2.1. Results of Winter Shading Simulation Profiles

The results from computer building simulations, of various shading profiles caused by unexpected occupant intervention with the solar aperture, other than the one specified for the “Zero Energy House”, are analysed and assessed having as basis the optimum fenestration shading strategy for winter as defined below.

a) Optimised Fenestration Shading Strategy for Winter

The optimized fenestration strategy for winter from the previous research study “Shading” [1] is outlined as having all glazed area unshaded during the day time to obtain maximum solar gains and achieve comfort indoor conditions in the range of 18.6 — 20.6 degrees Centigrade (Table 1, 1.0).

b) North Window Shutters Shaded

If North window shutters (Area=3.5m2) are left closed during the day in winter, the indoor temperature reduces by 0.1 to 0.2 degrees Centigrade (Table 1, 1.1) i. e. 1% to 1.5% departure from the temperature achieved in the optimized fenestration profile (Table 1, 1.0). However the indoor temperature is maintained within the comfort range for winter (18.6-22.6 deg. Celsius).

c) North and West Window Shutters Shaded

When in addition to North window shutters, the West ones are left closed during winter days, an insignificant temperature of further reduction of 0.1 degrees Centigrade occurs, and that only at certain hours of the day no obvious pattern (Table 1, 1.2). The small extent of temperature reduction is attributed to:

i) Orientation — West orientated windows have no direct solar gains in winter.

ii) Window Area — The west window area amounts only to 0.50m2. The indoor temperature is maintained within comfort levels.

d) North, West and Half South window Shutters Shaded

When in addition to North and West window shutters half South window area remains shaded during the day, an indoor temperature reduction of 4.0 to 5.0 degrees Centigrade incurs i. e. 23% to 30%. This temperature drop lowers the indoor temperature below comfort level by 2.0 to 5.2 degrees Centigrade (Table1, 1.3). The largest drop, of 5.2 degrees Centigrade, occurs between

09.0 to 22.00 hours. This span of time is that receiving the most of direct solar gain followed by six hours in the evening, as the result of time lag. The rapid reduction of indoor temperature is expected due to:

i) Orientation. South facing windows invite amounts of solar gains incident at small angles in winter. Thus interception of solar radiation on this orientation has direct effect on indoor temperature.

ii) Window Area. The south glazing area with solar aperture is limited by 17.5m2 which is a considerable amount of glazing reduction and consequently solar gains.

e) All Windows Shaded

When all windows remain shaded during winter days, indoor temperature decreases in the rate of

9.0 to 10.5 degrees Celsius (Table 1, 1.4). The additional shaded window area is of equal (17.50m2) as in the previous shading window profile above (Table 1, 1.3) however the indoor temperature reduction in current profile is 1.0 degree more. This is expected as all glazed area is shaded and there is no solar access at all. The indoor temperature drops further by 4.0 degrees to its lowest levels which at certain hours (09.00 to 18.00) is even lower than outdoor temperature (Table 1, 1.4).