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SourceComparison of Standard 90.1-07 and the 2009 IECC

with Respect to Commercial Buildings Prepared by the Pacific Northwest National

Laboratory for the U.S. Department of Building Energy Codes Program

December 2009

http://www.energycodes.gov/publications/research/documents/codes/90-1_iecc_comparison_final_12-16-2009.pdf

ASHRAE 90.1-2007 IECC 2009

Spaces in buildings used primarily for living and sleeping. Residential spaces include dwelling units, hotel/motel guest rooms, dormitories, nursing homes, patient rooms in hospitals, lodging houses, fraternity/sorority houses, hostels, prisons, and fire stations.

Includes R-3 buildings, as well as R-2 and R-4 buildings three stories or less in height above grade. (not R-1, hotels and motels) All else is considered commercial.

Comply with the Envelope

Requirements

Comply with the Mechanical/SWH

Requirements

Comply with the Power & Lighting

Requirements

Section 502 90.1 Section 5 Sections 503 and 504 90.1 Section 6 Section 505 90.1 Section 9

Document Compliance with

the IECC

Plan Review

Inspection

ASHRAE 90.1-2007 IECC 2009

Has a specific designation of semi-heated space (3.4 Btu/h/ft2 up to 15 or 20 for climate zone 5 or 6) and comparable thermal envelope provisions that are less rigorous than those for heated spaces. (Tables 5.5-1 through 5.5-8 for the appropriate climate zone)

No such provision for semi-heated; only conditioned or unconditioned. (Table 502.2(1))

TABLE 303.1.3(1) DEFAULT GLAZED FENESTRATION U-FACTOR

TABLE 303.1.3(2) DEFAULT DOOR U-FACTORS

ASHRAE 90.1-2007 IECC 2009

Considers glazing less than 60 degrees from the horizontal plane as skylights.

Considers glazing 15 degrees or less from vertical as skylights. (Glazing over 15 degrees from vertical is part of the wall.)

IECC 15 + degrees = Skylight ASHRAE 31 + degrees = Skylight

Roof/Skylight Area Roof/Skylight Area

ASHRAE 90.1-2007 IECC 2009

The total skylight area shall be less than 5% of the gross roof area.

The total skylight area shall not exceed 3% of the gross roof area.

ASHRAE 90.1-2007 IECC 2009

A WWR of less than 40% allows using a provision parallel to 2009 IECC.

ASHRAE allows you to exceed 40% window to wall area.

Glazing beyond the 40% maximum WWR requires a building to be evaluated under ASHRAE 90.1-2007.

ASHRAE 90.1-2007 IECC 2009

Portions of walls above grade are treated as above grade and portions of the same walls that are below grade are treated as below grade.

Any wall that is <15% above grade and 85% or more below grade is considered entirely a below-grade wall. Similarly, a wall >15% above grade would be considered entirely an above-grade wall.

ASHRAE 90.1-2007 IECC 2009

Doors that are more than one-half glass are considered fenestration.

Opaque doors are doors having less than 50% glass area and should b e considered as part of the gross area of above-grade walls that are part of the building envelope.

 

  

ASHRAE allows climate Zone 1, 2, and 3 exemptions to Vestibules

IECC allows climate Zone 1 and 2 exemptions

ASHRAE 90.1-2007 IECC 2009

Required in Climate Zones 4 – 8 only.

Required if space is conditioned.

ASHRAE 90.1-2007 IECC 2009

Allows for an increase in the allowable maximum U-factor (reduction in required R-value) for certain roof/ceiling assemblies if the roof meets certain reflectance (high albedo) and emissivity requirements.

This allowance is not provided in the 2009 IECC.

ASHRAE 90.1-2007 IECC 2009

Non-motorized dampers acceptable in Zones 1, 2 and 3.

Many more requirements.

Non-motorized dampers acceptable in buildings under 3 stories and for buildings of any height in Zones 1, 2, and 3.

ASHRAE 90.1-2007 IECC 2009

Does not limit HVAC equipment oversizing.

Limits HVAC equipment oversizing (Section 503.2.2). Heating and cooling equipment and systems shall not exceed the loads calculated in accordance with section 503.2.1 (references ASHRAE/ACCA Standard 183.)

ASHRAE 90.1-2007 IECC 2009

Tends to be more rigorous and, in some cases (e.g., fume hoods, cooling towers, dehumidification, and kitchen exhaust hoods), has requirements that are not in the IECC 2009.

Some of the HVAC equipment not listed in the IECC may be included in the IMC because it is a family of codes.

ASHRAE 90.1-2007 IECC 2009

Requires the delivery of Operation and Maintenance (O&M) manuals for the building systems. (Sections 6.7.2.2 and 8.7.2)

Requires that an operating and maintenance manual be provided to the building owner by the mechanical contractor. (Section 503.2.9.3)

ASHRAE 90.1-2007 IECC 2009

Contains a Space-by-Space method as an alternative to the by-building-type prescriptive tables for lighting power limits (Section 9.6.1 and Table 9.6.1)

The interior lighting power is the floor area for each building area type listed in Table 505.5.2 times the value from Table 505.5.2 for that area. Each building area shall be treated as a separate area.

ASHRAE 90.1-2007 IECC 2009

ASHRAE requires automatic lighting shutoff and has similar requirements for overriding automatic shutoff (e.g. 2 hours vs. 4 hours) and for sleeping unit controls as IECC.

IECC also has requirements for light reduction controls, holiday scheduling and daylight zone control that are not included in ASHRAE.

ASHRAE 90.1-2007 IECC 2009

(Retail Area 1 x 1.0 W/ft2) (Retail Area 2 x 1.7 W/ft2) (Retail Area 3 x 2.6 W/ft2) (Retail Area 4 x 4.2 W/ft2)

(Retail Area 1 x 0.6 W/ft2) (Retail Area 2 x 0.6 W/ft2) (Retail Area 3 x 1.4 W/ft2) (Retail Area 4 x 2.5 W/ft2)

ASHRAE 90.1-2007 IECC 2009

Table 9.4.5 lists LPDs for tradable vs. nontradable surfaces, but lighting zones are not designated.

Table 505.6.2(1) lists lighting zones and Table 505.6.2(2) lists LPDs for each of 4 lighting zones and for tradable and nontradable surfaces.