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Automatic Control Vs Individual Control. Do The Costs Add Up?
The need for control is part of human nature and as more of our buildings are being designed to empathise, complement and nurture human behaviour, they are becoming increasingly ‘alive’, governed by intelligent building management systems controlling elements such as temperature, light and CO2 levels.
One of these prime elements is the sun and the impact it has on the internal environment of buildings, namely glare, light and the biggest problem of all, solar heat gain. There are systems, both automated and manual, that can help to alleviate these problems, but which ones work best to overcome which problem, and do they really offer a cost effective solution?
The ideal: human control internally; fixed or automated control externally
The basic rule is that internally, people should be in control of minimising glare whilst externally, fixed or automated controls should take care of solar heat gain.
In recent studies by the BRE, external shading was identified as the most effective method of controlling solar heat gain. For south-facing windows, horizontal sloped louvres provide the most effective solution whilst on east and west facing windows, vertical sloping louvres are best.
Fixed brise soleil is now commonplace on commercial and public buildings and has been for some years. It effectively offers a proven solution to eliminate solar heat gain by shading glass façades.
elimination of glare
In offices, glare is a major concern as computer workstations are now in everyday use and regulations regarding display screen equipment now apply. In most instances, blinds which can be manually adjusted by the occupants are sufficient to eliminate glare.
So between them, fixed brise soleil and internal manual blinds can manage solar heat gain and glare, but can more be done? With intelligent buildings and intelligent, responsible design come new intelligent systems. So what are they, how do they work and do they offer a realistic, cost effective solution?
optimal Shading 100% of the time
Fixed position systems can only provide shading for some of the time, motorised solar shading can provide shading 100% of the time. Motorised solar shading due to its nature and additional components such as motors, wiring and controls systems, is more expensive in terms of initial capital outlay. In addition, other factors need to be considered: - operating costs (energy, manpower, maintenance), performance (consistency, reliability, predictability) and extensibility (flexibility, better use of resources).
Whilst it may be more costly in terms of initial outlay, motorised solar shading can offer financial returns – often within a matter of years. Shading can significantly reduce energy consumption as building interiors will be naturally cooler and benefit from natural light. Less air conditioning and lighting is therefore required. Compare this to the initial outlay plus running costs, and in most cases, solar shading and even motorised solar shading will quickly pay for itself.
Different variations on all of these systems can be achieved and by carefully applying these at the design stages, considerable savings in energy consumption and the creation of comfortable and responsible workspace can be achieved.
dedicated central solar control system
These automated solar shading systems should however be controlled by a central solar control system, separate to the building management system (BMS). A centrally controlled, stand-alone system ensures that the workspace inside the building is conducive to achieving the optimum working environment.
For example, at the BT offices at Brentwood, where a separate solar shading control system has been implemented, the external motorised blinds, covering three floors, across eight different elevations, react to the movements of the sun during the day.
The system will automatically raise and lower the blinds in accordance with the amount of solar heat gain on the elevation affected. However, should an individual wish to override the system to suit their own personal glare control requirements, this can be done through individual manually controlled overrides.
As a consequence of this flexibility, the system will automatically reset the blinds to their starting positions, either at the end of the working day or when it detects a rise in temperatures. This ensures the building’s environment returns to predetermined levels and the overall aesthetics of the building is restored to normal.
Bexley Business Academy
Another example of an automated system in use is at the new Bexley Business Academy, vertical motorised solar shading has been installed, following the sun and eliminating solar heat gain whilst allowing the maximum natural light into the building. To provide the teachers with control over their individual environments, override switches have been installed in each room. These allow them to darken a room, for example, to show a presentation, by closing the solar shading outside their window. If left closed after a class has finished, The shading control system overrides the switches and returns the louvres back into their required position for that time.
Whilst these external, intelligent systems work well to counter the sun, offering reduction of heat gain and a method of reducing energy consumption, internally manually operated blinds are still the norm. The majority of us are comfortable, living and working in environments that are becoming more automated with processes now no longer in our control but being managed and governed by intelligent systems. There is still a need for individual control and internal blinds offer this, providing protection against glare with the simplest of touch.
Human Input still vital
So, in short, we need a mixture of both – automated and manual control. Let technology externally manage the sun and minimise heat gain whilst allowing individuals to manage glare within their own space. There may come a time when automated controls take over throughout, but for the moment, let’s share the responsibility.