Bosman trials alternative cooling solution for barrel room

By Ilana Koegelenberg

Bosman Family Vineyards in Wellington has always been at the forefront of technology and recently installed two indirect evaporative coolers in its new barrel store, achieving low temperatures and high humidity with low energy input.

COVER BM00 1 please clean the floor in PSInside Bosman’s new ‘barrel’ store.

Lelienfontein, home of Bosman Family Vineyards, was originally issued to a French Huguenot in 1699. The first generation of the Bosman family arrived on the farm almost a century later in 1798. Here they produced wine on the estate up until 1957, when the family turned their focus to their vine nursery. In 2007, eighth-generation Petrus Bosman returned to the long-held family dream and released the first wines from their newly renovated 260-year-old cellar.


Any wine lost during the production process is a loss in profit. At various points in the winemaking process, wine volume is lost, and at each point, losses should be minimised.

Apart from the occasional and unforeseen human error in the cellar leading to a wine loss, wine is lost through carrying out routine operations such as transfers, filtration, and bottling. Wine is also lost through evaporation during storage in oak barrels, sometimes referred to as the “angels’ share”.

This loss can be as high as 10%, depending on the conditions in the cellar (temperature and humidity), and the length of time the wine is stored in the barrel. To manage this evaporation loss and to maintain wine quality by minimising the ullage in the barrel, the lost volume is regularly replaced or topped up with wine of similar quality.

When factoring in the cost of a necessary power supply upgrade for a refrigerated cooling installation, the indirect evaporative cooling solution proved more cost effective.

This is a significant added cost to production, not only because of the wine volume that has been lost, but also due to the cost per litre of the replacement-topping wine, as well as the labour costs incurred when carrying out the barrel-topping operations.


Winemaking literature suggests that the ‘ideal’ temperature for the storage of wine is 13°C — a temperature that corresponds closely to the typical underground cellar temperatures found in countries like France.

It is not clear if this was scientifically proven or just what was mostly available and found to be suitable. However, it was also noted that it is generally accepted that higher storage temperatures, if held relatively stable, can be quite acceptable for extended periods.

Pandell (1996) published a research paper that concluded that if the storage temperature was increased from 13°C to 23°C, the ageing process of wine quickened by a factor of between 2 and 8, depending on the wine. His conclusions indicate that the lower the temperature, the longer wine takes to age, but given steady temperature and acceptable conditions, moderately cool temperatures are acceptable.

The room is positively pressurised with the help of dampers. The new imported plastic barrels being trialled. Two Seeley super-cooled Climate Wizard units were installed to control the temperature and humidity of the room.

Experience in the industry has also found that not only temperature, but also humidity is a concern where wine is aged in barrels. Low humidity causes excessive loss of wine through evaporation, leading to increased costs of barrel handling required for topping up.

In a climate such as South Africa’s, where natural conditions will not allow adequate temperature control for barrel storage, some form of mechanical air conditioning needs to be applied to maintain the desirable environmental conditions.


Bosman has gained a reputation for always seeking out the latest and greatest technology — not only in their agricultural practises but also their winemaking. Petrus Bosman is experimenting with an entire range of innovative things, using energy-efficient equipment throughout the farm.

As such, he has been keen to try out a new type of barrel they saw in Spain: an alternative to the traditional wooden oak barrel commonly used throughout the world. These 1 500ℓ vessels* are made from plastic and are square shaped, claiming various benefits and cost savings.

To properly conduct this new ‘experiment’, he needed a controlled environment in terms of temperature and humidity for the various types of wines he had in these imported new plastic ‘barrels’. He contacted Marius Louw of Louwco Cooling Solutions in Wellington, with whom he has had a long-standing relationship, to assist with a cooling solution for this new store. (The room also houses pallets of bottled wine, ready to be shipped out to various areas.)

There was a requirement for 20°C inside with a minimum humidity of 70% (with 34°C dry bulb and 19°C wet bulb temperatures).


Seeley International has spent a lot of time and research working on solutions tailor-made for the wine industry. As such, they did a study comparing three cooling options: direct evaporative cooling; refrigerated air conditioning; and indirect evaporative cooling.

  1. Direct evaporative cooling

Traditionally used in hot dry climates and characterised by:

  • Limited temperature control of the space, typically a minimum of 25°C to 27°C.
  • Increased humidity in the conditioned space.
  • 100% outside air is used to cool the space.

Cooling performance is adversely affected by ambient conditions of high relative humidity (RH).

