Clean glass = light gain = increased production = reduced energy consumption
During a considerable part of the year, crops can use all the natural light they can get. The principle that then applies is: 1% more light = 1% higher production. This is when a thoroughly clean greenhouse really pays off.
Any greenhouse will get dirty over time. Algae, dust, soot, sand and residues of crop protection products. They all reduce the incoming light. In case of light-loving crops, such as fruit vegetables and cut flowers, this irrevocably adversely affects production. This is why cleaning off the greenhouse quickly pays off.
The contracting firm Poot Reiniging in Maasdijk in the Netherlands specialises in two areas: cleaning and coating. During cleaning it is important that the glass becomes really clean, while keeping any existing permanent or temporary coating intact. ‘We first discuss the nature of the dirt accumulation and how best to remove it with the grower. We are able to provide advice on the basis of our experience and some growers have their own preference. When you maintain it properly, the glass generally gets nice and clean without the need of using aggressive cleaning agents,’ says owner Erik Poot.
Whenever possible, the greenhouse roof is simply brushed off with water. ‘Should this not be sufficient, we use an industrial soap in consultation with the customer,’ he says.
Erik Poot of Poot Reiniging
But that’s not all, there are other possibilities as well. ‘In areas where there are deposits of grease, chalk or rust, the ReduSystems GS-4 is a good product. There are also always some stubborn spots: for example, near the vent windows there is often a strip of aluminium deposit because the water always drips down at the same point. It is impossible to clean that with soap alone. GS-4 is a very suitable product for this purpose.’
Serious instances require a more aggressive fluoride cleaning agent. ‘That requires a great deal of care,’ says Poot. ‘For example, you need to provide due consideration to the environment: bulb crops are totally unable to withstand fluoride.’
So if it is at all possible, when there is considerable dirt accumulation, he prefers GS-4. ‘This product cleans well and is less corrosive than aggressive cleaning agents,’ he says.
On average, his customers have their greenhouse cleaned twice a year, although some do so more often. Poot says he does notice the effects of climate change: ‘Because of a number of successive hot summers, growers have started to apply chalk or coatings more frequently, including growers who never did so before. They then skip a cleaning round. After all, the coating is removed in autumn using a cleaning agent, such as ReduClean. This product has a cleaning effect at the same time. Because of this, our work has shifted somewhat: less brushing and far more coating.’
More light in the greenhouse also means reduced energy consumption. Here’s the basic rule: 10% more light translates into approximately 3% less gas consumption.
Anne Elings explains why crops grow better with more light
For a good part of the year, the level of natural light is below optimal for most crops. Any additional light that then enters the greenhouse contributes to improved production and quality, says Anne Elings, Plant Physiologist at Wageningen University & Research.
Cleaning greenhouses with fluoride based agents
The horticultural sector often uses a cleaning agent based on fluoride to clean glass. Fluoride chemically cleans the surface of the glass. Several minutes after application the treated glass along with the dirt is rinsed off. But this principle should not be applied to synthetic greenhouse roof coverings.