Packaged and rooftop units
A packaged unit houses everything — compressor, condenser, evaporator and fans — in a single casing, rather than splitting it between indoor and outdoor units. It’s often mounted on the roof (hence “rooftop unit”), with conditioned air ducted down into the space. It’s a common, practical choice for single-storey commercial buildings with open-plan space.
How it works
A packaged unit puts everything — the compressor, condenser, evaporator and fans — in a single casing, rather than splitting it into indoor and outdoor units. It’s frequently mounted on the roof, and conditioned air is ducted down into the space below. Many include a fresh-air intake, integral heating, and an “economiser” that uses cool outside air for free cooling when conditions allow. See how air conditioning works.
Pros and cons
Pros: all-in-one, with plant outside or on the roof, freeing up internal space; relatively quick and straightforward to install where the building suits it; can combine cooling, heating, fresh air and free cooling in one unit; well-matched to large open areas.
Cons: best for single-storey buildings with roof access and ducting routes; serves zones or open areas rather than giving fine room-by-room control; the roof structure must take the weight; ducting and roof penetrations need designing in.
Best for / not ideal for
Ideal for single-storey retail, supermarkets, warehouses, restaurants, gyms and light industrial units with roof access and open-plan space. Less suitable for multi-storey buildings or those needing many individually controlled zones — where VRF is the better fit.
Capacity and design
Packaged units are sized to the open area or zone they serve and the ductwork that distributes the air, with fresh-air and heating requirements built in. As with any commercial system, design starts from a commercial heat-load calculation.
What it costs
Often cost-effective to install where the building suits it, since much of the system is contained in one unit.
Compliance: packaged units carry refrigerant (F-gas obligations), and larger installations may come under TM44 inspections.
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