The high demands for level of lighting on the bookshelves and the architects wishes for the artificial lighting system, causes the heating load from artificial light to be much higher than the heating load from people and equipment. The overall internal heating load is high and will give high indoor temperatures outside the heating season. A effective way to overcome this problem is to control the artificial lighting system, especially that on the bookshelves in such a way that they are shut off or subdued most of the time outside heating season.

Daylight simulations showed that it is possible to shut off most the artificial light about 65% of the opening hours if controlled by the level of daylight at minimum 200 lux. In the BSim2002 model of Albertslund Library the artificial light at the bookshelves is subdued and shut off most of the time during summer as found in the daylight simulations.

4.3 Indoor Thermal Climate From the simulations made with BSim2002 the following indoor tempera" tures in different parts of the library has been found during opening hours. Figure 13 shows the mean indoor operative temperature during opening hours for the different sections of the library during a warm and sunny week.

Figure 13 shows that the indoor temperatures are at a satisfying level in the summer. Table 1 shows the annual number of hours the mean indoor operative temperature exceeds 26 °C and 27 °C, respectively for all sections in the library.

3.5. Conclusion

According to Danish guidelines indoor thermal climate in offices, DS474, the annual number of hours during the opening

hours for a whole year should not exceed 100 of hours above 26 °C and 25 hours above 27 °C and the maximal indoor temperature should not exceed 30 °C. Table 1 and figure 13, shows that these guidelines are held for Albertslund Library. Furthermore, table 1 shows that the amount of hours with overtemperatures are low. The east section of the library has a high internal heating load per m2 and only one skylight for exit, thus getting higher indoor temperatures then the rest of the library. Overall it can be concluded that the indoor thermal climatic conditions for Albertslund Library is satisfying.

2. Conclusions

Based on the detailed simulation work that has been carried out during the design phase the following overall conclusion can be made.