‘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.

‘Why Automate Windows' Part 2

'Window Orientation and Cabling'

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.

The process of opening windows of any orientation can be automated to provide easy access to the outside air for natural ventilation or for the provision of smoke ventilation no matter where the windows are located. There are various types of window openings currently available:

‘Hung’ on the outer frame, ‘hung’ refers to the part of the frame which is hinged allowing the vent pane to open, ‘top hung’ refers to a window which is hinged at the top, ‘top hung - open out’ suggests that the window is hinged at the top and opens outward. There are many types of arrangement using these two parameters, including ‘bottom hung - open out’ providing a hopper type window, generally used for smoke ventilation.

‘Hung’ windows can be fitted on ‘butt’ hinges to the outer frame, but more frequently are fitted on ‘variable geometry friction hinges’. These are usually made of stainless steel and are concealed in the space around the vent frame to outer frame and are actually fitted near to the ‘hung’ outer frame member, being placed on corresponding jambs. They are known as variable geometry as the hinges often move the vent frame away from the ‘hung’ outer frame once they are opened.

Centre pivot, or offset pivot windows have simple pivot points on the jambs and can rotate 180 degrees for easy cleaning. These are available in both horizontal and vertical pivot arrangements.

Both ‘hung’ and ‘pivot’ arrangements can be used in sloped facades or roofs.

Glazed or solid banks of opening louvres can also be incorporated into an effective natural and/or smoke ventilation system.

Parallel opening windows are becoming a frequent feature in modern architecture, offering  a simple ‘push out’ arrangements taking the whole vent away from the facade line and offer an excellent mode of ventilation.

All these arrangements can have one or more actuators fitted to provide simple operation and security. In order to calculate the number and size of the actuators required the size and weight of the window needs to be identified, together with its material, the hinge mechanism, and what free area is needed for ventilation. Free area is the area open to allow for ventilation which needs to take into consideration cills and reveals which compromises the free area.

The Geometric Free Area (GFA) of the opening window is calculated as the leading edge of the opening vent ‘x’ the distance opening, plus the two open triangles on each side of the open vent. The GFA can never exceed the maximum opening in the outer frame, or the ‘throat’ as which air can pass. Building Regulation, Approved Document B 2007, states that the method of calculation should only include the leading edge of the opening vents by the maximum opening of the window. Here adjustments may need to be made to the calculation regarding both possible obstructions and the presence of reveals and cills.

Depending on the opening, or stoke distance of the vent to outer frame, a variable efficiency is achieved for the free area provided, this is known as the coefficient of discharge (CV). Depending on the design of the windows and the area being ventilated, this is crucial to efficient operation and the design of the window configuration that needs to be detailed at the early design stages. More importantly the provision of free area for smoke ventilation is crucial in case of fire - again early involvement of a ventilation specialist is crucial.

Once the windows are designed, actuators will need to be placed on brackets to ensure that when a window vent opens the chain actuator operates to the geometry of the opening window. It is vital that this is correctly achieved for all opening positions of the vent to ensure long life of the actuator and correct operation as specified. A poorly designed actuator fixing can cause the actuator to clash with the outer frame which may not be noticeable, but will ultimately lead to damage to the frame and failure of the actuator Early confirmation of design details will ensure that the correct parts and preparations are completed on the windows to make site fixing effective and efficient, accurate and most of all to a high standard. Cabling between the actuator and the control panels seems like a straightforward task, but not one that should be tackled without prior planning, particularly if 240v actuators are being used. If tails are going to be left are these going to run through the window material, if so are bushes required and internal preps to the windows and or curtain wall? What material, what colour of cable should be used - who is going to install and where to? So many questions - all of these need to be answered at the design stages so that a safe and efficient installed system is provided.

To meet the aesthetic requirements of the client, consideration and detailing at early design stages again is crucial. Whilst the sheathing colours of cables may not match the colours of the window system, actuators can be powder coated to match the internal finish of the window making the installation as neat as possible.

As mentioned throughout this series, one of the most important aspects in delivering a cost effective and efficient system is the early involvement of a natural ventilation and smoke control specialist. A complete installation involves many trades working side by side and one experienced specialist overviewing the whole provision.

In the next and final issue we will cover the control of the actuators and the contractual process along with covering free area calculations guidance under the new Approved Document B 2007, and how to achieve this effectively and safely.

SE Controls operate across the globe with offices in several continents, with dedicated 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.

‘Why Automate Windows’ Part 1. ‘Fresh Air & Actuators’

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.

One of the main reasons to automate windows is that of convenience. Not all windows are located at reachable height and may need a pole to operate, in some larger rooms and corridors many windows may need to be opened, so clearly an automated solution is preferable. On securing premises in the evening, automated systems can ensure all windows are closed prior to setting alarm systems. Other benefits can include ‘night time cooling’ strategies, when premises may not be occupied, and an automated solution can operate above ground windows on a time switch basis.

The integration of automated windows into a complete building management system can ensure the most efficient use of energy. Many of BREEAM excellent rated projects in the UK today use natural ventilation strategies based on window automation.

But why do we need to ventilate our buildings? According to Approved Document F and CIBSE it is mainly for health reasons offering the occupiers appropriate Indoor Air Quality (IAQ). Inadequately ventilated buildings can harbour such gases as radon, a naturally occurring gas in the earth, hydrogen sulphide, which often results from the bacterial breakdown of organic matter in the absence of oxygen, carbon monoxide, by combustion processes, dust, virus and fungal spores. The presence of any of these elements can prove to be the cause of ‘sick building syndrome’.

