Greenhouse Heating Cost Calculator
Estimates the daily cost to heat a greenhouse based on its size, the inside-outside temperature gap, and fuel price. Helps growers budget winter heating expenses.
About this calculator
Greenhouse heating costs depend on three main drivers: the surface area losing heat, the temperature differential driving that heat loss, and the cost of the fuel replacing it. The formula used here is: Daily Heating Cost ($) = greenhouse_area (sq ft) × temperature_difference (°F) × 0.001 × fuel_cost ($/gallon) × 24. The constant 0.001 represents a simplified overall heat loss coefficient (BTU per sq ft per °F per hour) combined with a fuel energy conversion factor. Multiplying by 24 converts an hourly rate to a daily cost. In practice, actual heat loss depends on glazing type (glass, polycarbonate, polyfilm), insulation, infiltration rate, and structural design. Use this calculator as a planning estimate; for precise sizing, consult a greenhouse engineer using ASHRAE heat-load methods.
How to use
Say you have a 5,000 sq ft greenhouse, maintaining 65°F inside when it's 25°F outside (a 40°F difference), and propane costs $2.50 per gallon. Enter 5,000 for Greenhouse Area, 40 for Temperature Difference, and 2.50 for Fuel Cost. The calculator computes: (5,000 × 40 × 0.001 × 2.50) × 24 = (500) × 24 = $12,000... Let me recalculate: 5,000 × 40 = 200,000 × 0.001 = 200 × 2.50 = 500 × 24 = $12,000 per day. If this seems high for your operation, verify your glazing insulation value and consider adding thermal curtains to reduce the effective heat loss coefficient.
Frequently asked questions
How does glazing type affect greenhouse heating costs in winter?
Single-layer polyethylene film has the highest heat loss rate (roughly 1.1 BTU/hr/sq ft/°F), while double-layer inflated film cuts that nearly in half. Twin-wall polycarbonate panels offer better insulation still, and glass with thermal curtains can approach the performance of polycarbonate. Upgrading from single to double-layer poly on a large greenhouse can reduce heating fuel consumption by 30–40%, paying back the investment within one or two heating seasons depending on fuel prices. The heat loss coefficient in this calculator is a simplified average — adjust your interpretation based on your actual glazing.
What is the temperature difference I should use for greenhouse heating calculations?
Use the design temperature difference, which is the gap between your desired interior growing temperature and the lowest expected outdoor temperature for your region (typically a 97.5% or 99% winter design temperature from ASHRAE climate data). For example, if you grow tomatoes at 60°F and your area's winter design low is 10°F, use a 50°F difference. Using average temperatures will underestimate peak heating demand and risk crop loss on cold nights. Always design for the worst-case scenario and then model average conditions separately for budget forecasting.
How can I reduce greenhouse heating costs without sacrificing crop temperature?
The most effective strategies are adding thermal mass (water barrels, concrete floors) to store daytime solar heat, installing thermal blanket curtains that close at night to cut radiative heat loss, sealing air infiltration at vents and door gaps, and using zone heating to keep only occupied benches at full temperature. Switching from propane to natural gas or biomass boilers can also substantially lower fuel cost per BTU. Many growers recoup insulation investments within a single heating season in cold climates where fuel bills otherwise dominate operating costs.