Beyond just air conditioning

Multi-service chilled beams can be very effective at servicing office buildings, particularly in refurbishing existing buildings to modern standards. NIGEL ATKINSON explores their considerable potential The list of challenges in the development of existing office and public buildings is extremely long both in terms of project management and technical success. Introducing air conditioning and other technical services in a scheduled time frame to meet the requirements of building regulations, codes, and modern standard practices has proven to be — if not elusive — at least an extremely demanding task. Balancing regulations and guidelines for energy performance, indoor climate, acoustic and lighting conditions whilst maintaining flexible use of space and improved working conditions within sustainable and attractive buildings can prove to be problematical. However, many potential risks can be reduced by the correct application and selection of the air-conditioning system. Multi-service chilled beams have featured in many project success stories, utilising new methods in the design-implementation process. In addition to the many advantageous features of chilled-beam systems, the willingness to take the utmost advantage of project re-engineering and prefabrication has paid dividends — not only in keeping within budgets but also in providing space-efficient, productive, healthy and comfortable working environments. Offices are continuously in a state of change as enterprises adapt their organisations to meet new business challenges, it is essential to build-in the flexible use of space within the building and its technical services without reducing the perception of indoor environment. System features Over the last 15 years, chilled beams have been proved to respond to challenges faced in the development of office buildings. Active chilled beams can provide cooling, heating and ventilation. Passive chilled beams provide only cooling and can be complemented by displacement or mixed ventilation. Good indoor climate and acoustic conditions can be realised in developments where suspended ceilings are the practical finish. However, exposed chilled beams can maximise the limited floor-to-ceiling heights common to many 30-year-old buildings. The chilled-beam system responds well to layout changes, especially when partitioning has been taken into account during the design phase. Variations to and from landscape/cellular offices and even meeting rooms can be realised without substantial alterations and with only minor adjustments to airflow and/or water flow. The application of chilled beams in refurbishment is also beneficial because the space demand for plant rooms and distribution ductwork and pipework is relatively low as energy is transported by water. The airflow rates of the system need only to satisfy the indoor air quality requirements (10 to 15 l/s/per person). The cooling capacity ranges up to 90 W/m2, which conforms to Part L2B energy-performance incentives, or reservedly even up to 120 to 150 W/m2. Low specific fan powers (SFP) (2 to 2.5 kW/m3/s) can be realised by careful location of air-handling plant room and good ductwork topologies. Pumping costs can also be relatively low due to low water flow rates of effective terminal units and 2-way valve control, combined with variable-speed pumps. As the operation of chilled beams is based on two or four pipes with high-temperature chilled water (HTCW), the chillers can achieve high coefficients of performance. Alternative energy sources (indirect free cooling using, for example, dry air coolers, cold storage and geothermal applications) can be considered and used effectively in response to growing energy-efficiency challenges. Likewise, using ‘ultra’-low-temperature hot water ensures efficient running with condensing boilers or makes it possible to use waste heat sources. Chilled-beam systems also have low maintenance requirements and offer reliable and hygienic operation without the need to remove condensate. Multi-service chilled beams Multi-service chilled beams combine features and advantages with those that prefabrication offers by integrating many components into one unit. The most common technical services of interest for integration are direct/indirect lighting, room controllers, sensors, valves, flexible hoses, sprinklers and fire and smoke initiation, exhaust air, public address and voice alarm systems, occupancy control, sound absorption, power and data cabling and connections. Correctly proportioned and directed lighting is of paramount importance to the working environment. Multi-service beams provide elegant options for positioning both uplighting and downlighting, delivering well managed luminance and balanced contrast. Multi-service chilled beams provide an exciting architectural platform for customisation and design appearance, which often shortens the design phase and streamlines sub-supplier operations. After the evaluation of potential concepts and careful studies of the building construction carried out by the technical design team, the requirements and targets are defined together with the developers, investors and/or builders. Even if the requirements for the architecture, space programs, flexibility, energy performance and indoor environment quality have been set, additional efforts and close coordination from the whole team will be required to task plan and implement the schedule. At this stage, space demand and locations of plant rooms, shafts, risers and bulkheads are defined. It is also important to agree the match between the finish of the floors and ceilings with technical properties and performance of the room air-conditioning concept. By devoting time and effort at the preliminary design stage followed by the virtual design stage (CFD modelling) and dynamic demonstrations using model rooms (laboratory testing), the correct performance of air conditioning and lighting, aesthetics and practical connectivity between the terminal units and distribution systems are ensured. Contractors also play a very important role in ensuring fluent installation and realisation of substantial timesaving. The implementation of an office development is remarkably changed by shifting the activity to manufacturing stage and reducing dramatically the number of shipments to the site. Benefits of prefabrication The benefits of prefabrication are well documented, especially in refurbishment projects. Technical components incorporated into multi-service units (plug-and-play) can be monitored and tested at the factory, reducing installation time on site and ensuring total quality. Site management is more straightforward than in conventional multi-supplier projects, with fewer installation teams at site requiring continuous co-ordination. Conflicts and confrontations are fewer, and schedules can be met. Site security can be maintained more easily. Total investment costs are very competitive, and, in many cases, great savings can be obtained in running and maintenance costs. As a whole, prefabrication in office developments can lead to very effective collaboration. It can create also a good basis for sound partnerships with continuous development. Nigel Atkinson is sales director with Halton Products Ltd, 5 Waterside Business Park, Witham, Essex CM8 3YQ. Literature Building Regulations, Approved Document L2B, ‘Conservation of fuel and power in existing buildings other than dwellings’. Building Regulations, Approved Document F1, ‘Means of ventilation’. REHVA, ‘Chilled beam application guidebook’ CIBSE; TM 27 ‘Flexible building services, principles for designers’. CIBSE; Lighting Guide 7, ‘Office lighting’. BSRIA, ISSO, IDAE; ‘Climatic ceilings and chilled beams, applications of low temperature heating and high temperature cooling’. REHVA Chilled Beam Application Guidebook CIBSE ; TM 27 Flexible building services, Principles for Designers CIBSE; Lighting Guide 7 Literature Building Regulations, Approved Document L2B, ‘Conservation of fuel and power in existing buildings other than dwellings’. Building Regulations, Approved Document F1, ‘Means of ventilation’. REHVA, ‘Chilled beam application guidebook’ CIBSE; TM 27 ‘Flexible building services, principles for designers’. CIBSE; Lighting Guide 7, ‘Office lighting’. BSRIA, ISSO, IDAE; ‘Climatic ceilings and chilled beams, applications of low temperature heating and high temperature cooling’. REHVA Chilled Beam Application Guidebook CIBSE ; TM 27 Flexible building services, Principles for Designers CIBSE; Lighting Guide 7
Related links:



modbs tv logo

Agile working explained

Julia Kitchen explains what agile working is and how companies can achieve it.

Dr Gavin Dunn: Managing responsibility

Dr Gavin Dunn, CEO of CABE discusses how the industry needs to handle responsibility better. 

Calendar