Wis. Admin. Code Department of Safety and Professional Services SPS 322.53

Current through December 30, 2024

Section SPS 322.53 - Calculation procedure

(1) GENERAL. Except as specifically allowed under this section, the standard reference design and proposed design shall be configured and analyzed using identical methods and techniques.

(2) REFERENCE AND PROPOSED DESIGNS. The standard reference design and proposed design shall be configured and analyzed as specified by Table 322.53-1. Table 322.53-1 shall include by reference all notes contained in Table 322.31-1.

(3) CALCULATION SOFTWARE TOOLS. Calculation procedures used to comply with this section shall be capable of calculating the annual energy consumption of all building elements that differ between the standard reference design and the proposed design and shall include the following capabilities:

(a) Computer generation of the standard reference design using only the input for the proposed design. The calculation procedure may not allow the user to directly modify the building component characteristics of the standard reference design.

(b) Calculation of whole-building sizing as a single zone for the heating and cooling equipment in the standard reference design residence in accordance with s. SPS 322.40(3).

(c) Calculations that account for the effects of indoor and outdoor temperatures and part-load ratios on the performance of heating, ventilating and air conditioning equipment based on climate and equipment sizing.

(d) Printed code official inspection checklist listing each of the proposed design component characteristics from Table 322.53-1 determined by the analysis to provide compliance, along with their respective performance ratings.

Building Component	Standard Reference Design	Proposed Design
Above-grade walls	Type: mass wall if proposed wall is mass; otherwise wood frame	As proposed
	Gross area: same as proposed	As proposed
	U-Factor: from Table 322.31-2	As proposed
	Solar absorptance = 0.75	As proposed
	Emittance = 0.90	As proposed
Basement and crawlspace walls	Type: same as proposed	As proposed
	Gross area: same as proposed	As proposed
	U-Factor: from Table 322.31-2 with insulation layer on interior side of walls	As proposed
Above-grade floors	Type: wood frame	As proposed
	Gross area: same as proposed	As proposed
	U-Factor: from Table 322.31-2	As proposed
Ceilings	Type: wood frame	As proposed
	Gross area: same as proposed	As proposed
	U-Factor: from Table 322.31-2	As proposed
Roofs	Type: composition shingle on wood sheathing	As proposed
	Gross area: same as proposed	As proposed
	Solar absorptance = 0.75	As proposed
	Emittance = 0.90	As proposed
Attics	Type: vented with aperture = 1 ft² per 300 ft²ceiling area	As proposed
Foundations	Type: same as proposed	As proposed
Doors	Area: 40 ft²	As proposed
Orientation: North U-Factor: same as fenestration from Table	As proposed
322.31-2	As proposed
Glazing^a	Total area^b=(a) The proposed glazing area; where the proposed glazing area is less than 18% of the conditioned floor area	As proposed
	(b) 18% of the conditioned floor area; where the proposed glazing area is 18% or more of the conditioned floor area Orientation: equally distributed to four cardinal compass orientations	As proposed
	U-Factor: from Table 322.31-2	As proposed
	SHGC = 0.40 Interior shade fraction: Summer (all hours when cooling is required) = 0.70 Winter (all hours when heating is required) = 0.85	As proposed Same as standard reference design^c
	External shading: none	As proposed
Skylights	U-Factor: from Table 322.31-2	As proposed
Thermally isolated sunrooms	None	As proposed
Air exchange rate	Specific Leakage Area (SLA)^d = 0.00036 assuming no energy recovery	For residences that are not tested, the same as the standard reference design; For residences without mechanical ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air exchange rate^e but not less than 0.35 ACH; For residences with mechanical ventilation that are tested in accordance with ASHRAE 119, Section 5.1, the measured air exchange rate^ecombined with the mechanical ventilation rate^f, which may not be less than 0.01 X CFA + 7.5 X (N br + 1) where: CFA = conditioned floor area N br = number of bedrooms
Mechanical ventilation	None, except where mechanical ventilation is specified by the proposed design, in which case: Annual vent fan energy use: kWh/yr = 0.03942 X CFA + 29.565 X (N br + 1) where: CFA = conditioned floor area N br = number of bedrooms	As proposed
Internal gains	IGain = 17,900 + 23.8 x CFA + 4,104 X N br (Btu/day per dwelling unit)	Same as standard reference design
Internal mass	An internal mass for furniture and contents of 8 pounds per square foot of floor area	Same as standard reference design, plus any additional mass specifically designed as a thermal storage element^g but not integral to the building envelope or structure
Structural mass	For masonry floor slabs, 80% of floor area covered by R-2 carpet and pad, and 20% of floor directly exposed to room air;	As proposed
	For masonry basement walls, as proposed, but with insulation required by Table 322.31-2 located on the interior side of the walls;	As proposed
	For other walls, for ceilings, floors, and interior walls, wood frame construction	As proposed
Heating systems ^h,i	Fuel type: same as proposed design efficiencies:	As proposed
	Electric: air-source heat pump with prevailing federal minimum efficiency;	As proposed
	Nonelectric furnaces: natural gas furnace in
	accordance with Table 322.31-3;	As proposed
	Nonelectric boilers: natural gas boiler in accordance with Table 322.31-3;	As proposed
	Capacity: sized in accordance with section SPS 322.40(3)	As proposed
Cooling systems ^h,j	Fuel type: electric	As proposed
	Efficiency: in accordance with prevailing federal minimum standards	As proposed
	Capacity: sized in accordance with section SPS 322.40(3)	As proposed
Service Water Heating ^h,k	Fuel type: same as proposed design	As proposed
	Efficiency: in accordance with prevailing federal minimum standards	As proposed
	Use: gal/day = 30 + 10 X N br	Same as standard reference
	Tank temperature: 120°F	Same as standard reference
Thermal distribution systems	A thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies	Same as standard reference design, except as specified by Table 322.53-2
Thermostat	Type: manual, cooling temperature set point = 78°F; heating temperature set point = 68°F	Same as standard reference design

