‘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 CO_2. 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.