Building automation – impact on energy efficiency - Siemens ...

5.2 Customer benefits resulting from
eu.bac Cert
For the product user, eu.bac Cert guarantees a high-degree of
• energy efficiency and
• product quality
as set forth in the corresponding EN / ISO standards and European Directives.
The energy efficiency of individual room controllers can be documented as follows:
Impact on energy savings
As mentioned earlier, the control accuracy of individual room controllers is
measured and confirmed with a certificate. The control accuracy has a direct
<strong>impact</strong> on the behavior of room users. The poorer the control accuracy, the
more likely the user is to adjust the room setpoint as a result of poor comfort.
The chart below illustrates how much energy (in %) a controller with control accuracy
of 0.2 K saves versus a controller with control accuracy of 1.4 K. Please
note the following:
Eu.bac has reduced the required minimum control accuracy in EN15500 from 2
K to 1.4 K.
Source: "Centre Scientifique et Technique du Bâtiment (CSTB)", France
Siemens individual room controllers achieved very solid values. For example,
for Desigo RXC21/fan coil with actuators for heating 0.2 K and cooling 0.1 K.
Impact of actuator on
energy savings
It is well known that characteristics (time constants, adjustment response, characteristic
curve, etc.) for field devices have a direct <strong>impact</strong> on control accuracy.
In other words, we achieve different levels of control accuracy with the same individual
room controllers and temperature sensors, but using different valve actuators
(motor, thermal modulating, thermal on/off) and thus different energy
savings. On the flip side, the variously equipped control circuits cause differences
in the costs of the control circuit.
The chart below illustrates that a higher investment in motor driven valves
makes sense versus thermally driven valves (in the comparison with the previous
chart, curve "natural gas heating H3"/Southern France):
• The amortization period for the investment is shorter
• Then operating costs are lower as a result of larger energy savings
• And the <strong>impact</strong> on the environment declines in line with the energy savings
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