What is HVAC? Heating, Ventilation and Air Conditioning.

HVAC is the new frontier in Building Systems as proper management via a Building Management System will reap large energy savings per year.

Air conditioning circulates the air and makes your home more comfortable. It maintains the temperature at a suitable level, dehumidifies, and removes dust and particles from the air,

Here are some ways to increase its efficiency:

• Clean and inspect filter screens regularly. This will keep electricity consumption at its best and eliminate dust and pollen from conditioned air.
• Use light coloured curtains to reflect sun and heat outward.
• Set the air conditioning unit to re-circulate cool air instead of drawing in warmer outside air.
• Protect the outdoor cooling units from the sun. Place them on the south or shady side of your house.
• Be sure your television, radio and stereo are off when no one is watching or listening.
• Generally, you should turn your heating/cooling system off when the space in unoccupied. You can use a time-clock to turn them on prior to occupancy again if you like. Do not heat storage and unoccupied areas, like the basement or garage.
• Incorporate a Building Management System in new builds.

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Inverter air conditioners are the most energy efficient

Two main kinds of air conditioners are inverter and non-inverter systems.

The motor in an inverter air conditioner is self-regulating. This means the motor speed varies continually to maintain an even room temperature.

In contrast, non-inverter air conditioners have a single-speed motor that frequently turns off and then on again.

Inverter air conditioners are more expensive, but save on energy costs over time.

Split AC systems consist of an indoor and an outdoor unit. They also user inverter technology, but will save you money due to greater energy efficiency and durability.

he size, or cooling capacity, of an air conditioner is indicated by its BTU, or British Thermal Unit. This is a measurement of how much heat the unit can add or remove from the air per hour.

The most energy-efficient air conditioner for your needs will have a BTU suited to the size of the space you want to cool.

Other factors also have some effect. For instance, the best BTU for your space depends on climatic conditions.

It’s also affected by the positioning of the building, the type and quality of the insulation, the type and size of your windows and the height of your ceilings.

In general, the recommendation for air conditioners in South Africa is 500 BTU per square metre.

For example, a 20 m² room would require an air conditioner with 10 000 BTU.

Determine the air conditioner’s energy efficiency ratio:

Each air conditioner has a specific energy efficiency ratio (EER).

EER is the cooling capacity of a unit – its BTU – divided by the kilowatts per hour (kWh) it uses at full power.

Say a 10 000 BTU air conditioner were to use 1 200 kWh. It’s EER can be calculated as 10 000 / 1 200, which equals 8.3.

A recent market survey of the EER for the most efficient air conditioners all scored above 12.

The higher the EER rating, the more efficient the air conditioner – and the less it will cost you to run.

A 12 EER rating is an excellent energy-efficiency rating for an air conditioner. Some of the best devices can even reach more than 12 EER. The best mini split air conditioners have an extremely high 12+ EER rating.

What are the the most energy efficient Light Bulbs? LED’s.

LEDs use much less energy than incandescent bulbs because diode light is much more efficient, power-wise, than filament light. LED bulbs use more than 75% less energy than incandescent lighting

You will save energy, money and eye strain by lighting your home properly. Follow these guidelines:

• The wattage of a bulb is not a measure of the amount of light it gives, but rather the energy it uses. For instance, a 100 watt bulb gives 50% more light than four 25 watt bulbs.
• Fluorescent lamps give five times the light and last up to 10 times as long as ordinary bulbs.
• Fluorescent lighting is more economical – Watt for Watt than incandescent bulbs. They use less energy and can last about 10 times longer. (Image on Slide: Use Electricity Wisely – In the Bedroom)
• Never confine lighting to one part of the room. Avoid heavy contrast by using lamp shades that direct light both up and down.
• Try not to install multiple lights (lamps or lighting fixtures) on a single switch. Above all, turn lights off whenever possible because, they use electricity while they burn.
• Clean your lamps and bulbs regularly, because dirt decreases the amount of light given out.
• Dimming switches allow you to regulate the light level and reduce electricity consumption to some extent.
• Use lampshades with a white liner. Liners should be sufficiently dense to hide the bulb but should transmit soft, even light.
• Use low energy lamps for exterior lighting.
• In a domestic and work environment a task light like a desk lamp is far more energy efficient than general lights at the ceiling because it lights only the area that needs to be lit from a very short distance.

