Heating Cost Comparison for Illinois Homes: Natural Gas, Electric, Propane, and Heat Pump

Illinois Home Heating Costs Broken Down

A meaningful heating cost comparison starts with understanding what's actually included in each fuel's cost structure. This section provides the baseline numbers for each fuel type, followed by the framework for a true apples-to-apples comparison.

Natural Gas Heating Costs in Illinois

Natural gas is the dominant home heating fuel in Illinois — approximately 75% of Illinois homes use natural gas as their primary heating fuel, according to the U.S. Energy Information Administration. Illinois has an extensive natural gas distribution network connecting most urban and suburban areas, with pipeline service through utilities including Nicor Gas, Peoples Gas, North Shore Gas, and Ameren Illinois gas distribution.

Current Illinois residential natural gas prices (2025-2026 heating season) range from approximately $0.90 to $1.30 per therm depending on utility territory, weather conditions, and whether a customer has a fixed-price ARES contract. One therm equals 100,000 BTU of natural gas energy content. A 96% efficient condensing gas furnace delivers approximately 96,000 BTU to your living space per therm consumed.

A typical 1,800 square foot Illinois home built in the 1980s with average insulation consumes approximately 600–900 therms per heating season (November through March). At $1.10/therm average cost, that's approximately $660–$990 for the season — or roughly $130–$200 per month during peak winter months.

Key variables affecting your natural gas heating cost:

• Home size and insulation quality: The single largest variable — well-insulated homes can cut consumption 30–50%
• Furnace efficiency: A 96% AFUE furnace uses 25% less gas than an old 80% AFUE unit for the same heat output
• Supply price: Weather-driven winter spikes can push gas prices 50–100% above spring/summer levels in tight-supply years — locking in a fixed ARES supply price before the heating season hedges this risk
• Thermostat habits: Each degree of average temperature increase adds approximately 3% to heating load

Electric Resistance Heating Costs in Illinois

Electric resistance heating — baseboard heaters, electric furnaces, and electric coil space heaters — converts electricity to heat at 100% efficiency. Every kilowatt-hour consumed delivers exactly 3,412 BTU to your living space. This sounds efficient, but electricity in Illinois costs approximately 14–16 cents/kWh all-in for residential customers. At those prices, electric resistance heating costs approximately $4.10–$4.70 per 100,000 BTU delivered — roughly four times the per-BTU cost of natural gas.

For a home that would use 600 therms of natural gas for heating (60,000,000 BTU), equivalent electric resistance heat requires approximately 17,580 kWh — costing $2,460–$2,810 at current rates, compared to $660 for gas. The economics of electric resistance heating in Illinois are difficult to justify for whole-home heating except in homes with no gas access and very low electricity rates (e.g., off-peak time-of-use pricing).

Propane Heating Costs in Illinois

Propane serves approximately 8% of Illinois homes, concentrated in rural areas outside the natural gas distribution network. Propane prices are more volatile than pipeline natural gas and vary significantly by location and delivery contract terms. Illinois residential propane prices typically range from $1.80 to $2.50+ per gallon, with price spikes during severe cold snaps when regional supply tightens.

One gallon of propane contains approximately 91,500 BTU. A 95% efficient propane furnace delivers approximately 86,900 BTU per gallon consumed. To match the heat output of 600 therms of natural gas, you need approximately 689 gallons of propane — costing $1,240–$1,720 at current prices. Propane heating typically costs 60–80% more than natural gas heating annually.

Heat Pump Heating Costs in Illinois

Modern cold-climate air-source heat pumps are a categorically different technology from electric resistance heating. Heat pumps move heat from outside to inside rather than generating it directly — consuming 1 unit of electricity while delivering 2–4 units of heat, depending on outdoor temperature. This ratio is called the Coefficient of Performance (COP).

At moderate Illinois winter temperatures (30–45°F), current cold-climate heat pumps (such as Mitsubishi Hyper Heat, Bosch IDS, or Carrier Infinity systems) achieve COPs of 2.5–3.5. At these performance levels, heat pump heating costs per BTU are comparable to or lower than natural gas. At very cold temperatures (below 10°F), COP drops to 1.5–2.0 — still significantly better than electric resistance but less competitive with gas. Below 0°F, supplemental electric resistance heating typically activates.

For a home requiring 60,000,000 BTU of seasonal heating, a heat pump averaging COP 2.8 would consume approximately 6,272 kWh of electricity — costing approximately $880–$1,000 at current Illinois residential rates. This is 10–50% higher than gas in current absolute terms, but the gap narrows as gas prices rise and electricity costs fall (particularly with competitive ARES rates and off-peak pricing).

