122 TECHNOLOGY / LIGHTING CONTROL
Balancing the demand for natural light and the need to manage radiant heat is leading to a new breed of sophisticated control system for lighting and motorised blind management. Phil Hardy of Philips Dynalite reviews the development of the two control systems.
DAYLIGHT HARVESTING
As technological advances facilitate much finer degrees of control over a building’s internal environment, the expectations of users for levels of comfort, controllability and energy efficiency have moved to take advantage of new possibilities. The result can be an almost symbiotic relationship, in which buildings are able to work with their occupants in a far more dynamic manner than has ever previously been possible. One aspect that is attracting great attention is the use of light—both natural and artificial— and finding the optimum balance. Both the energy efficiency of a building and occupant comfort can be profoundly affect- ed by the building’s orientation to the sun. Sunlight falling on a building facade usually results in both heat and light transfer to the interior. While these may be welcomed during winter, they often cause problems through overheating and glare in summer. The focus historically—especially in hotter climates—has therefore tended towards mitigation strategies against the effects of solar radiation. Fixed shading can prove effective in this respect, particularly in terms of blocking solar heat, which would otherwise lead to the need for additional cooling and the requisite energy to provide that cooling. However, emerging green targets and oc- cupant comfort factors have spawned a new appreciation for the benefits of natural light—leading to the practice now known as ‘daylight harvesting’. This has shifted the focus towards building designs that are flex- ible enough to protect against the summer heat, while still able to embrace natural light and heat at other times.
Façade and fenestration The key to optimising the balance of natural and artificial light is the design of the façade and fenestration (window layout) of a building. The use of motorised blinds in a building can assist in regulating the internal environment in a range of different light and heat conditions. In such situations, heat management is more important than light management because heating and cooling account for a much higher percentage of energy usage than lighting typically does.
The simplest form of integrated lighting and blind system might utilise a timer to change blind settings depending on the time of day and season, with the lighting levels automatically adjusted accordingly.
Sense and sophistication The simplest form of integrated lighting and blind system might utilise a timer to change blind settings depending on the time of day and season, with the lighting levels automatically adjusted accordingly. The introduction of sensors and more sophisti- cated programming, however, make for a system that responds to real environmental factors and delivers enhanced energy and natural light benefits.
In the zone Despite the benefits of an intelligent automated lighting and blind system, it is still important for users to have a level of local control. Because people have differ- ent tolerances to light, a manual override - available from the desktop or from a wall panel - is necessary to provide a capability to make adjustments as required. However, with the capacity for local con- trol, there is also potential for individual users to collectively unbalance the carefully programmed settings for the building.
An integrated future Automated blinds and lighting control have synergistic roles in building energy manage- ment. Architects and developers need to understand that the two solutions comple- ment each other and that the design and implementation of an integrated system will
result in much easier on-site integration, and a better outcome for the building and its users. The growing use of open-source communi- cation protocols—such as RS485, LonWorks and KNX—is facilitating more sophisticated blind and lighting integration. However, this is not the only aspect of an ‘integrated approach’ which impacts performance. Other factors can play a significant role, if the design of a building is not considered on a holistic basis. For example, if highly polished louvers are used they may reflect visible light into a room. The position of daylight sensors inside must be chosen care- fully to avoid false lux readings causing the lights to be dimmed or switched off leaving workspaces with insufficient illumination. With improvements in integration between lighting and shading, buildings will work with their occupants more dynamically in the future to allow hitherto unprecedented levels of controllability and comfort. Where comfort and efficiency have historically been regarded as incompatible goals, the careful inclusion of daylight harvesting technologies will serve to reduce over- all energy usage while increasing indoor environmental quality in a more natural and sustainable manner.
www.dynalite-online.com Phil Hardy is ANZ Dimension Channel Manag- er at Philips Dynalite.
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