Planning for change

Carlo Gavazzi, BMS, BEMS, Building management systems, controls
A practical response to churn — Kevin Sheldrake.

Buildings frequently change use and are refurbished for new occupants, and businesses often reconfigure their workplaces as demands change. Kevin Sheldrake of Carlo Gavazzi UK, argues the case for a building-controls solution with flexibility to meet whatever the future brings.

It is said that the only constant in business is change. In many organisations, office layouts are subject to frequent changes. This process is referred to as the churn rate, expressed as the percentage of the staff moved during a year. Churn rates are higher than ever before as many businesses look to boost staff productivity by moving to collaborative working environments. Out go cellular offices and in come open-plan desk arrangements complemented by breakout hubs and even chill-out zones.

Changing the layout of a building, be it an office or a factory environment where new production lines may be introduced, will have considerable impact on the building services. Lighting switches, heating thermostats and power sockets may need to be relocated, for example.

The building controls strategy needs to be considered at the outset to accommodate the likelihood of future changes to the building services. The drawback with many conventional building-control systems is that each data point needs to be wired back to the direct digital controller controller (DDC). Not only does this complicate the initial installation, particularly in applications with widely-distributed data points, but it also makes it difficult to accommodate changes easily.

An alternative is a simple 2-wire bus system to control building services.

This system has many advantages where the workplace may change in the future. It is flexible, modular and expandable. 2-wire bus technology significantly simplifies the field level wiring, eliminates expensive wiring home runs and saves money on wiring and installation costs when compared with traditional device-to-DDC solutions.

Furthermore, the installation cost is reduced significantly without increasing material cost due to the reduced need for DDC inputs and outputs (I/Os) and the use of standard sensors.

2-wire bus systems reduce commissioning time and offer the possibility to integrate HVAC and lighting controls, for example, at the field level — one network, two solutions. Systems are based on bus-powered sensors and actuators and small I/O modules. The cost savings of such a decentralised I/O solution can be considerable.

The beauty of a 2-wire bus system is that it can be expanded by simply extending the bus cable and adding extra I/O modules. This means it is truly flexible and modular, again saving on the costs of any future expansion and accommodating any late and future changes to office layouts.

Carlo Gavazzi’s Dupline 2-wire bus system, for example, provides many other advantages too. Unlike RS485-based solutions, Dupline can be wired using free topology for the cable, including ring, star etc. The cable does not need to be screened or twisted, and it can be run next to power cables without fear of interference. Many of the field devices are powered by the bus itself, which simplifies installation by removing the need for additional power supplies.

BEMS, BMS, building management systems, Carlo Gavazzi, Controls
The amount of wiring at the field level of a BMS can be massively reduced by a 2-wire bus system rather than separate wiring runs to each device.

The benefits of opting for such a 2-wire bus system are ably demonstrated in a recent installation at a UK manufacturing site for a leading supplier of sit-on lawnmowers. When the company wanted to introduce a new line of equipment, it needed to move the production facility around, including the relocation of services such as lighting switches on supporting pillars of the factory.

Dupline provides the flexibility to move services around as required. All the installer has to do is to drop a cabling pair down from the 2-wire bus to the switch. This cabling pair only supplies a data signal; no power is involved as the control devices are powered by the bus.

Dupline offers the same benefits when it comes to accommodating office churn. At a major office development in the south-east of England where the system was employed, lighting and heating controllers in offices were easily relocated following office moves. Here, the 2-wire bus runs around the office in the suspended ceiling, with data cabling dropping down to standard room-temperature set-point controllers and lighting switches.

Again, there was no movement of power cables required to facilitate the change. Over the life of the office, this flexibility will bring about considerable savings in costs to the end user.

According to the Building Research Establishment, controls are the easiest and most cost-effective solution for saving energy in buildings.

Clients and building occupiers, however, have failed to exploit advanced control solutions, says the BRE, because many of the innovative technologies they employ are perceived to be overly technical and complex to operate. This perception, when coupled with a lack of information on the subject, has resulted in a poor uptake of control technologies and a subsequent failure to significantly reduce the carbon footprint of buildings and to provide a better environment for occupants.

Simple 2-wire bus solutions such as the Dupline system offer a cost-effective means of improving the poor take-up identified by BRE.

Kevin Sheldrake is business development manager at Carlo Gavazzi UK.

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