When plant reaches the end of its life, an owner can reinstate the same arrangement or change the system type. Each route carries different cost, disruption and risk.
Replacing cooling plant like for like is faster, cheaper to design and far less disruptive, because the distribution, the electrical supply and the controls stay as they are. Changing the system type can deliver better efficiency, better control and lower maintenance, at the cost of a longer programme, more design work and interventions throughout the building rather than only in the plant area.
Like for like replacement at a glance
The failing equipment is replaced with equivalent modern plant of the same type and roughly the same capacity, reusing the existing distribution, pipework, ductwork and electrical supply. Design effort is modest, disruption is concentrated at the plant, and the programme can often fit within a shoulder season. Efficiency improves because the new equipment is better than what it replaces, but the system limitations remain.
Changing the system type at a glance
The opportunity is taken to move to a different arrangement, such as from constant volume ducted systems to variable refrigerant flow, from individual splits to a central system, or from an ageing chiller plant to a district cooling connection. Efficiency and control improve materially, but the change touches distribution, electrical supply, controls and often ceilings throughout the building.
Design and approval effort
Like for like replacement: Limited, since capacity and distribution are already established.
Changing the system type: Substantial, requiring load calculations, distribution design and electrical assessment.
Disruption to occupants
Like for like replacement: Concentrated at the plant area and any riser connections.
Changing the system type: Extensive, since work reaches ceilings and distribution throughout the building.
Efficiency improvement
Like for like replacement: Moderate, limited by the existing distribution and control arrangement.
Changing the system type: Potentially large, because the whole system is matched to current demand.
Programme
Like for like replacement: Short enough to fit between cooling seasons in many buildings.
Changing the system type: Long, usually phased across zones over several months.
Capital cost
Like for like replacement: Lower, with the saving concentrated in reused distribution and electrical infrastructure.
Changing the system type: Higher, sometimes by a multiple, depending on how much distribution is replaced.
Risk of unpleasant discoveries
Like for like replacement: Lower, although existing pipework condition can still surprise.
Changing the system type: Higher, because opening ceilings across a building reveals what was concealed.
Fit with a wider refurbishment
Like for like replacement: Neutral, as it can be done at any time.
Changing the system type: Strong, since sharing access and ceiling works with other trades reduces the real cost.
When like for like replacement wins
- Plant that has failed unexpectedly and must be replaced before the cooling season.
- Buildings where distribution and controls are in good condition and correctly sized.
- Occupied assets where intervention inside tenant areas is impractical.
- Owners planning to sell or reposition the asset within a few years.
When changing the system type wins
- Buildings where the existing distribution is undersized, leaking or at the end of its life.
- Assets undergoing a wider refurbishment where ceilings are open anyway.
- Multi tenant properties where individual control and metering would support the letting strategy.
- Long term holds where a decade of lower running cost justifies the disruption.
How to decide
Let the condition of the distribution decide, not the condition of the plant. If pipework, ductwork and controls are sound and correctly sized for the current use, replace like for like and spend the saving on controls and commissioning. If the distribution is leaking, undersized, uninsulated or serving a layout the building no longer has, replacing only the plant delivers a modern machine chained to the problem that limited the old one. Where a wider refurbishment is planned, bring the system change into it rather than running two disruptive projects.
Commission a load calculation against the current use rather than reusing the original design figure, since occupancy, equipment and even the facade may have changed. Survey the distribution for condition, insulation and leakage, and check the electrical capacity available for any new arrangement. Ask for operating cost estimates for both options based on your own consumption data rather than on manufacturer ratings at design conditions. Confirm the applicable code requirements for ventilation and energy performance with the reviewing authority before design, as these provisions are updated periodically.
Domira works on buildings that already exist: surveying what is installed, specifying the systems that have to be replaced, and running maintenance and refurbishment work around the people using the property. Tell Domira which asset you are responsible for and we will say what we would inspect first.
Frequently Asked Questions
Should I replace air conditioning with the same system type?
If the existing distribution and controls are sound and correctly sized, usually yes, because reusing them saves a great deal of cost and disruption for a modest efficiency penalty. If the distribution is failing, undersized or serving a layout that no longer exists, a like for like replacement locks in a limitation for the life of the new plant.
When is the best time to replace cooling plant?
Before it fails, during the cooler months, and ideally alongside any other works requiring access to ceilings or risers. Emergency replacement during the cooling season costs more, limits equipment choice to whatever is available, and usually means accepting a like for like solution whether or not it was the right one.
Does new air conditioning plant need an electrical supply upgrade?
Sometimes. Modern equipment is often more efficient and may draw less, but a change of system type can alter the load distribution, the starting characteristics and where the supply is required. Have the electrical capacity and the distribution assessed as part of the design rather than discovering a constraint after the equipment has been ordered.
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