PHPP-IP | Course II - 7.0 - Windows Shading

2021

Up and Running with the Passive House Planning Package (9.7 IP) Module 2 | Class 3 | Shading

Q: How do you calculate the winter heating energy demand?

A: (QT + QV) - η

Transmission + Ventilation LOSSES

(QS + QI)

Solar + Internal GAINS

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2021

Q: How do you calculate the winter heating energy demand?

A: (QT + QV) - η

(QS + QI)

Transmission, done!

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Q: How do you calculate the winter heating energy demand?

A: (QT + QV) - η

(QS + QI)

Solar Gain

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2021

Q: How do you calculate the winter solar gain from windows?

A: QS = r

SHGC

AWIN

GWINTER

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Q: How do you calculate the winter solar gain from windows?

A: QS = r r = dirt

SHGC

non-perpendicular-radiation

AWIN glazing-fraction

GWINTER winter-shading-factor

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NYPH: Up and Running with PHPP

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2021

Q: How do you calculate the winter solar gain from windows?

A: QS = r r = dirt

SHGC

non-perpendicular-radiation

0.95

AWIN glazing-fraction

0.85

________

GWINTER winter-shading-factor ________

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Glazing Fraction (% of window that is glass)

A-glass

A-window

= Glazing-Fraction

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2021

Example •

1 Window, 2’ wide, 4’ tall

• • •

SHGC: 0.4 Glazing Fraction: 0.74 NYC, South-Facing. Winter G = 192 kBtu/ft2

What is the winter-time solar gain if the shading factor is 0.85?

What if the shading factor is 0.24? bldgtyp | NYPH

Example •

1 Window, 2’ wide, 4’ tall

• • •

SHGC: 0.4 Glazing Fraction: 0.74 NYC, South-Facing. Winter G = 192 kBtu/ft2

QS = r QS = r r = dirt

SHGC 0.4

(2’

non-perpendicular-radiation r = 0.95

AWIN

GWINTER

4’)

192 kBtu/ft2

glazing-fraction

0.85

0.74

winter-shading-factor

0.85

r = 0.51 bldgtyp | NYPH

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2021

Example •

1 Window, 2’ wide, 4’ tall

• • •

SHGC: 0.4 Glazing Fraction: 0.74 NYC, South-Facing. Winter G = 192 kBtu/ft2

QS = r QS = 0.51

SHGC 0.4

AWIN (2’

4’)

GWINTER 192 kBtu/ft2

QS = 313 kBtu/winter

bldgtyp | NYPH

Example •

1 Window, 2’ wide, 4’ tall

• • •

SHGC: 0.4 Glazing Fraction: 0.74 NYC, South-Facing. Winter G = 192 kBtu/ft2

QS = r QS = r r = dirt

SHGC 0.4

(2’

non-perpendicular-radiation r = 0.95

AWIN

GWINTER

4’)

192 kBtu/ft2

glazing-fraction

0.85

0.74

winter-shading-factor

0.24

r = 0.14 bldgtyp | NYPH

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2021

Example •

1 Window, 2’ wide, 4’ tall

• • •

SHGC: 0.4 Glazing Fraction: 0.74 NYC, South-Facing. Winter G = 192 kBtu/ft2

QS = r QS = 0.14

SHGC 0.4

AWIN (2’

4’)

GWINTER 192 kBtu/ft2

QS = 86 kBtu/winter

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Shading Factor Inputs

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2021

oover

Shading Factors

dover

hHori

oreveal

dreveal

dHori bldgtyp | NYPH

Shading 1 Object (rH)

Shading 2 Reveals (rR)

Shading 3 Overhangs (ro)

Shading 4 Additional (rother)

Shading 5 Temp. (z)

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h hori: Dimension from the bottom edge for the glazing, up to the highest point of the shading object.

11' - 9"

2' - 8"

2021

d hori: Dimension from the glass face, to the high point of the shading object.

23' - 0"

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d reveal: The ‘exposed’ frame of the window.

O reveal: How far ‘back’ in the wall the glazing is.

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2021

Asymmetrical Shading?

Casements, ‘Lift+Slide’ or any other mulled window type will have a much larger side reveal on one side than the other. However, PHPP only allows for the input of a single value for the d reveal and so an average value should be used in these cases.

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Asymmetrical Shading?

5”

70”

dreveal = (5” + 70”) / 2 bldgtyp | NYPH

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2021

Asymmetrical Shading?

O reveal-2 O reveal-1

PHPP Manual. Section 18.4.4: “First lateral shading determined ... and the respective reduction factor rR ascertained [using OReveal-1]. The course of the sun symmetrical to the window normal in the case of windows the northern or southern side, therefor the reduction radiation incident due to lateral shading on one side 0.5 (1-rR).

is is is on of is:

This value is entered as an additional reduction factor. The calculation of the reveal shading now only takes place using the actual window reveal of a few inches [OReveal-2].

Unfortunately this approach cannot be generalized for other alignments of the window, only estimates will help here.”

1' - 4"

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6 3/4"

1' - 5 1/4"

1' - 4"

2' - 0"

6 3/4"

d over: Dim. from the top edge of the glass, to the bottom of the overhead shading object

1' - 5 1/4" 2' - 0"

o over: Dim. of the overhang, from face of glass to the outermost point.

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2021

'Other’ Shading Screens, louvers, railings, and other elements will also all contribute to the shading of glazing units. In order to take this into account, the total shading factor (%) is entered for both the summer and winter seasons.

These shading factors can be calculated in many ways, depending on the specific element under consideration.

Consult your certifier for specific calculations for your project and products being used.

Values are entered as a single % for winter, and a single % for summer. (0%=fully shaded, 100%=no shading)

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Temporary Shading For temporary summer shading, a special input is allowed to take into account deployable / moveable shading elements (either user or automatic operation).

Some typical values are shown below: Triple Glazing Shading Type

Double Glazing

Exterior

Interior

Exterior

Interior

Blinds, vertical lamellas

0.06

0.70

0.07

0.60

Blinds, lamellas 45°

0.10

0.75

0.12

0.65

Roller blinds white

0.24

0.60

0.25

0.50

Roller blinds grey

0.12

0.80

0.14

0.75

-

0.60

-

0.50

Foil Lower values = MORE shading

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2021

Trees?

For trees (especially deciduous trees) an additional calculation for the effect of their shading can also be entered as ‘other’ shading for winter and summer.

See the PHPP Manual section 18.4.2 for more information on this calculation if you would like to try and use it.

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PHPP Manual 18.4.6 Separate software for calculating shading “In principle, it is always possible to use special tools for calculating any kind of shading situation. A horizon line and the resulting reduction factor can now be determined almost automatically using the relevant hardware and software.” ….

“It is not possible to use the results of a separate software for building certification. In this case, the standard shading algorithms of PHPP are always to be used.”

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