// CODE SNIPPET
N1105.4.2 (R405.4.2) Residence Specifications
Go To Full Code Chapter
The standard reference design and proposed design shall be configured and analyzed as specified by Table N1105.4.2(1). Table N1105.4.2(1) shall include, by reference, all notes contained in Table N1102.1.3.
TABLE N1105.4.2(1) [R405.4.2(1)]
SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS| BUILDING COMPONENT | STANDARD REFERENCE DESIGN | PROPOSED DESIGN | ||
| Above-grade walls | Type: mass where the proposed wall is a mass wall; otherwise wood frame. | As proposed | ||
| Gross area: same as proposed. | As proposed | |||
| U-factor: as specified in Table N1102.1.2. | As proposed | |||
| Solar absorptance = 0.75. | As proposed | |||
| Emittance = 0.90. | As proposed | |||
| Basement and crawl space walls | Type: same as proposed. | As proposed | ||
| Gross area: same as proposed. | As proposed | |||
| U-factor: as specified in Table N1102.1.2, with the insulation layer on the interior side of the walls. | As proposed | |||
| Above-grade floors | Type: wood frame. | As proposed | ||
| Gross area: same as proposed. | As proposed | |||
| U-factor: as specified in Table N1102.1.2. | As proposed | |||
| Ceilings | Type: wood frame. | As proposed | ||
| Gross area: same as proposed. | As proposed | |||
| U-factor: as specified in Table N1102.1.2. | 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 an aperture of 1 ft2 per 300 ft2 of ceiling area. | As proposed | ||
| Foundations | Type: same as proposed. | As proposed | ||
| Foundation wall area above and below grade and soil characteristics: same as proposed. | As proposed | |||
| Opaque doors | Area: 40 ft2. | As proposed | ||
| Orientation: North. | As proposed | |||
| U-factor: same as fenestration as specified in Table N1102.1.2. | As proposed | |||
| Vertical fenestration other than opaque doors | Total areah =
(a) The proposed glazing area, where the proposed glazing area is less than 15 percent of the conditioned floor area.
(b) 15 percent of the conditioned floor area, where the proposed glazing area is 15 percent or more of the conditioned floor area. |
As proposed | ||
| Orientation: equally distributed to four cardinal compass orientations (N, E, S & W). | As proposed | |||
| U-factor: as specified in Table N1102.1.2. | As proposed | |||
| SHGC: as specified in Table N1102.1.2 except for climate zones without an SHGC requirement, the SHGC shall be equal to 0.40. | As proposed | |||
| Interior shade fraction: 0.92 — (0.21 × SHGC for the standard reference design). | Interior shade fraction: 0.92 — (0.21 × SHGC as proposed) |
|||
| External shading: none | As proposed | |||
| Skylights | None | As proposed | ||
| Thermally isolated sunrooms | None | As proposed | ||
| Air exchange rate | The air leakage rate at a pressure of 0.2 inch w.g. (50 Pa) shall be Climate Zones 0 through 2: 5.0 air changes per hour. Climate Zones 3 through 8: 3.0 air changes per hour. |
The measured air exchange rate.a | ||
| The mechanical ventilation rate shall be in addition to the air leakage rate and shall be the same as in the proposed design, but not greater than 0.01 × CFA + 7.5 × (Nbr + 1) where: The mechanical ventilation system type shall be the same as in the proposed design. Energy recovery shall not be assumed for mechanical ventilation. |
The mechanical ventilation rateb shall be in addition to the air leakage rate and shall be as proposed.
