In most factories and warehouses the loading bay area is a bustling hub of activity, critical to the success of the business’ logistical operations. However, each time loading bay doors are opened, a huge amount of heat can be lost into the atmosphere. In fact on a typical winter’s day, a factory that uses a standard doorway measuring some 4m wide and 6m high will lose more than 100kW of heat as soon as the doors are opened.  

An air curtain can be an economic and efficient solution. By correctly installing one above a loading bay door, more than 80% of the building’s energy can be retained inside, resulting in savings on energy bills and reducing a company’s carbon footprint.

The concept behind air curtains is simple. Air curtains effectively minimise the amount of cold air coming into a building through its doorway, keeping the warm air inside.  Without an air curtain, heat will escape through an open door as natural convection causes it to be lost at the top, and replaced at the bottom by cold air coming in.  

Air curtains disrupt and minimise this flow, providing a continuous stream of air circulated across a doorway serving a conditioned space. Modern air curtains can operate with 60/40 condensing boilers and heat pumps. While an air curtain can contribute to the heating around an entrance (unless it’s an ambient or no heat model) it will actually work alongside a building’s heating system, rather than replacing it.  

Maximise the benefits

It’s important to remember that air curtains should always be specified on the size of the door, not the kW output. Air curtains can be fitted horizontally or vertically, and must be installed inside the doorway, as close to the opening as possible.  Air curtains must be just wider than the doorway opening with an overlap at both sides. They can be surface mounted or recessed and are generally available in 1, 1.5 and 2m lengths which can be seamlessly joined together if required.  

The jet stream must be correctly configured in order to maximise energy savings. The air discharge should reach across the entire height and width of the opening, at a suitable temperature, and must be strong enough to counter the volume of air coming in. If the air stream is too powerful or doesn’t have enough velocity, it won’t be effective.  

The use of advanced, automatic controls can improve energy efficiency, and will ensure the equipment is working at the optimum setting at all times. Adding weather compensation technology will enable an air curtain to react to outdoor temperatures, further enhancing efficiency.  

In addition to reducing heat loss, air curtains can be used to improve the effectiveness of extraction/filtration systems in factories and processing plants with odour, smoke, gas or dust particles that need to be contained to avoid causing a nuisance to neighbouring properties and the general public.

By creating an invisible barrier between the clean and the polluted area, ambient air curtains, installed in each delivery doorway, can draw in the air that is about to escape from the building. The odorous air will be blown down towards the floor and, before touching it, will return back into the building. The installation principles are different to standard air curtains – for example much lower discharge velocities are required. Companies such as Biddle can provide advice and guidance.  

When properly installed, an air curtain can make a significant difference to a building’s overall heat loss. Without adequate provisions to stop natural convection, heat – and money – will simply disappear out of the door.  And, as a further benefit, air curtains can improve the effectiveness of extraction/filtration systems, helping to prevent odour, smoke, gas or dust from escaping.  

Biddle’s Invisidor range of air curtains, for example, is available in varying options and designs to suit all applications.