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Table 6. Duct Locations and Specifications for the Benchmark

Prototype Foundation Type

Benchmark Duct Specification

One-Story

Two-Story or Higher

Supply Duct Surface Area (ft2)

Return Duct Surface Area (ft2)

Supply Duct Insulation (Conditioned Space) Return Duct Insulation (Conditioned Space) Supply/Return Duct Insulation (Unconditioned Space)

All

All

All

All

All

    • 0.27

      × FFAa

    • 0.05

      x Nreturns × FFA

(Maximum of 0.25 × FFA)

    • 0.20

      × FFA

    • 0.04

      x Nreturns × FFA

(Maximum of 0.19 × FFA)

R-3.3

None

R-5.0

Duct Material

All

Sheet Metal

Duct Leakage excluding Air Handler (Inside + Outside) Air Handler Leakage (Inside + Outside)

All

All

10% of Air Handler Flow (9% Supply, 1% Return) (Percentage lost to each space equal to percentage of duct area in that space, as specified below.

5% of Air Handler Flow (1% Supply, 4% Return)

Percent of Duct/Air Handler Leakage Imbalance (Supply Minus Return, 5% of Air Handler Flow in All Cases) Made Up By Outside Air

Slab-on-grade or raised floor

Vented crawl space

Basement or conditioned crawl space

100% Outside air 100% Outside air

37% Outside air 37% Outside air

100% Outside airc

60% Outside airc

Multi-family

100% Outside airc

100% Outside airc

Slab-on-grade or raised floor

100% Atticb

65% Atticb, 35% Conditioned Space

Crawl space

100% Crawl space

65% Crawl space, 35% Above-Grade Conditioned Space 65% Basement, 35% Above-Grade Conditioned Space

Basement

100% Basement

Multi-family

100% Conditioned Space

100% Conditioned Space

Slab-on-grade or raised floor

100% Atticb

100% Atticb

Crawl space

100% Crawl space

100% Crawl space

Basement

100% Basement

100% Basement

Multi-family

100% Conditioned space

100% Conditioned space

Slab-on-grade or raised floor

15% Total (33% return fraction)

11.8% Total (42.2% return fraction)

Vented crawl space

15% Total (33% return fraction)

11.8% Total (42.2% return fraction)

Basement or conditioned crawl space or multi- family unit

5% Total (0% return fraction)

3% Total (0% return fraction)

Supply Duct Location

Return Duct and Air Handler Location

Total Leakage to the Outside and Fraction on the Return Side (Calculated Based on Values Specified Above)

Finished floor area (ft2) If the Prototype does not have an attic, then this percentage of duct leakage in the Benchmark is assumed to be in an attached garage. If the Prototype does not have an attached garage, then the leakage is assumed to be in conditioned space. It is assumed that supply leakage to the outside is 5% of total air handler flow when ducts are entirely within the thermal envelope in a 1-story house, and 3% of total air handler flow in a 2-story house. a b c

Domestic Hot Water

The specifications in Table 7 and Table 8 shall be used for the domestic hot water (DHW) system in the Benchmark. For multi-family housing units with a central hot water system, the Benchmark shall have individual systems using the same fuel type. Both storage and burner capacity are determined using the guidelines recommended by ASHRAE in the HVAC

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