Which Heating Fuel Saves the Most Money in Illinois: A BTU Analysis

The only intellectually honest way to compare heating fuels is on a per-BTU-delivered basis at current prices. This table does that comparison for Illinois conditions in 2025-2026.

Assumptions: Illinois residential gas price $1.10/therm; electricity $0.15/kWh standard rate; propane $2.20/gallon; 600-therm-equivalent annual heating load; heat pump COP represents weighted seasonal average for Illinois climate. Off-peak electricity rate reflects ComEd Hourly Pricing overnight average.

Key Findings

• Natural gas with a high-efficiency (96% AFUE) furnace remains the cheapest per-BTU option at current Illinois prices on standard utility rates
• A heat pump using off-peak electricity is actually cheaper per BTU than gas at current prices — and the advantage grows as time-of-use pricing becomes more accessible
• A heat pump on standard utility rates costs 20–35% more than gas but still dramatically outperforms electric resistance and propane
• Propane heating costs more than double natural gas — the primary reason propane customers who gain gas grid access almost universally convert
• Electric resistance heating has no viable economic case for primary Illinois home heating at current prices

Hidden Costs of Home Heating in Illinois

The fuel costs above represent only part of the true cost of home heating. Several important cost categories often go unaccounted in simple fuel comparisons.

Equipment Costs and Replacement Timing

Heating equipment has a finite service life and replacement cost that should be amortized across its useful life in any honest total-cost comparison:

• High-efficiency gas furnace (96% AFUE): $3,000–$5,500 installed, 20–25 year service life = $120–$275/year capital cost
• Standard efficiency gas furnace (80% AFUE): $2,500–$4,000 installed, 15–20 year service life = $125–$267/year capital cost
• Cold-climate air-source heat pump system: $8,000–$18,000 installed (after federal and utility incentives, $5,000–$12,000), 15–20 year service life = $250–$800/year capital cost
• Propane furnace: Similar to gas furnace equipment cost, but propane customers also face tank rental or ownership costs typically $100–$300/year

Including capital costs significantly changes the heat pump economics: at $8,000 net installed cost over 20 years, the annual capital cost ($400) added to operating costs brings total heat pump cost closer to gas. But federal IRA credits and utility rebates can reduce heat pump installed cost by $3,000–$10,000, substantially improving the capital cost comparison.

Maintenance and Repair Costs

Annual maintenance costs vary by system type:

• Gas furnace: Annual tune-up approximately $80–$150; typical major repair $300–$800; heat exchanger replacement $800–$1,500
• Heat pump: Annual service approximately $100–$200; typical major repair $200–$600; compressor replacement $1,500–$3,000
• Propane: Similar to gas furnace, with the addition of tank inspection and safety check costs

Natural Gas Supply Price Risk

Illinois residential natural gas prices are exposed to significant weather-driven volatility. During the 2021 polar vortex event, spot natural gas prices in the Midwest spiked to 50–100x normal levels for brief periods. Customers on utility default gas supply who heat during these events pay elevated prices that can add $100–$400 to a single month's bill. Locking in a fixed natural gas supply price through an Alternative Gas Supplier (AGS) before the heating season — ideally between April and August — eliminates this risk. See our guide to gas peaker season for optimal timing strategies.

Insulation and Air Sealing: The Overlooked Category

No fuel switch delivers returns as high as proper insulation and air sealing for many older Illinois homes. An energy audit (available through ComEd and Ameren's energy efficiency programs, often at reduced or no cost) frequently identifies air sealing and insulation improvements that reduce heating load 15–35% — translating directly to lower heating costs regardless of which fuel you use. Illinois utility energy efficiency programs also provide rebates for insulation improvements that can cover 30–50% of project costs.

Fixed vs. Variable Gas Supply: The Price Lock Opportunity

Illinois's deregulated natural gas market allows residential and commercial customers to lock in fixed gas supply prices through Alternative Gas Suppliers. This doesn't change your delivery rate (paid to your utility), but it insulates your supply price from seasonal spikes. The optimal window to lock in gas supply prices is spring through summer (April–August), when gas prices are seasonally depressed before heating season demand builds. For more detail, see our natural gas seasonal pricing guide.

Best Heating System Recommendations for Illinois Homeowners

With the cost framework established, here are concrete recommendations for different homeowner situations.

Existing Gas Infrastructure: Maximize Your Current System

If you have a functioning gas furnace with more than 5 years of remaining useful life, the most cost-effective actions are:

1. Ensure furnace is properly maintained and tuned (annual service)
2. Lock in a fixed gas supply price before the heating season
3. Address air sealing and insulation deficiencies identified by an energy audit
4. Install a programmable or smart thermostat (saves 8–12% on heating costs automatically)

A gas furnace replacement decision is straightforward when the existing furnace fails: replace with a 96% AFUE condensing furnace. The efficiency improvement over an older 80% AFUE unit pays back the modest incremental cost within 3–5 years in fuel savings.

