Keeping cool
In December 2009, Christine Stevens, who lives in Avondale Arizona, was obliged to live in her car for 11 days after the city authorities condemned her home. The reason for their action was that Stevens did not have a refrigerator and, according to local building codes, all Avondale homes are required to have a fridge. And air conditioning.
Living without a refrigerator is not an offence in most jurisdictions, but it certainly put Stevens in a tiny minority of Americans, 99.5 per cent of whom do have a fridge. In fact, a recent survey suggested that the refrigerator would be the one domestic appliance that Americans would find the hardest to live without. Americans, of course, are not alone in this. But nonetheless it represents a remarkable change in the way we live our lives. After all, the first mass produced domestic refrigerator was only introduced in 1918.
As an appliance category they are less than a century old. Yet it has been estimated that there are currently around 500 million fridges in the world, and that they are being produced at a rate of approximately 60 million a year. Everyone, it seems, wants to keep things cool. This, of course, is not a recent requirement. Man has been doing it for thousands of years. The first recorded ice house was built in Iran around 1700 BC. Ice houses were used to store ice throughout the year, before the invention of refrigeration. They were usually underground chambers built close to natural sources of winter ice such as freshwater lakes.
During the winter, ice and snow would be taken into the ice house which was packed with insulation such as straw. It would remain frozen for many months, often until the following winter, and could be used as a source of ice during summer months. And the ice was used for much the same purposes that we use fridges and freezers today – storing perishable foods, cooling drinks, or allowing the production of ice-cream!
In the 19th century, American entrepreneur Frederic Tudor made his fortune by selling ice cut from ponds in the Massachusetts winter to customers in the Caribbean. By 1833, he was even shipping ice to Calcutta in India – at that time some 26,000 kilometers (16,000 miles) and four months away from Boston.
Ice boxes – rudimentary fridges – were in common use in the 19th century amongst the reasonably well-off to keep food fresh for two or three days. However, they required regular purchases of fresh blocks of ice from the ice man.
Refrigeration catches on
The first experiments in producing artificial refrigeration had taken place in the 1750s, and a small number of crude systems were in operation by the 1850s. But once viable electric refrigerators became available, they quickly caught on. In 1920, about 75,000 American homes had a fridge. But between 1921 and 1935, annual production rose from 5,000 machines to 1,700,000. By 1937, nearly half of all Americans had one. Take-up in Europe was much slower. In the 1930s, only wealthy European families had fridges, and it was not until after the Second World War that ownership became more commonplace. Even in 1958, just 10 per cent of French and 12 per cent of British homes had a fridge, while ownership levels were as low as two per cent in Spain, the Soviet Union and Japan. Sweden, the home of Electrolux, was the European exception where by the end of the 1950s just over half of families were supporting the national brand. The impact of refrigeration on our daily lives has been immense. It has, for example, radically changed what we eat, how we buy food and where from.
The fitting of a compression refrigeration unit to a New Zealand ship in 1882 led to a boom in the meat and dairy industries of countries such as Australia, Argentina and Brazil. In the second half of the 19th century, Britain, for example, was able to import a similar proportion of its food as it does today. Nonetheless, before the widespread use of domestic refrigeration, fresh foods still had to be purchased and used each day – even if they had already traveled half way around the world. Meat was bought during the daily trip to the butcher's, and the milkman made his rounds every morning.
Over the past 75 years, since Frederick McKinley Jones invented a portable air-cooling unit for trucks, it has been possible to transport perishable food long distances at any time of the year. As a result, countries such as Spain and Holland have transformed their agricultural economies by shipping fresh produce around Europe. We now expect to be able to buy seafood from Asia, fresh fruit and vegetables from South America and Africa whenever we go to the supermarket. The very idea of a supermarket itself, where a family can buy an entire week's food in one trip, is dependent on refrigeration and a cool supply chain. As a result, we eat better.
Freezing food converts its water content into ice crystals. This reduces the amount of water available to micro-organisms such as bacteria which spoil food, and the low temperatures slow down the rate at which bacteria can multiply. The vitamin content of frozen food is often higher than that of fresh food – because it has not had time to deteriorate while in transit from farm to fork. Or indeed from ocean to fork. Fish begins to decline in quality immediately after it has been caught. Freezing it as soon as possible retains freshness. Frozen fish in our supermarkets is largely frozen at sea on board the fishing vessel, or frozen in port within hours of being caught. Paradoxically, therefore, frozen fish can be fresher than fresh fish.
