‘Why Automate Windows' Part 3
'Control and Contractual Process'
Will Perkins - Managing Director - SE Controls
In this
series of articles by Will Perkins we look at the provision of adaptive natural ventilation for healthy and efficient buildings and the safety provision of
smoke ventilation. The series attempts to explain some of the pitfalls in the
lack of early design and understanding of such systems.
In this
third and final part of the introduction to automating windows we look at how
to control actuators in order to offer building users the most flexible and
sustainable methods of achieving the ultimate goal - good air quality.
The
simplest method of control is by wiring actuators up to a single on / off
switch which will offer either an open or closed window condition for one or
many windows wired together. A more sophisticated, but still a simple solution,
is to have the windows operable on a ‘rocker’ type switch. Windows will slowly
open when pushed one way, slowly close when pushed the other, and when allowed
to back to its central position the windows remain at the incremental position.
Whilst both these options are the most basic form of window automation, manual
override switches with this functionality are often fitted to more complex
installations in order to offer building users an element of control and to
efficiently adapt to changing internal and external conditions
As
mentioned previously, some actuators will be required to operate in case of
fire for smoke ventilation. These actuators will be rated at 24 V dc and a
control panel will be provided with a step down transformer from the mains
which will constantly charge a 24 V battery. In case of a power outage the 24 V
batteries will continue to operate the windows for safe heat and smoke evacuation
keeping exit routes clear of toxic smoke.
Taking the
system further and now beginning to add some ‘logic’, an adaptive natural
ventilation system can be provided. The adaptive natural ventilation control
strategy monitors internal and external conditions and activates the vents or
windows to provide a productive and efficient learning or working environment.
There may
be a need to close the windows should it start to rain. A rain sensor can be
fitted to the roof and when activated can ensure windows are safely closed to
stop water ingress. Further options can include seven day timers which ensure
windows are always closed for security outside normal room accommodation hours,
such as in offices, schools, etc. For night time cooling or early morning purge
time, clocks can be utilised to ensure that the automatic opening vents operate
at the optimum time.
Cost
effective sensors can be installed into areas where banks of windows have been
automated and these same sensors can control proportional opening of windows to
finely control comfort levels of temperature and CO2. Low levels of
CO2 have been proven to be conducive to improved levels of
concentration and learning, this is particularly important in schools.
Wind
direction can contribute towards an effective ventilation strategy and with a
‘weather station’ installed on the roof of a building and more complex
programmable controls, algorithms can be introduced which offer the most
effective solutions by using wind driven ventilation strategies to control the
comfort of an internal environment. Most importantly, window automation
strategies must be combined with a buildings overall heating strategy, to
maximise energy savings and offer the most sustainable solution. Early
appointment of a window automation and ventilation specialist is imperative if
the structure is to make best use of these options.
It is
common to see a ventilation strategy within a building, as explained above,
that is interfaced with the fire alarm system. An entire window automation system
can be linked so that it operates as a smoke ventilation system in case of a
fire. Should this be the case, actuators will need to be 24 V DC instead of a
directly connected to the mains power supply. Whilst sounding very complicated
there are some very cost effective ways to achieve this dual function. Also
important to note, is that if an automated system is linked in to a smoke
control strategy, then a preventative maintenance package needs to be adopted
to ensure that the life safety system can operate as designed in the case of a
fire.
Occupants
need to be fully aware of automated window and ventilation systems which are
installed into their new or refurbished buildings - many people wish to have
full control over their own working environment, it’s not always to everybody's
taste! With initial education and an agreement of what constitutes a sensible
working environment for all, saving in energy usage can be achieved.
Taking all
the energy and ventilation resources into consideration, including areas of
solar gain and wind direction, the building can be effectively modelled to show
what can be achieved at various times of the day and under different changing conditions.
There are
various standards that need to be adhered to ensure compliant installations;
these include current building regulations and British Standards. However, new
products standards are now being introduced from Europe for smoke control
systems. The family of new standards fall under EN 12101 and covers ten parts
of controlling smoke in a fire condition. For smoke ventilation the use of CE
marked ventilators along with the requirements and testing methods are an
important factor that specifications are requiring. A further important
standard is EN 60335-2, which covers protection of the public where mechanical
devices are present. Where mechanical automatic opening vents are operational under 2.5 metres (2.5 m from
floor level) then protection against trapping is necessary. Protection may be built
into the actuator or separate devices may be needed, to mitigate the potential
risk.
The
contractual process for installation of window automation and smoke control
packages covers many on-site specialists, including the window manufacturer,
installer, electrical systems, heating system, fire alarms, etc. So care in
selecting a competent specialist that can offer a complete design solution all
the way through to after care is crucial to getting a well-designed and
integrated installation. Split packages where responsibility for different elements
falls to different companies often lead to poorly designed, costly and
inefficient systems.
An example
of this usually resorts to the facade contractor selecting the most
competitively priced actuator which meets their quality standards, but with little
reference to the power that the device consumes. A single device taking 18
Watts of power may seem a small amount of power to run a single actuator,
multiply this by 100 actuators and the consumption runs to 1.8 Kilowatts.
Compared to a 12 Watt device the saving in power alone is 33%, but more
importantly the control system will need to handle more power as a result and
increase installation control panel costs.
The most
cost efficient way of specifying and installing adaptive natural ventilation
systems and smoke control systems is to approach a specialist who can offer a
complete design package, from design through to installation and maintenance.
Not only can this approach offer a balanced approach as far as the system is
concerned, but by offering specialist ventilation design advice at
architectural concept stage can reduce building costs and as importantly,
future running costs which effects the buildings long term sustainability. Often
initial budgets omit significant packages necessary to implement adaptive
natural ventilation successfully, later causing poor compromise and ill feeling
towards the technology. At SE Controls the complete supply chain is supported,
the main areas being:
Design & Cost Planning
During early design stages SE Controls can assist the client and
design team in specifying the most cost efficient and practical solution for
natural ventilation, smoke ventilation and window automation.
Approval and Tendering Process
SE Controls offers coordination with the client, the approving
body and bidding contractors throughout the tendering process.
• Coordination with approving body
• Production of specifications for tendering
• Planning and mid-tender meetings.
Coordination
At early stages of the project vital information is required by
the contractor. AOV openings may be built into the shell and the core of the
building including, walls, roofs and facades.
Commissioning Handover, Training and Optimisation
During the final completion stages of the project build phase,
SE Controls will commission the ventilation system. This will typically involve
detailed cause and effect testing of all the system components against the
design specification. SE Controls trained commissioning engineers will then
hand over the system to the client together with detailed operating
instructions and training. After occupation the system can be optimised to suit
client requirements.
The most
important decision a specifier can make is selecting the right specialist for
the project as early as possible.
SE Controls
operate across the globe with offices in several continents, with specialists
offering clients expert advice based on local legislative requirements. Visit
the website at www.secontrols.com for further information. To discuss your
requirements with SE Controls, or request literature, please call their head
office in Lichfield on 01543 443060.
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