4. Clasificaci´ on 75
4.2. Combinaci´ on de clasificadores
5.1.1. Influencia del par´ ametro c y t´ecnicas de selecci´ on de
Developments in intelligent buildings have not been limited to advances in technology in the areas of computers, communications and building engineering. Changes in societal attitudes that reflect a higher standard of living have highlighted issues associated with the provision of a healthy working environment. This is being reflected in an increasing demand for high quality office space, spread across all classes of buildings, and a need for advanced information processing and communications systems. Hartkopf (1995) outlines the technologies and services that are part of the intelligent building infrastructure. Some of these are shown in Table 4.2.
Table 4.2 An outline of the technologies and services that form part of the intelligent building infrastructure
Infrastructure Services
Enclosure 䊉 load balancing
䊉 solar control
䊉 heat loss control
䊉 daylighting
䊉 passive and active ventilation
䊉 passive and active solar heating Interior 䊉 spatial quality
䊉 thermal and air quality, visual quality
䊉 acoustic quality in the individual workstation
䊉 new workgroup concepts
䊉 shared services and amenities
Telecommunications 䊉 external connectivity and command centres
䊉 vertical chases and satellite closets/rooms
䊉 horizontal networks and horizontal plenums
䊉 service hubs and shared equipment
䊉 conference hubs, connectivity
Site 䊉 transport
䊉 streetscape, public access and thoroughfares
䊉 relationship with the community
Treated Space
Intelligent Building Management System
air quality
fire/life/safety
HVAC
motion
lighting
access
voice
video
data
Developers of building systems of all types have been challenged to deliver on these demands. The successes to date have created a new opportunity for adding value to the capabilities already inherent in the building. Intelligence has become ‘distributed’
enabling micro zones to exist independently of the rest of the building. For organizations, this is an important consideration. Organizations modify space to suit business needs.
People, by their nature, tend to modify their work environment to suit personal tastes and corporate identities. The ability of building systems to interact using distributed intelligence enables a successful outcome to be achieved.
Site specification is important in terms of the delivery of services. It is not enough to assume that technology and site specification represent separate criteria and can be dealt with individually; rather, it should be assumed that the site and the technology are intimately linked with the allocation of services. Lehto and Karjalainen (1997) focus on the user-orientated approach to site and technology in order to deliver energy management through extensive analysis of the brief, addressing all aspects of the building’s function, to ensure the building can be effectively and efficiently structured to provide optimal functionality.
4.3.1 Capabilities of the intelligent building
The overriding function of the intelligent building system is to support the capabilities inherent in it (Figure 4.1). Clearly it is necessary to consider an intelligent building as a single entity unifying objectives of the owner in delivering the building’s desired capabilities with the adaptability and functionality desired by the occupants.
As with the systems present in the intelligent building it is possible to list the capabilities. They include:
䊉 sensing human presence and/or occupancy characteristics in any part of the building and controlling the lighting and HVAC systems based on appropriate pre-programmed responses
Figure 4.1 Typical functional zone and its attributes.
䊉 performing self-diagnostics on all building system components
䊉 alerting security and fire alarm systems and monitoring the location of occupants in case of emergencies
䊉 sensing the intensity and angle of light and solar radiation, temperature and humidity, and adjusting the building’s envelope according to the desired interior performance levels
䊉 monitoring electrical outlets for malfunctioning equipment
䊉 monitoring access to the building and individual building spaces
䊉 detecting odours and pollutants and responding by increasing ventilation rates
䊉 distributing electric power to computers on demand or in accordance with a preset priority schedule and automatically activating reserve batteries or back-up systems
䊉 selecting the least cost carrier for long distance telephone calls
䊉 activating ice-making or heat storage systems when the utility signals that discounted rates are in effect
䊉 providing better acoustic privacy by activating white noise systems to mask background noise.
4.3.2 Heating, ventilation and air conditioning (HVAC)
HVAC systems directly influence productivity through the health of the occupants and so are a major factor in the operation of both the building and business. Research on intelligent control strategies by Zaheer-Uddin (1994) has shown improved performance can be achieved by reducing the HVAC zone size. This has been achieved both by the introduction of improved direct digital control (DDC) technology, distributed processing and more adaptive spatial planning in general. Systems have been developed that deliver HVAC using both the traditional approach, where the ducting is installed in the plenum space and air is directed downward, and in floor-ducted systems that supply air in an upward direction. Personal environmental control systems that integrate technologies to deliver cooling/heating to the individual are also available and are impacting greatly on the development of future HVAC systems.
