Winter Heating Cost Simulation for Rental Apartments—A Thorough Cost Comparison of Air Conditioners, Oil Heaters, and Electric Heaters

Not Making Mistakes When Choosing Winter Heating

Every winter, many people living in rental apartments worry about high heating costs. With so many heating appliances available—air conditioners, oil heaters, electric heaters, gas heaters, electric carpets—which one offers the best value for money? This article simulates actual running costs and explores the optimal solution for rental apartments.

Energy Consumption and Monthly Costs of Major Heating Appliances

Prerequisites

• •Room size: 6-tatami (approximately 6-10 tatami) living room / 1LDK
• •Usage time: 8 hours per day (2 hours in the morning + 6 hours in the evening)
• •Usage period: 5 months from November to March (winter season)
• •Electricity rate: ¥31/kWh (2025 average standard level)
• •Heating oil price: ¥115/L (2025 national average standard level)
• •City gas rate: ¥170/m³ (standard level)

Monthly Cost Simulation of Each Heating Appliance (6-Tatami Room)

※Actual costs vary significantly depending on outside temperature, insulation performance, and usage patterns.

Characteristics of Each Heating Appliance and Suitability for Rental Apartments

Air Conditioner: The Most Efficient Main Heating Appliance

Advantages:

• •COP (coefficient of performance) is 3-5 times higher, the highest among all options
• •Can be used for both cooling and heating, so no additional investment is needed
• •In most rental apartments, it is already installed
• •Does not pollute the air (no combustion)

Disadvantages:

• •Slow startup (takes 10-15 minutes to reach set temperature)
• •Dries out the air (using a humidifier together is effective)
• •Old air conditioners have low COP values, resulting in higher electricity costs

Important Notes for Renters: If the installed air conditioner is old (a model from more than 10 years ago), its COP value may be less than half that of current models. Check the model number and confirm the COP value. If it is significantly old, it may be worth consulting with your landlord or property manager about replacing it with a new unit.

Oil Heater: Good Value for Money, but Restrictions Apply in Rentals

Advantages:

• •High heating efficiency and quick startup
• •More cost-effective than electric heating when heating oil prices are low
• •Powerful heating capability

Disadvantages:

• •May be prohibited depending on the rental contract
• •Regular ventilation is required (risk of carbon monoxide poisoning)
• •Hassle of purchasing, storing, and refueling heating oil
• •Risk of violating rental agreements due to storing heating oil (hazardous material storage)

Important Notes for Renters: An increasing number of rental properties prohibit or require consent before using oil heaters. In particular, apartments with high airtightness such as steel-frame and reinforced concrete buildings often prohibit their use due to the risk of carbon monoxide poisoning from inadequate ventilation. Always check your lease agreement before purchasing.

Electric Heaters (Ceramic/Halogen): Specialized for Spot Heating

Advantages:

• •Warms up instantly when turned on (fastest startup time)
• •Affordable to purchase (approximately ¥3,000-8,000)
• •No installation work required, no rental restrictions
• •Ideal for spot heating specific areas (in front of desk, around feet)

Disadvantages:

• •High power consumption (800-1,200W), making electricity costs high if used to heat the entire room
• •Inefficient as a heating method for the entire room

Optimal Usage for Renters: The most rational way to use these heaters is as supplementary heating until your air conditioner reaches the set temperature, or for spot heating your feet while working at your desk. Avoid using them constantly to heat the entire room, as this will cause electricity costs to skyrocket.

Gas Fan Heater: Excellent Value in City Gas Buildings

Advantages:

• •Running costs are comparable to or lower than air conditioners in some cases
• •Quick startup
• •Unlike oil heaters, no fuel refilling is needed

Disadvantages:

• •A room with a gas outlet (gas socket) is required
• •High equipment purchase cost (¥20,000-40,000)
• •Ventilation is required (though not as much as with oil heaters)

Important Notes for Renters: To use a gas fan heater in a rental apartment, a gas outlet must be present in the room. Most properties only have gas outlets in the kitchen, and retrofitting work typically requires landlord approval. If your rental has a city gas contract and already has a gas outlet in the living room, it would be an ideal choice.

Electric Carpet: Energy-Efficient Supplementary Heating

Advantages:

• •Low power consumption (200-400W at medium setting) with good value for money
• •Provides comfortable warmth from your feet at low temperature
• •No rental restrictions

Disadvantages:

• •Requires a lifestyle of sitting or lying on the floor
• •Cannot heat the entire room on its own

Optimal Usage: It is most effective when used in combination with air conditioner heating. Even if you lower the air conditioner's set temperature by 1-2°C, warming your feet with an electric carpet will maintain or improve the perceived temperature. This can reduce your total monthly electricity bill.

Recommended Optimal Heating Cost Strategy for Rentals

Basic Pattern: Air Conditioner + Electric Carpet

• •Use the air conditioner as base heating set at 18-20°C
• •Supplement foot warmth with an electric carpet
• •Maintain comfort while saving approximately ¥1,000-1,500 per month by lowering the air conditioner's set temperature by 2°C

Cost-Saving Enhancement Pattern: Window Insulation + Air Conditioner Optimization

• •Apply heat-insulating film or bubble wrap (air cushion material) to windows
• •Switch to thicker curtains
• •This alone can improve air conditioner efficiency by 20-30%, resulting in monthly savings of ¥2,000-4,000

Emergency/Spot Assistance: Ceramic Fan Heater

• •Use a ceramic heater only for the first 15 minutes while the air conditioner is warming up
• •Use at 500-600W setting for foot heating while working at your desk

Summary: Heating Selection Chart for Rentals

With the right choice of heating appliance and smart usage habits, you can reduce your winter utility costs by tens of thousands of yen annually. When choosing heating for a rental apartment, it is important to compare not just "initial costs" but also "running costs."

Windows are the primary source of heat loss and gain in rental housing. By selecting and installing insulation films or sheets correctly, you can significantly reduce winter cold and summer heat while lowering utility costs. This article explains how to choose products that allow restoration to original condition and shares installation tips.