Today we are also much more aware of VOC’s  (Volatile Organic Compounds), which have significant vapour pressures which can  affect the environment and ultimately human health. In newly fitted buildings VOC’s are often present in high quantities in materials such as setting paint and new carpets, these ‘smells’ can easily be identified in the atmosphere. Whilst many are non-toxic at the levels present, VOC’s can still have chronic effects on health. Today anthropogenic VOC’s are tightly regulated, particularly in materials used indoors, but ventilation strategies can play a big part in negating the risk.

In busy buildings, body odour, an increase in moisture from breathing and build-up of CO², often leads to lethargic working or learning environments, resulting in poor working performance - this issue has been well documented in schools where an ‘appropriate indoor air quality’ is crucial to learning ability.

It is crucial that the ventilation strategy is decided at the outset of the design process. By adopting either a completely natural ventilated solution or a hybrid mixed mode solution with mechanical cooling for in only the harshest of weather conditions, can significantly reduce a buildings running costs.

So we have covered the practical reasons and the need for ventilation in our buildings today, but how do we achieve the ‘automation’?

A window ‘actuator’ is usually an electrical device which is placed on the leading edge of a window to open and close a window to various degrees as required. These come in two basic types, a ‘chain’ actuator and a ‘linear’ actuator. Chain actuators are the most compact and operate by pushing a one way folding chain out from a flush motorised housing fitted to the frame or opening light. In areas where windows are much larger, linear actuators, based on fixed ‘screw’ and motor principle may be used.

Whilst these devices may seem to be simple, window actuators do come in a very wide range of sizes and typical offer the following choice specification:

Voltage: Either in 24V DC or mains 230V AC ratings. Where smoke control is required 24V DC actuators are used so that these can be operated from an independent battery back-up in case of fire and power outage in the building.

Load: Usually indicated in amperage and is very important to consider when specifying a complete system. Often cheaper units are less efficient and require greater loads which results in an increase of control panels to operate at the higher amperage, not to mention the increased energy requirements.

Force: Indicated in Newtons (9.81 N = 1Kg) and required to open and close the window safely in all weather conditions. Referring back to efficiency, the available force within the unit should be as efficient as possible to reduce the amperage required. Some larger windows may need two actuators to perform correctly.

Stroke: This is the distance the actuator travels creating the safe opening of the window normally indicated in millimetres.

Speed: Indicated in millimetres per second. This is an important consideration in smoke ventilation situations where smoke vents must fully open with a 60 second time limit.

Size: Units vary in size depending on their specification but housings are very important to be considered when looking at the space available within the reveal, the size of the vent and the stroke required.

Intelligence: Some basic actuators rely on simple switches to limit and run the actuator motor, where occupant intervention is required. Some more sophisticated devices offer resistance feedback and information on where the actuator is within its cycle by the use of incremental volt measurement.

The most important aspect of all these variables is getting the right actuator in the right place to do the job most effectively with the minimum of maintenance. As mentioned earlier it is crucial to get a specialist involved at the very early design stages to determine the most efficient product and designs available. Leaving the choice of actuator to the lowest common denominator - cost, can have a serious detrimental impact on an installations performance and  on-going maintenance requirements.

In the next article we will cover free area calculations guidance under the new Approved Document B 2007, and how to achieve this effectively and safely.

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.

Continued growth creates more new jobs at SE Controls

Continued growth and success at international smoke and natural ventilation solutions specialist, SE Controls, has led the company to take on a further 8 new technical and customer support staff, bringing the total of new jobs created during the past year to 21.

SE Controls’ most recent appointments cover a range of roles including business development; technical sales and key account management as well as installation engineering and project management.

The new staff are not only helping SE Controls meet growing demand for its fire safety and energy efficient ventilation solutions, but represent a significant investment in its future, which is underlined with the appointment of its fourth Trainee Project Leader in the past 12 months.

Maj Mohammed joins Faisal Amir, Ross Cameron and Sion Wilcox, who are being mentored by SE Controls’ experienced project leaders as well as studying for a BTEC level 4 HNC Diploma in construction and the built environment through the company’s in house training and development academy.

“Much of the success we’re experiencing is down to the quality of our people and their outstanding abilities in their respective areas of expertise, explained SE Controls’ Managing Director, Will Perkins. “This, in turn, has helped us grow and support our domestic and international developments, which has enabled us to create a range of new job opportunities here in the UK.”  

He added: “We have a very clear focus on the future of our business and our business development plans demand continued investment in high quality people to ensure we have the right people in place to maintain our high standards of design, technical and project management as well as supporting our increasing focus on customer service, support and quality.”

SE Controls is already in the process of seeking the next Trainee Project Leaders to join its team and the company’s latest recruitment and career opportunities are always posted in the ‘Careers’ section of its website, which can be found at www.secontrols.com.

SE Controls specialises in the design, project management and installation of advanced smoke ventilation and natural ventilation solutions to meet the needs of architects, contractors, building services engineers and facilities managers worldwide. Further information on SE Controls’ products, solutions and projects can be obtained by visiting www.secontrols.com or calling +44 (0) 1543 443060.