How should you specify aircon for a Bali villa?

Aircon decides two things in a Bali rental villa: your largest utility bill and a disproportionate share of your reviews. Both are settled at specification, not in operation.

Inverter versus fixed speed

Inverter units vary compressor speed to match demand rather than cycling on and off at full power. They use substantially less electricity, run more quietly and hold temperature more evenly.

Fixed-speed units are cheaper to buy and more expensive to run, and the cycling is audible, which matters at 3am in a bedroom.

On a villa with five or six units running through peak season, the running cost difference is the single largest energy saving available to you and it pays back the price difference quickly.

Specify inverter units throughout. This is not a close decision.

Sizing

Undersized units are the most common fault in Bali villas, and the symptom is a guest complaint rather than an obvious failure.

Sizing depends on room volume, glazing area and orientation, insulation, ceiling height and how many people occupy the room. Bali villas commonly have high ceilings, large glazed openings and minimal insulation, all of which increase the load.

An undersized unit runs continuously, never reaches temperature, costs more to run than a correctly sized one and produces the review that says "the aircon didn't work".

Have it specified properly rather than by rule of thumb, and size for the room as built rather than the room on the drawing.

The electrical connection

This is where villas get caught.

Your PLN connection has a contracted capacity in VA, and running five or six aircon units plus a pool pump, water pump and water heating simultaneously draws a great deal.

An undersized connection trips under load — which happens precisely when the villa is full, in peak season, with paying guests in it.

Check the connection capacity before buying and compare it against what the property actually runs. If you are building, specify capacity at design stage and confirm the local network supports it, because upgrading later costs money and takes time, and in some areas needs infrastructure work.

Where to put units and where not to

Every bedroom, without exception, in a rental villa. A bedroom without aircon is a bedroom guests complain about.

Living areas, where they are enclosed. Open-sided tropical living spaces are designed to work without it and adding units to them is expensive and ineffective.

Not directly over the bed. Guests complain about the draught.

Outdoor condensers away from bedrooms and the pool deck, because they are noisy and they appear in photographs.

Drainage planned properly. Condensate has to go somewhere, and units draining onto a terrace or a wall cause staining and eventually damage.

Reducing the load before you install anything

Design. Cross-ventilation, deep overhangs, orientation away from the worst afternoon sun, and shading. A building designed for the climate needs less cooling, which is cheaper to install and cheaper to run.

Ceiling fans in every room, which cost almost nothing and allow a higher thermostat setting for the same comfort.

Glazing. Large west-facing glass is a heat load. Shade it.

Insulated roofs, which are frequently omitted in Bali builds and which matter more than most single decisions.

The guest behaviour problem

Guests leave aircon running in empty rooms with doors open to the garden. There is no polite solution.

Key-card or occupancy-linked systems help in properties where that is practical. Door sensors that cut the unit when a door is open exist and work. A note asking guests to close doors does very little.

Budget for the reality rather than the ideal — your electricity bill in a full month reflects how guests actually behave.

Maintenance

Clean filters regularly. Dirty filters reduce output, increase consumption and produce the "it doesn't get cold" complaint. This should be on your housekeeping schedule, not an annual event.

Service the units on a schedule. Gas, coils, drainage.

Replace rather than repeatedly repair. An old unit is costing you in electricity and in reviews, and replacement with an inverter model pays back.

Brief your manager to report performance drops early, because the guest who mentions it in a review has already had the bad experience.