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Air curtains are just the ticket for keeping the cold out and the customers in at Dutch railway stations, says Martin Phillips

When existing railway stations across the Netherlands were refurbished and redesigned to maximise their retail potential, energy-efficient, high-performance air curtains were specified to help keep the cold out and the shoppers and diners in.

Unlike the utilitarian Dutch railway stations of old, the new facilities, located in major cities including Amsterdam, Rotterdam and Utrecht, have a strong commercial focus, with a range of shopping and dining outlets being added to attract travellers.

Railway stations are notoriously difficult to heat, and it was therefore important to find a climate control solution that would keep the heat in and the cold out, delivering a comfortable environment – in turn increasing footfall for shops and restaurants.

Air curtains have an important role to play in controlling internal climates.

Without an air curtain, heat will naturally escape from an open door, with warm air spilling out of the top and being replaced by cold air coming in at the bottom.

Air curtains minimise the amount of cold air entering a building, while keeping the warm air inside – improving comfort levels for customers and staff, and also reducing energy use.

NS Stations, a major Dutch railway operator, understood the benefits of air curtains and how they could help to control the stations’ indoor climates, while the appointed consultants working on the stations commissioned Biddle to supply products for the new facilities in Amsterdam, Rotterdam and Utrecht.

Sales manager for Biddle BV Aize Broersma explains: “We were approached because of our expertise in air curtain installations, our ability to configure bespoke solutions and the five-year warranty we offer.

“In terms of energy consumption, a poorly designed, selected, installed or controlled air curtain can actually be worse than not having an air curtain installed at all, so it’s essential to make the right decisions.

We worked closely with the consultants to configure a high-performance, energy-efficient solution.”

Intelligent answer

Biddle’s Invisidor CA2 model was selected. It incorporates a unique function that allows the air curtain to be automatically controlled through self-regulating, intelligent technology, providing energy savings of up to 75 per cent when compared with manual controls.

Research has revealed that at the time of installation, an air curtain is typically set to operate at a mid-speed setting and is rarely adjusted.

This results in the air curtain continually operating at a single air volume and temperature.

However, as internal and external conditions constantly vary, this means the air curtain will only be operating at the optimum setting some of the time, and for the rest of the time will be on either too high or too low a setting, wasting energy and money.

Biddle’s CHIPS (Corrective Heating and Impulse Prediction System) control, a feature of the Invisidor CA2 air curtain, prevents this inefficient operation. Outside and return air temperature sensors enable the difference between the external and inside temperature to be measured.

The bespoke control algorithm then ‘translates’ this into the theoretical strength (a combination of air volume and velocity) required for optimum control in a no-ventilation situation.

The difference between the actual inside temperature and the desired inside temperature then enables calculation of how much heat is required, and the air curtain’s discharge temperature is adjusted accordingly.

The Invisidor CA2 ensures the most appropriate settings are always selected – delivering optimum performance, the highest efficiencies and maximum comfort.

The technology also negates any need for end-users to manually adjust fan speeds and heating levels.

At two Amsterdam stations, Biddle products have also been combined with existing heat pumps on site – including a Daikin Variable Refrigerant Volume (VRV) heat pump installed at one of the stations – offering an even more efficient solution.

Heat pumps convert naturally occurring low-grade heat from the surrounding outdoor air into high temperature heat, which can then be used to reduce the primary fuel consumption of mechanical equipment, such as air curtains. 

The Daikin heat pump draws heat from the outside air and supplies it to the air curtain, opposed to the air curtain deriving warm air from conventional sources such as direct electric heating or low, medium or high pressure hot water.

In this case, the heat pump minimises the need for electricity and can yield energy savings of over 70 per cent.

Aize Broersma says: “Conventional air curtains using hot water or electricity lower energy usage, as they reduce the amount of heating required, but adding a heat pump to the system can significantly increase energy efficiency and financial savings.”



Martin Phillips is group marketing manager for Biddle

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