Façade management as an integral element of building control
Why stop at controlling a building’s services when you can control the building itself? Charlotte Townend explains.
It is estimated that in the UK only around 2% of solar shading in buildings is automated. Yet, automation brings better control of building’s lighting and ventilation — as well as making better use of solar energy.
Automation can also reduce the energy used for a building’s lighting, heating and cooling. Inside, occupants benefit from maximising the use of available daylight, without discomfort from direct sunlight or excessive contrasts in light levels.
In bioclimatic architecture, the comfort and well-being of the occupant are the most important factors. This approach recognises that visual and thermal comfort, together with air quality, can have a direct impact on factors such as a person’s well-being, health and productivity.
Climate is the most crucial aspect of the concept of bioclimatic architecture. The UK’s variable climate does not provide the conditions needed to ensure thermal comfort for occupants all year long. There is thus a need to heat or cool buildings to allow for these changes in conditions and to achieve the best interaction between climates, buildings and the occupants’ needs.
In schools, for example, many factors can influence the quality of the learning environment — including lighting, natural daylight levels and the elimination of glare. All these factors need to be addressed and work in harmony to create conditions that are conducive to effective learning, a child’s development, health, work-rate and overall success.
To achieve such aims in any type of building, effective controls of façade applications, including blinds, shutters, curtains and windows, must be in place. There are many decisions to be made regarding the specification of the most appropriate controls and how they should integrate with other building services.
For example, to make the most of energy savings using natural lighting, the use of artificial lighting sources also needs to be considered and how they harmonize with natural light. Artificial light sources need to be correctly regulated using the most appropriate types of programmed timer systems and presence/movement detectors.
External building walls are the focal point and the link between the interior and exterior environments. This link can be managed by using different types of façade-control systems. For example, local controls within a room utilise manual independent switches. Zonal controls can be installed to cover all the sunshades in a predetermined area. More sophisticated, user-friendly software-based open systems can interface with lighting, HVAC, security, audio-visual and other building-services functions for a fully integrated and flexible approach.
Advanced façade management employs a single programmable computer module and uses data collected from weather sensors to determine when and where sunshades should be automatically deployed. For maximum energy savings, when the indoor temperature is below its threshold and the Sun intensity is above its threshold, the blinds move to a predetermined position.
Real-time climate data can be fed to a smart building-management system to contribute to overall energy savings of a building. By tracking the Sun, blinds can be automatically positioned to Sun elevation, building latitude during the day and every day throughout the year. Leading manufacturers, such as ABB and Somfy, have developed a range of products which provide Sun tracking and shadow management. These are techniques now widely being used for effective façade management.
Most heat gains and losses occur through building walls, which thus can impact on the comfort of the occupants and the building’s energy consumption. The automation of solar shading can provide excellent thermal-comfort control and help to insulate the building, ensuring heating and cooling are optimised by real-time response to the climatic conditions outside and maximising the advantages of solar gain. This can not only reduce power consumption within the building, but can also result in the down-sizing of the heating/cooling equipment that has been installed.
A range of façade-management systems are available from basic low-voltage systems with simple switches, through to remote controls and stand-alone systems using proprietary bus technology.
KNX-certified products are available for the automatic control of shading devices. KNX works by transmitting and exchanging information along a single common control highway (a bus network) that is compatible with a range of products from different KNX product manufacturers. All relevant data, for example the exact position of blinds, is sent in the form of a telegram. 6-way actuators are available for evaluation purposes. These actuators reduce the number of bus stations required, allowing for a more cost-effective system. The parameters for each output can be adjusted individually, and the outputs can also be used as a switching actuator for lighting.
Through KNX, façade products can be simply integrated seamlessly with other building-control systems — critical at a time when the need for energy-efficient buildings is greater than ever before. Façades, HVAC systems, lighting controls, smart metering, emergency lighting, alarms and door-entry systems, occupancy simulation — all can be harmonized and controlled by the KNX open protocol. All building-services functions can then be monitored, programmed and diagnosed via the Internet or LAN.
Up to 40% savings on energy consumption, a reduced carbon footprint and future proofing can be achieved with KNX technology. Its open independent protocol ensures forwards and backwards compatibility, given the huge array of worldwide leading manufacturers and components that support KNX. It is also a stable proven technology that will reduce daily operational costs and is easily integrated with third-party systems.
Façade management is wholly relevant to the demands of Part L of the Building Regulations and the implementation of energy-efficiency measures. It is an often overlooked discipline but one which is set to grow. For optimum results, automated solar shading should be specified as early as possible; bringing it into the building-design concept at a later stage may be both more costly and achieve less effective façade management.
In the UK and Europe, the occupants of many buildings — including Baseler Securitas, Frankfurt; BNP Bank Building, Geneva and ABN Amro, Amsterdam — are already reaping the benefits of improved visual and thermal comfort with effective façade management whilst the operation of the buildings themselves benefit from improved energy efficiency.
KNX technology opens the door to even more opportunities for fully integrated building control embracing all services.
Charlotte Townend is market manager for commercial building solutions with Somfy, a member of KNX UK KNX UK
