ENERGY MANAGEMENT - BSEE February Issue

Trevor S Palmer, Managing Director at Sontay, examines the role that field and control peripheral devices can make in reducing energy consumption.

Energy use in commercial and public buildings is under increasingly intense scrutiny.

It is not only the moral responsibility of those of us in the building services sector to do something about reducing fuel consumption but it also a legal obligation under the EU Energy Performance of Buildings Directive and, subsequently, Part L of the Building Regulations as legislated within the UK during the past few years.

This legislation obliges designers, building owners and facilities management companies to integrate fuel and carbon reduction measures in new build projects and during the refurbishment of existing estates. They are also required to design into buildings the capability to monitor, report and account for energy usage.

Applying these standards to new builds demands the application of additional hardware peripherals. Yet, within the scope of an overall project, these extra devices will have very little impact on the total project cost of the building’s system.

Existing buildings represent a much bigger challenge. They account for 99% of the nation’s stock and for nearly 20% of all carbon emissions, according to last year’s findings contained in the All Party Urban Development Group’s Report, “Greening UK Cities’ Buildings”. Retrofitting energy reduction technologies here is an entirely different proposition. Material, and in particular, installation costs are heavily impacted, making them a costly proposition and, as a result, bringing a much longer return on the initial capital investment made.

The recent introduction onto the market of a new breed of control products is helping to cut installation costs for these newly required systems. These new devices are especially relevant in reducing refurbishment costs in the existing buildings market since the majority are based on wireless technologies, such as mesh and self healing tree type networking. These offer much more reliable performance compared to the point to point systems currently on the market.

In the past, what would have required hard wiring to and from the out-station control panels, sensors and other peripheral monitoring equipment can now be replaced with wireless communication. This transition is not unlike the evolution we have seen in wireless computer networks.

Wireless sensing products, in particular, offer numerous advantages from a facility management and “life of building” perspective. Wired sensors are typically located in areas of the space which help make installation easier rather than fulfilling what should surely be their primary focus - to optimise monitoring, energy usage and occupant comfort. Wired sensors and interconnecting wiring are also rarely recovered and re-utilized during any renovation or refurbishment as a building occupants requirements change.

Wireless sensors can offer the facilities manager the flexibility within a building to adapt to the changing circumstances of the occupants without the need for major re-wires and disruption to the building operation. These wireless products can also be located once the structure is completed, thereby eliminating the risk of damaged sensor housings and wiring during the building construction process. Location of the sensors can then be determined by the requirements of the building user at a much later time, with the occupant optimising energy usage, space and comfort. These products can be easily re-used and relocated during building refurbishments to suit an occupant’s latest needs, offering a much more sustainable approach whilst reducing the future cost of system refits.

Another area where sensing devices can help reduce energy usage centres on the difference between Air Quality and Carbon Dioxide sensors. Many installers often use Air Quality sensors to control occupancy demand ventilation and fresh air input to a building. However, these sensors typically only sense Volatile Organic Compounds (VOCs). The use of this type of sensor for fresh air demand control can result in excessive amounts of fresh air being introduced into the building. The enthalpy of this air can considerably increase energy demands as it requires conditioning it to meet the occupancy conditions specified within a building.

In contrast, Carbon Dioxide sensors are seen as a more accurate way of controlling fresh air demand in a building based on occupancy. This device is particularly important to ensure the accurate measurement of Carbon Dioxide levels within a room or building which, if too high, will create a stuffy, unproductive working environment and drowsiness. Measuring Carbon Dioxide content is a key requirement in the multi-billion pound Building School for the Future programme currently underway in the UK. In fact, In fact, as part of this programme, Building Bulletin 101 actually specifies limiting CO2 levels within teaching and learning spaces to 1500 parts per million. So, it almost goes without saying that specifying the right sensor is a critical first step in delivering on this objective.

Metering is another area of the BMS market which has literally exploded in sales volume in recent years as a result of the new energy legislation. Facilities are now required to monitor energy usage intervals, and together with the large increase in domestic apartment blocks with centralised domestic hot water, central heating systems.

This has led to a significant increase in demand for heat and energy meters in the buildings control market. As a result, metering and sub-metering equipment is now a key part of the building peripherals eco system.

The installation of this type of equipment requires both mechanical and electrical trades to become involved and work effectively together.

Costs involved can have an adverse affect on first project cost (especially billing software). So, it is important to consider when choosing products that specifications and quality are examined and closely compared, rather than simply to look at the bottom line cost. Often what appear to be competitively priced products can have a high overall system life cost. For example, low reliability and repeatability can lead to costly service visits and downtime if heating systems need to be drained to enable a repair. The result in such cases will be unhappy clients and also high energy usage if products with poor accuracy are used to control building parameters.

Buildings are responsible for generating significant CO2 emissions. Much of this CO2 is generated by energy hungry and sometimes inefficient building services. As an industry we are well placed to act. Control peripheral technologies certainly exist which will enable us to make a difference now and in the future. With equipment correctly selected and specified, we can meet the legislative challenges and help deliver low carbon buildings on new build and refurbishment projects today.

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