Replacement issues for air conditioning

Published:  16 January, 2007

The issues affecting replacement decisions — Philip Ord.

New Government regulations place increasing pressure on a building’s owners or users to control and reduce energy use, coupled with stricter requirements on indoor air quality. How do they affect building services in the renovation and conversion markets, and should you replace an ancient air-conditioning system that still seems to work well? PHIL ORD explains more.

If you are not yet aware of the major drive to reduce the UK’s carbon emissions, just where have you been hiding?

Energy use in buildings is now known to be responsible for over 30% of all the UK’s greenhouse gas emissions, and Part L of the new Building Regulations is intended to ensure that all new commercial buildings and renovations take this into account to help Britain meet its environmental commitments.

But what do you do with an air-conditioning system that is 10, 15 or even 20 years old, still serviced regularly and performing adequately for its user? Is it better to replace this now or wait until the system is on its last legs?

Energy prices

The answer comes from considering energy prices, which are set to continue rising for the foreseeable future. Old systems are considerably less efficient than the latest systems available now — and thus will cost more and more to run.

An air-conditioning system installed 10 years ago will be around 75% less efficient than state-of-the-art systems available today. Couple this with the inherent decrease in efficiency of the system due to mechanical wear and tear from years of operation, and old systems stand out as costing a disproportionate amount to run.

Customers are always going to be suspicious of the ‘scrap the old and fork out for new’ approach, but now may be just the right time — and you may not have to scrap the old completely every time.

Options exist to remove the old system and start from scratch, but also readily available now is ‘replace technology’, which allows the reuse of refrigerant piping and control wiring — a considerable cost of any installation.


Some systems reuse controllers and some even reuse the indoor units — so only the outdoor unit is replaced. It is a bit like replacing the engine and clutch in a car but keeping the rest, which is perfectly usable.

This approach represents a considerable reduction in installation time and disruption to your customer’s business. In addition, they will also start saving energy (and therefore cost) immediately and will actually be better off in the long run. Such a new system will also reduce carbon-dioxide emissions compared to an old system!

As well as energy efficiency, indoor environmental control has come on in leaps and bounds in the last decade. Today’s high-tech, inverter-driven systems bear little resemblance to the stop/start condensers of yesterday, primarily because they offer much more automatic control of energy usage. One of the main reasons for the vast improvement in energy efficiency is the use of inverter-driven compressors.

In essence, inverter-driven condensers only use the amount of energy needed to bring the temperature (up or down) to the required level at that particular point of the day. Primarily because they are not constantly switching on at full power they therefore consume far less energy — and all customers will be aware of the sharp rise in energy costs over the last 10 years. The accurate control of the inverter is only the start of the revolution that has taken place in the last five to 10 years.

There are systems that can use the energy extracted from one part of a building while it is being cooled to heat another part — balancing the energy requirement. Other systems can link into renewable energy sources such as geothermal ground source to reduce energy consumption even more.

The latest trend sees air conditioning linking to a building’s water heating to potentially replace the need for a traditional boiler, which will further reduce carbon-dioxide emissions.

So, should you be looking to convince your customers that they need to replace what seem to be hard-working, but old systems?

Of course you would expect me to say ‘yes’. But I hope at least to have demonstrated some of the real benefits of modern environmental control.

Final decision

The final decision is really a question of how much your customers watch energy prices. How aware they are of the need to be ‘green’ and reduce carbon-dioxide emissions. How much will they take a lead from you on these issues, and how much they would expect you to take a lead in proactively looking to protect them from legislation and future increases in fuel prices? The ball is firmly in your court!

Phil Ord is City Multi product marketing engineer with Mitsubishi Electric, which has produced a number of free CPD-accredited guides on issues affecting the industry. Visit the company's web site for more information.

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