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Efficient lighting programmes can be implemented by:

• Replacing traditional incandescent bulbs with compact fluorescent light bulbs (CFLs).
• Replacing old fluorescent tubes with efficient fluorescent tubes.
• Replacing old magnetic ballasts with electronic ballasts in fluorescent tube systems.
• Installing lighting control systems (motion and lux level sensors)
• Using light-emitting diode (LED) technology wherever possible. LED’s are now able to replace most conventional lighting applications, such as traffic lights, down lighters, streetlights, security lights and even strip lighting to replace fluorescent tubes.
• Making streetlights more efficient e.g. by replacing mercury vapour lights with high pressure sodium lights or LEDs that operate on around a third of the power. LED lights have more than double the life span.

LED bulbs range in warmth from cool blue-white light to a sunny yellow light. They can also be used to create ultraviolet light and a variety of colors, in case you want rainbow colored under-counter lights, for instance. Some LEDs are dimmable, while others give off a constant illumination.

LED A bulbs have a bulbous shape and are useful for lamps and regular ceiling lights. They don’t cast light evenly, though, so are not great for larger spaces or where you want really good illumination (such as for a studio.

It’s also important to note that LEDs throw out more blue spectrum light than incandescent bulbs and CFLs. Blue light is particularly bad for interfering with circadian rhythms by suppressing melatonin production. So, if you are looking for a night light or evening lamp, go for an LED with warm light instead of a clinical blue hue. Warmer light is around 2700K (with K meaning Kelvin for temperature). White light is about 3000K, while blue-white light is 5000K or more.

Straton Electrical always recommend that consumers embark on an energy savings programme, like installing LED Light Bulbs, before installing a Solar PV System for electricity cost savings.

 

Does unplugging appliances save electricity?

The short answer is Yes! The energy costs of plugged-in appliances can really add up, and unplugging these devices could save your up to R400 a year. Another benefit of unplugging your appliances is protection from power surges and load shedding.

• Using small kitchen appliances instead of the stove can save energy. Toasters, electric grills and skillets, slow cookers, electric coffee pots and bottle warmers usually require less energy than the stove when used correctly.
• Use an electric kettle to boil water, not a sauce pan or a microwave.
• When vacuuming, empty or replace the dust bag frequently.
• A faulty appliance will not work efficiently and can waste energy. Repair or replace them promptly.

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Small appliances are typically small household electrical machines, also very useful and easily carried and installed.

Small appliances include those used for:

• Beverage-making, such as electric kettles, coffeemakers or iced tea-makers
• Cleaning, such as Vacuum cleaner
• Cooking, such as on a hot plate or with a microwave oven
• Lighting, using light fixtures
• Thermal comfort, such as an electric heater or fan

Many small appliances perform a combination of the above processes such as mixing, heating by a bread machine.

Energy Efficient Kettles:

The estimated cost to boil a normal kettle per boil is R0.34.

An average family boils the kettle 3-5 times a day giving an average cost per year to boil water of R620.50.

Our choice of Energy Efficient kettle is the Russell Hobbs Eco-Kettle with a printed Eco Element that is 50% lighter than normal and heats up in 2 seconds with instant stop technology. Russell Hobbs say that over 6 Million kettles are sold in South Africa annualy and if every one of those bought was an Eco Kettle then we could collectively save R558 Million rand in electricity per year and reduce Carbon Consumption by as much as 78 Million kg per annum.

 

The energy-efficient cooking winner is the microwave oven!

Choosing to cook with a microwave vs oven can use from 30% to as much as 80% less energy. Microwaves use high-frequency radio waves to heat the water molecules inside food.

