Working towards emissions reductions

If an organisation used more that 6,000 MWh of electricity through half-hourly meter in 2008 it will be affected by CRC. In practice, this will include organisations with an annual electricity bill of around £500,000 and over. The CRC will have a major impact on the energy efficiency of existing building stock. An organisation will need to purchase carbon emission allowances each year for every tonne of carbon they emit, and the cost of these permits will increase year on year.

Improving the energy efficiency of an organisation’s older structures will therefore be vital in reducing the financial impact of the CRC. But refurbishment projects require careful thinking in order to maximise long-term return on investment, not only in terms of energy efficiency but also occupant comfort.

In addition, working within the constraints of older building stock can bring with it many challenges particularly when installing a new heating and cooling system.

Products such as chilled beams can be easily integrated into an existing building to provide an energy efficient comfort cooling system to improve occupant comfort and improve productivity. Chilled Beams can be integrated into most ceiling systems.

Chilled beams

Chilled beams offer energy savings compared to other cooling systems because they can work at higher chilled water temperatures of around 14°C, meaning they can take advantage of free cooling, which means that the external air temperatures can be used to provide chilled water without having to run the chillers so less energy is used for cooling. In addition, because flow and return temperatures are typically between 14°C and 17°C, the systems are ideal for use with low carbon technologies such as ground source heating.

There are two types of chilled beam system; active and passive, but both use water as the heat transfer method to provide cooling. Passive beams rely on natural convection to provide cooling – hot air rises to the ceiling, where it is cooled by the passive beam; this causes it to fall to the floor, drawing in more warm air. Active beams incorporate an air diffusion unit, which introduces conditioned air to the occupied space. Air is forced through a series of nozzles, increasing its velocity and lowering the air pressure, which induces warm room air through the beam to be cooled.

Chilled beams can also incorporate other services such as lighting and fire alarms, where they are referred to as Integrated Service Modules (ISMs). The ISM has at its heart a chilled beam, which is enclosed by an architecturally designed metal casing. ISM’s, are particularly effective in applications where the existing concrete soffit is to be exposed by elegantly combining electrical and mechanical systems in a module. This solution has the additional advantage in that it provides flexibility in terms of future room layouts.

Putting it to use

ISMs were the product of choice for 10 Hills Place, Oxford Street, London where units featuring both active chilled beams and Micro Prism Optic (MPO) luminaires were installed as part of a refurbishment and extension project.

MPO technology minimises direct and reflected glare in conformity with both EN12464 and CIBSE LG7. The luminaires are linked to a DALI lighting system and a combination of passive infra-red absence detection and daylight sensors ensure lighting energy consumption is kept to a minimum.

Ho-Yin Ng, Director at Amanda Levete Architects commented: “Bespoke integrated chilled beams which combined the electrical and mechanical systems of the cooling, ventilation and lighting were designed and developed with SAS International into a slim line aerodynamic profile. This matched the aesthetic of the building, whilst maximising headroom and areas of the soffit, leading to an increased sense of space.”

Tony Martin at M&E Consultants, the Barn Partnership, agrees: “Integrated Service Modules have provided the best solution for this project based on the floor to ceiling height and the decision to leave the soffit uncluttered.” The active chilled beams provide 470W/m of cooling and 370W/m of heating to the internal envelope.

Cost savings

Organisations can reap the rewards of cost savings by implementing these systems now. Changing heating and cooling systems in offices can improve energy efficiency. In addition measures such as energy efficient lighting and effective lighting control can create additional savings.

Another energy efficient solution that can help reduce the cost impact of the CRC are chilled ceiling systems. These radiate cooling downwards to provide quiet, draft free comfort to occupants.

Chilled ceiling solutions are manufactured with a copper element bonded into the rear of a metal ceiling tile, resulting in a flush finish and opportunity to reconfigure room space by using flexible partitioning without the need to reconfigure the services, which will benefit both the landlord and the tenant. Chilled ceiling systems can be installed within a 100mm ceiling void which, for refurbishment projects, brings comfort cooling to properties with minimal floor to ceiling heights.

As the chilled element is integrated within the ceiling panel they free up valuable office space for occupation and use. This is often overlooked but is of increasing importance as space provision, particularly in offices, demands that the use of the floorplate is maximised.

Chilled ceiling systems can be installed in zones, which can be individually controlled, allowing unoccupied areas to be isolated and shut down to save energy.

Refurbishment projects are inevitably challenging as there is the need to balance the requirements of the tenants for comfort, the landlord’s financial considerations and the building’s physical constraints. When you add to this the additional challenge of meeting emissions reductions goals under the CRC, the role of the consulting engineer becomes increasingly important. Working with an existing building is not without its challenges, but with a cohesive design team working together with a committed manufacturer, delivery of solutions that can improve energy efficiency can be achieved.