The results of ParaSol and Rayfront simulations will be described in this section. Figure 1 shows the annual heating demand as an average value for all four directions for each glazing type and climate. For the Stockholm climate the energy demand decreases from 78.2 kWh/m2,yr to 68.4 kWh/m2,yr for the low-e DG and 67.6 kWh/m2,yr for the AR low-e DG window. The low-e AR DG decrease the energy demand with 2.1% compared to the low-e DG. For all climates, replacing one of the panes in a double-glazed window from a clear to a low-e coated pane reduces the heating demand by 12-14%. Applying an AR-coated low-e pane reduces the heating demand somewhat further, approximately with 1-2%. The total energy saving for this room is about 160-240 kWh/year.

Summertime, the indoor temperature is not extremely high. The most common way to reduce overheating in multi-family houses in Nordic climates is to use cross ventilation by opening windows. The highest temperature without this extra ventilation is 340C for the standard glazing, however just for a couple of hours per year. For the

Applying an AR-coating on a low-e window increases the light transmittance by 13% and the transmissivity by 14%. The calculated solar and light transmittance and the transmissivity Tr for the three glazing combinations are displayed in Table 4.

low-e windows there are almost 1000h with temperatures over 30oC. Figure 2 describes this as a duration diagram i. e. for Stockholm in the south direction. The Copenhagen and Helsinki climates (not shown here) have very similar results. Figure 3 shows Tsol (average values of all four directions for May) for each window and climate. The difference of the low-e and the AR low-e DG is about 3%. The g-values are shown in figure 4 (average monthly values for May in all four directions) for each window and climate. The difference between g — values of the low-e DG and AR low-e DG is approximately the same as for the