Why air conditioning is more than a match for radiators
Moving away from traditional heating — Philip Ord.
Philip Ord believes that if a building requires cooling, the same system should also be used to provide heating — reducing energy costs and carbon emissions.With the continued increase in electronic equipment in commercial buildings coupled with the rise of legislation and planning controls demanding energy efficiency and exacting levels of air quality, the use of VRF air conditioning has grown steadily year on year. Many of these systems take the heat rejected by IT equipment to offset a building’s cooling requirements, thereby providing a highly efficient overall system. Advances in inverter-control and in product development and design now mean that air conditioning is also highly effective at heating different areas as well as cooling. Given these facts, why do the vast majority of these same buildings still use traditional forms of heating such as radiators? A year-long study* at our Hatfield offices has demonstrated that water-cooled air conditioning is over 500% more efficient at heating an office than a traditional boiler/radiator system and over 300% better at combined heating and cooling than a boiler/chiller combination. Using the test data, we have also been able to demonstrate that a normal air-cooled air-conditioning system is also much more efficient for heating and for combined heating and cooling than the boiler/chiller, so VRF systems really are starting to prove their own worth within the UK’s built environment. Yet many offices still rely on radiators for heating. But why? It may be true that the heat from an air conditioning ceiling or wall unit is more difficult to control directly at all of the points in a room. However, with the latest advances in airflow and vane technology, most such issues surrounding now come down to better programming, office layouts or the actual siting of equipment — rather than the effectiveness of the air conditioning itself. In addition, if we actually look at the heating system that we are comparing VRF to, and that we have just become used to over the years, it is generally reliant on oversized radiators that are often too hot to touch and belting out heat in a very uncontrolled on or off manner. In buildings with both heating and air-conditioning systems and without careful and effective controls, there will also be times when the ‘heating’ is competing with the ‘cooling. Building owners looking to reduce costs by lowering their fuel bills could do worse than asking if it is time to do away with two distinct and competing systems — especially when manufacturers are claiming that air conditioning can manage perfectly well on its own. For me, there is no real argument these days for installing radiators in a new built property. The case for energy efficiency has been won by VRF air conditioning, both in heating and in cooling, as clearly demonstrated by our year-long trials. Where air conditioning has, perhaps, missed a trick is in tapping into the retro-fit market in a way that utilises the infrastructure left by a radiator system, which is where the latest developments in floor-standing air-conditioning units may well provide the answer. The latest ducted floor-standing units are specifically designed for wall-attached installation at floor level and can readily fit into the space left by a radiator. They offer an easy way of retrofitting buildings that used to have radiators and which have no other space available for air conditioning. These units are capable of 60 Pa static pressure, which delivers an impressive air throw to give an even and natural distribution of heat energy around the room that is very similar to the convection flow of heat from radiators. Coupled with new technology that can now deliver what is effectively free hot water using the heat-recovery process of VRF and buildings really can do away with their entire boiler system. There really is no reason why the air-conditioning industry cannot effectively challenge the engrained ‘traditionalist’ mindset and help us all achieve more flexible and controllable heating systems that are much better suited to modern working conditions. This will not only be good for the air-conditioning and building services industry, it will also lower the fuel bills of hard-pressed businesses, whilst allowing them more efficient and controllable heating — not to mention the significant reduction in emissions that would be achieved as we convert the country’s commercial building stock one property at a time. *Mitsubishi Electric conducted a year-long study into a WY GSHP condenser providing heating and cooling for a 150 m2 open-plan office with a predominantly south-west-facing aspect through four ducted indoor units. The system was compared with a modern efficient boiler (with a COP of 0.95) and a chiller system that has passed the Enhanced Capital Allowance scheme requirements. Copies of the 70-page report are available by calling 01707 282880. Philip Ord is product marketing manager for Mitsubishi Electric’s Air Conditioning Systems.