This tool helps you estimate the expected time (ET) for completing a given task based on multiple input parameters.

## How to Use the ET Estimator

To use this calculator, fill all the fields with the required data:

- Day of Year: Enter a number between 1 and 365.
- Latitude: Enter the latitude in degrees. Use positive numbers for the northern hemisphere and negative numbers for the southern hemisphere.
- Altitude: Enter the altitude above sea level in meters.
- Average Temperature: Enter the average temperature in Celsius.
- Solar Radiation: Enter the solar radiation in MegaJoules per square meter per day.
- Wind Speed: Enter the wind speed in meters per second.
- Relative Humidity: Enter the relative humidity in percentage.

Once the fields are completed, click the “Calculate” button to estimate the evapotranspiration (ET) in millimeters per day.

## Calculation Method

This calculator estimates the evapotranspiration using the FAO Penman-Monteith equation, which is a standardized method for computing reference ET. The formula incorporates several climatic parameters including solar radiation, wind speed, air temperature, and relative humidity. It calculates the net radiation, soil heat flux, and aerodynamic resistance to determine ET accurately.

## Calculator Limitations

While this calculator uses the FAO Penman-Monteith equation, which is widely accepted and accurate under a variety of conditions, it has limitations including:

- The accuracy of the input data: Inaccurate measurements of temperature, humidity, wind speed, or solar radiation can lead to erroneous results.
- Assuming uniformity: It assumes the land surface is homogeneous and that the climate parameters are uniform across the given area.
- Simplification: Some environmental factors such as soil types, vegetation, and specific local microclimates are not included in this calculation, which might affect the actual ET.

## Use Cases for This Calculator

### Use Case 1: Calculate the Price of a Basic Electrical Installation

Enter the total square footage of the area and the number of electrical outlets needed. The estimator will calculate the total cost, including labor and materials, giving you an accurate estimate for your basic electrical installation project.

### Use Case 2: Estimate the Cost of Installing Light Fixtures

Provide the number of light fixtures you want to install along with the type of fixtures (e.g., recessed lights, chandeliers). The calculator will give you an estimate of the total cost, allowing you to plan your budget efficiently for your lighting project.

### Use Case 3: Determine the Budget for Rewiring a House

Input the square footage of your house and the number of floors requiring rewiring. By specifying if the walls will be opened or not, the estimator will provide you with an accurate budget for the entire house rewiring project, helping you make informed decisions.

### Use Case 4: Calculate the Cost of Installing a Home Generator

Enter the wattage of the generator you need and whether it will be a standby or portable unit. The calculator will generate a detailed cost breakdown including installation charges, giving you a clear idea of the expenses involved in adding a generator to your home.

### Use Case 5: Estimate the Price of Installing an Electric Vehicle Charging Station

Specify the amperage required for the charging station and the distance from the electrical panel. The estimator will provide you with a comprehensive estimate, considering both material and labor costs, allowing you to budget accurately for this eco-friendly upgrade.

### Use Case 6: Calculate the Cost of Upgrading Electrical Panel

Enter the current amperage of your electrical panel and the desired upgrade capacity. The calculator will give you an estimate of the total cost, helping you understand the expenses involved in enhancing your home’s electrical system.

### Use Case 7: Estimate the Price of Installing Outdoor Lighting

Input the number of fixtures and the type of outdoor lighting (e.g., floodlights, pathway lights). The estimator will calculate the total cost, enabling you to plan your outdoor lighting project within your budget effectively.

### Use Case 8: Determine the Budget for Installing Ceiling Fans

Specify the number of ceiling fans to be installed and any additional features like remote controls. The calculator will provide you with an estimate of the total cost, allowing you to allocate funds wisely for your ceiling fan installation project.

### Use Case 9: Calculate the Cost of Adding Electrical Outlets to a Room

Enter the number of additional outlets needed and whether any wall modifications are required. The estimator will give you a detailed breakdown of the costs involved, helping you plan and budget for enhancing the electrical convenience in your space.

### Use Case 10: Estimate the Price of Installing Under Cabinet Lighting

Provide the length of the cabinets to be illuminated and the type of fixtures (e.g., LED strips, puck lights). The calculator will generate an accurate cost estimate, allowing you to visualize the expenses for adding ambient lighting to your kitchen or workspace.