It is understandable health-estate managers play it safe when it comes to AHUs in sterile areas. But, argues Moducel sales manager Joe Wiekowski, they should be taking on energy-efficient designs
The health sector is traditionally conservative when it comes to specifying an air-handling unit (AHU), even for non-critical areas.
But with increasing demands for better energy savings and reduced lifetime costs, it pays to take advantage of the latest advances in technology and more energy-efficient designs.

Understandably, health estate managers tend to play safe by using familiar systems and equipment. Rightly so, when you consider that they are designing systems for critical areas such as operating theatres, intensive-care and high-dependency units and other sterile areas.

But, applying the same formula in non-critical areas can result in AHUs being over-engineered before specification, which, in turn, ramps up costs and leads to energy wasting.

Buildings account for almost half the energy consumption and carbon emissions in the UK. Hospitals, by their nature, function 24/7 and, by default, are a major contributor. Mandatory air-conditioning inspections are being introduced in January 2009 to help improve efficiency, reduce electricity consumption, operating costs and improve existing

systems. This will provide health- estate managers with a great opportunity to examine their AHUs and choose a more energy-efficient model when refurbishing or renewing. All healthcare management, design engineers, estate managers and operations managers are fully aware of the Health Technical Memorandum (HTM O3-01), which gives comprehensive advice and guidance on the design, installation and operation of specialised building and engineering technology used in the delivery of healthcare.

The less familiar European Energy using Products directive (EuP) provides rules for eco-design and aims to encourage manufacturers to design products with environmental impacts in mind throughout their entire life cycle.

The latter poses a dilemma for health-estate managers wanting to do the right thing for the efficient management of their hospitals' environment, employees and patients - while at the same time meeting the essential criteria for HTM.

Hospitals are major users of electrical energy, and electrical demand is the fastest-growing energy end-use category. This is expected to continue growing in the next 20-30 years unless an alternative is found. A significant reduction in energy consumption, as suggested by the European Climate Change Programme (ECCP) is possible, but only if action is taken during the design phase. This is because the pollution caused during a product's lifecycle is determined at that stage, and most of the costs involved are committed then.

The industry is working hard to develop more energy-efficient products, but addressing CO4 (revision due 2008) and HTM specifications - combined with demands for efficiency of
equipment, hygiene and access - can be difficult for many manufacturers to achieve.

AHU manufacturer Moducel strives to improve its designs to meet strict requirements. That includes AHUs featuring Plastisol-coated external panels to ensure a wipe/wash clean, uncluttered external appearance (other than for access doors). Clean, smooth,
internal surfaces help minimise friction losses in the air-stream and make a major contribution towards good hygiene. Inner flanges on Pentaposts help to create positive air seals behind the panels, cutting air leakage to an absolute minimum.

Other design issues that need to be considered include the use of energy-efficient optimised coils. The design needs to reflect the usage of the component and, where possible, take advantage of natural ventilation or free cooling.

Heat-recovery coils, when fitted again, can be optimised and be much more efficient if built into the original design.

Standard recovery coils cost money - by optimising the coil design you can achieve a far greater return on that money and the increase in capital cost is quickly recovered.

Within the AHU, access sections allow for coil-cleaning and routine disinfection. Stainless-steel wet sections and the use of dagger plates isolates components and provides ease of sterilisation.

There is also a demand for a greater use of fresh-air units to ensure stale air and bacteria are not continually re-circulated around hospitals, through the air-handling and ventilation system.

This should be paramount in the mind of the engineer during the design phase - and with free cooling, should be the basis of the design brief. Serviceability is another key design concept, with man-size doors, accessible components and service vestibules when specified.
When routine maintenance is convenient, units will operate free of trouble.

Currently the acceptable range of fans within the AHU/ventilation systems can be of the axial, centrifugal, cross-flow, mixed-flow or propeller type, depending on the requirement of the
system.

As a major energy user, the health sector can benefit substantially from what technology has to offer.

By recognising that non-critical areas do not need to be over-engineered substantial savings can be realised without compromising the welfare of employees or patients.