Like other electronic systems, building services controls have undergone a transformation in recent years and now offer very high levels of sophistication as well as incorporating the latest technologies.The important thing,though, is to maintain a clear vision of why the controls are there and who is going to be using them.Failure to take these factors into account will often lead to systems whose potential is under-used,thus negating the anticipated return on investment. They may even end up wasting energy rather than conserving it.

Another consideration is the cost of installation.As the cost of the controllers themselves comes down,the installation now forms a more significant proportion of the overall cost.As a rule of thumb, simpler controls cost less to purchase and to install,particularly when retrofitting to existing systems.

One of the major driving forces behind the growth in control systems has come from Part L of the Building Regulations,demanding higher efficiencies. This will soon be reinforced by the Energy Performance of Buildings Directive (EPBD) and the Waste Electrical and Electronic Equipment(WEEE)Directive.

The EPBD,due to come into force from January 2006,will give buildings an Asset Rating and an Operational Rating, based on the quality of the building and its plant and on the way that the plant is operated. This has significance for control strategies and their role in energy management.

The WEEE Directive impinges on disposal of plant and these disposal costs will be influenced by the ability of the controls to optimise the performance of plant and extend its life.

In addition,major energy users will be required to meet targets for carbon dioxide emissions. Those who miss their targets will be subject to financial penalties,while those who exceed targets will be able to sell their surplus carbon allowances via the European Emissions Trading Scheme.For the first time,saving energy has the potential to generate a new revenue stream.

All of these pressures have led to a stronger focus on controlling the energy performance of buildings.Unfortunately,it is often assumed that better control requires highly complex,expensive control systems. In fact,very significant savings can often be achieved with simpler systems.

At the end of the day, complex controls are only as good as the people who are using them on a day to day basis.A complex building management system (BMS) certainly has the potential to provide high levels of control,but its very complexity can stand in the way of optimum performance. For example,if the OEM manual that comes with the system is so complicated that the contractor can’t understand it, there is a very real danger that it will not be installed or commissioned properly.

It’s also important to remember the importance of commissioning by specialists and budget for this when calculating the project costs. Some controls may be considered as commodity items now but correct commissioning is still essential.Setting an inappropriate time delay on a presence detector controlling lighting,for instance,can cause ‘nuisance’ switching and eliminate the good will of the people in the workspace.

Similarly, it’s important to remember that the control functions of the BMS are likely to change with time and simple controls are generally more flexible and better able to respond to changes in building use.In contrast,tweaking a BMS often requires third party specialists whose hourly rates match their skills levels.Often this will result in the BMS being bypassed rather than going to the expense of reinstating a system that is perceived to offer little benefit.

The important thing is that the operator feels comfortable in interfacing with the control system – even if it’s just to tell them there’s a problem that requires specialist attention.The worst thing to do is present them with a system that is so intimidating they are discouraged from accessing it at all.

It’s also important to ensure that people feel they have some control over their working environment;so input from people is to be encouraged rather than avoided.

Fortunately, specifying user-friendly controls does not have to compromise on performance because the latest generation of intelligent standalone controls combines a high level of functionality with ease of use and an element of local control.

A case in point is the use of lighting controls to optimise energy consumption,often by using presence detection to switch lighting on and off,and photocells to dim the electric lighting in response to natural daylight levels.Both of these functions can be achieved with varying levels of complexity so there is plenty of scope for making the control strategy fit the use.

For instance,at a simple level,presence detectors may be installed in areas that are unoccupied for much of the time,such as on stairwells,so that the lighting is only on when the area is unoccupied. In an open plan office,though,there will need to be some linking to adjacent areas to maintain lighting in real or notional corridors when the office space is occupied.

There is a common misconception that this level of functionality can only be achieved with a dedicated busbased control network but this is not the case. Today’s powerful micro-processors enable a great deal of programming capacity to be packed into an uncomplicated device,with the ability to share information with other devices through simple wiring connections.

Where photocells are used,the electric lighting will dim when there is sufficient daylight to maintain the required illuminance. However,it is also important to bear in mind that each person’s visual requirements will vary with age and with the visual complexity of the task they are performing.

In these situations,providing manual override of the pre-set levels will enable individuals to make limited adjustments to the lighting level at their workstation.

The use of simpler systems is often the most effective approach when upgrading or retrofitting controls to existing plant.Another commonly encountered example is the control of warm air heaters used in large open spaces such as factories and assembly areas.These items of equipment are often factory-fitted with rudimentary controls that only offer very basic levels of control.

Just replacing these basic controls with an electronic time and temperature controller,with programmable optimum start,can make a big difference to running costs. And these savings will be even greater if the optimiser that is used is included in the government’s Energy Technology List. Products included on this list are eligible for Enhanced Capital Allowances,so that 100 percent of the tax allowances on the investment can be reclaimed in the first year, rather than being spread over a number of years on a reducing balance basis.

In retrofit situations,the first step is to carry out a detailed energy audit of the existing systems to see how they are performing and what measures can be taken to improve performance.This approach ensures that each area of the building services is considered in the context of its use and those who are using it.It also enables an accurate calculation of return on investment for each of the measures being proposed so that the most appropriate and cost-effective steps are taken.

The Building Regulations now require that every new and refurbished building, which includes refurbished or new plant,in England and Wales is provided with a building log book.This log book will focus attention on how the building will be run and the methods used to achieve that – including how well the control strategies are suited to the use of the building.

Up to now this requirement has not been rigorously enforced but,with the introduction of the EPBD,log books will become standard and specifiers will be forced to look more closely at the control strategies they introduce.As this happens,we can expect to see more attention given to the needs of the user and greater reliance on powerful stand-alone controllers that retain a simple front end for increased ease of use.