  • Modest capital cost of installation.
  • Low power requirements.
  • Low cost of operation.
  1. Refrigerated air conditioning

Applicable for most climates and characterised by:

  • Precise temperature and humidity control is possible.
  • Removes moisture from the conditioned space.
  • Closed cooling — cools the internal air, and draws little or no outside air.
  • Operates in all climates if designed correctly.
  • High capital cost.
  • High power requirements.
  • High operating cost.
  1. Indirect evaporative cooling

Very effective in hot climates that are dry and those that are moderately humid and characterised by:

  • Much lower temperature of supply than a direct evaporative cooler.
  • Good temperature control available.
  • No additional moisture added to or removed from the conditioned space.
  • 100% outside air is used to cool the space.
  • Usable in moderately humid climates.
  • Moderate capital cost.
  • Low power requirements.
  • Low operating cost.


Louw, who previously used Seeley’s products in agricultural applications (particularly at vineyards in Kakamas), contacted the local Seeley team and together they devised a suitable solution.

And so came about South Africa’s first pre-cooled wine-specific application for Seeley. (As there is another Seeley unit serving the growing room, the client was not completely new to the brand.)

Generally, the capital expenditure for indirect evaporative cooling equipment such as that of Seeley’s, is much higher than the outlay for refrigerated AC. However, because of the Bosman farm’s remote location, another cost had to be factored in: that of a power upgrade.

The cost of upgrading the power supply to support a refrigerated AC solution and all the equipment that comes with it, would have been exorbitant. “We calculated that to put up a refrigeration cooling solution instead, the price would have been about 20–30% more expensive to meet the same temperature and humidity requirements,” explains Louw. “That’s just because of the low power requirement. Not even considering the added benefit of low operating costs.”

A tour through the lab and cloning production, from left: Marius Louw (Louwco); Hennie Verster (Seeley International); Mark Hendricks (Seeley International); and Tossie Louw (Bosman). Lelienfontein, home of Bosman Family Vineyards, is known for both its agricultural and winemaking side.

Two Seeley Climate Wizard Supercool CW-H15S units were installed to deliver:

  • Supply airflow: 3 400ℓ/s
  • Supply temperature: 15.8°C
  • Input power: 6kW

Climate Wizard Supercool is the latest evolution of the successful Climate Wizard range of indirect evaporative coolers. It achieves even greater cooling capacity by adding a specially designed direct evaporative stage after the indirect heat exchanger. By using this technique, the very low supply temperatures achieved by the indirect heat exchanger are further cooled with required moisture being added to the supply air.

The unit’s ability to provide the necessary cooling performance at a very low operating cost is due to the fact that it uses no mechanical compressors or harmful refrigerants.

The system at Bosman meets all the client’s requirements despite a very high ambient temperature, and the room is also positively pressurised with the help of dampers. These dampers relieve the temperature in the room when the room reaches a certain internal static pressure. Because the room is constantly being supplied with fresh air, the pressure would continue to rise if the pressure is not relieved. Hence, its set-up to keep the room pressurised just enough to not have any germs or dust enter the space.

The walls and roof are also very well insulated, and controls were kept simple.


 Owner    Bosman Family Vineyards
 Project manager   Marius Louw (Louwco Cooling Solutions) 
 Contractor  Louwco Cooling Solutions 
 Product suppliers  Indirect evaporative coolers  Seeley International 
 Dampers   Advantage Air 
 Ducting  Entity Sheetmetal 


Flexcube oxygen-permeable maturation vessels, known as ‘new generation barrels’, are now widely used across all major wine-producing markets, where they co-exist with traditional oak barrels.

There are many reasons why plastic tanks are attractive for the wine industry. First of all, they are custom-designed for use in this industry; second, the tanks provide a maximum use of floor space; third, oxygen can permeate through the walls of the plastic tanks because the polymers used in their construction allow for ‘controlled permeation’; fourth, the tanks are sealable; and fifth, these tanks provide significant cost savings.

Significant savings occur with the use of a plastic tank instead of an oak barrel. A barrel imparts flavour for three to five years, and some plastic tank manufacturers claim a useful life of at least 20 years.

Other cost-comparison studies show that a Flextank pallet tank barrel is about 12% of the cost of an equivalent volume in conventional oak barrels. The savings are due to the cost of the actual wood used in wine production and the labour saved in handling the amount of wine.

Source: Carey, Richard (PhD). Evolution of the plastic tank in the winery. Wines & Vines.


  • How wineries vastly reduce “Angels’ share” with low energy cooling costs. White paper by Seeley.

Click below to read the January/February 2018 issue of Cold Link Africa



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