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3.5.5.Floors

Floor Name

Applicability

All floor surfaces

Definition

A unique name or code that relates the exposed floor to the design documents. Exposed floors include floors exposed to the outdoors and floors over unconditioned spaces, but do not include slab-on-grade floors, below grade floors, or interior floors.

Units

Text, unique

Input Restrictions

None

Baseline Rules

None

 

Floor Type

Applicability

All exterior floor surfaces, optional

Definition

One of three categories of exposed floor assemblies used to determine minimum prescriptive insulation requirements. The three floor type categories are: a) mass floor, b) steel joist floor, and c) wood and other floors. These are defined in Standard 90.1-2013 and the associated User's Manuals. This building descriptor is not used for the purposes of this manual, since the type for the baseline building is fixed at “steel joist”. This building descriptor can often be derived from other information in the model and may not be required as an explicit input.

Units

List: mass floor, metal joist floor, and wood and other floors

Input Restrictions

This building descriptor input is optional and may be derived from other inputs.

Baseline Rules

The baseline building floors shall be of type “steel joist.”

 

Floor Geometry

Applicability

All exterior floors, required input

Definition

Floor geometry defines the position, orientation, azimuth, and tilt of the floor surface. The details of how the coordinate system is implemented may vary between software programs. The data structure for surfaces is described in the reference section of this chapter.

Units

Data structure: surface

Input Restrictions

There are no restrictions other than that the surfaces defined must agree with the building being modeled, as represented on the construction documents or as-built drawings.

Baseline Rules

Baseline building floor geometry is identical to the proposed design.

 

Floor Construction

Applicability

All floors, required input

Definition

A reference to a construction assembly for the proposed design

Units

Dimensionless reference

Input Restrictions

All floor surfaces must reference a construction assembly that meets the mandatory measures of the baseline standards.

Baseline Rules

Exterior floors in the baseline building are of type “steel joist.” The insulation requirements depend on the baseline standard and the climate zone and are given in Table 3.5.5-1. The baseline building constructions shall be modeled as layers, which are defined in Table 3.5.5-2.

Table 3.5.5-1: Baseline Building R-value and U-factor Criteria for Exposed Floors

Climate Zone

Nonresidential

Residential

Semi-Heated

Name

U-factor

Name

U-factor

Name

U-factor

1

NR

0.350

NR

0.350

NR

0.350

2

R-19

0.052

R-19

0.052

3

4

R-30

0.038

R-13

0.069

5

6

R-30

0.038

7

R-19

0.052

8

R-38

0.032

 

Table 3.5.5-2: Baseline Building Exposed Floor Construction Assemblies

Construction

Layer

Thickness (inch)

Conductivity (Btu/h ft F)

Density (lb/ft²)

Specific Heat (Btu/lb F)

R-value (ft²·°F·h/Btu)

U-factor (Btu/ft²·°F·h)

Floor R-38

Interior air film (flow down)

-

-

-

-

0.92

-

carpet and pad

-

-

-

-

1.23

-

4" concrete

4

1.3333

140

0.2

0.25

-

R-38 insulation between joists

-

-

-

-

28

-

metal deck

0.06

26

480

0.1

0.00

-

Semi-exterior air film

-

-

-

-

0.46

-

Total for assembly

        

30.86

0.032

Floor R-30

Interior air film (flow down)

-

-

-

-

0.92

-

carpet and pad

-

-

-

-

1.23

-

4" concrete

4

1.3333

140

0.2

0.25

-

R-30 insulation between joists

-

-

-

-

23.5

-

metal deck

0.06

26

480

0.1

0.00

-

Semi-exterior air film

-

-

-

-

0.46

-

Total for assembly

        

26.36

0.038

Floor R-19

Interior air film (flow down)

-

-

-

-

0.92

-

carpet and pad

-

-

-

-

1.23

-

4" concrete

4

1.3333

140

0.2

0.25

-

R-19 insulation between joists

-

-

-

-

16.37

-

metal deck

0.06

26

480

0.1

0.00

-

Semi-exterior air film

-

-

-

-

0.46

-

Total for assembly

        

19.23

0.052

Floor R-13

Interior air film (flow down)

-

-

-

-

0.92

-

carpet and pad

-

-

-

-

1.23

-

4" concrete

4

1.3333

140

0.2

0.25

-

R-13 insulation between joists

-

-

-

-

11.63

-

metal deck

0.06

26

480

0.1

0.00

-

Semi-exterior air film

-

-

-

-

0.46

-

Total for assembly

        

14.49

0.069

NR

Interior air film (flow down)

-

-

-

-

0.92

-

Carpet and pad

-

-

-

-

1.23

-

4" concrete

4

1.3333

140

0.2

0.25

  

Metal deck

0.06

26

480

0.1

0.00

-

Semi-exterior air film

-

-

-

-

0.46

-

Total for assembly

        

2.86

0.350
90.1-2019

Floor Name

Applicability

All floor surfaces

Definition

A unique name or code that relates the exposed floor to the design documents. Exposed floors include floors exposed to the outdoors and floors over unconditioned spaces, but do not include slab-on-grade floors, below-grade floors, or interior floors.