Microwave Energy Saving Tips:

• Defrost your food in the refrigerator instead of the microwave oven: it is more economical.
• Use your microwave oven to cook small to medium quantities of food. To cook larger portions of meat, it is better to use a conventional oven.
• Some microwaves do not heat up foods evenly. Wrap foods in plastic to hold in the steam, this will help to give even heating. Be very careful not to cover the foods too well, steam can burn you badly when you open the packet, so leave a flap open for the steam to escape.
• Cooking time is an important factor when determining energy efficiency levels. Compare cooking times when you cook the same food in the microwave, in the standard oven, on stove top elements or in a pressure cooker. You will easily see which method of cooking is more efficient depending on quantity, volume and food types.
• Follow the Manufacturers instructions to ensure that food is cooked correctly. Keep in mind that microwave recipe books give the cooking times required by the appliance used by the authors. Adjust cooking times to suit your micro- wave rating.
• Never turn your microwave on when it is empty, you could damage it.
• Keep the edges of your microwave door and its hinges clean. To wash the inside of your oven, boil a cup of water in it and then wipe the sides with a damp cloth.

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A Microwave takes about 1200 watts per hour for an average microwave to run.

Microwaves are the most energy-efficient means of cooking, followed by slow cookers, hobs, and lastly ovens, so use your microwave as much as possible – and remember to turn it off at the wall after use to conserve even more energy (nobody uses them as a clock anyway!)

In 1947, Raytheon built the “Radarange”, the first commercially available microwave oven. It was almost 1.8 metres (5 ft 11 in) tall, weighed 340 kilograms (750 lb) and cost about US$5,000 ($57,000 in 2019 dollars) each. It consumed 3 kilowatts, about three times as much as today’s microwave ovens, and was water-cooled. The name was the winning entry in an employee contest. An early Radarange was installed (and remains) in the galley of the nuclear-powered passenger/cargo ship NS Savannah. An early commercial model introduced in 1954 consumed 1.6 kilowatts and sold for US$2,000 to US$3,000 ($19,000 to $29,000 in 2019 dollars). Raytheon licensed its technology to the Tappan Stove company of Mansfield, Ohio in 1952. Under contract to Whirlpool, Westinghouse, and other major appliance manufacturers looking to add matching microwave ovens to their conventional oven line, Tappan produced several variations of their built-in model from roughly 1955 to 1960. Due to maintenance (some units were water cooled), in-built requirement, and cost (US$1,295 ($12,000 in 2019 dollars)), sales were limited.

Japan’s Sharp Corporation began manufacturing microwave ovens in 1961. Between 1964 and 1966, Sharp introduced the first microwave oven with a turntable, an alternative means to promote more even heating of food. In 1965, Raytheon, looking to expand their Radarange technology into the home market, acquired Amana to provide more manufacturing capability. In 1967, they introduced the first popular home model, the countertop Radarange, at a price of US$495 ($4,000 in 2019 dollars). Unlike the Sharp models, a motor driven mode stirrer in the top of the oven cavity rotated allowing the food to remain stationary.

In the 1960s, Litton bought Studebaker’s Franklin Manufacturing assets, which had been manufacturing magnetrons and building and selling microwave ovens similar to the Radarange. Litton developed a new configuration of the microwave oven: the short, wide shape that is now common. The magnetron feed was also unique. This resulted in an oven that could survive a no-load condition: an empty microwave oven where there is nothing to absorb the microwaves. The new oven was shown at a trade show in Chicago, and helped begin a rapid growth of the market for home microwave ovens. Sales volume of 40,000 units for the U.S. industry in 1970 grew to one million by 1975. Market penetration was even faster in Japan, due to a less expensive re-engineered magnetron. Several other companies joined in the market, and for a time most systems were built by defence contractors, who were most familiar with the magnetron. Litton was particularly well known in the restaurant business.
Residential use

While uncommon today, combination microwave-ranges were offered by major appliance manufacturers through much of the 1970’s as a natural progression of the technology. Both Tappan and General Electric offered units that appeared to be conventional stove top/oven ranges, but included microwave capability in the conventional oven cavity. Such ranges were attractive to consumers since both microwave energy and conventional heating elements could be used simultaneously to speed cooking, and there was no loss of countertop space. The proposition was also attractive to manufacturers as the additional component cost could better be absorbed compared to countertop units where pricing was increasingly market-sensitive.

