In any warehouse, doors are essential but their capital and running costs can vary widely for any given size and so great care is needed when comparing the different types. In busy environments the slow roller shutter doors have given way to the popular, fast-acting PVC roller doors, and the main reason is energy cost as the former were often left open for an entire shift.
An alternative to fast PVC roller doors is air curtains but when comparing both types potential buyers should obtain detailed capital and running costs from suppliers, not forgetting other costs like damage from forklifts hitting the roller doors or just mechanical breakdowns. JS Air Curtains, for example, claim that elimination of damage repairs alone suffered by roller doors can repay the capital costs of air curtains.
But as with all air curtains, there is still always a need for an exterior security door for when the premises are closed so that is a cost which must be factored in. Some rapid roll, insulated, slatted doors will serve as both a security door and internal door for traffic, another cost factor to consider. The equation is further complicated by the human accident issue. Rapid roll doors have been known to hit employees on the head while some forklift operators drive too fast at them as to cause collisions.
Both rapid roll doors and air curtains are effective at keeping out pests like rodents, insects and birds, an important issue in food and drug premises, but the latter are more so because when the roller doors are open there is always the risk of vermin ingress, which does not apply to air curtains.
At present, warehouse doors do not qualify for financial help under the Carbon Trust scheme but perhaps a case could be made for air curtains if it can be shown that there are significant energy savings compared with other door types. Within moments of opening a loading bay door the internal temperature can drop by up to 10 deg C. Comparative temperature readings show a drop of between 4 deg C and 10 deg C every time a warehouse door is opened but with an air curtain the difference is normally only 1 deg C. Heating can be provided with electric elements or more economically with low pressure hot water. Air curtains can also provide an ambient air seal without any heating and so have very low running costs.
Air curtains also have hidden benefits. They can, for example, induce warm air down from high level that would otherwise be lost through the roof, so helping to eliminate cold spots. Moreover, when combined with an energy-saving control unit such as the SmartElec 2 from Airbloc, both power consumption and energy costs can be cut by up to 50%. Outside temperature sensors can also turn the elements off in warmer times, whilst timers will ensure the units only operate when required. Size also matters with air curtains. They can, for example, seal doorways up to 10 mt high. A fast roller PVC door at that height would take some time to close and so it could slow down forklift movements and also loose more energy than air curtains.
For decades now many warehouse operators have used inflatable dock seals to minimise energy losses when loading/unloading lorries. They can deliver good results here but maintenance and damage costs are issues to consider. Air curtains, could, therefore, be a better alternative on the loading dock.
Paying more respect to door issues makes sense if only to meet the Energy Act 2011. Energy usage is a key issue for warehouses and if these premises fail to obtain an E rating or above for their energy certificates they will be put out of business by 2018.
Warehouse & Logistics News
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