Bow Bells, the £55M development on Cheapside, London, has energy efficiency built into its design. At the heart of this is an intelligent building management system that controls the amount of power being used.
BOW BELLS, Stanhope's development in Cheapside, was designed for optimum energy efficiency. The 20 hectare development is awaiting the arrival of its first tenant. The development slashes energy usage, with an emissions rating designed to better Part L stipulations by more than 20%.

Contributing factors include:

· High-efficiency boilers and chillers

· Heat recovery of 60-70% on
air plant

· A facade combination of
high-performance, double-glazed units together with triple-skin external ventilation

· Automatic solar blinds

Systems house Integrated Controls Systems (ICS) from Wokingham, Berkshire, installed the systems to control the plant under a contract worth £650,000 from Bovis Lend Lease.

Intelligent system

The structure and specification of the intelligent system called for extensive localised control of variable-speed drives (VSDs), eliminating the requirement for centralised motor-control panels.

To achieve the objectives, ICS interfaced with plant power centres, the large low-voltage distribution boards provided by electrical contractors that undertook power wiring to the VSDs, or other packaged pieces of equipment.

ICS carried out all secondary wiring from the VSDs to the various devices they served, and interfaced them with the building management system (BMS). It took the role of lead co-ordinator between the electrical and mechanical contractors.

In the absence of traditional panels, ICS built 25 distributed BMS plant-control enclosures dedicated to specific pieces of equipment or plant, normally determined by its location in the building.





The enclosures variously control boilers, pumps, chilled-water plant and air-handling units. They also monitor passenger lifts, smoke- extraction systems, public-health amenities, and landlord and tenant switchboards.

To cater for a possible dual tenancy of the building, two enclosures on each of the seven floors have been fitted with a Cat 5 interface. This offers the facility to connect Tridium Java Application Control Engine (JACE) communications controllers/routers to constant volume boxes and the 64 fan coils on each floor.

In essence, the JACE has been used as the management-level platform, using a LON interface to connect to the constant-volume boxes and fan coil units; a separate Modbus connection to a series of electricity, and all other metering operations; and building automation and control networks (BACNet) communications with the VSDs.

'The initial specification at Bow Bells was for an infrastructure to meet all HVAC requirements,' says ICS managing director John Reid 'We have provided added value by enabling landlords and tenants to connect their own metering systems into our infrastructure.'

The ICS installation supports the automatic blind system, siting the Somfy controls package on the same PC as the BMS, and wiring in the motor controllers connected to the blinds and associated control sensors. Lighting systems, according to Reid, could be similarly treated through the fast-growing Dali lighting protocol.

He points out that the distributed nature of the BMS controls facility minimised wiring by placing controllers discretely around the building next to the equipment they serve. It also did away with some of the traditional features of a standard motor control panel by using a BACNet link to monitor operating parameters and status.

This has enabled standard operations, such as the operation of VSDs, to be carried out via an integrated key pad rather than interrogating a control panel with switches displaying alarms and other status information.

'There is a seamless link - the VSDs are now an extension of the BMS,' adds Reid. 'They are effectively another controller node, and should be used as such. They are programmable, and in certain circumstances associated BMS devices, such as dampers and actuators, have been directly connected to the VSD.'

Additional activities

The ICS installation, combined with Tridium's communications capability, controls central plant systems by the use of various communication mediums. It also features an infrastructure that is able to support additional activities to the initial HVAC requirements.

'This open system has power and versatility that offers tremendous opportunities for owners who commit to Tridium,' says Reid. 'The system is so flexible and comprehensive we can satisfy almost any communications application.'

Having completed the shell and core contract for Bovis Lend Lease and Roger Preston and Partners, the consultant, ICS is currently undertaking the fit-out of three of the floors at Bow Bells for Icelandic bank Landsbanki.