By 1972, Litton (Litton Atherton Division, Minneapolis) introduced two new microwave ovens, priced at $349 and $399, to tap into the market estimated at $750 million by 1976, according to Robert I Bruder, president of the division. While prices remained high, new features continued to be added to home models. Amana introduced automatic defrost in 1974 on their RR-4D model, and was the first to offer a microprocessor controlled digital control panel in 1975 with their RR-6 model.

1974 Radarange RR-4. By the late 1970s, technological advances led to rapidly falling prices. Often called “electronic ovens” in the 1960s, the name “microwave oven” later gained currency, and they are now informally called “microwaves”.

The late 1970’s saw an explosion of low-cost, countertop models from many major manufacturers.

Formerly found only in large industrial applications, microwave ovens increasingly became a standard fixture of residential kitchens in developed countries. By 1986, roughly 25% of households in the U.S. owned a microwave oven, up from only about 1% in 1971; the U.S. Bureau of Labor Statistics reported that over 90% of American households owned a microwave oven in 1997. In Australia, a 2008 market research study found that 95% of kitchens contained a microwave oven and that 83% of them were used daily. In Canada, fewer than 5% of households had a microwave oven in 1979, but more than 88% of households owned one by 1998. In France, 40% of households owned a microwave oven in 1994, but that number had increased to 65% by 2004.

Adoption has been slower in less-developed countries, as households with disposable income concentrate on more important household appliances like refrigerators and ovens. In India, for example, only about 5% of households owned a microwave oven in 2013, well behind refrigerators at 31% ownership. However, microwave ovens are gaining popularity. In Russia, for example, the number of households with a microwave oven grew from almost 24% in 2002 to almost 40% in 2008. Almost twice as many households in South Africa owned microwave ovens in 2008 (38.7%) as in 2002 (19.8%). Microwave oven ownership in Vietnam was at 16% of households in 2008—versus 30% ownership of refrigerators; this rate was up significantly from 6.7% microwave oven ownership in 2002, with 14% ownership for refrigerators that year.

Consumer household microwave ovens usually come with a cooking power of 600 watts and up, with 1000 or 1200 watts on some models. The size of household microwave ovens can vary, but usually have an internal volume of around 20 liters (1,200 cu in; 0.71 cu ft), and external dimensions of approximately 45–60 cm (1 ft 6 in–2 ft 0 in) wide, 35–40 cm (1 ft 2 in–1 ft 4 in) deep and 25–35 cm (9.8 in–1 ft 1.8 in) tall.

As of 2020, the majority of countertop microwave ovens (regardless of brand) sold in the United States were manufactured by the Midea Group.

Energy consumption: As of 2006, a typical microwave oven consumed more energy in standby power usage around the clock than it does on heating food.

Electric ovens that are used regularly can be significant consumers of energy in households.

Consumers who make regular use of their ovens should carefully consider their choice of oven before making a decision to purchase.

To protect consumers from purchasing inefficient electric ovens, Minimum Energy Performance Standards (MEPS) have been set for electric ovens. Currently, only large electric ovens with an Energy Efficiency Rating of Class B or better can be sold. With regards to small/medium electric ovens, an Energy Efficiency Rating of Class A or better can be sold.

The larger an electric oven, the more energy required to heat the oven space. As a result, the most important decision to be made when purchasing an electric oven from an energy efficiency perspective is what size oven to purchase. Ideally, consumers should purchase the smallest oven that meets their baking and roasting needs.

