Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 419

transpired thermal collector in Section 7.4.2.6. The air path differs from
time to time depending on pressure variation caused by demands. For data
center ventilation, when outdoor air is too cold (less than 7.2 °C (45°F)),
the air is mixed with data center warm exhaust air before entering the data
center.
7.4.2.6 Transpired Solar Thermal Collector
About 300 m 2 of collectors are installed on the south façade of the south
wing. The flow rate is 4720 m 3 /s (10,000 CFM) at 100% fan speed and it
varies approximately linearly with fan speed. The solar air heating system
was sized based on ventilation and space heating needs.
When the average labyrinth temperature is lower than the setpoint
temperature of 19.5 °C (67°F), and the transpired solar collector
temperature is 8 °C higher than the setpoint temperature, the fan will start.
The fan speed will ramp up slowly. A coefficient (0 to 100) for controlling
the fan speed is calculated based on several variables, but the fan speed
is limited between 10 and 80% of the maximum rate. If the fan speed
coefficient is lower than 90, and if the outdoor temperature is higher than
18.3 °C (65°F) or the transpired collector temperature is not more than 3 °C
higher than that of the average labyrinth temperature, the fan stops.
Some performance data for the transpired solar collector were measured
during a visit to the building by the authors. On a clear sunny day at 10:30
A.M., with inlet at 10 °C (50°F) and 3.78 m 3 /s (8000 CFM), the outlet
air reached 26.3 °C (79.4°F). The collector plate temperature was 29.4 °C
(85°F). The collected heat rate was about 72.5 kW.
7.4.2.7 Natural Ventilation
For natural ventilation ( Figure 7.49 ) , the southern vision windows are
manually operable or controlled with an automatic actuator, while on the
north side, the lower windows are manually operable and upper windows
are automatically controlled (because they are out of reach). The building
occupants manually operate the windows to suit their needs. A
workstation-based task manager interface notifies occupants when
conditions are optimal for natural ventilation and windows may be opened.
The actuated windows are operated primarily to support nighttime