Hoop House
Calculate hoop house surface area, heat loss, heater size, and material cost for gable and arched greenhouses. Free online greenhouse sizing tool for farmers and gardeners.
About This Calculator
The Hoop House Calculator helps farmers, gardeners, greenhouse builders, and agricultural professionals estimate the surface area, heating requirements, and material cost for hoop houses and greenhouses. Whether you are planning a small backyard greenhouse for seasonal vegetables or a large commercial operation, this calculator provides accurate estimates for both gable and arched/Quonset greenhouse designs.
Methodology: The surface area is calculated by summing all exposed surfaces — end walls, side walls, and roof sections. For a gable-type greenhouse, the end walls are a combination of rectangular and triangular sections (gable ends), and the roof consists of two sloping rectangular panels. For an arched/Quonset greenhouse, the roof is modeled as a half-cylinder and the ends as half-circles, with optional rectangular side walls below. Heat loss is computed using the standard building physics formula: Q = A × U × ΔT, where Q is conductive heat loss in kilowatts, A is the total surface area in m², U is the heat loss coefficient (U-value) of the chosen covering material in W/m²·K, and ΔT is the temperature difference between inside and outside in °C. The required heater capacity is then calculated by dividing the heat loss by the heater efficiency. Material cost is simply the surface area multiplied by the material unit price.
Regional Notes
India (IN): Greenhouses are increasingly popular in Indian horticulture, especially in hilly regions like Himachal Pradesh, Uttarakhand, and Jammu & Kashmir for off-season vegetable production. Common sizes range from 100-500 m² for small farms. Polyethylene film (200-micron) is the most widely used covering material. The National Horticulture Mission provides subsidies for greenhouse construction. Outside winter temperatures in north Indian plains drop to 5-10°C, while hill stations can see 0-5°C.
United States (US): Hoop houses are widely used in US agriculture for season extension, particularly in USDA zones 3-7. The USDA Natural Resources Conservation Service (NRCS) offers cost-share programs for high tunnels through the Environmental Quality Incentives Program (EQIP). Common sizes are 20-30 ft wide and 48-96 ft long. In cold climates (USDA zone 4-5), double-layer polyethylene with inflation is standard practice. Outside design temperatures vary from -30°C (Minnesota) to -5°C (Pacific Northwest).
United Kingdom (UK): Greenhouses are common in UK gardening and market gardening. The Royal Horticultural Society (RHS) recommends greenhouses for extending the growing season. UK greenhouses typically use glass or twin-wall polycarbonate. Standard sizes range from 6×8 ft to 10×12 ft for hobby gardens and larger for commercial operations. Outside winter temperatures average 0-5°C in most regions. Building regulations may apply for commercial greenhouses over certain size thresholds.
Frequently Asked Questions
What is a hoop house or greenhouse?
A hoop house or greenhouse is a transparent confined space made from polycarbonate, glass, or polyethylene that mimics favorable conditions for plants to grow. It is mostly used to grow crops in places where extreme weather makes outdoor growing difficult. A greenhouse controls temperature, humidity, pressure, and carbon dioxide levels to ensure healthy plant growth.
How do you calculate greenhouse surface area?
Greenhouse surface area is calculated by adding the areas of all exposed surfaces — end walls, side walls, and roof sections. For a gable greenhouse, this includes the rectangular side walls, the triangular gable ends, and the sloping roof panels. For an arched or Quonset greenhouse, the roof is a half-cylinder and the ends are half-circles with optional rectangular side walls below.
What is the formula for greenhouse heat loss?
Greenhouse heat loss is calculated using the formula: Q = A × U × ΔT, where Q is the conductive heat loss in watts, A is the total surface area in square meters, U is the heat loss coefficient (U-value) of the covering material in W/m²·K, and ΔT is the temperature difference between inside and outside in °C. The result is divided by 1000 to convert to kilowatts.
How do I choose the right heater for my hoop house?
To choose the right heater, first calculate the conductive heat loss of your greenhouse using the surface area, material U-value, and temperature difference. Then divide the heat loss by your heater's efficiency (as a decimal) to determine the required heater capacity in kilowatts. Always oversize by 10-15% to account for air leakage, thermal bridging, and extreme weather conditions.
What are the different types of greenhouses?
Common greenhouse types include Gable (peak roof with triangular ends), Arched or Quonset (half-cylinder shape), Lean-to (attached to an existing wall), and Gothic arch (pointed arch shape). Each design has its own advantages for space utilization, heat retention, cost, and structural strength. Gable greenhouses are most common for larger commercial operations, while Quonset designs are popular for hobby and seasonal use.
What is the best covering material for a greenhouse?
The best covering material depends on your climate and budget. Polyethylene film (4-6 mm) is the most affordable option with U-values of 6.3-6.5 W/m²·K. Inflated double-layer polyethylene reduces heat loss to about 4.0 W/m²·K. Glass offers durability and light transmission with a U-value of 5.7 W/m²·K. Insulated glass (double glazing) is the most energy-efficient at 2.7 W/m²·K but also the most expensive.
How does temperature difference affect heater sizing?
The temperature difference (ΔT) between inside and outside directly determines heat loss and therefore heater sizing. A larger ΔT — for example, growing tropical plants at 30°C in a region where winter temperatures drop to -10°C (ΔT = 40°C) — requires a significantly larger heater than a greenhouse maintaining only 10°C above outside temperature. For each degree of temperature difference, heat loss increases proportionally.
What size greenhouse do I need for my plants?
For hobby gardening, a greenhouse measuring 2.5 m × 3 m provides enough space for seasonal vegetables and flowers. For year-round growing, a 3 m × 6 m greenhouse can support a family's vegetable needs. Commercial operations typically use greenhouses 8-10 m wide and 20-50 m long. Consider walkway space (at least 60 cm), bench width (60-90 cm), and headroom (at least 2 m at the peak) when planning your greenhouse dimensions.