Air-conditioning is the theme of this month’s product focus. Dave Smith introduces the section with a look at some of the issues surrounding the replacement of old air-conditioning systems

The replacement of rooftop packaged air-conditioning systems has become a matter of urgency. All over the world there are hundreds of thousands of these systems that have been operating for more than 20 years.

Once the mainstay of the air-conditioning product offering, they have been supplemented by other technologies but the principles behind them remain valid. However, the units still operating use a refrigerant, R22, that is a hydrochloroflourocarbon (HCFC) deemed to be part of the cause of damage to the ozone layer.

No new equipment using this refrigerant can be sold, so it makes sense to examine some of the issues raised by replacement.

In the UK, many thousands of such systems are subject to EU legislation which means the supply of new R22 for the purpose of servicing existing units will be progressively restricted until its total ban in 2010.

After that date, owners will be reliant on supplies of reclaimed refrigerant to service their plant. And this is not the only pressure on owners of these systems.

Many of the systems have completed their natural lifespan and are now difficult and costly to maintain. They do not meet current standards for energy performance, noise and the like, and they do not meet building occupiers’ expectations of cooling and heating.

Running costs are high and there is no means of controlling what was essential a fixed air volume system operating continuously whatever the real load demand. Replacement is now essential.

Once this nettle has been grasped, the issues are as follows:

  • legislation
  • planning
  • refrigerants
  • equipment and total project costs
  • controls
  • energy efficiency
  • just plain efficiency
  • delivery to site
  • servicing
Fortunately, rather than having to replace these systems with a different technology and calculating on high capital and project costs as well as lengthy downtime, the recent redesign of the rooftop packaged concept by its traditional manufacturers such as Carrier, means that like-for-like but thoroughly updated products are now available.

These can be installed within the day and, most importantly, exactly match existing roof curbs and plumbing, electrical and ductwork connections, cutting project costs, eliminating planning headaches and delivering modern energy efficient, controllable systems using acceptable refrigerants such as R407C and R410A.

Both off-the shelf and bespoke designs can be catered for, and can use the latest energy-saving controls technology.

Source

Building Sustainable Design

Postscript

Dave Smith is product leader for Carrier Air Conditioning's new Replacement Rooftop Systems Team