Air supply

With energy prices and carbon emission scrutiny going only one way, organisations are being urged not only to reconsider their air conditioning and air management systems, but also to examine what modern BEMS (building energy management systems) might do for them. Among those making the case are Ian Ellis, president of the Building Controls Industry Association and marketing manager with Siemens Building Technologies. "A careful assessment of existing energy-efficient automation and control solutions can help drive significant savings," he asserts, "with these savings reducing the overall cost of a building's use." Ellis makes the point that up to 50% of the costs of a building are energy-related, and suggests that implementing a BEMS is the first step towards achieving energy cost savings up to 30%. For him though, reaching that magic number is about adopting a logical approach that includes: developing an engineering specification that looks to the long term; verifying your approach against the standards; and not forgetting the value of data monitoring and system integration. Long-term thinking means not ruling out certain functionality simply to save upfront construction costs. You'll pay the price later, he says. Similarly, it's important to check your specification against BS EN 15232: 2012 'Energy performance of buildings, Impact of Building Automation, Controls and Building Management'. "This specifies a structured list of control, building automation and technical building management functions, which have an impact on energy performance," explains Ellis. Indeed, the standard confirms the 30% energy saving differential between what it terms 'Class A' versus 'Class C' BEMS. What about data monitoring? "Buildings are constantly changing environments and BEMS can drift in performance, due, for example, to lack of maintenance," comments Ellis. "15232 recommends a minimum of annual reviews of the building controls and annual training for users. Continually assessing, checking and updating the system is not only a smart way to get the most from any BEMS, it is also a proactive management strategy." And much the same applies to management data around a building's performance. Says Ellis: "BEMS can be used to monitor, manage and control not only HVAC services but also systems such as lighting and blinds. So, it is important to specify a system that is based on open communication protocols, such as BACnet and KNX, to get the integration. Display of all information on a single user interface helps to improve operation and reduce training needs." So much for new BEMS. When it comes to maintenance, though, one of the key issues remains poor HVAC circuit balancing. Symptoms are typically complaints over working spaces that are too cold in winter, hot in summer, or both. And the perennial problem is that typical 'fixes' are both costly – as engineers install larger pumps, resize components, change night setback and morning start-up times, and adjust flows – and ineffective. As David Hudson, senior product engineer with pipe jointing manufacturer Victaulic, explains: "For example, resetting an HVAC system start-up time from 7:30am to 5:30am leads to a plant operating at capacity two additional hours per day. This equates to a 25% increase in energy consumption, cancelling any energy savings that night setbacks are designed to achieve." Additional consequences include increased wear on pumps and HVAC components, and reduced control-valve authority. He contends that climate problems are not normally caused by control malfunctions or sizing errors. "Often, they can be traced to incorrect flow rates attributable to incorrect terminal-unit balancing," asserts Hudson. "Engineers normally design HVAC systems with excess capacity. Transferring that energy to terminal units and AHUs (air-handling units) is the challenge. So the key to HVAC system effectiveness is properly controlled flows to the terminals." As for why this can be so difficult, you need look no further than the fact that HVAC system flows should alter throughout any 24-hour period, due to solar gain and site occupancy changes in the building sectors impacting demand. "In an unbalanced system, sectors of a building have underflow or overflow conditions that impact control-valve authority and therefore climate," insists Hudson. "Proper hydronic balancing is the key to cost-effective performance." The cost of getting it wrong? For every degree above 20°C there is an 8% increase in heating costs, while every degree of cooling below 23°C adds 15%. "By applying circuit balancing techniques to each valve, it is possible to achieve proper balance throughout a system so that all circuits receive specified design flows," states Hudson. And we might add that it's also worth checking for issues such as clogged strainers and coils – and for that matter, blocked or inefficient AHU filters or any of the other components that impact pressure drop and hence energy-related costs. When pumps, chillers and other components operate at the lowest possible load, facilities managers benefit from less wear and tear, longer equipment life, and lower energy and maintenance costs. R22 refrigerant ban From 1 January 2015, the supply and storage of ozone depleting HCFCs (hydrochlorfluorocarbons), including widely used R22 refrigerant, will be banned. And, according to Kevin Groves, of HVAC services specialist Ergro, property owners and facilities managers who depend on the estimated 750,000 systems still running R22 better not be caught napping. Why? Because the ban will result in a need to convert or replace the vast majority. That was among key messages at a recent London forum, which fielded a panel comprising Ergro's Groves alongside Martin Fahey of Mitsubishi Electric, Saleem Fazal of law firm Taylor Wessing, Trevor Lake of accountancy adviser LB Group, and Graham Wright from Daikin UK. "Next year seems a long way off, I know," concedes Groves, "but when the ban hits, it won't only mean that R22 will be unavailable. Any equipment that currently runs on R22 will be unserviceable – making for more costly consequences, if people don't plan ahead." For him, the main problem is a lack of awareness. Most building operators and owners don't yet feel any urgency, he says. Yet as the ban date approaches demand will soar, so prices will likely rise. Meanwhile, after the deadline any breakdown will lead to long-term downtime and potentially empty buildings, with the associated risk to business continuity. "No new R22 plant has been made since 2003 but, with the ban on the use of R22 looming, it is critical that plans are drawn up to ensure replacement of old systems," confirms Daikin's Wright. And Mitsubishi's Fahey adds: "Air conditioning that's more than 10 years old will no longer be supported, so companies need to start planning replacement programmes now." Each also points to the potential logistics nightmare, particularly where local authorities are involved. Companies in cities and towns might well need to apply for permission to close a street and use a crane for the removal and replacement of plant – never something that can be organised at short notice. However, where plant replacement is necessary, the financial blow can be eased if you plan ahead, according to LB's Lake. "There are substantial allowances, up to 100% tax deduction for managing system changes in line with the legislation. Capital allowance can also reduce the burden, but they may not always be available at the current levels," he says. Whose problem is this? Fazal, who heads up real estate disputes at Taylor Wessing, explains that both landlords and tenants should be concerned about who is legally responsible. "It's very complex if you rent part of a building. Liability will depend on the terms of the lease and the type of system. You should protect yourself now in respect of future costs."