Sustainable Building Operation Using Simulation - Low Energy Cooling for Sustainable Buildings - page 227

By means of information technologies, control and simulation actions can also take
place at different locations, so that there are no additional requirements on site for the
building automation system. Only the software interfaces for communication need to
be provided.
6.2.1 Functions and Innovations in Building Management Systems
Energy Consumption Control
The MS are commonly used to control the building and its energy supply systems and
only in some cases also for monitoring the cooling and heating energy consumption of
the building. Since the energy consumption depends strongly on ambient conditions
like temperature and solar irradiation, a simple monitoring provides no detailed infor-
mation on whether the system and the building control work properly and are energy
efficient. If a standard energy management system is installed, at least the yearly or
even monthly energy consumptions of the building can be compared with historical
energy consumption data using degree day normalization methods. However, since
historical data only for long time periods is analysed, this is more a passive than a real
active energy management tool.
Model-Based Control
For the implementation of an active energy management system the monitoring data of
the building and plant performance should be compared with predicted values at daily,
hourly or even shorter intervals using real operating conditions like weather data and
time schedules for room and building occupancies. Instead of comparing measured
and predicted energy consumption, the models can also be used for active control of
the building and the heating, cooling and ventilation systems. Such applications are
for example:
Optimization of heating up/cooling down periods after night-time or weekend
energy-saving time or for partly used rooms when the internal thermal mass of
the building is being considered.
Energy-optimized strategies for the control of the sun shading system in order to in-
crease solar gains in winter and to prevent overheating in summer when the building
envelop properties and internal mass are being considered.
Control of night ventilation cooling by regulating the mechanical ventilation system
as a function of predicted weather or by automated window openings for natural
ventilation.
Control of solar-driven absorption/adsorption cooling systems using weather fore-
cast data. For example, the room temperature can be set at 22 ◦ C instead of 24 ◦ Cif
the weather conditions are optimal for a solar cooling system.