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title	Resource use

In the table below the consumption of different resources is compared.

Greenhouses can achieve net negative electricity use.
Scenario 1.5 (LED + CHP) has a net negative electricity use. This mean that on an annual basis the greenhouse sells more electricity to the grid than in buys. This is the result of a higher efficiency of LEDs and increased CHP operation for heating, compared with HPS-lamps.
Illumination results in a higher water use.
The higher greenhouse temperatures in combination with higher PAR sums result in a higher water use for illuminated scenarios.
HPS results in a higher water use than LEDs.
When using LEDs instead of HPS, the water use is reduced. LEDs does not emit Near-InfraRed radiation to the crop, resulting in lower crop temperatures and consequently less transpiration.

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Performance

The overall performance is expressed in terms of environmental and economical feasibility and sustainability and is compared in the Table below.

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Illumination increases energy demand
The greenhouse without illumination naturally has the lowest energy costs, but has also a substantial lower production. The lower production will have a detrimental impact on the financial feasibility.
LED illumination has lower energy demand than HPS
When comparing the illuminated greenhouses, the cases with LED lighting clearly have lower costs than the greenhouses with HPS lighting. This benefit is to be expected, but has to be weighed against the higher initial investments for LEDs compared with HPS-lamps to determine the financial feasibility.
CHP decreases costs but increases CO2 emissions
Under the assumed economical conditions, options with CHP lead to lower costs, but higher CO2 emissions.

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Scenario with lowest energy use:
No artificial illumination logically requires the lowest energy (1.1). Using illumination increases energy use, variable costs and crop production significantly. When artificial illumination is applied LEDs result in the lowest energy use (1.3).
Scenario with lowest CO2 emissions in future energy net:
Scenario 1.2 (HPS without CHP) has the highest electricity consumption, but the lowest CO2 emissions. In these scenarios it was assumed that the electricity from the grid stems from renewable sources. If the average CO2 emission of electricity in the public grid of the Netherlands (350 gram per kWh in the early 2020s) is assumed, Scenario 1.2 becomes the greenhouse with the highest CO2-emission: 51.5+234.6 x 0.350 = 134 kg/(m² yr). The dominant share of emissions is then produced elsewhere.
Scenarios with lowest CO2 emissions in current energy net:
Assigning this 350 gram CO2 emission to public grid electricity would mean that the CO2 emission associated with Scenario 1.4 would increase with 87.1 x 0.35 = 20 kg/(m² yr), whereas the CO2 emissions associated with Scenario 1.5 would decrease by 32.7 x 0.35=11.4 kg/(m² yr).
This shows that LEDs always outperform HPS lighting.

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