The distribution of control zones and hence the number of zones that can exist on each floor is aligned with the type of HVAC system used (Table 4.3). This may pose difficulties if a broad distribution of functional zones is created in the process of providing the desired work places, thus limiting the opportunity to align building system control zones with
Table 4.3 Attributes and types of HVAC systems used in intelligent buildings
HVAC attributes
䊉 Horizontal distribution: air, water, none
䊉 Horizontal distribution: ceiling, floor, furniture supply/return
䊉 Environmental load management and load balancing
䊉 Split ambient and task conditioning: individual controls
䊉 All air systems and mixed mode systems
䊉 High performance systems
䊉 Air quality management and energy management
䊉 Chilled ceilings
䊉 Geothermal ground water systems
building use zones. Furthermore, Bell et al. (1991) shows that a disparity between building system control zone boundaries, functional boundaries and building use zones may produce areas that can never be balanced effectively.
4.3.3 Lighting
The primary objective of lighting is to provide acceptable levels of illumination for all aspects of occupation. Lighting should reflect the different needs of occupants and the ambient level of natural light to ensure that optimal time-based illumination levels are achieved. Aligned with this is an aim to reduce energy consumption, without compromising energy effectiveness, and to provide flexibility in operations for people in the building. Lighting control, or more specifically, the effective utilization of daylighting, is a critical factor in any energy strategy.
Too often the idea of ‘acceptable levels of illumination’ has meant monotonous banks of fluorescent lights strategically located in a regular matrix throughout the entire floor.
This lighting scheme fails to consider the individual needs of people and is destined to contribute to an unhealthy working environment. Haessig (1993) has identified a number of important attributes to consider when integrating lighting systems (Table 4.4).
Just as the threshold of cold and hot differs with individuals, so does the perception of changes in illumination. It has been shown that creating a visually dynamic space is no less energy efficient and, more importantly, encourages lower absenteeism and greater productivity. Hence it is valuable to talk about ‘the quality of light’, where quality encompasses intensity, interaction with natural light and the use of a dynamic visual plane, one that encourages variation in the intensity of the light across the floor. Opposing this is the reality of lighting in most office environments. The first list focuses on the requirements. The second list focuses on reality.
The requirements:
䊉 minimum guaranteed light levels at every workstation dependent on task
䊉 no glare
䊉 no concentrations of light
Table 4.4 Attributes and types of lighting systems used in intelligent buildings
Lighting attribute
䊉 Fibre bundles
䊉 High frequency fluorescent lights
䊉 Internal and external shading devices
䊉 Integrated control systems
䊉 Occupancy sensing
䊉 Daylight harvesting
䊉 Light tubes and light shelves
䊉 Atriums and daylight bridging
䊉 Variable refractive index glass
䊉 Fenestration
䊉 user control (different levels) at every workstation
䊉 use of daylighting wherever possible
䊉 end users have the facility to control the microenvironment; central control can change the light levels at the macro level
䊉 better use of vertical lighting
䊉 better use of direct/indirect lighting that is co-ordinated with the building’s structure
䊉 400 lux across the floor, 800 lux (via a task light) to work on paper and 200 lux in corridors.
The reality:
䊉 unacceptable direct source glare on computer screens
䊉 no facility to vary the light levels at an individual workstation
䊉 no minimum guaranteed light levels at each and every workstation
䊉 light distribution is dramatically variable, with ‘peaks and troughs’, due to partitioning, columns, walls, despite uniform ceiling grid layout
䊉 light distribution is not evenly diffused
䊉 widespread reflections on computer screens
䊉 offices are cave-like with gloomy walls and ceilings.
4.3.4 Access, egress and security (AES)
Francis (1992) states that the security strategy used is driven, and in some cases imposed by, the physical restrictions of the building (i.e., site specification and function). Because of this spread in the focus of responsibility, the functional variation of each space ensures that no one AES system is appropriate over the entire building.
Office spaces are identical in many respects. As with HVAC and lighting, however, the dynamics of a space are very different once it is occupied. Each tenant may require a different security regime to meet particular aspects of the business, whether that is security of equipment, data and information, and/or personnel. This is further complicated by the inclusion of several floors or part floors of the building that may or may not be adjacent in an individual business domain. Such a regime adds additional complexity when integrating AES with HVAC and lighting occupation zones.
To satisfy the security aspirations of the occupants without restricting the movement of people throughout the building, various systems and devices are used that are controlled by both the tenant and the facility manager. These systems, particular to their role in the building, establish the complexity of any subsequent integration of AES systems and the transparency of AES systems to the building’s occupants. Those functions that are building driven include:
䊉 intelligent lift control
䊉 automated alarm points
䊉 emergency warning information systems (EWIS)
䊉 CCTV and video surveillance of building forecourts and public spaces.
The desired level of security is dependent on the type of security required and how the devices used to achieve this interact with other building systems. Examples of the devices and techniques used are:
䊉 smart cards, either swipe or proximity
䊉 video surveillance
䊉 occupancy sensors
䊉 keypad-coded doors and door grouping
䊉 user authorization
䊉 remote monitoring
䊉 biometric devices (voice, fingerprint, iris)
䊉 phone/security access
䊉 secure lifts.
Unfortunately, factors such as tenant risk and lack of integration of AES systems across the domain of the building can reduce the effectiveness of the installed AES system components.