Manufacturers must focus on developing innovative technologies that support energy efficiency goals and promote a sustainable future. The latest technological advancements in chillers can reduce energy consumption and improve sustainability. Gboyega Obafemi explains how.
The economic downturn that is still impacting heavily on the hvac industry makes it critical that manufacturers deliver energy efficient building solutions that reduce total life cycle building costs and comply with relevant industry legislation, including Eurovent and BREEAM.

Chillers, one of the biggest energy consumers in commercial buildings, have seen technological breakthroughs. When CFC and HCFC refrigerants were designated for phaseout, an environmentally responsible alternative was developed.

When a powerful and intuitive chiller controller was needed, the first full-screen, full-colour, microprocessor control centre was introduced.Compressor technology (scroll, screw and absorption) and heat exchanger technology (evaporators) have all seen innovation that has made them much more energy efficient.

Air-cooled screw chillers that can deliver design full load efficiencies up to 3.4 EER, and European Seasonal Energy Efficiency Ratios (ESEER) up to 4.8, are now being introduced into the market. ESEER is especially important as off-design conditions are typically encountered for more than 97 per cent of annual operating hours. In many cases, these next-generation chillers can exceed the performance of existing installed chillers by as much as 30 per cent. These premium efficiency levels are made possible by the use of variable speed drive (VSD) technology and proven compressor designs.

These chillers are also leaving smaller carbon footprints. They are doing this in several ways.

First, they are doing it directly, by using responsible refrigerants such as HFC-134a, which has no ozone depletion potential and no phase-out date, as per the Montreal Protocol.

Secondly, they are reducing refrigerant in chillers by up to 15 per cent compared to conventional design by implementing technologies such as hybrid falling film evaporators and micro-channel condenser coils. Thirdly, they are reducing the number of fittings and connections which reduces the opportunity for refrigerant to be emitted into the atmosphere.

Chillers are therefore increasing building sustainability through high efficiency operation which minimises power generation needs, and ultimately CO₂ emissions which are responsible for 98 per cent of the global warming potential associated with chillers. Advances in water-cooled chiller technology have focused on the driveline and heat exchangers.

Centrifugal chillers that use permanent magnetic motors and active magnetic bearing to eliminate mechanical contact losses in the driveline are now becoming a global norm. When combined with VSD technology, previously impossible efficiencies can be achieved.

An ancillary benefit of driveline advancements is that chiller sound levels are being substantially reduced. With no mechanical contact in the chiller driveline, only refrigerant gas noise is left in the chiller. This means that the traditional 'good' sound levels of 80-85 dBA (at 1m) are now being superseded by chiller sound levels that do not exceed 73 dBA (at 1m) when operative at standard Eurovent conditions.

Substantial improvements in equipment sustainability can be attributed to new innovative evaporator designs. Much like air-cooled chillers, some manufacturers are now supplying water-cooled chillers with hybrid falling film evaporators. These heat exchangers are delivering improved heat transfer and reduced refrigerant charges. Some manufacturers are even able to provide chillers that have 30 per cent less refrigerant than typical chiller designs.

Advanced chiller technologies come at a premium. Fortunately, many building owners are dispensing with traditional first-cost purchasing philosophies and now concentrating on the value these technologies deliver. Purchasers of premium chillers include medical and data centres, universities, government buildings and manufacturing plants. Many less well-funded installations are also investing in these technologies, such as primary education and general-use commercial buildings.

The specification of premium efficiency and sustainable equipment is expected to continue to increase as customer and legislative requirements become more and more stringent.

• Gboyega Obafemi is executive director of HVAC and Control Products in Europe for Johnson Controls