^a Glazing shall be defined as sunlight-transmitting fenestration, including the area of sash, curbing or other framing elements, that enclose conditioned space. Glazing includes the area of sunlight-transmitting fenestration assemblies in walls bounding conditioned basements. For doors where the sunlight-transmitting opening is less than 50% of the door area, the glazing area is the sunlight transmitting opening area. For all other doors, the glazing area is the rough frame opening area for the door including the door and the frame.

^b For residences with conditioned basements, R-2 and R-4 residences and townhouses, the following formula shall be used to determine glazing area: AF = As X FA X F where:

1. AF = Total glazing area.

2. As = Standard reference design total glazing area.

3. FA = (Above-grade thermal boundary gross wall area)/(above-grade boundary wall area + 0.5 x below-grade boundary wall area).

4. F = (Above-grade thermal boundary wall area)/(above-grade thermal boundary wall area + common wall area) or 0.56, whichever is greater.

And where:

5. Thermal boundary wall is any wall that separates conditioned space from unconditioned space or ambient conditions.

6. Above-grade thermal boundary wall is any thermal boundary wall component not in contact with soil.

7. Below-grade boundary wall is any thermal boundary wall in soil contact.

8. Common wall area is the area of walls shared with an adjoining dwelling unit.

^c For fenestrations facing within 15 degrees of true south that are directly coupled to thermal storage mass, the winter interior shade fraction may be increased to 0.95 in the proposed design.

^d Where Leakage Area (L) is defined in accordance with Section 5.1 of ASHRAE 119 and where: SLA = L/CFA where L and CFA are in the same units.

^e Tested envelope leakage shall be determined and documented by an independent party approved by the code official. Hourly calculations as specified in the 2005 ASHRAE Handbook of Fundamentals, Chapter 27, page 27.21, Equation 40, Sherman-Grimsrud model, or the equivalent shall be used to determine the energy loads resulting from infiltration.

