REMEMBER TO COMPLETE THE SIX-PAGE FORM FOR EACH HOUSING UNIT TYPE

4.7 Point System Instructions

For wall insulation, either wood frame walls or thermal mass walls may be selected for site-built houses. The points for the thermal mass wall ECM depend on the R-value of the insulation, the heat capacity of the heavyweight material, and the location of the insulation.

In Section E of the example form, the window area is the percentage of window area as a fraction of the total conditioned floor area. For example, a house with 1,000 conditioned square feet and 120 square feet of window area has a 12% window area.

The sash type can either be aluminum with thermal break, or wood/vinyl (vinyl is considered to be equivalent to wood). Sections F through L cover window measures that can then be used to modify the absolute contribution of the windows to the point total.

Window area, glazing layers, and sash type in these sections must be consistent with those selected in Section E.

In Section I of the example form, the points are determined for sun tempered designs by completing three equations for both heating and cooling. Note that this section is completed in addition to Section E, only if the window orientation is not evenly divided among the four cardinal directions. In Equation A of Section I, the area of each orientation is entered as a fraction of the total window area. For example, if 20% of the windows are on the north side, then the entry above “N” is 0.20. In Equation B of Section I, the quantity “X” calculated in Equation A is multiplied by the total window area percentage and the shading coefficient (SC). The total window area percentage is entered as a fraction of one. For example, if the total window area is 10% of the heated floor area, then the entry above “%AREA” is 0.10. If the actual shading coefficients are not available from manufacturers’ data, use the data in Table 4.1, Window Shading Coefficients.

Window Shading Coefficients

Glass Type Single Layers Double Triple

Clear 1.00 0.88 0.79

Heat-Absorbing 0.77 0.64 0.56

Reflective 0.40 0.31 0.30

Low-E - 0.78 0.70

Table 4.1: Window Shading Coefficients

Equation C of Section I uses the quantity "Z" from Equation B in two different locations.

By using this equation, you can determine the heating and cooling points for the sun tempered section.

NOTE: Totals for Sections A through N are entered on page 5 under S p a c e Conditioning Total. Add the heating and cooling points from the first four pages of the example form and the top of page 5 to get a separate total for heating and cooling.

Section O uses the

Space Conditioning Total

for heating and cooling in equations for the HVAC equipment to determine the

Total Heating and Cooling Points.

In Section O, first enter the appropriate space conditioning total in the parentheses in Step A (heating) and Step C (cooling). Complete the equations in Steps A and C, and insert the results in the parentheses above the letters “X” and “Y” in Steps B and D, respectively. The efficiency of the heating and cooling equipment must also be entered in Steps B and D. In Section O, use the AFUE and SEER values from the Federal Energy Label, which is required for all residential furnaces, and air conditioners.

You may choose any of the different types of heating equipment listed in Step B. It is recommended that all allowable equipment be tried and the heating points compared.

Equipment with higher fuel costs will often make it extremely difficult to meet the required point total.

The numbers obtained from Steps B and D for both heating and cooling in Section O are the

Total Heating and Cooling Points,

and are rewritten at the bottom of page 5 of the point system form. The

Total Heating and Cooling Points

on the bottom of page 5 are only the points from Section 0.

The DHW point system on page 6 applies to all equipment types. The equations for the DHW heaters are based on the number of bedrooms in each unit. To calculate the points for this page, enter the Energy Factor in the blank above “EF” on the appropriate line.

The DHW heater points are added and the total is entered in the space at the middle of page 6.

To determine the

TOTAL POlNTS

on page 6, copy the heating point total and the cooling point total from the bottom of page 5 into the appropriate blanks. Also, copy the

TOTAL DHW

from page 6. Calculate the

TOTAL POINTS

by adding the three values. The

TOTAL POINTS

must be equal to or greater than the

MINIMUM REQUIRED POINT TOTAL

shown just beneath the

TOTAL POINTS.

Note that the required points vary with the number of bedrooms because of varying hot water usage. If the points are less than the

MINIMUM REQUIRED POINT TOTAL,

you must make adjustments by changing some of the ECM levels to meet the criteria. If the points are greater than the minimum total, you can use the selected ECMs, or adjust the ECMs to lower costs.

The

EST/MATED UNIT ENERGY COST

over 25 years is calculated and appears at the bottom of page 6. Enter the conditioned floor area in square feet. The

EST/MATED UNIT

ENERGY COST

is shown in units of hundreds of dollars.

4.8 Point System Example

In order to better illustrate how the point system form is completed, following is an example of ECM categories and values. Compare these ECM values against the example point system form on the following pages.

