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We are obsessive foodies, deep into gastronomic satisfaction. The point of cooking is to produce delicious satisfying food – it’s one of life’s greatest pleasures. There’s no point in saving energy if the result tastes horrible. A microwave oven will never produce a good roast, whatever it says on the box. Unless pasta is fresh cooked in plentiful boiling water it will always be less than perfect. However, there are also many ways that a cook can produce food that tastes as good, and often better, with less time and energy.

We buy all our oil, grains, pasta and fairtrade coffee from an organic wholesaler and store them under the stairs (we put together a large bulk order with friends). Almost all our vegetables come from a local organic box scheme or the allotment. Occasional meat comes from local suppliers and is either free range, organic, or from rare breeds (which is effectively organic and far cheaper). In summer we fish for the invasive American Signal Crayfish, which have taken over the local rivers. With nets draped over bicycle wheels, in an hour we can pull up 4 kilos. And, of course, we compost all kitchen waste, including paper bags.

We cook casseroles and stews in an old bedside cabinet we have converted to a “haybox” cooker. We filled it with offcuts of Celotex insulation trimmed to tightly fit a Le Creuset casserole (it has to be cast iron). We bring the casserole to the boil on the stove (allow 20 minutes on the stove for meat dishes), slide it into the “cooker”, fit in two extra blocks of insulation around the pot to completely surround it, and close the door. The residual heat cooks rice in 30 minutes and meat casseroles in three hours.

Water is a great store of heat. making it well suited for central heating. However, like all materials that store heat well, it requires a lot of energy to heat up; it takes as much energy to bring one saucepan of water to the boil as it would take to heat up the amount of air in a small bedroom from freezing to a cosy 21°C.

Then, once the water has been brought to the point of boiling, it takes a huge additional injection of heat to make it boil. This is called the latent heat of evaporation. Raising the temperature just one degree from 99° to boiling requires half as much energy again as it took to heating the water from cold. When you next bring a pot of water to the boil notice that it seems to heat up quite fast and then spends ages on the edge of very hot and boiling- that’s because it is accumulating the additional heat needed to boil. This is why a watched pot seems to never boil. (At the other end of the spectrum, it also takes a huge amount of energy to freeze water, which is why freezers and ice makers are such energy guzzlers).

It makes no difference to cooking whether water is at 99°C or boiling at 100°C. What is more, most food doesn’t even need water that hot. Most vegetables cook at around 90°. Meat cooks happily at any temperature over 85°C and can sometimes taste better. Almost all germs and health nasties found in food are killed in temperatures over 80° and the few that aren’t need temperatures far higher than you’d ever use to cook.

So, given all this, why does cooking always require boiling water? In a few cases, the action of the boiling water is an important part of the cooking. The action of the boiling helps separate the strands of spaghetti and other pasta. In some recipes, the food is boiled uncovered so that the cooking liquids can be concentrated and used later. These cases are the exceptions, though. The main advantage of boiling water to the cook is that it keeps a constant temperature. If the water is not boiling, it is hard to know whether it is 70° or 80° or 90°. Boiling water, though, is always exactly 100°. It’s like having a built in thermostat. If you put in more heat it will simply boil faster. You need to lock it up in a pressure cooker for the temperature to go higher.

Golden Rules
• Buy saucepans with lids that fit. A saucepan covered with a well fitting lid uses a quarter less energy when boiling than a saucepan without a lid (and the kitchen doesn’t fill with steam).
• Always keep the lid on the saucepan even when the water is heating up
• Use a saucepan that is the right size for the amount to be cooked and use enough water to cover food by no more than half an inch
Many foods can be boiled a short time, then removed from the heat and left in the hot water to complete their cooking. This method of cooking is advantageous from many points of view; it’s very low on energy (of course) and it frees up the stove top for other purposes. But the best argument is that many foods taste far better if they’ve been cooked a longer time at lower heat. Heavy boiling, in particular, can be quite damaging to vegetables. What is more, in a busy kitchen with numerous distractions, it is very easy to forget to check boiled vegetables at a crucial time and turn around to find that they have turned to mush. Sit-boiling allows the cook far more control over the degree of cooking.

Bring to boil, boil for the specific time, then remove for the specified time.

Additional boiling time Sitting time
Medium Soft Boiled egg Bring to boil in cold water Remove immediately from heat 4 minutes
Large Soft Boiled egg Bring to boil in cold water Remove immediately from heat 5 minutes
Old Potato (quartered) Bring to boil in cold salted water 10 minutes 10 minutes
New Potatoes (small) Put into boiling salted water 5 minutes 15 minutes
Carrots (slices) Bring to boil in salted water 10 minutes 10 minutes
Rice Bring rice to boil in double its own volume of cold salted water 10 minutes 30minutes- 1hr











Some things can easily be cooked at the same time in the same pot – hard boiled eggs for example can always be cooked with peas or pasta. Multi-tiered steamers allow even more flexibility as you can add and remove different ‘layers’ above the pan of boiling water.

Don’t think waste water – think stock! The end product water from boiled vegetables, is a rich flavoured stock that can be used as the basis for soups and sauces. Good stock comes from lentils and pulses, potatoes, onions, leeks, parsnips. It is best not to use water from sweet vegetables such as peas, carrots, or from cabbage and green leaf vegetables which can produce bitter water.

This is especially true of the water from boiled meat. Many world cuisines have developed classic meals that boil meat and serve it with a soup made from the boiling water. Two classic examples are:

• Steamboat – is a form of Chinese hot pot fondu particularly loved in Singapore and Malaysia. A group of people sit around a cauldron of boiling water, dunking in skewers of meat and fish. When they have finished the skewers, they break eggs into the richly flavoured stock water and drink it as a soup. There are many similar meat and soup combinations in Chinese food.

• Jewish chicken soup – A chicken is boiled with root vegetables and a few flavourings (mostly dill and pepper). The soup is served in bowls accompanied by slices of the meat. The vegetables are usually saved to be later mashed into hot cakes for frying. When finally stripped of meat, the chicken bones can be boiled again for more stock.

Microwaves are bloody brilliant and every low energy cook should have one. They are fast, extremely energy efficient, and effective. Forget about the health scare stories- providing the door closes properly, a microwave cooker is a lot safer than any normal high heat oven.

From a culinary point of view, though, they are limited. Because they do not use direct heat, they cannot produce the delicious textures or caramel flavours of high heat roasting or frying. Their role is therefore best as a tool to supplement other forms of cooking and performing a few particular tasks for which they are well suited:

Cooking in the serving dish
Cooking something in a saucepan on the stove and then pouring it into a serving dish waste time, energy, and doubles the washing up. There are several dishes that microwaves can perform excellently in the pot.

• Sauces – especially white (Bechémel sauce), chocolate
• Frozen peas and beans
• Heating thing up – precook vegetables and reheat at the last minute in the microwave.
• Puddings

• Potatoes for baked potatoes
• Meat for grilling and barbecues. It is very hard to achieve the right conditions to grill or barbecue a piece of meat so that it is thoroughly cooked without being burnt or dried out. Not an energy saver in this case, but a very useful health tip.