Excel tool to calculate greenhouse lighting costs 

Greenhouse Energy Model (GEM)

Optimum energy management is central to successful CEA operations, for CEA depends greatly on energy inputs – electrical as well as thermal. The purpose of the GEM software program is to provide a user‐friendly, flexible, computerized tool to assist existing and potential greenhouse operators to design and control CEA greenhouses, optimally, based on local climate, greenhouse physical characteristics, energy rate schedules, and the crop needs. Other possible users include students, commercial and private investors, utility engineers, land‐use planners, and governmental agencies.

Vertical Farming

Vertical farming has been in the news quite a bit lately and if you have found it on this website, then you likely know the general idea behind it. Most of our Controlled Environment Agriculture Colleagues are not very excited about the idea for a multitude of reasons. The largest reason to be unenthusiastic is the sheer volume of energy that will be required to power the supplemental lighting and operate the other environmental controls. This idea has been called ‘Environmentally irresponsible” and the following presentation goes through some of the calculations that support such a statement. Professor Albright was invited to international conferences in Great Britain to present an agricultural engineer’s calculations that demonstrate the high environmental cost of such a project.

Plant Factories/Warehouse Farming

We receive many inquiries about the conversion of warehouses to plant factories. While this is certainly possible, the amount of energy required to produce a single head of lettuce if one must provide all of the lighting to the plant artificially may surprise you!

A photovoltaic panel converts energy from the sun to produce electricity. With the increasing interest in urban agriculture (vertical greenhouses), often there is a desire to combine photovoltaic panels with supplemental lighting. Many people do not realize the sheer size of the photovoltaic system that would be necessary to provide enough light for leafy green production. The ratio (as shown in these calculations) is roughly 3.4 times the square footage in PV panels to 1 square foot growing area.

Download Photovoltaic panels for greenhouse lighting

Furthermore, if electricity from power plants is purchased to operate supplemental lighting in an enclosed area (like a warehouse) our calculations show that for every pound of leafy greens produced, roughly four pounds of carbon dioxide in the atmosphere. These calculations were made with idealized lights. When actual lighting performance data is used, that number changes to 10 pounds of carbon dioxide put into the atmosphere for every pound of lettuce produced.

Download Energy cost of producing lettuce indoors vs. in a greenhouse


Aquaponics is the combination of aquaculture (producing fish for human consumption) with hydroponics using the fish waste to provide some of the nutrients the plants require. This is a very complex problem which presents many challenges that must be overcome TO BE PROFITABLE. Many small systems exist and produce varying numbers of fish and produce, but often with not enough volume (product sold per unit time) to be profitable with the high input costs of energy required to operate both systems. Often both the fish and plant systems are designed to be housed in the same structure sharing the same airspace. The very first design change we would suggest is to separate the two growing environments (fish and plants).

Download Aquaponics design challenges