Gas Furnace Replacement Decision: Gas or Heat Pump?

When a gas furnace reaches end of life, the decision between gas replacement and heat pump installation deserves careful analysis. Factors favoring heat pump replacement:

• You have or plan to add rooftop solar (dramatically reduces effective electricity cost)
• You want to reduce carbon footprint (Illinois's grid is 55%+ carbon-free and improving)
• Your electrical panel is already adequate (no major upgrade cost)
• You qualify for maximum IRA incentives (up to $8,000 in HEEHRA rebates + 30% 25C credit)
• Gas prices are volatile or trending higher in your area

Factors favoring continued gas use:

• You need a same-day replacement (heat pump system installation is more complex)
• Your home is in a zone with frequent deep cold snaps below 0°F requiring extensive supplemental heating
• Your electrical service would require significant panel upgrade
• You have an older home with existing ductwork sized for high-temperature gas heat distribution

Rural Illinois Propane Users: The Conversion Math

For rural Illinois homeowners on propane with no natural gas grid access, a cold-climate heat pump conversion almost always produces a positive ROI — even at Illinois electricity rates. The math: saving $1,000–$1,300/year in fuel costs versus gas pays back a $10,000 heat pump installation in 8–10 years (before incentives), and in 4–6 years after IRA credits and utility rebates. This is among the clearest heat pump upgrade opportunities in the residential market.

New Construction

For Illinois new construction, all-electric construction with a cold-climate heat pump is worth serious evaluation. Eliminating the gas service connection avoids $3,000–$5,000 in utility connection costs, and all-electric systems are fully compatible with Illinois's decarbonizing grid. Federal and utility incentives are also largest for new construction that incorporates high-efficiency heat pumps, insulation, and EV-ready wiring.

Frequently Asked Questions: Illinois Home Heating Cost Comparison

What is the cheapest way to heat a home in Illinois?

At current prices, natural gas with a high-efficiency (96% AFUE) furnace is the lowest-cost option for most homes with existing gas infrastructure — approximately $1.15 per 100,000 BTU delivered. A heat pump using off-peak electricity rates is competitive at roughly $0.84/100K BTU, but requires specific rate structure access and smart charging capability.

How much does it cost to heat an Illinois home with natural gas?

A typical 1,800 sq ft Illinois home uses 600–900 therms per heating season. At $1.10/therm, that's $660–$990/season. Well-insulated homes use 400–500 therms; older poorly insulated homes may use 1,200 therms or more.

Are heat pumps effective in Illinois winters?

Modern cold-climate heat pumps maintain effective heating down to about 5°F, covering 95%+ of Illinois winter hours. Below 0°F, supplemental electric resistance heating assists — affecting a very small percentage of annual heating hours in most Illinois climate zones.

Is electric heat more expensive than gas heat in Illinois?

Electric resistance heating is 3–4x more expensive per BTU than gas at current Illinois rates. However, a heat pump with COP 2.8 is only 20–35% more expensive than gas on standard rates — and cheaper than gas with off-peak electricity pricing.

How does propane compare to natural gas for heating in Illinois?

Propane typically costs 60–80% more than natural gas per BTU delivered in Illinois. A home that would spend $690/season on gas might spend $1,400–$1,600 on propane. Propane serves rural areas without gas grid access where it's the primary alternative.

What are the hidden costs of switching heating systems in Illinois?

Major hidden costs include equipment installation ($3,000–$5,000 for gas; $8,000–$18,000 for heat pump), electrical panel upgrades ($1,500–$4,000 for older homes), ductwork modifications ($2,000–$5,000), and propane tank rental fees. Federal IRA incentives can offset $3,000–$10,000 of heat pump installation cost.

What heating system has the lowest carbon footprint in Illinois?

A heat pump powered by Illinois's grid — which is already 55–60% carbon-free due to nuclear — has a lower carbon footprint than natural gas combustion, and this advantage grows as Illinois's grid decarbonizes toward its 2045 carbon-free target.

Can I lock in my natural gas price in Illinois?

Yes. Illinois's deregulated gas market allows customers to contract with alternative gas suppliers (AGS) at fixed prices. The optimal window to lock in is April through August, before heating season demand drives prices higher.

Are there Illinois rebates for upgrading to a heat pump?

Yes. The federal IRA provides up to $8,000 through HEEHRA rebates and up to $2,000/year through the 25C Energy Efficient Home Improvement Credit. ComEd and Ameren also offer heat pump rebates. Total incentive value for eligible households can reach $10,000–$12,000.