Use suitable curtains, close blinds during strong sunlight, and report damaged seals or obvious building defects to the landlord.
For homeowners, improvements to insulation and air sealing may require an initial investment, but they can reduce cooling demand over the long term.
The best upgrades depend on the building. A home with a poorly insulated roof may benefit more from roof improvements than from replacing perfectly functional curtains.
13. Use Dry Mode When Conditions Call for It
High humidity can make a room feel warmer than its actual temperature.
When the air contains substantial moisture, sweat evaporates less readily from the skin, making it harder for the body to cool itself.
Some air conditioners include a dry mode designed to remove moisture from indoor air.
This mode may be useful during humid conditions when the room feels damp or sticky, even if the temperature is not extremely high.
However, dry mode is not automatically more energy-efficient than normal cooling in every situation. Its operation varies by model, and it may still use the compressor.
It is also not a replacement for a dedicated dehumidifier in every damp environment.
If you use dry mode, pay attention to comfort rather than simply choosing the mode because it sounds economical.
Avoid excessive dehumidification, which can make indoor air uncomfortably dry.
If humidity remains high despite appropriate air conditioning, investigate other sources of moisture, such as leaks, inadequate bathroom ventilation, or damp building materials.
In humid climates, balancing temperature and moisture is often more effective than lowering the thermostat to an unnecessarily cold setting.
14. Do Not Ignore Routine Professional Maintenance
Cleaning the filter is important, but some maintenance tasks require a trained technician.
Over time, the indoor and outdoor coils may accumulate dirt. Drainage lines can become blocked, electrical connections may deteriorate, and components can develop faults.
A poorly maintained system may cool less effectively, operate noisily, leak water, or consume more electricity than expected.
Periodic professional inspection can help identify these issues before they become more serious.
The appropriate maintenance interval depends on the system, the manufacturer's recommendations, and the conditions in which it operates.
During a service visit, a qualified technician may inspect the coils, drainage, electrical components, refrigerant system, and overall operation.
Refrigerant handling should be performed by appropriately qualified personnel. Low refrigerant levels are not something homeowners should attempt to correct by simply purchasing refrigerant and adding it themselves.
If your air conditioner suddenly stops cooling properly, develops ice on the indoor coil, repeatedly trips a circuit breaker, or produces unusual smells or sounds, arrange an inspection rather than forcing it to operate.
Maintenance cannot eliminate every possible fault, but it can help keep the equipment operating safely and efficiently.
15. Monitor Your Electricity Consumption
One of the most effective ways to control electricity costs is to understand how your household actually uses energy.
Many people know that air conditioning consumes electricity but have little idea how much their habits affect the monthly bill.
Start by recording your electricity consumption during a period of normal operation.
If your utility provides daily or hourly usage data, review it to identify patterns. Otherwise, compare electricity bills across similar periods, taking outdoor temperatures and household occupancy into account.
If you have access to a suitable energy monitor, you may be able to estimate how much electricity a particular appliance uses. Follow the manufacturer's instructions and use only equipment appropriate for the electrical system.
Remember that the power rating on an air conditioner is not necessarily its constant power consumption. Inverter models, in particular, vary their output according to demand.
A unit's actual energy use depends on its capacity, operating conditions, thermostat setting, efficiency, and runtime.
You can estimate operating cost using this formula:
Electricity cost = Energy consumed in kWh Γ Electricity price per kWh
For example, suppose an appliance consumes an average of 0.8 kW while operating for six hours.
Its estimated energy consumption would be:
0.8 kW Γ 6 hours = 4.8 kWh.
If the applicable electricity price were 3,000 Vietnamese dong per kWh, the estimated cost would be 14,400 Vietnamese dong for that period.
This is an illustration, not a prediction of the cost of running every air conditioner. Actual consumption can vary considerably, and household electricity tariffs may include different pricing tiers, taxes, or other charges.
Tracking real usage helps you determine whether changes to your habits are making a difference.
16. Avoid Cooling Empty Rooms Unnecessarily
If your home has several rooms, think about where cooling is actually needed.
Cooling an unused guest bedroom all afternoon may waste electricity, particularly if the room receives direct sunlight or has poor insulation.
If you use a single-room air conditioner, close the doors and windows of the room while it operates, provided ventilation needs are met.
If you have a multi-split or central system, use the available zone controls or thermostats to reduce cooling in areas that are not occupied.
However, do not assume that closing every interior door will always improve efficiency. Some central systems require particular airflow pathways, and restricting return air can reduce performance.
Follow the manufacturer's guidance for your specific system.
For homes with multiple air conditioners, it may be more efficient to cool the occupied room rather than operate every unit at once.
The right strategy depends on the layout, insulation, and type of equipment.
The general principle is simple: provide cooling where and when it is needed, without sacrificing comfort or indoor air quality.
17. Understand When It Makes Sense to Replace an Old Unit
An older air conditioner may consume considerably more electricity than a modern, efficient model of comparable capacity. However, replacement is a financial decision that deserves careful consideration.