|
|||
| Mechanical ventilation | Where mechanical ventilation is not specified in the proposed design: None Where mechanical ventilation is specified in the proposed design, the annual vent fan energy use, in units of kWh/yr, shall equal (1/ef) ×[0.0876 × CFA + 65.7 × (Nbr+1)] where: ef = the minimum fan efficacy, as specified in Table N1103.6.2, corresponding to the system type at a flow rate of 0.01 × CFA + 7.5 × (Nbr+1)
CFA = conditioned floor area, ft2. Nbr = number of bedrooms. |
As proposed | ||
| Internal gains | IGain, in units of Btu/day per dwelling unit, shall equal 17,900 + 23.8 ×CFA + 4,104 × Nbr where: |
Same as standard reference design. | ||
| Internal mass | Internal mass for furniture and contents: 8 pounds per square foot of floor area. | Same as standard reference design, plus any additional mass specifically designed as a thermal storage elementc but not integral to the building envelope or structure. | ||
| Structural mass | For masonry floor slabs: 80 percent of floor area covered by R-2 carpet and pad, and 20 percent of floor directly exposed to room air. | As proposed | ||
| For masonry basement walls: as proposed, but with insulation as specified in Table N1102.1.3, located on the interior side of the walls. | As proposed | |||
| For other walls, ceilings, floors, and interior walls: wood frame construction. | As proposed | |||
| Heating systemsd, e | For other than electric heating without a heat pump: as proposed. Where the proposed design utilizes electric heating without a heat pump, the standard reference design shall be an air source heat pump meeting the requirements of Section C403 of the IECC—Commercial Provisions. Capacity: sized in accordance with Section N1103.7. |
As proposed | ||
| Cooling systemsd, f | As proposed. Capacity: sized in accordance with Section N1103.7. |
As proposed | ||
| Service water heatingd, g | As proposed. Use, in units of gal/day = 25.5 + (8.5 × Nbr) where: Nbr = number of bedrooms.
|
As proposed Use, in units of gal/day = 25.5 + (8.5 × Nbr) × (1 — HWDS) where: Nbr = number of bedrooms. HWDS = factor for the compactness of the hot water distribution system. |
||
| Compactness ratioi factor | HWDS | |||
| 1 story | 2 or more stories | |||
| > 60% | > 30% | 0 | ||
| > 30% to ≤ 60% | > 15% to ≤ 30% | 0.05 | ||
| > 15% to ≤ 30% | > 7.5% to ≤ 15% | 0.10 | ||
| < 15% | < 7.5% | 0.15 | ||
| Thermal distribution systems | Duct insulation: in accordance with Section N1103.3.1. A thermal distribution system efficiency (DSE) of 0.88 shall be applied to both the heating and cooling system efficiencies for all systems other than tested duct systems. Duct location: same as proposed design. Exception: For nonducted heating and cooling systems that do not have a fan, the standard reference design thermal distribution system efficiency (DSE) shall be 1. For tested duct systems, the leakage rate shall be 4 cfm (113.3 L/min) per 100 ft2 (9.29 m2) of conditioned floor area at a pressure of differential of 0.1 inch w.g. (25 Pa).
|
Duct location: as proposed. Duct insulation: as proposed. As tested or, where not tested, as specified in Table N1105.4.2(2). |
||
| Thermostat | Type: Manual, cooling temperature setpoint = 75°F; Heating temperature setpoint = 72°F. |
Same as standard reference design. | ||
| Dehumidistat | Where a mechanical ventilation system with latent heat recovery is not specified in the proposed design:
None.
|
Same as standard reference design. | ||
For SI: 1 square foot = 0.93 m2, 1 British thermal unit = 1055 J, 1 pound per square foot = 4.88 kg/m2, 1 gallon (US) = 3.785 L, °C = (°F — 32)/1.8, 1 degree = 0.79 rad.
- Where required by the code official, testing shall be conducted by an approved party. Hourly calculations as specified in the ASHRAE Handbook of Fundamentals, or the equivalent, shall be used to determine the energy loads resulting from infiltration.
- The combined air exchange rate for infiltration and mechanical ventilation shall be determined in accordance with Equation 43 of 2001 ASHRAE Handbook of Fundamentals, page 26.24 and the "Whole-house Ventilation" provisions of 2001 ASHRAE Handbook of Fundamentals, page 26.19 for intermittent mechanical ventilation.
- Thermal storage element shall mean a component that is 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 shall be in the same room as fenestration that faces within 15 degrees (0.26 rad) of true south, or shall be connected to such a room with pipes or ducts that allow the element to be actively charged.
- 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.
- For a proposed design without a proposed heating system, a heating system having the prevailing federal minimum efficiency shall be assumed for both the standard reference design and proposed design.
