Swegon WISE - Interacting Functions with the Cooling;Heating Producer

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WISE User Manual
How does pressure optimization of the
supply air temperature work?
The supply air temperature from the air handling unit is opti-
mized to reduce the need of heating/cooling in the rooms.
There is a xed temperature setpoint value, which is used when
there is no heating or cooling requirement in the installation. It is
possible to set which rooms in the installation are to contribute
with their need of optimization.
Interacting functions with
the cooling/heating producer
Water optimization functions
Why optimize the cooling/heating producer?
The main purpose of the optimization functions is to reduce
energy consumption, but the functions also help to increase
comfort, reduce the risk of condensation and make it easier to
avoid oversizing.
The following types of optimization are available:
• Optimization of the supply ow temperature
Optimization of the supply ow temperature
Why optimization of the supply ow
temperature?
The demand for cooling and heating capacity varies greatly and
the maximum design demand occurs only during a very few
hours of the year. This allows for energy savings. The COP and
EER value for a heat pump or water chiller compare how much
capacity these produce, against the power they consume. The
higher COP and EER, the more ecient the equipment.
The amount of cooling or heating a liquid chiller or heat pump
can produce depends largely on the size of the temperature
dierence between the hot and cold side. This means that
electrical energy can be saved if the liquid chiller produces as
warm cooling medium as possible to meet the cooling require-
ments of the installation. Similarly, you don’t want to produce
warmer heating media than necessary. As a rule of thumb, for
every degree that the temperature of the cooling medium can
be raised or the temperature of the heating medium can be
lowered, 2-3% of electrical energy is saved.
Another advantage of the system not requesting colder cool-
ing media than needed in the cooling case is that the number
of hours when free cooling can be used on the liquid side is
increased.
In addition to saving energy, optimizing the supply tempera-
ture can lead to improved thermal comfort. When the cooling
demand in the room is low, a low supply temperature combined
with simple on/o control of the water ow risks leading to
impaired thermal comfort due to uctuating room temperature
and draughts.
How does optimization of the supply ow
temperature work?
WISE regulates the temperature in each room. If there are
waterborne climate products, the valves will be opened or closed
according to the cooling or heating needs of the room. The
demand for cooling or heating is calculated by a controller that
compares the measured temperature with the current tempera-
ture setpoint, see section Temperature control.
The controller calculates a degree of opening of each valve. If
the valve is far from fully open (degree of opening << 100%), this
means that the room would cope with a lower supply temper-
ature in the heating case and a higher supply temperature in
the cooling case. Conversely, an opening rate close to 100%
indicates that the system is struggling to maintain the correct
temperature in the room and needs a lower or higher supply
temperature.
The system allows an upper and a lower limit on the opening
degree of the valve to be set when the room requests a new
water temperature. As long as the room is between these two
valve opening settings, the room will not request a new water
temperature, even if there is a cooling or heating demand.
Operating case
If a room with cooling demand reaches a room temperature
within the limits, the cooling demand will disappear. The room
will therefore require a higher water temperature. This increase
of the requested water temperature is valid until the room either
has a cooling demand or reaches the maximum selected cooling
medium temperature in the installation. How quickly the room’s
required supply temperature changes can be set by adjusting
how many steps the optimization should take and how oen the
supply temperature is to be updated.