This conventional energy code compliance check list may be used for the following projects:
New single family residences,
Additions to existing residence or duplexes, and
Conversion of unconditioned space to conditioned space in residence and duplexes.
Glazing Percent of Gross Wall Area* 8% 12% 15% 18% 20% 25%
Insulation:
Exterior Wall R-1 1 R-1 I R-13 R-1 3 R-13 R-1 3
Under floor (over unconditioned spaces) R-1 I R-1 I R-1 I R-1 1 R-1 1 R-1 3
Attics & knee walls (ceilings) R-19 R-19 R-26 R-30 R-30 R-30
Ducts in attic or outside building R-8 R-8 R-8 R-8 R-8 R-8
Ductsin unconditioned spaces (crawl) R-6 R-6 R-6 R-6. R-6 R-6
Glazing U-factor (max.) any 0.75 0 .75 0.65 0.6 0.52
Double pane glazing with SHGC of .4 or less, thermal break if metal
Equipment efficienty ratings must meet or exceed current NAECA standards for water heater, heater, and air conditioner.
Duct connections must be properly sealed with mastic.
Caulking and weatherstripping must be properly installed.
Architect or engineer designs and calculations or a chapter 4 analysis based upon the 2000 International Energy Conservation Code with 2001 Supplements and local amendments are acceptable alternatives to the conventional energy code compliance
NEW TEXAS RESIDENTIAL BUILDING AND ENERGY CODE REQUIREMENTS AS OF 2002
In 2001, the Texas legislature passed two bills which affect building construction and energy-efficiency in the State of Texas:
Senate Bill 365: 2000 International Residential Code [IRC]
By January 1, 2002, all municipalities,(incorporated towns) in the State of Texas must adopt this building code for residential construction. Municipalities must adopt the Nation Electrical Code (NEC) for residential building. Both codes apply to new and remodeling.
Senate Bill 5: Energy Chapter (11) of the IRC for single-family residential and the 2000 International Energy Conservation Code [IECC], applies to all construction in the entire of Texas-residential, commercial and industrial, in both incorporated and unincorporated as of, September 1, 2002.
Energy Chapter [11] of the IRC can be used only for very limited applications. Chapter 11 can be applied only if the building’s glazing area does not exceed 15% of the area of the exterior walls for single-family or duplex or does not exceed 25% for townhouses. It is a prescriptive method and all applicable requirements of this chapter must be met. International Energy Conservation Code must be used for all other cases.
It can be met by one of three ways (no change in Austin):
1 .Prescriptive. Method [IECC, chapter 6]
Tables based on building type and glass area are provided.
Simplest, but only applicable to buildings within the same glazing limits as IRC Chap. 11 (see above)
2. MECheck Software Analysis
This free, downloadable, easy-to-use software allows more design options.
See http//energycodes.org or http://www.oikos.com/library/mec
Percentage of “above-code” or “below-code” is calculated automatically and appears on screen. Window shading code compliance is assumed. Any of the standard means are allowable: solar screens or southern-type low-e glass with a solar heat gain coefficient of 0.40 or less, or properly-sized overhangs.
3. Systems Analysis [Performance Method] [IECC, Chapter 5]. Most accurate, but more difficult to apply method. Allows for more flexibility.
City of Austin, Residential -Amendments to the IECC (in effect 12/10/01)
Two notable points:
1. Attic ventilation exception
Attic ventilation is prohibited if it were to introduce unconditioned air into locations within the
thermal envelope (insulation). For example, if the attic insulation is at the rafters instead of the attic floor, the attic shall not be ventilated [Amendment section 502.1.61.
2. Vapor barrier ban:
A vapor barrier (permeability rating of less than 1.0) on the warm-in-winter side of framing is
not allowed. See page 2 for information about vapor barriers in Central TX outside of Austin.
Use these design values when applying energy codes in Travis County. [IECC Ch. 3]. It is not necessary to understand these values to apply them.
