CULTIVATION AND TECHNOLOGY Airy roof insulation Fortunately, the Altez storage builders don’t regard this problem as so black-and-white. In the design of Van der Maas, they have been quite successful in keeping the heat out of the storage units thanks to a series of constructional solutions. The first thing they did was to place the insulation material away from the roofing. The designers have opted for the method of creating a 35 to 60 cm air space between the roof and the insulating board. The air insulation space runs from the ridge of the store to the walls and ends roughly three-quarters up the side walls. ‘The fact that the roof extends over the side walls provides extra insulation against sunshine on the walls’, Hoeckx explains. Because the insulation space runs through from below to above, there is also a natural draught which also gives some cooling for a hot roof. The outside temperature is, after all, usually much lower than the warming up of the roofing. Subsequently, Altez has also provided chocks of insulation between the screws of the insulation boards and the roof decking. They prevent the transfer of heat or cold to the insulation board and also provide better air circulation. The draught also deters vermin from settling in the ventilation space. The continuous half-roof of the storehouse clearly shows how the air insulation moves freely from the ridge to below. To keep the birds out of the air space, anti-light slat grids were mounted. Below, between the metal sheeting across to the concrete wall, wire gauze was stretched. ‘What can’t be seen from the outside are the ridge ventilation flaps, which enable air ventilation from the storage units. When they’re open, they provide extra natural draught and therefore faster air ventilation in the storehouse. That saves energy costs because the ventilators needn’t blow so hard’, according to Hoeckx. By placing these insulated shutters in the insulated ceiling and not on top of the roof, the shutters are better protected against all weathers. And it doesn’t require so much maintenance’, the building consultant told us. Doors in the shadow ‘As far as the insulation is concerned, the doors and windows are the weakest links in buildings’, he continued his lecture. ‘Well, we may not have windows in this building, but there are three swing-up doors. When, on a warm spring day, these doors are in the hot sun, you can always feel the inside warming up. The difference between door and wall can often be clearly felt. It is therefore advisable to keep the doors out of the sun. You can do that by placing the doors on the shadow side of the building.’ At Van der Maas, they have solved this ‘If you want to store potatoes for a long period of time, it is important to keep the storage temperature as level as possible for the entire storage period’, Jan Cees van der Maas explains. Potato World 2013 • number 3 25 Pagina 24

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