Electric ovens being sold must be labelled with a South African Energy Efficiency Label to help consumers understand the relative energy efficiency of different electric ovens.

• Use cooking utensils with flat bottoms and tight fittings covers.
• Be sure pots and pans completely cover the stove plates.
• Take advantage of the heat sensing control for stove plates. It allows the stove plate to cut of the electricity supply occasionally while still cooking. It does not affect the food, only your bill.
• Use a pressure cooker to conserve energy when cooking foods that take a long time, such as pot roasts, stews and steamed puddings.
• Do not overcook foods, especially vegetables. Overcooking destroys essential nutrients.
• For full efficiency from radiant stove plates the stove plate reflectors (underneath the stove plates) should always be kept clean.
• Bring foods to the boil quickly on the “high” setting, then turn the heat down to simmer to finish cooking.
• Do not use the grilling compartment to make toast – it is very expensive.
• Do not use the oven to heat the kitchen – it is very expensive and far less efficient than a heater
• Keep oven doors completely closed until food is cooked. Every time the door is opened, the oven temperature drops, and the heat must be replaced.
• Use the oven to prepare an entire meal – main course, vegetables and dessert. Remember to plan meals that cook in the oven at the same temperature.
• Allow free circulation of heat within the oven. Place pans and containers so that they do not touch each other, or the sides of the oven.
• To keep food warm place in a 66¦C (150¦F) or 82¦C (180¦F) oven. Do not leave it too long or your meal will be very dry.
• When buying a new stove, choose one with a convection oven. This type of oven uses less energy than conventional ovens and cooking time is substantially reduced

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Which is More Energy Efficient? Chest or Upright Freezers?

Because of the built-in sidewall insulation, chest freezers hold their cold temperatures very well and therefore use the least amount of energy to run. In fact, during a power outage or a household move to another locale, as long as the freezer lid is not open, an unplugged chest freezer can keep the contents frozen for two or even three days, depending on the frozen food quantity.

Freezer Energy Saving Tips:

• Freezers and refrigerators operate most efficiently when filled to the capacity recommended by the manufacturers.
• Never forget that only one-tenth of a freezer’s capacity should be used for freezing of fresh food at any one time. The freezer must work harder to remove heat, and uses more power. Example, 28 litres (one cubic foot) will store 12,5 to 15 kg (25-30 lbs.) of frozen food and will freeze about 1,5 kg (3 lbs.) of fresh food at a time.
• Food to be frozen should be placed in contact with those parts of the freezer that contain the refrigerant tubes, usually the sides of chest models.
• Defrosting of chest type freezers should be done once or twice a year. For upright models, defrosting should be done two or three times a year. NEVER allow frost build up to exceed 0,6 to 1,3 cm.
• By keeping a list of the location of foods in the freezers, the freezer can be kept open for a minimum of time, preventing the loss of cold air.
• The freezer should be kept as full as possible to prevent heavy icing.
• On all models keep condenser panels at the rear of the freezer clean and dust free for maximum efficiency and conservation of energy.
• A second freezer should only be operated when necessary.
• In a single door unit, it is essential that the separate freezer compartment has its own door intact. Otherwise the unit will tend to operate the whole of the refrigerator as a freezer – this can be expensive.

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Fridges and freezers account for the largest single energy consumption for domestic appliances. Reducing the amount of energy that these units consume rests on two actions:

1. Improving the thermodynamic (“cooling”) efficiency of the refrigeration cycle
2. Reducing the amount of heat gain (“heating”) from the environment

Commercial refrigeration has been around since John Gorrie invented the freezer in 1842. In the following 170 years, the evolution of technology and refrigeration has vastly improved and continues to do so.

Apart from improvements in the mechanical equipment, two major aspects where we can still improve on are increasing the “cooling” effect while reducing unwanted “heating”.