^f The combined air exchange rate for infiltration and mechanical ventilation shall be determined in accordance with Equation 43 of 2005 ASHRAE Handbook of Fundamentals page 27.23 and the "Whole-house Ventilation" provisions of 2005 ASHRAE Handbook of Fundamentals, page 27.18 for intermittent mechanical ventilation.

^g Thermal Storage Element means a component not part of the floors, walls or ceilings that is part of a passive solar system, and that provides thermal storage such as enclosed water columns, rock beds, or phase-change containers. A thermal storage element must be in the same room as fenestration that faces within 15 degrees of true south, or must be connected to a room with pipes or ducts that allow the element to be actively charged.

^h For a proposed design with multiple heating, cooling or water heating systems using different fuel types, the applicable standard reference design system capacities and fuel types shall be weighted in accordance with their respective loads as calculated by accepted engineering practice for each equipment and fuel type present.

ⁱ For a proposed design without a proposed heating system, a heating system of 90% annual fuel utilization shall be assumed for both the standard reference design and proposed design. For electric heating systems, the prevailing federal minimum efficiency air-source heat pump shall be used for the standard reference design.

^j For a proposed design home without a proposed cooling system, an electric air conditioner with the prevailing federal minimum efficiency shall be assumed for both the standard reference design and the proposed design.

^k For a proposed design with a non-storage-type water heater, a 40-gallon storage-type water heater with the prevailing federal minimum energy factor for the same fuel as the predominant heating fuel type shall be assumed. For the case of a proposed design without a proposed water heater, a 40-gallon storage-type water heater with the prevailing federal minimum efficiency for the same fuel as the predominant heating fuel type shall be assumed for both the proposed design and standard reference design.

TABLE 322.53-2

DEFAULT DISTRIBUTION SYSTEM EFFICIENCIES FOR PROPOSED DESIGNS^a

Distribution System Configuration and Condition	Forced Air Systems	Hydronic Systems
Distribution system components located in unconditioned space	0.80	0.95
Distribution systems entirely located in conditioned space^c	0.88	1.00
Proposed "reduced leakage" with entire air distribution system located in the conditioned space^d	0.96	-
Proposed "reduced leakage" air distribution system with components located in the unconditioned space	0.88	-
Ductless systems^e	1.00	-

^aDefault values given by this table are for untested distribution systems, which must still meet minimum requirements for duct system insulation.

^b Hydronic systems means those systems that distribute heating and cooling energy directly to individual spaces using liquids pumped through closed loop piping and that do not depend on ducted, forced air flows to maintain space temperatures.

^c Entire system in conditioned space means that no component of the distribution system, including the air handler unit, is located outside of the conditioned space.

^d Proposed "reduced leakage" means leakage to outdoors not greater than 3 cfm per 100 ft2 of conditioned floor area and total leakage not greater than 9 cfm per 100 ft2 of conditioned floor area at a pressure differential of 0.02 inches w.g. across the entire system, including the manufacturer's air handler enclosure. Total leakage of not greater than 3 cfm per 100 ft2 of conditioned floor area at a pressure difference of 0.02 inches w.g. across the entire system, including the manufacturer's air handler enclosure, shall be deemed to meet this requirement without measurement of leakage to the outdoors. This performance shall be specified as required in the construction documents and confirmed through field-testing of installed systems as documented by an approved independent party.

^e Ductless systems may have forced airflow across a coil but may not have any ducted airflows external to the manufacturer's air handler enclosure.

Wis. Admin. Code Department of Safety and Professional Services SPS 322.53

CR 08-043: cr. Register March 2009 No. 639, eff. 4-1-09; correction in (2), (3) (b), (d), Table 322.53-1 made under s. 13.92(4) (b) 7, Stats., Register December 2011 No. 672.