EXTERIOR DESIGN CONDITIONS AND VALUES
Condition Value Condition Value
Winter Design Dry-Bulb 28 Heating Degree Days (HDD) 1735
Summer Design Dry-Bulb 98 Cooling Degree Days (CDD) 2862
Summer Design Wet-Bulb 74 Climate Zone 5B
SUMMARY OF RESIDENTIAL REQUIREMENTS IN CENTRAL TEXAS
Highlights of the 2000 International Energy Conservation Code [IECC] and Chapter 11, (Energy) of the 2000 International Residential Code [IRC]. These codes apply to all single-family housing In Texas as of January 11, 2002. For Austin, there is almost nothing significantly different in the new energy codes from requirements that have long been In place. In other parts of Texas, this may not be true.
1. The Energy Chapter (11) of the IRC or Chapter 6 of the IECC for residential construction can be met only through a prescriptive method; and only by meeting all applicable requirements of the chapter; and only if the building’s glazing area does not exceed 15% of the gross area of the exterior walls for single-family or duplex or 25%, for townhouses.[IRC N1101.2 and IECC 601.2]
2. Chapter 5 of the IECC: does contain simple prescriptive tables for houses with a specified glass area. (This also applies to multi-family construction of three stories or less.) Note the following: Ceiling insulation must average R-30. Lower R at vaulted ceilings may be offset by higher R at flat ceilings. Tables for steel framing and high-mass walls (e.g. rammed earth) have been added [505.2.4.16 & .17].
3. Remodels must meet the new building and energy requirements [IRC 102-7.19 IECC 101.4.2.2]. The 2000 IECC insulation and sealing requirements apply to any altered wall. If a window is replaced, the new window must comply with all of the new requirements.
4. Vapor barrier requirements / exceptions / exclusions [IECC 502.1.1] In Austin, vapor barriers (material with a permeability rating of 1.0 or higher) are not allowed on the warm-in-winter side of the a wall. (new Austin amendment)
a. In the hot, humid parts of Texas (Climate areas 2B, 3B-C, 4B, 5A-B) outside of Austin, vapor barriers on the warm-in-winter side of a wall are not required by code. Furthermore, they are not recommended.
b. in a hot, humid climate, vapor barriers on the warm-in-winter side cause moisture and mold problems. In cold climates, vapor barriers on the warm-in-winter side prevent moisture problems
c. Kraft paper-faced insulation batts, are not recommended in our hot, humid climate. Unfaced batts or blown-in insulation are preferred.
5. Better requirements to reduce heat-gain through glass. The more descriptive term Solar Heat Gain Coefficient (SHGC) is now used instead of Shading Coefficient (SC). (SHGC and SC are not identical in value.)
a. A SHGC of 0.40 is the maximum heat gain through glass now allowed [IECC 502.1.5]. (The former Austin code allowed a maximum SHGC of 0.455 or a SC of 0.50.)
b. In a hot climate, the lower the SHGC, the better. To find out the SHGC, look on the window for the NFRC label (National Fenestration Rating Council).
6. Recessed can lights are now required to be air-tight-rated (IC-AT). [IECC 502.1.3]
7. AC duct sealing, insulating, and air-balancing requirements. [IECC 503.3.3]
a. R-8 duct insulation is required for ducts outside thermal envelope. [lECC 2001 Supplement table 503.3.3.3]
b. Designers, architects, and engineers should design chases, floor joists, trusses, and any other affected parts of the structure (including stairs) to accommodate these larger ducts.
c. Duct sealing must be done in accordance with the Mechanical Code [IMC] – all beams, joints, boots, start collars and all other connections). Only mastic and UL-181A or B tapes are allowed for sealing. Mastic is a lifetime sealant. Tape is not. Cloth duct tape is forbidden. [503.3.3.4.3] (Not new in Austin)
d. Air flow in ducts must be balanced with balancing dampers or other means [503.3.3.7].
8. Storage type water heater requirements [IECC 504.7]. Water heaters with vertical risers must have heat traps on the inlet and outlet of the water heater. (may be internal or external). Water heaters in Austin must be gas-fired, or if electric, then they must be heat-pump type, solar, or have a heat recovery or heat reclaim system. (Austin code amendment; not new).
9. Cooling equipment must be sized using ACCA Manual J load calculations. [IRC M1401.3] (ACCA-Air Conditioning Contractors Association). This is not a new requirement.