A car showroom is a large glazed volume with a high roof, display lighting and doors that open for vehicles. The people load is small beside the solar gain and the air that comes in with a car. Trying to hold a shop setpoint in the whole hall is how plant gets oversized and still fails at the door. Cool the sales desks and any closed office. If the effective rated output is more than 12 kW, GOV.UK air conditioning inspections guidance sets out the operator's TM44 inspection duty. Refrigerant work needs an F-gas certified company.
Height, glass and the vehicle door
Floor area times a retail watts figure ignores height and the roller or folding door. When that door opens, the cooled air leaves. Design the occupied desk zone as the place you will actually hold, and treat the door bay as a space that will track outdoors for a few minutes at a time.
Offices, a handover lounge and a first-floor mezzanine are closed or semi-closed zones with a normal people load. They are often the rooms worth cooling properly. The showroom lighting and the glass still heat the desk if the desk sits in the hall, so put that fabric in the desk-zone load.
Air that has to arrive at the sales desks
Desks in the middle of a hall need air that arrives at head height without a gale across paperwork. Several smaller indoors, or a ducted run serving the desk strip, often behave better than one cassette lost in the roof.
Staff sitting all day are the HSE comfort question: reasonable workplace temperature, no legal maximum.
Roof structure, three-phase power and delivered cars
Roof plant needs a structure check, access for service, and a fall for rain and defrost water. A unit over a valeted car is a condensate complaint. Ground stands at the rear need airflow and a position that is not blocked by delivered vehicles.
Larger plant may need three-phase power and a landlord or franchisor approval for the elevation.
Frequently asked questions
Can we hold a setpoint in the whole showroom?
Often no, once height, glass and vehicle doors are honest. Cool the sales desks and closed rooms. Treat the door bay as a space that will warm when cars move.
Should a mezzanine office share the showroom unit?
A closed office is its own zone. The desk units in the hall will not cool it through a shut door. Put it on the survey as a separate indoor unit if it is in scope.
Can the indoor unit sit in the showroom roof apex?
It can be mounted high and still miss the people. In a tall hall the air has to be brought to the occupied band. A unit that only stirs the apex will disappoint. High roofs stratify. A unit in the apex can cool the steel and not the salesperson.
Should the showroom be left at 18C overnight?
No. Customers walking the cars are transient. Write a setpoint policy so the hall is not left at 18C overnight. Staff sitting all day are the comfort case, under HSE workplace temperature guidance, which sets no legal maximum.
Where can a tail lift meet the pipework?
Pipes across a showroom must be routed so they are not the thing a tail lift hits. Agree protection and access before the cars are back on the floor.
Core buying guides
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Related guides
Sources and further reading
How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.