Diffuse lightbulb

That's a very good question. There is no ready answer to that. You need a product specialist for climate screens to make tailor-made advice for your situation together with you and your screen installer.

Diffuse light is important for growing crops in greenhouses. Certainly with high-growing crops such as tomatoes and peppers with a dense leaf package. Diffuse light penetrates deeper into the crop, so that a larger leaf surface is illuminated, the plant can absorb more CO2 and process it into assimilates for growth, production and quality. Diffuse light not only penetrates deeper into the crop, it also reduces the stress of the crop because no direct sunlight falls on it. Direct sunlight gives more heat, with diffused light it stays cooler in the greenhouse, which keeps the plant temperature lower, which results in more even growth. There is also less need for airing, which in turn ensures a more stable climate with higher humidity and CO2. Recent studies have also shown that diffused light has a production-increasing effect.

If we have slightly cloudy weather, or, as mentioned earlier, veil clouds, you can say that the light is lightly scattered, so we have a low Hortiscatter. In heavily cloudy weather, the sunlight is much more scattered. This allows us to achieve a high Hortiscatter. That high Hortiscatter with a much better distribution is what we are actually looking for, this light comes much deeper into the crop, so that the lower leaves also receive more light, which benefits the photosynthesis process. Only in heavily cloudy weather does not only scatter the light better, more light is also blocked, it is darker.

Diffuse lightexample

If I read this like this, we should have slightly cloudy weather all year round for an optimal climate in the greenhouse. Unfortunately, we don't have this climate anywhere, so we will have to create the optimal growing climate for the plants in the greenhouse.

Diffusedlightphotography

Diffuse all incoming light in a permanent way is mostly done with diffused glass on the greenhouse. Diffusion of the light in a certain period, usually the summer, is often done by spray a coating on the greenhouse. A flexible solution for making the light diffuse is using an screening installation which is provided with a screen that makes the light diffuse. For all ways there are advantages and disadvantages. No way is only right or only wrong, they can even be used in combination. The most important thing is to create the optimal growing climate for the crop in the greenhouse.

A perfect distribution and increasing photosynthesis sounds great, but there is also a downside. To explain this I come back to the previously described clouds.

Diffused lighting living room

The clouds make the light diffuse so that you no longer see a shadow. In the shade it is always darker and therefore less light. Diffuse light seems to come from all sides, which is why there is more light in places that would otherwise be dark due to the shadow of the direct light.

With a bit of cloud cover, the sunlight is hardly hindered, you will notice that the sun's rays are not as strong as without clouds. You will also still see your own shadow, although it will be less sharp. The thicker the cloud cover, the more the sun's rays are dimmed and so you no longer see your own shadow.

The LightLab of WUR Greenhouse Horticulture can measure the degree of light scattering (diffusivity) in accordance with NEN standard 2675. This value is expressed as a percentage between 0 and 100 in Hortiscatter, with a value of 0 indicating that the measured material does not scatter the light and a value of 100 represents a 'perfect' distribution of light, scattering the same amount of light to each corner. This is called a Lambertian light scattering and is the theoretical maximum achievable. Simulations with light models in combination with greenhouse climate models and crop growth models show that, in theory, photosynthesis increases with the Hortiscatter. Of course this depends on many parameters such as the crop type, overall light level in the greenhouse and use of additional CO2. Other effects of diffuse light can also play a role, such as the microclimate around the plant and lower temperatures in the head.

Diffused lighting interior design

As we have just discussed, we can diffuse light with the help of the clouds. We can do a lot these days, but it is not yet possible to create a cloud cover above the greenhouse at a local level. As discussed in my previous blog 'Why Screens?', we grow in greenhouses to be able to grow the crops in a more controlled manner and all year round. We can diffuse the light in the greenhouse. There are several ways to do this from permanent to temporary and flexible.

With a diffuse screen or screens you have a flexible way to diffuse the sunlight. There are different varieties of screens with all different screen values to shade a certain level of sunlight, but also with different Hortiscatter values. You can use a diffuse energy saving screen, the main function of this screen type is maximum saving energy with a minimal shadow effect. The Hortiscatter of this type of cloth is around 50%. Cloths with a higher Hortiscatter automatically also have a higher shadow effect, which makes them less suitable as an energy saving screen at daytime in colder periods, but more suitable for optimizing the photosynthesis process in high-growing crops. Cloths with a high Hortiscatter and a higher shade effect are usually used to protect the crop against high radiation in the summer.

On a summer day where the sun shines cheerfully in a clear blue sky, we are dealing with direct light. If you are outside during the day you can see your own shadow very clearly. To protect ourselves from the sun's rays, we sit under a tree or a parasol. On a cloudy day, the sun's rays are as it were dimmed by the clouds. The clouds make the light diffuse, you can see that because you see less or no shadow when you are outside. Whether you see your shadow depends on how thick the clouds are.

What is diffuse? According to the dictionary, 'diffuse' means 'without clear boundaries' and 'unclear'. In horticulture we refer to diffused light, which refers to light where you see little or no shadow, light that is evenly scattered and distributed.