Freezing can also help us to reduce the amount of food we waste. In November 2009, a UK government agency which looks at reducing waste, estimated that around one third of all of the food that is bought in the UK is thrown away – some 6.7 million tonnes. Not only is this a shocking waste of the resources that went into the production of the food, but each tonne of food waste was also said to be responsible for 4.5 tonnes of CO2.
The prodigious growth in the variety of dairy products that are available, and the development of whole new food industry sectors such as fresh fruit juices and smoothies, relies entirely on the ability of refrigeration to prevent them from spoiling. If refrigeration has radically altered what we eat and how we live, its impact – in the shape of air conditioning – on where we live and what we do has been almost as profound.
Climate control
Keeping cool is something that mankind has sought to do for thousands of years, and protecting people from extremes of summer heat has influenced the architecture of many civilizations. Buildings would be designed with high ceilings, deep, shaded porches and arcades, and windows placed to maximize cross-ventilation.
For personal comfort, hand held fans were used in China from at least the 2nd century BC. In the 15th century Leonardo da Vinci designed and built a mechanical ventilating fan. In British India large swinging fans called punkahs were used to avoid discomfort for the Ladies and Gentlemen of the Raj. Indeed when things got too bad for them and their French counterparts in South East Asia, the colonials physically removed themselves from the plains to hill stations, such as at Darjeeling in the Himalayas, where altitude provided a cooler climate.
Extreme heat made many areas of the south western United States marginal places to live until the 20th century. But, since the advent of air conditioning, former desert states such as Arizona, Nevada, New Mexico and Texas have seen the fastest rates of population growth in the country. Some 98 per cent of new homes in the southern states are now built with air conditioning. Air conditioning enables us to regulate and control our physical environment, and people feel better – and work better – when the environment that they are in is within their comfort zone. For a clothed person that is around 20-24° C in summer. Above this range, most people begin to feel a degree of discomfort. Air conditioning has meant that architects no longer have to take account of windows and natural ventilation in order to provide comfortable working environments when designing offices. As a result, they have been able to create buildings with acres of glass stretching from street level to skyscraping upper floors. Office buildings can now be built with large floor plates in which space many meters from an exterior wall can be occupied by desks and workers.
But air conditioning was not developed to aid personal comfort, but rather to optimize manufacturing processes. The first modern air conditioning system was developed in 1902 to improve and regulate process control in a printing plant. It was then quickly applied to other industries such as the production of photographic film and tobacco processing.
Temperature and humidity control are still essential for some of today’s vital manufacturing processes: the production of microchips, for example, and pharmaceuticals. Some hospital procedures, such as open heart surgery require controlled low temperatures, while others, such as birthing suites, demand consistent warmth. And where would we be without climate control in computer centers which indirectly affect so many areas of our everyday lives? It is safe to assume that people are going to want to continue to keep cool, and that with increasing affluence in countries such as China, India and Brazil, further expansion of the market for refrigeration and air conditioning will follow.
But making sure that short-term cooling doesn’t come at the long-term cost of global warming is a challenge that all equipment manufacturers face, and, for example, energy efficiency is now a central design criterion for much of the machinery and equipment produced at GEA. One imaginative way in which GEA is making significant savings in energy requirements is to use the heat created by air conditioning systems to provide heating in the same building.
This approach recognizes the fact that in many buildings heating and cooling are required simultaneously and the demands on air conditioning are contrary. In a supermarket, for instance, dairy products, meat and vegetables remain fresher longer when they are cooled, but the rest of the shop needs to be at a normal ambient temperature. Service stations cool their shops in the summer, but need hot water in the car wash. And cooled air is often required even on cool days in office buildings, hospitals or universities, in data processing and communication centers.
So GEA has developed a single unit that combines a heat pump and chiller to provide for simultaneous heating and cooling. This simple but effective solution is particularly energy efficient when cooling and heating requirements are about equal – which is the case in most temperate climates for about one third of the year. This means that places can be warm enough and cold enough at the same time – which is what mankind has always wanted.
More information:
- How Refrigeration works
- Refrigeration at GEA