- For a proposed design home without a proposed cooling system, an electric air conditioner having the prevailing federal minimum efficiency shall be assumed for both the standard reference design and the proposed design.
- For a proposed design with a nonstorage-type water heater, a 40-gallon storage-type water heater having the prevailing federal minimum energy factor for the same fuel as the predominant heating fuel type shall be assumed. For a proposed design without a proposed water heater, a 40-gallon storage-type water heater having 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.
-
For residences with conditioned basements, R-2 and R-4 residences, and for townhouses, the following formula shall be used to determine glazing area:
AF = As × FA × F
where:
AF = Total glazing area.
As = Standard reference design total glazing area.
FA = (Above-grade thermal boundary gross wall area)/(above-grade boundary wall area + 0.5 × below-grade boundary wall area).
F = (above-grade thermal boundary wall area)/(above-grade thermal boundary wall area + common wall area) or 0.56, whichever is greater.
and where:
Thermal boundary wall is any wall that separates conditioned space from unconditioned space or ambient conditions.
Above-grade thermal boundary wall is any thermal boundary wall component not in contact with soil.
Below-grade boundary wall is any thermal boundary wall in soil contact.
Common wall area is the area of walls shared with an adjoining dwelling unit. -
The factor for the compactness of the hot water distribution system is the ratio of the area of the rectangle that bounds the source of hot water and the fixtures that it serves (the "hot water rectangle") divided by the floor area of the dwelling.
- Sources of hot water include water heaters, or in multiple-family buildings with central water heating systems, circulation loops or electric heat traced pipes.
- The hot water rectangle shall include the source of hot water and the points of termination of all hot water fixture supply piping.
- The hot water rectangle shall be shown on the floor plans and the area shall be computed to the nearest square foot.
- Where there is more than one water heater and each water heater serves different plumbing fixtures and appliances, it is permissible to establish a separate hot water rectangle for each hot water distribution system and add the area of these rectangles together to determine the compactness ratio.
- The basement or attic shall be counted as a story when it contains the water heater.
- Compliance shall be demonstrated by providing a drawing on the plans that shows the hot water distribution system rectangle(s), comparing the area of the rectangle(s) to the area of the dwelling and identifying the appropriate compactness ratio and HWDS factor.
TABLE N1105.4.2(2) [R405.4.2(2)]
DEFAULT DISTRIBUTION SYSTEM EFFICIENCIES FOR PROPOSED DESIGNSa| DISTRIBUTION SYSTEM CONFIGURATION AND CONDITION | FORCED AIR SYSTEMS | HYDRONIC SYSTEMSb |
| Distribution system components located in unconditioned space | — | 0.95 |
| Untested distribution systems entirely located in conditioned spacec | 0.88 | 1 |
| "Ductless" systemsd | 1 | — |
- Default values this table are for untested distribution systems, which must still meet minimum requirements for duct system insulation.
- Hydronic systems shall mean 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 airflow to maintain space temperatures.
- Entire system in conditioned space shall mean that no component of the distribution system, including the air handler unit, is located outside of the conditioned space.
- Ductless systems shall be allowed to have forced airflow across a coil but shall not have any ducted airflow external to the manufacturer's air handler enclosure.
Upcodes Diagrams
Related Code Sections
N1105.4.2 [RE] Energy Efficiency, (R405.4.2) Residence Specifications
include, by reference, all notes contained in Table N1102.1.3.
TABLE N1105.4.2(1) [R405.4.2(1)]
SPECIFICATIONS FOR THE STANDARD REFERENCE AND ...
R405.4.2 [RE] Residential Energy Efficiency, Residence Specifications
, by reference, all notes contained in Table R402.1.3.
TABLE R405.4.2(1)
SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS ...
R405.4.2 [RE] Residential Energy Efficiency, Compliance Report
the standard reference design and the proposed design with user inputs to the compliance software to generate the results. A site-specific energy analysis ...
R405.4.2 [RE] Residential Energy Efficiency, Compliance Report
the standard reference design and the proposed design with user inputs to the compliance software to generate the results. A site-specific energy analysis ...