Remarks on Winter Shading Strategy and Human Intervention

The results derived from building simulations, of window shading profiles in winter, indicate that if shutters remain closed on the North West orientated fenestration, the reduction of solar gains and consequently the drop of indoor temperature is insignificant (0.1 to 0.2 deg. Celsius Table 1, 1.0,

1.1, 1.2). This is mainly attributed to:

i) Area — The window area on North and West sides is limited.

ii) Orientation-There is no direct solar incidence on these facades.

However if South facing glazing is left shaded, in winter, the solar losses are considerable; an area of 10% of shaded South orientated windows causes a reduction of indoor temperature by 2.0 degrees Celsius and reaches 10.0 degrees reduction as the shaded window area increases. The reduction is attributed to the large amounts of solar gains received by fenestration on this orientation, due to the low solar path and the small angles of incidence. This results to rapid

deviation of indoor temperature from comfort levels (Tables 1, 1.3 and 1.4). When all windows are left closed the indoor temperature drops below outdoor temperature (Table 1, 1.4).

The above results emphasise the sensitivity of the manually operated shading devices and the associated uncertainties which could hinder the successful performance of the design of the “Zero Energy House”.

Table 1: Shading ^ fenestration profiles for winter and effect on indoor temperature

No. Profile

WINDOW SHUTTERS

INDOOR TEMPERATURE °C

Orientation

Area(m2)

Strategy

Average T

Ave. Deviation*

Deviation

WINTER DAY BETWEEN 07.00-19.00 HOURS

1.0

South

35.00

Open

All Unshaded

West

0.50

Open

19.70

BASE

0.0 — 0.0

North

3.50

Open

Winter Optimal

1.1

South

35.00

Open

Shaded North

West

0.50

Open

19.55

— 0.15

0.1 — 0.2

North

3.50

Closed

1.2

South

35.00

Open

Shaded N-W

West

0.50

Closed

19.50

— 0.20

0.2 — 0.3

North

3.50

Closed

1.3

South

17.50

Open

Shaded NWS

South

17.50

Closed

1/2

West

0.50

Closed

14.96

— 4.74

4.3 — 5.2

North

3.50

Closed

1.4

South

35.00

Closed

All Shaded

West

0.50

Closed

10.03

— 9.67

8.9 — 10.5

North

3.50

Closed

* Deviation: Deviation from BASE Winter Optimal Indoor Temperature of “Zero Energy House” — : Indicates decrease of Temperature from BASE

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