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Descriptions: HERS BESTEST Tier 1 Test Cases

The following Tier 1 test cases are provided by the HERS BESTEST procedure:

  • Case L100: The Base Case Building. This is a 1539 sq.ft., single-story, wood-frame, fully-vented crawlspace home with 270 sq.ft. of single-glazed windows (distributed with 90 sq.ft. on the north and south faces and 45 sq.ft. on the east and west faces). The walls are insulated with R-11 insulation and the ceiling and floor are insulated with R-19 insulation. This is the case against which most other cases are compared to determine if the rating tool can accurately determine energy differences due to changes in building configuration.
  • Case L110: High Infiltration (1.5 ach). Exactly the same as Case L100 with the exception of the infiltration rate, which is increased from its base case value 0.67 air changes per hour (ach) to a value of 1.5 ach.
  • Case L120: Well Insulated Walls and Roof. Exactly the same as Case L100 except that the wall insulation is increased from R-11 to R-23 and the ceiling insulation is increased from R-19 to R-58.
  • Case L130: Double-Pane, Low-Emissivity Windows with Wood Frames. Exactly the same as Case L100 except that the single-glazed windows are replaced with high-efficiency windows having an overall U-factor of 0.30 and an overall Solar Heat Gain Coefficient (SHGC) of 0.335.
  • Case L140: Zero Window Area. Exactly the same as Case L100 except that the windows are replaced with wood frame walls having R-11 insulation.
  • Case L150: South-Oriented Windows. Exactly the same as Case L100 except that the entire 270 sq.ft. of windows is moved to the south face of the home.
  • Case L155: South-Oriented Windows with Overhang. Exactly the same as Case L150 except that an opaque overhang is added at the top of the south facing exterior wall. The overhang extends outward 2.5 feet and is positioned 1 foot above the top of the 5-foot high windows.
  • Case L160: East- and West-Oriented Windows. Exactly the same as Case L100 except that all the windows are moved to the east and west faces of the building with 50% (135 sq.ft.) on each face.
  • Case L170: No Internal Loads. Exactly the same as Case L100 except that the internal gains are reduced from 68,261 Btu/day to zero.
  • Case L200: Energy Inefficient. Exactly the same as Case L100 except for the following:
    • Infiltration rate is increased from 0.67 ach to 1.5 ach,
    • Exterior wall insulation is replaced by an air gap,
    • Crawlspace floor insulation is removed, and
    • Ceiling insulation is reduced from R-19 to R-11.
  • Case L202: Low Exterior Solar Absorptance. Exactly the same as Case L100 except that the solar absorptance of the roof and walls is reduced from 0.6 to 0.2.
  • Case L302: Uninsulated Slab-on-Grade. Exactly the same as Case L100 except that the floor system is changed from a fully-vented crawlspace to an uninsulated, concrete slab-on-grade.
  • Case L304: Insulated Slab-on-Grade. Exactly the same as Case L302 except that R-5.4 exterior foundation insulation is added around the slab perimeter.
  • Case L322: Uninsulated Basement. Exactly the same as Case L100 except that the floor system is changed from a fully-vented crawlspace to an uninsulated conditioned basement with 1-0" of the uninsulated basement wall and the uninsulated floor band joist exposed. This case is not used for cooling energy load results.
  • Case L324: Insulated Basement. Exactly the same as Case L322 except that R-11 insulation is added at the inside of the basement walls and the floor band joist. This case is not used for cooling energy load results.

With the exception of Cases L322 and L324, each of the above test cases is simulated in Colorado Springs, CO to evaluate heating energy loads and in Las Vegas, NV to evaluate cooling energy loads.