The R600 refrigerant, more commonly known as Butane, is the most commonly used in all domestic refrigeration products. R600 is a readily available naturally occurring hydrocarbon that has less of an environmental impact compared with its synthetic equivalent, R134 (Tetrafluoroethene).

Keeping the inside of fridges cool is also no easy task. The ideal insulation would consist of a hyper-reflective surface held at a vacuum to eliminate radiation and the transfer of heat. Unfortunately, current technology combined with product durability and manufacturing costs limits the extent to which this approach can be pursued. The next best thing we can do is decrease heat conduction by improving insulation materials.

Key Feature differences between Chest and Upright Freezers:

Chest Freezers usually come with at least one wire basket to help you organize the contents. You can segregate types of foods using cardboard boxes to better organize freezer contents. However, chest freezers require a lot of bending, reaching, and moving frozen foods to find what you’re looking for.

That being said, they do accommodate odd-shaped, long, or large items that may be difficult to place in an upright freezer. There are some models on the market that have a bottom drawer accessible from the outside of the chest freezer, but while this can add convenience to a chest model, it will also reduce capacity slightly.
Upright Freezer

Probably the best convenience feature of an upright freezer is the ability to better organize the frozen foods, making it easier to monitor and rotate contents to keep frozen foods current. Some upright models have versatile storage systems with adjustable and removable door storage bins, sliding, adjustable shelving, and pull-out baskets or bins.

All these features add to the ease of sorting and storing contents. Although you can better organize an upright, there are constraints. Items such as large turkeys or long, frozen items may not fit without removing a shelf to accommodate the size.

Our Choice:

The Defy Solar Hybrid Chest Freezer – DMF475S + SOL006 which uses Solar Energy and the Electrical grid to run the same unit. This 254 liter solution will simply use as much solar energy that is available and use the electrical grid when there is no solar energy. In doing this it can use a combination of solar and electrical grid at the same time, ensuring you get the most out of the solar system provided.

The most energy efficient refrigerator style is a top-mount freezer refrigerator.

The variation in how much energy savings can be achieved with a top-mount freezer refrigerator depends in part, ENERGY STAR® states, on whether it has an ice dispenser. Generally a top-mount freezer refrigerator that has earned ENERGY STAR® certification uses less energy than a 60-watt light bulb.

• Choose a refrigerator of a size based on the needs of your family – a refrigerator operates at peak efficiency when filled.
• Do not overload your fridge, excessive products in your fridge will lower the quality of the food and use more electricity – as much as 10-20% more for each extra product.
• Do not set freezing temperatures lower than necessary, it wastes as much electricity as excessive heat.
• Thick frost on chilling panels reduces cooling ability. If you do no t have a frost-free model, defrost your refrigerator when frost is between 0,6 to 1,3 cm thick.
• Do not open your refrigerator door needlessly. By getting into the habit of removing and replacing several articles at once, you will reduce the loss of cold air.
• Let hot foods cool down before placing them in the refrigerator. (To prevent bacterial growth allow about 20 minutes standing time).
• Be sure the seal around your refrigerator door is intact. (Close the door on a piece of paper: if you can pull the paper out easily, the seal should be replaced).
• Remove all heavy wrapping from food before storing it in the refrigerator.
• Cover all liquids stored in the refrigerator (especially frost-free models).
• Foods should be placed slightly apart on refrigerator shelves to allow the cooling air to circulate.
• Exposed condenser coils/panels (usually at the back of the unit) MUST be kept clean and dust free. When cleaning you must be careful not to damage the panels.
• Do not place the refrigerator near the stove or against an uninsulated wall that faces the sun.
• Allow adequate space around the refrigerator for free air circulation. The air carries heat away from the fridge – if air can not circulate, the fridge can not work properly.
• Switch on the energy saving switch, if one is fitted to the refrigerator.
• Switch off, empty or clean your fridge, when taking an extended holiday.

