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Taking the heat out of the café

15 February 2013

Blenheim Palace has 'gone green' by using ceiling fans to keep patrons cool. The secret is ensuring that effective air movement and good ventilation don't use excessive energy. 

We often talk about the heat in the kitchen, but an adjacent café can also be the victim of unacceptable levels of heat if its ventilation is not carefully planned. Yet effective air movement and good ventilation need not use excessive energy, particularly where a well thought through green policy is applied.

Blenheim Palace, one of the UK’s largest visitor attractions, and home to the Duke and Duchess of Marlborough, is one such location. In 2012 the Palace undertook a major redevelopment project to improve its catering and retail facilities following recent growth in visitors to over 550,000 per year.

The Pleasure Gardens Deli is a family orientated café at Blenheim Palace that provides a wide range of hot and cold snacks as well as dishes specifically designed to appeal to children. With its adjacent Adventure Playground, Marlborough Maze and other attractions, it is a welcome retreat for families.

When the Palace refurbished the café this year, the Palace’s green policy took an important role, with designers considering the environmental impact of every aspect. Rather than going the energy-greedy air conditioning route, the Palace chose low energy Omega ceiling fans from Fantasia to ensure a cooling environment for café patrons.

The four Omega fans use DC rather than the more traditional AC motors, resulting in a 60 per cent reduction in energy consumption. In an AC motor the magnets require constant power, while DC motor magnets turn off and on, so using under half the power.

Assuming there are four warmer and eight cooler months each year, and energy costing 9p per Kwh, with the four ceiling fans running in the café between 10:30 am and 3:30 pm every day, the annual electricity bill will be less than £9.

After 2012 dealt one of the coolest summers for a decade, this coming summer could well surprise with spells of hot, dry weather. And every parent knows that when they get too hot, toddlers and young children can easily become fractious. But a quick visit to the Palace’s Pleasure Gardens Café, with the refreshing cool air movements from the overhead ceiling fans, will revive everyone and help to take the heat out of the day.

When in cooling mode, for summer use, most fans are designed to run counterclockwise, with their upturned side of the blade leading as they spin. This way they blow air downwards. The breeze created by this air movement speeds up the evaporation of perspiration on human skin, which makes the body’s natural cooling mechanism much more efficient.

Air naturally stratifies, with hot air rising, and cooler air settling at lower levels. In winter the difference between the temperature at floor and ceiling can be considerable. There is no point in letting the heat that rises to the ceiling stay there. Indeed, this would amount to inefficient use of central heating.

But the ceiling fan is then run slowly in reverse, usually clockwise, with the downward side of the blades leading. This gentle movement causes air at high level to travel down the outside edges of the room, creating less of an air flow, but effectively transferring heat from ceiling height to lower in the room.

Thus the warm air trapped at ceiling level can be reclaimed and drawn down where it is wanted, without the cooling evaporation found from running the fan at the higher speeds. The effect is to make the central heating more efficient.

By using high quality, larger motors than necessary, fans run very smoothly and virtually silently, with minimal vibration.

Ceiling fans are easily installed and can be fitted in place of a conventional light fitting.

Where ceilings are low, fans are flush mounted, close to the ceiling, but where there are high ceilings, fans are drop mounted on a rod which can be anything from 12 - 72 inches.

Ceiling fans can be controlled by a pull cord, wall control or remote control. In public places such as the café at Blenheim, safety determines that remote control, well away from public access, is used.

All quality fans have three speeds, and run both forward and in reverse, enabling the level of electricity used to match the needs of a particular season and in so doing, minimizing power use.

Air conditioning cools the temperature of the ambient air, but it is extremely greedy on energy consumption, so not compatible when applying a green policy. For optimum operation, it requires efficient ‘air tight’ buildings that do not have traditional, draughty windows and doors, so it is not appropriate for heritage properties. Air con also produces a dry atmosphere which can provoke allergic reactions in some people.

The main difference between air conditioning and ceiling fans is that ceiling fans don’t actually cool the air. Rather, they move the air around, so you feel much cooler.

Humans sweat when they get hot. The resulting evaporation of perspiration from the skin has a cooling effect, so being in a room with ceiling fans cools you down.

A large ceiling fan can be considerably more efficient in term of energy use than the most efficient air conditioning unit.

Air con can, in some cases, be the answer, but with an ever increasing emphasis on environmental aspects, today there is a positive move back to the use of ceiling fans to cool people down. Provided the ceiling fan is properly sized for the room, its efficiency in moving and circulating air far exceeds that of an air conditioning unit.

And there is something inherently pleasant about being in fresh air rather than a processed environment.

Ceiling fans have a very long history. Back in ancient Egypt, the fan bearer who stood beside the Pharaoh, used a large feathered fan, sometimes suspended from the ceiling, to move the air around the king, keeping him cool.

And long before electricity was commonplace, mechanical ceiling fans were successfully introduced in factories during the industrial revolution. Workers suffering from heat exhaustion created primitive fans by attaching metal or wooden blades to the overhead rotating shafts that were used to drive machinery.

During the 1860s and 1870s factories in the southern United States increasingly used water-powered turbines and drive belts to spin multiple ceiling fans to cool the workforce.

Steam powered, belt driven systems would serve a whole network of fans, such as in restaurants, large offices or department stores. These were popular in warmer areas of the world long before the advent of modern air conditioning and the widespread use of electricity.

Philip Diehl, head of a pioneering electronics company, invented the first electric motor suitable for use with Singer sewing machines, and in 1882 a derivative of his motor was used for the first electric ceiling fan.

By the early 1900s the electric ceiling fan was fairly commonplace, particularly in countries with hot climates. Then the first half of the 20th century saw the development and growth of air conditioning, with ceiling fans falling out of favour.

But with the energy crisis of the 1970s, ceiling fans again became widely popular because of their low energy consumption relative to other cooling systems.

Today there is a strong case for using ceiling fans as a low energy consuming method of increasing airflow and providing cooling in a variety of locations.

Much loved heritage properties such as Blenheim Palace, which are architecturally spectacular, were originally constructed in the days when design was paramount, yet little account was taken of environmental considerations. Draughty windows and doors, poor insulation and inefficient use of energy were commonplace in the past.

Since adopting a ‘go green’ approach and joining the Green Tourism Business Scheme in 2009, Blenheim Palace has significantly improved its environmental and social performance, resulting in a more efficient business, using natural resources carefully.

So today when you visit the Pleasure Gardens Café, you will see four Fantasia Omega ceiling fans keeping the café customers cool while having virtually no detrimental impact on the environment.

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