A

Floor Type & Insulation Infiltration

Window Type and Area

F,G,H Heat-Absorbing, Reflective, or Low-Emissivity Glass I Sun Tempered Design

J,K,L R-1, R-3, R-5

. . . aluminum sash + thermal break . . . 12% window area

. . . natural gas furnace, AFUE 0.90 . . . air conditioner, SEER, 10.0 . . . gas, Energy Factor 0.60

Unit Type: EXAMPLE

Proposer:

A: CEILING INSULATION POINTS

Heating Cooling

R-49 6.3 0.6

R-60 6.6 0.9

Points for A:

Heating El: WALL INSULATION POINTS (Select either Wood Frame or Thermal Mass Walls)

Wood Frame Walls Thermal Mass Walls (Outside, Inside, Mixed: location of insulation)

Heat Capacity H

Outside -13.6 -0.8 -3.3 4 Inside -13.6 -1.3 -3.3 Mixed -13.2 -1.3 -3.0 Outside -13.4 -0.4 -3.2 6 Inside -13.4 -1.0 -3.2 Mixed -13.0 -0.8 -3.0 Outside -13.2 -0.1 -3.1 8 Inside -13.3 -0.8 -3.2

Mixed -12.9 -0.5 -2.9

10

Outside -13.2 0.1 -3.0 Inside -13.2 -0.6 -3.1 Mixed -12.8 -0.2 -2.8

12

C: FLOOR INSULATION POINTS

Very Tight 11.0 0.1

Points for D:

Heating Cooling

E: WINDOW TYPE AND AREA ("10%" = 10% of heated floor area)

Window Area: 10% 12% 14%

H C H-C H C

Wood/Vinyl 11.7 3.3 11.6 2.9 11.5 2.4 Triple Glass

Alum. NA NA NA NA NA NA

AL & TB 12.3 3.6 12.5 3.2 12.5 2.8 Wood/Vinyl 12.9 3.6 13.2 3.2 13.4 2.8

16%

F: HEAT-ABSORBING GLASS (“10%” = 10% of heated floor area) G: REFLECTIVE GLASS ("10%" = 10% of heated floor area)

Window Area: 10% 12% 14%

H C H C H C Single Glass NA NA NA NA NA NA Double Glass -2.6 1.7 -3.0 2.0 -3.2 2.5 Triple Glass -2.9 1.4 -3.3 1.8 -3.7 2.1

H: LOW-E GLASS ("10%" = 10% of heated floor area)

Window Area: 10% 12% 14%

H C H C H C

Single Glass NA NA NA NA NA NA

Double Glass 1.9 0.4 2.7 0.6

Triple Glass 0.8 0.3 0.9 0.4 1.1 0.5 I: SUN TEMPERED (Calculate points by using equations A, B and C)

Heating Points

A: (Enter fraction of total window area for the 4 orientations: N, E, S, & W) ( 49.6 x ___ + 97.2 x ___ +151.0 x___ + 79.7 x___) - ( 94.4 ) = ___

N E S W X

B: (%Area = 0.10 for window area, 10% of heated floor area) ______ X x 1.54 = ____

A: (Enter fraction of total window area for the 4 orientations: N, E, S, & W) ( -10.3____ x -21.2 x ____ -20.9 _____ x -28.3 x ____

N E S W

) + ( 20.2 ) = ____

X B: (%Area = 0.10 for window area, 10% of heated floor area)

x x

X _____ x 1.54 = _____

SC %AREA Z

C: ____

J: R-1 MOVEABLE INSULATION ("10%" = 10% of heated floor area) No cooling points for moveable insulation

Window Area: 10% 12% 14% 16% 18%

H H H H H

Single Glass

Alum. NA NA NA NA NA

AL & TB NA NA NA NA NA

Wood/Vinyl NA NA NA NA NA

NA NA NA NA NA

Double Glass Alum.

AL & TB 0.7 0.8 1.0 1.1 1.3

Wood/Vinyl 0.6 0.7 0.8 1.0 1.1

NA NA NA NA NA

Triple Glass Alum.

AL & TB 0.4 0.5 0.6 0.6 0.7

Wood/Vinyl 0.3 0.4 0.4 0.5 0.5

NA

K: R-3 MOVEABLE INSULATION (“10%” = 10% of heated floor area) No cooling points for moveable insulation

Window Area: 10%

Wood/Vinyl 1.1 1.3 1.5 1.8 2.0 2.2

12% 14% 16% 18% 20%

Wood/Vinyl 0.6 0.7 0.8 1.0 1.1 1.2

Points for K:

Heating L: R-5 MOVEABLE INSULATION ("10%" = 10% of heated floor area)

No cooling points for moveable insulation Window Area:

M: SUNSPACES (No cooling points for sunspaces)

w/ Glass Roof w/ Solid Roof

and Single Glass: 7.8 and Double Glass: 15.5

and Single Glass: 3.2 and Double Glass: 7.8 Heating:

N: LIGHT ROOF COLOR (No heating points for roof color) Cooling:

For roof R-values below R-30 0.0

For roof R-values R-30 and above 0.0 Points:

Cooling SPACE CONDITIONING TOTAL (Total Sections A through N)

HEATING COOLING

In document Residential E nergy Evaluation (Page 33-41)