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One solution that we particularly like is the newly released Defy Solar Fridge option. Obviously we would prefer that you install Solar PV to power your entire home but the price point of the Defy option is quite compelling for those on a budget:

The Defy Solar Hybrid Range offers an estimated 40% Reduced Energy Consumption

With rising energy tariff increases in South Africa, the cost of energy is almost 4 times higher than inflation and has made a significant impact on all South African pockets. Solar options have been available, however, are only accessible to a select few given the high costs.

Defy has found a way to change this, with a solution that sets a new benchmark in energy consumption, all the while maintaining continuity in functionality. Defy’s All New Solar Hybrid Range uses one simple solar panel that will power the entire fridge or freezer for up to 36 hours with no batteries or converters. The idea behind this innovation is to power homes with the most affordable, versatile and renewable technology that exists today.

During the day the unit will run completely off the sun’s energy and as the sun sets, the internal mechanism will switch back to the electrical grid allowing the unit to run efficiently. Having daytime stable energy, powered by the sun, will reduce energy consumption and the carbon footprint of coal supplied electricity. With Defy’s Hybrid solution, affordable energy has never been this accessible.

The process of purchasing one of these Solar Hybrid units begins with the customer calling Defy’s customer service line. The shopper will be directed to the nearest Defy store and a team of installers will be dispatched to the customer’s home, where they will assess the potential placement for the solar panels in relation to the fridge-freezer unit.

The entire process, from contacting the customer service line to purchasing the Solar Hybrid unit, to having it installed, is expected to be completed within three days.

“The total cost is less than R6,000,” says Defy Marketing Manager, Cagdas Fidan. “Although the prices may vary from one dealer to another it will still be less than R6,000 and the solar panels are included in that price.”

While the retail price includes both the desired Solar Hybrid unit and the accompanying solar panel, customers will still need to pay for the installer’s “consumables”. Fidan explains that this additional cost for brackets and cables will be kept to a minimum. The unit, panel and installation will also come with a warranty.

While Defy’s Solar Hybrid range is more expensive than other fridges and freezers of the same capacity, Albas explains that saving on an electricity bill would eventually see the unit paying for itself.

Appliances that heat water are the highest consumers of electricity in the home:

There has long been a debate over what method of dish washing has the lowest environmental impact: hand washing or using a dishwasher. The consensus is that dishwashers are the better choice because they most efficiently use water, using an average of 22 litres of water – or only 7.5 to 15 litres for Energy Star efficient models – per full load, whereas hand washing consumes 7.5 litres of water for every minute the tap is running and far more soap.

• Dishwasher energy consumption can be reduced by turning off the dishwasher after the final rinse and before the drying cycle. The clean dishes can then be wiped with a dry cloth.
• Fill the dishwasher completely before operating. Partial loads waste electricity and water.
• Short wash cycles, rinse-only cycles, mid-cycle turn-off, and other features are designed for energy conservation as well as convenience.
• Connect your dishwasher to COLD water supply unless otherwise directed. Normally only one wash and one final rinse cycle requires hot water which is heated by an element in the dishwasher.
• The dishwasher filters must be kept clear of debris. A blocked filter reduces efficiency and wastes energy.
• Proper loading is important for the dishwasher to work efficiently.
• Use a dishwasher that has an “AIR DRY” option.
• Try to find a unit that has a high temperature setting that can be disabled with a switch.

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Dishwashers use less water (and less hot water) than using a sink.

The key is buying a dishwasher that is not an energy pig and realizing you will only be able use during the “good times”. The good times are those times when the batteries are full and the sun is still shining or the wind is still blowing. Using your dishwasher when the batteries are low means more generator time and more fuel consumed.

A decent dishwasher will use less than 1kWh per load. If you turn off the water heating element and electric drying element, a dishwasher will consume closer to 500 watt hours per load, not including the energy required to pump and heat the water.

The ENERGY STAR Most Efficient list for 2021 lists the Miele G 6935 SCi dishwasher as the most energy efficient dishwasher with a projected Annual Energy Use (kWh/yr) of 199 kW and with a projected 11.25 litres of water use per cycle.