value

Slab
R-Value and Depth

Crawl Space Wall
R-Value

0.35

0.60

NR

38

20 or 13+5

13/17

30

10/13

10, 2 ft

10/13


Table Notes:
  • R-Values are minimums.  U-Values are maximums.  R-19 batts compressed into a nominal 2x6 framing cavity such that the R-value is reduced by R-1 or more shall be marked with the compressed batt R-value in addition to the full thickness R-value.
  • The fenestration U-factor column excludes skylights.
  • “10/13” for Basement Wall Insulation values means R-10 continuous insulated sheathing on the interior or exterior of the home or R-13 cavity insulation at the interior of the basement wall.
  • R-5 shall be added to the required slab edge R-Value for heated slabs.
  • Insulation sufficient to fill the floor framing cavity (with a minimum of an R-19) can replace the required R-30 Floor R-Value where framing depth is limited.
  • “13+5” for Wood Frame Wall Insulation values means R-13 cavity insulation plus R-5 insulated sheathing.  If structural sheathing covers 25% or less of the exterior, insulated sheathing is not required where structural sheathing is used.  If structural sheathing covers more than 25% of the exterior, structural sheathing shall be supplemented with insulated sheathing of at least R-2.
  • For Mass Walls, R-17 applies when more than half of the insulation is on the interior of the mass wall.

B. The Simulated Performance Option – Software programs may be used to show compliance with the Building Envelope requirements of the Nebraska Energy Code.  RESCheck is a software program that is available for free at the U.S. Department of Energy’s Building Energy Code website.

Additional Residential Building Envelope Notes

  • R-30 shall be deemed to satisfy the R-38 Ceiling Insulation requirement where ever the full height of uncompressed R-30 insulation extends over the wall top plate at the eaves.  (Prescriptive Package Only)
  • Where the design of the roof/ceiling assembly does not allow sufficient space for the R-38 insulation, R-30 may be substituted.  But this reduction in R-vale shall be limited to 500 square feet or 20% of the total insulated ceiling area, whichever is less. (Prescriptive Package Only)
  • Access doors from conditioned space to unconditioned space shall be weatherstripped and insulated to a level equivalent to the surrounding surfaces.
  • The Table provided does not apply to steel framed ceilings, walls or floors systems.
  • 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 10 feet below grade or to the basement floor, whichever is less. 
  • Walls associated with unconditioned basements shall meet the insulation requirements unless the floor overhead is appropriately insulated.
  • The insulation on Slab on Grade floors shall extend downward from the top of the slab on the outside or inside of the foundation wall. 
  • The top edge of Slab on Grade insulation installed between the exterior wall and the edge of the interior slab may be cut at a 45 degree angle away from the exterior wall.
  • An area weighted average of fenestration products shall be permitted to satisfy the U-factor requirements.
  • Up to 15 square feet of glazed fenestration per dwelling unit may be exempted from the U-factor requirement.
  • One side-hinged opaque door assembly up to 24 square feet in area may be exempted from the u-factor requirement.
  • The building thermal envelope shall be durably sealed to limit infiltration with compliance demonstrated and documented with either a visual inspection using the attached Air Barrier and Insulation Inspection Component Criteria Checklist completed by a code official or a responsible party independent from the installer of the insulation or with a blower door infiltration test.  
  • Wood-burning fireplaces shall have gasketed doors and outdoor combustion air.
  • All recessed lighting shall be IC-rated and labeled as meeting ASTM E-85 with no more than 2.0 cfm of air movement from the conditioned space into the ceiling cavity.
  • All recessed lighting shall be sealed with a gasket or caulk between the housing and the interior wall or ceiling covering.

Additional Residential Mandatory Requirements of the Nebraska Energy Code

  • At least one thermostat shall be provided for each separate heating and cooling system.
  • When the primary heating system is a forced air furnace a programmable thermostat is required.
  • Heat pumps with supplementary electric resistance heating must be equipped with controls that prevent heater operation when the heating load is capable of being met by the heat pump.
  • Supply duct work in unconditioned attic or outside of the building envelope must be R-8 insulation.
  • Return duct work in unconditioned attic or outside of the building envelope must be R-6 insulation.
  • All ductwork must be sealed.
  • Duct leakage pressure testing is required if any part of the mechanical system (including ductwork) is located outside of the conditioned space.
  • Heating and cooling systems must be sized appropriately in accordance with Section M1401.3 of the International Residential Code.
  • Building framing cavities shall not be used as supply ducts.
  • Circulating hot water systems must be insulated to at least an R-2.
  • A minimum of 50% of the lamps in permanently installed light fixtures shall be high-efficacy lamps.
  • Additional requirements are established for pool and snow melt systems.
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