Since the late 1800s, the Ludvig Svensson textile factory has stuck to its original business concept: manufacturing high-quality textiles for interior furnishings. More than one hundred years later, the company still makes interior textiles for sale both by the metre and as finished draperies. But these days Ludvig Svensson relies on more technically advanced materials for the bulk of its revenues.
When competition from low-wage countries threw the Swedish textile industry into crisis in the 1970s, the management of Ludvig Svensson made a fateful decision to move up the value chain, ultimately finding the right niche with fabrics designed as screens for climate control in greenhouses. Those products now make up about 70 per cent of the company’s sales.
Taming the greenhouse effect
The basic function of a greenhouse is to trap short-wave solar energy for conversion to long-wave heat energy. But hobbyist gardeners and professional growers alike have long wrestled with an inherent problem: greenhouses can get hot as a sauna during the day but still lose most of that heat once the sun goes down. Cold nights are of course the big problem in northerly latitudes, while daytime overheating is the challenge as you move south. And in desert climates you’ll get it from both sides. On top of that, different plants require various temperature and light conditions to do their best.
So the ideal greenhouse allows you to fine-tune heat, light and cooling as flexibly as possible. On top of that, you need to manage humidity that can lead to mould.
Ludvig Svensson provides greenhouse climate control systems based on sophisticated textiles, where screens are raised and lowered by electric motors. It’s all managed by thermostats, timers and advanced electronic controls. Svensson screens can be made of strips of aluminium foil alternating with translucent polyester plastic. The foil reflects sunlight to keep the greenhouse cooler during the day, while the polyester admits the right amount of light for plant growth. The electronics see to it that shadow and light are correctly balanced as the sun moves across the sky. Most growing operations will require direct sun in the morning and evening, with more shade during the hottest hours.
During night time hours, when the greenhouse needs to be kept warm, the aluminium strips reflect heat back into the structure, and the polyester also helps to hold in heat, though not as effectively as the aluminium segments. Svensson screens are also made with aluminium alternating with open sections for improved ventilation.
All about energy—and money
Ludvig Svensson’s biggest customer segment is manufacturers of greenhouses for commercial growing operations, and for these buyers energy efficiency is a crucial sales argument. The ability to close screens for the night can reduce energy costs by between 43 and 75 per cent in a greenhouse requiring a heating system, and even a greenhouse that uses only ambient heat can remain 3 – 5°C warmer with Svensson screens. This reduces the risk of frost damage and improves plant growth.
In climates requiring cooling fans and other powered ventilation systems, Svensson screens keep down the number of operating hours, which of course also cuts energy use and costs.
These days interior design architects are also showing an interest in screens that fulfil a technical function. Office complexes with large glass surfaces are popular with occupants for their views and natural lighting, but they create special challenges in regulating the indoor climate. Greenhouse screens are natural for such applications, since they admit light while keeping heat outside. These functional and aesthetic screens have a promising market among building operators for both environmental and economic reasons.
Published in February 2009