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About
the building The General Secretariat for Information Systems
(GSIS) building in Athens is a public, administration agency belonging to the
Greek Ministry of Economy and Finance. It is an unusual office building, as
it was built as a factory in the 1960s and converted to offices in the 1990s. Objectives Refurbishment
Strategy Solar Gain Control External perforated metal horizontal and vertical
shading devices were fitted to the south and west facades to reduce solar
gain which previously caused overheating. Lighting All lighting was replaced with energy efficient T5
luminaires, with electronic dimming capabilities. The lighting automatically
dims in response to natural daylight levels to minimise the use of artificial
lighting.
Heating and Cooling Prior to refurbishment, fan coil units met the
thermal and cooling requirements of the office areas. These were grouped in zones and provided
heating with pumped, boiler heated water. Similarly, water was passed through
central chillers when necessary to provide cooling. The units were equipped
with local controls (thermostat and speed controls) and operated
independently of any other environmental parameters. Consequently, it was
common practise to have the fan coil units operating at full capacity whilst
the windows were open. Also, the water pumps operated at full capacity
regardless of the heating or cooling demands of the building. During the refurbishment, wall mounted thermostats
were introduced to control the operation of each fan coil unit. All
thermostats were wireless and communicated with a centralised BEMS. The
thermostats were configured to operate only when the offices were occupied
and in night setback mode, when the office was cooled. The valves of the fan
coil units were replaced with motorised valves, which could be controlled
through the BEMS. Magnetic contacts were installed at the windows, which
could switch off the fan coil units when the window was opened. To make the operation of the pumps more efficient,
calorimeters (combined with flow meters) were installed in all primary
circuits to measure the thermal loads of each zone. Inverters were also
installed to control the output of the pumps. The calorimeters are monitored
constantly and the speed of the pump is automatically adjusted to respond to
demand for heated or cooled water. Ceiling fans were introduced to make use of the
evaporation cooling effect. These are connected to the centralised system and
switch on or off depending on whether a person has been detected by the
occupancy sensor, or if the temperature exceeds a preset level.
For
this part of the innovation procedure, temperature and CO2 sensors were
installed. Also, the central wire and wireless network for each floor was
installed. In the next few days the installation of inverters and
calorimeters will be done. Ventilation Before the refurbishment, air handling units
pre-conditioned the air from outside. These were distributed in zones, each
of which served a number of office areas. The building is the workplace for
1400 permanent employees spread over 30,000 m2. Offices were
densely occupied and CO2 concentrations were sometimes extremely
high. A Demand Control Ventilation system was installed.
Motorised Volume Dampers were installed to the air handling unit zones. Air
quality and CO2 concentration is monitored and the dampers are
opened when the CO2 concentration increases above a preset level.
When the CO2 concentration is below this level, the dampers are
set to provide at least 30% fresh air to the offices. At these times, the
unused fresh air is directed to other zones, ensuring that the air circuit is
kept balanced. An additional damper has been installed between the fresh air
supply and return air to compensate when there is an overall excess of fresh
supply air and redirect it to the return air stream. This redirected air is
already preconditioned and therefore reduces the amount of energy that the
air handling unit consumes to precondition the fresh air. All measurements
from the Motorised Volume Dampers and CO2 and air quality sensors
are visible to the SCADA system.
Renewable Technologies A photovoltaic array was installed, consisting of 19
semi-transparent cells.
GSIS solar PV installation Energy Management, Control &
Monitoring Economiser control
Sustainability and Materials Commissioning Several technical problems were encountered but
these were relatively minor and were generally caused by the fact that the
building remained operational throughout the refurbishment, and new systems
had to be installed into a building with existing infrastructure. For
example, in order to replace the motorised valves on the fan coil units, the
system needed to be drained, which was not possible whilst the building was
in use. A special process had to be devised where the water in the central
water pipes was cooled to freezing, in order to stop water leaking from the
fan coil units. It was decided to install a completely new BEMS as
part of REVIVAL, which would operate independently from the existing BEMS.
The new BMS is successful and is essential for troubleshooting in such a
large building. The solar PV installation also delivers the expected savings. Monitoring In
the frame of the present task, a very detailed monitoring strategy will be
defined and the specific performance of each of the major subsystems defined
will be monitored using the appropriate protocols and instrumentation. The
protocols and monitoring techniques that are going to be used have been
established either by international bodies and organizations or have been
developed in the frame of previous research projects. In addition, a survey
will be planned and performed among the employees of the building in order to
evaluate the level of thermal comfort and indoor environment quality
achieved. The
monitoring system will be included into the BEMS. For this purpose additional
heating volume meters and electricity meters will be installed and a special
performance specification for the BEMS will be written. The
monitoring phase will have the duration of a whole year and the obtained data
are going to be analysed and evaluated in order to identify the efficiency of
the implementation of the proposed energy saving strategies and technologies
in the building. The Completed Building The GSIS design team were able to integration “low
energy and sustainable design” into the refurbishment process, as targeted in
the original contract. The GSIS is a public, administrative building and has
experienced severe, bureaucratic delays and communication issues during the
refurbishment. The fact that the building was still in use during
refurbishment mean that for safety reasons, some work had to be carried out
on weekends, causing delays. The concepts of sustainable building
refurbishment are not widely recognised in The
demand control ventilation strategy, where CO2 sensors are used to
control the supply of outdoor fresh air based on the actual occupancy of the
room, is an effective way of saving energy. However, occupant satisfaction at the GSIS building after refurbishment was not
as high as expected, with users commenting on the indoor temperature and air
quality in particular. The ventilation system may have been more
successful if it provided a gradual increase in fresh air supply as the CO2
concentration increased, rather than responding to fixed CO2
limits. This feature was not possible at the GSIS building due to limitations
of the existing infrastructure.
Dissemination. ·
Monitoring of the indoor air quality of the
GSIS building within the frames of the EU project REVIVAL, Group of Building
Environmental Studies, 2007 ·
Results of the BEMS monitoring on the energy
consumption and indoor air quality of the GSIS, Group of Building
Environmental Studies, 2008 ·
Article published in the national magazine ‘Energy
Point’, May 2008 ·
Final results of the G.S.I.S. renovation,
submitted to the 7th International Conference on Sustainable Energy
Technologies, August 2008. ·
Energy and environmental design of the GSIS
building, Energy at Urban Areas, Athens, 29 Nov. 2006 |
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