The reference case of SIEEB corresponds to the preliminary design of the building with optimized envelope. The characteristics of building envelope includes the low e-values of windows, walls and roof. For energy simulation, the whole building is divided into 28 thermal zones according to location and function of each zone. In each zone, different categories of spaces were considered in respect of their use in the building, e. g. office, laboratory/meeting room, atrium, corridor and underground space (box). Among these, the offices, laboratories and atrium are conditioned spaces and, the corridors and underground space (box) are non-conditioned spaces. The HVAC systems, four-pipe induction unit (FPIU), were simulated for providing thermal comfort conditions inside each zone by primary air distribution. The internal loads and the set points of thermal comfort conditions for each category of space corresponding to Reference Case are shown in Table 2.

As per the requirement and functioning of the building, the schedule for the occupancy and lighting is considered from 8 AM to 10 PM (functioning hours of the building) as 100% throughout the year. This is defined according to the occupation hours of Tsinghua University. However the schedule for equipment is considered from 8 AM to 5 PM as 100% and from 5 PM to 10 PM as 40% of the total equipment load.

Table 2. Reference case — Loads and thermal comfort conditions

The HVAC systems are considered to be off during mid seasons (16 March — 14 May and 16 September-31 October) of the year. The climatic data used for simulations is based on test reference year (TRY) for Beijing climate. The results of simulations are presented below:

Figure 3 shows the annual energy demand for cooling, heating and lighting & equipments in percentage of total energy demand. It can be seen that the energy demand for air­conditioning has a very high contribution in total energy loads. Cooling demand dominates the building energy loads (40%) and the heating demand is relatively lower (18%).

It can also be observed that the internal loads (lighting and equipments) are very important and have accounted for about 42% of total energy demand. The monthly energy demand for cooling, heating and lighting & equipments are shown in figure 4. The peak loads for cooling, heating and lighting & equip. in SIEEB are 963, 357 and 230 kW respectively.

Figure 4. SIEEB (Reference case) — Monthly Energy Demand