Units

Text: unique

Input Restrictions

None

Baseline Building

None

 

 

Floor Type

Applicability

All exterior floor surfaces, optional

Definition

The category that defines the baseline building prescriptive floor requirements

Units

List: Mass, Steel-Joist, Wood-Framed and Other

Input Restrictions

As designed

Baseline Building

The baseline building floors shall be of type “steel-joist”

 

 

Floor Geometry

Applicability

All exterior floors, required input

Definition

Floor geometry defines the position, orientation, azimuth, and tilt of the floor surface. The details of how the coordinate system is implemented may vary among software programs. The data structure for surfaces is described in the reference section of this chapter.

Units

Data structure: surface

Input Restrictions

As designed

Baseline Building

Baseline building floor geometry is identical to the proposed design

 

 

Floor Construction

Applicability

All floors, required input

Definition

A specification containing a series of layers that result in a construction assembly for the proposed design. The first layer in the series represents the outside (or exterior) layer and the last layer represents the inside (or interior) layer. See the building descriptors above for floor construction type.

Units

List: layers

Input Restrictions

 As designed, with the construction assembly defined by a series of layers. Each layer specified, must consist of materials as described in Section 3.5.2.

NOTE: Standard 90.1-2019, Table A9.2-1 in Appendix A specifies the effective insulation/framing layer R-values for roof and floor insulation installed between metal framing 4’ OC. These values are intended to be used for all other framing, 16”, 2’, and 3’.

Baseline Building

The exterior floor type for the baseline building is steel joist. The baseline building wall construction shall be modeled as layers. The U-factor required for baseline wall construction is defined in Table 25. The layer by layer construction corresponding to each U-factor shall be modeled as shown in Table 26. For existing buildings, the baseline walls shall follow the same rules as new buildings.

Table 25. Standard 90.1-2019 Requirements for Baseline Steel Joist Floors for Non-Residential Space Conditioning Categories

 

U-factor

(Btu/ft2. °F. h)

Nonresidential

Residential

Semiheated

Climate Zone 0 and 1

U-0.35

U-0.35

U-0.35

Climate Zone 2

U-0.052

U-0.052

U-0.35

Climate Zone 3

U-0.052

U-0.052

U-0.069

Climate Zone 4

U-0.052

U-0.038

U-0.069

Climate Zone 5

U-0.052

U-0.038

U-0.069

Climate Zone 6

U-0.038

U-0.038

U-0.069

Climate Zone 7

U-0.038

U-0.038

U-0.052

Climate Zone 8

U-0.038

U-0.032

U-0.052

 

Table 26. Baseline Building Exterior Floor Construction Assemblies

Construction

Layer

Thickness (inch)

Conductivity (Btu/h ft °F)

Density (lb/ft²)

Specific Heat
(Btu/lb °F)

R-value (ft²·°F·h/Btu)

 

U-value (Btu /ft²·°F·h)

Floor R-38

Interior air film (flow down)

0.92

 

Carpet and pad

1.23

 

4" concrete       

4

1.3333

140

0.2

0.25

 

R-38 insulation between joists

28

 

Metal deck

0.06

26

480

0.1

0.00

 

Semi-exterior air film

0.46

 

Total for assembly

30.86

0.032

Floor R-30

Interior air film (flow down)

0.92

 

Carpet and pad

1.23

 

4" concrete

4

1.3333

140

0.2

0.25

 

R-30 insulation between joists

23.5

 

Metal deck

0.06

26

480

0.1

0.00

 

Semi-exterior air film

0.46

 

Total for assembly

26.36

0.038

Floor R-19

Interior air film (flow down)

0.92

 

Carpet and pad

1.23

 

4" concrete

4

1.3333

140

0.2

0.25

 

R-19 insulation between joists

16.37

 

Metal deck

0.06

26

480

0.1

0.00

 

Semi-exterior air film

0.46

 

Total for Assembly

19.23

0.052

Floor R-13

Interior air film (flow down)

0.92

 

Carpet and pad

1.23

 

4" concrete

4

1.3333

140

0.2

0.25

 

R-13 insulation between joists

11.63

 

Metal deck

0.06

26

480

0.1

0.00

 

Semi-exterior air film

0.46

 

Total for assembly

14.49

0.069

NR

Interior air film (flow down)

0.92

 

Carpet and pad

1.23

 

4" concrete

4

1.3333

140

0.2

0.25

 

Metal deck

0.06

26

480

0.1

0.00

 

Semi-exterior air film

0.46

 

Total for assembly

2.86

0.35