Energy saving

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Energy saving describes the goal of reducing current energy consumption in the future. The reference to the term results from the context and is not defined in a certain way, neither in terms of the type of energy nor by the consumer. It can therefore include all types of energy or be limited to certain energy carriers or energy sources . And it can be understood globally as well as related to a specific economy or an individual company or a private household .

In a narrower sense, energy saving refers to all measures that are suitable for achieving reduced energy consumption. The aim of energy saving measures is often to increase energy efficiency , i.e. the amount of useful energy achieved in relation to the primary energy used . However, the aim can also be to reduce the amount of useful energy required.

The term found its way into German legislation as early as 1976 as a result of the first oil crisis with the Energy Saving Act (EnEG - full title: Law for the Saving of Energy in Buildings ) . The Energy Saving Ordinance from 2001 is based on it and also relates to the energy consumption of buildings in Germany .

Classic Heliowatt alternating electricity meter

Causes and methodological approaches

There are financial incentives to save energy; there may also be constraints or restrictions . It is possible that an energy source

  • is available (temporarily or permanently) in less than the desired amount, e.g. B.
    • due to insufficient funding capacities
    • due to insufficient capacity of a grid connection or a pipeline
    • due to insufficient power plant capacity
    • due to delivery difficulties (e.g. due to political tensions, wars or weather conditions)
  • causes undesirable (avoidable or unavoidable) side effects.

In market economies , prices rise, including energy prices, as long as demand exceeds supply (see market equilibrium ). If there is a lower price elasticity of demand or a low price elasticity of supply, small differences between supply and demand can lead to large price swings.

The desire and the ability to reduce high (current and / or expected future) energy costs prompt the implementation of energy-saving measures. An eco-tax can increase the incentive, while at the same time relieving the economical and ecologically active consumers financially through the financial compensation paid back by the state ( eco-bonus , green check ).

  • In 1973, the so-called “first oil crisis” worldwide was an occasion to consider and implement energy savings: The oil price rose sharply, and there were temporary supply bottlenecks.
  • Shortly before, in 1972, the study The Limits to Growth Worldwide , published by the Club of Rome , had made people aware that there are limits to economic growth in industrial societies. a. through limited amounts of fossil fuels and other raw materials and resources .
  • In the 1970s, environmental policy was established and environmental awareness increased significantly.

In terms of method, the following approaches can be used to save a certain form of energy:

  • Reducing the energy requirement by foregoing certain services. Dispensing with additional functions often offers great energy-saving potential. (Example: reduce building heating in unused rooms)
  • Increasing efficiency improves the utilization of the energy used, an example is the increase in efficiency by reducing dissipation . Consumption can often be reduced significantly through increased efficiency (examples: thermal insulation , energy-saving lamp ). Depending on the framework conditions set, an increase in efficiency simultaneously leads to rebound effects that can significantly reduce or even cancel out the savings effect.
    • Increasing efficiency also includes the use of previously unused portions of energy (such as heat recovery or additional use of waste heat , e.g. through condensing boilers )
    • Intelligent controls of the operating parameters of machines, devices and other systems make an important contribution to saving energy today. For example, the efficiency of internal combustion engines depends on many different operating conditions. Control measures to increase the efficiency of combustion engines began many years ago with the simple adjustment of the ignition point . Today, very fast microprocessors evaluate a large number of measurement parameters with which the various components of motors are dynamically controlled in such a way that the highest motor efficiency can be achieved for each currently measured combination of measured values. This also includes the aforementioned waiver of certain services that are not needed, such as idle work.
  • The use of alternative forms of energy is not actually a saving of energy. However, this approach can reduce or completely replace the form of energy originally used. Energy savings can only be achieved if the use of the new form of energy is more efficient than the one to be replaced (keyword: energy balance ). Examples of alternative energy use are: daylight instead of electrical lighting, muscle power instead of motor, natural gas instead of coal. The higher efficiency can also lie in the energy supply: natural gas heating instead of electric heating does not save energy in the house, but when generating electricity in a power plant.

Political jurisdiction

In Germany is on the federal level , the Federal Ministry of Transport, Building and Urban Development (BMVBS) for the coordination and development of state energy saving measures (economic development), or energy conservation laws ( Energy Conservation Act ), responsible. The theme also touches on the areas or departments Environment of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) and the economy of the Federal Ministry of Economics and Technology (BMWi).

The goal declared in the course of the energy transition of reducing energy consumption by 20% by 2020 compared to 2008 is likely to be clearly missed, as the Federal Ministry of Economics stated in the National Action Plan on Energy Efficiency (NAPE) at the end of 2014. According to a meta-analysis by the Wuppertal Institute for Climate, Environment and Energy , in which 14 scientific studies were evaluated, only a reduction of 10% to 15% is achieved with existing measures.


Economic incentives to save energy

The economically feasible savings potential for total consumption (electricity, heating, transport) through increased efficiency in households, production facilities and office buildings is often astonishingly high; 20% to 30% are quite common. The Wuppertal Institute even assumes 40%. In many cases - especially in private households - savings are also economically feasible, around 50% in total consumption and much higher values ​​(even well over 90% depending on the previous condition) in some areas, such as heating. In contrast, national and international climate protection targets ( Kyoto Protocol ) assume significantly lower potential, and practical implementation often falls far behind these more modest guidelines; In some cases, it can be seen as a success if at least consumption does not increase.

The subject of energy consumption and energy saving is widely recognized as an item on the social agenda. However, what is often missing, especially in a commercial context, is information about the exact consumption and costs involved in a particular action. In addition, only disadvantages are known about many alternatives that they had in their early days, but have now often been solved. It is therefore difficult to be energy efficient. In connection with this information deficit, the term energy transparency has become common in recent years .

The EU has made a binding stipulation that the fleet consumption of newly sold vehicles must gradually decrease from an initial 160 grams of CO 2 / km to 120 grams of CO 2 / km (see ECCP European program for climate protection ) (120 grams / km corresponds to approx. 5 liters of petrol / 100 km or 4.5 liters of diesel / 100 km). That is why all car manufacturers are making every effort to sell their customers smaller or more economical models.

Polluter-based cost allocation

The intensive consumption of fossil primary energy has far-reaching effects on the environment . The costs for the elimination of the environmental damage or for the compensation of those affected have so far only rarely been attributed to the polluters. The first political demands to avoid environmental influences had led to technical improvements ( catalytic converter , flue gas desulphurisation , environmental protection regulations), but not to energy savings.

In many cases the polluter pays principle does not apply. In commercial buildings, building owners, users and operators are often completely separate actors who are linked to one another via more or less complex contracts. The actors who could implement energy-saving measures in these constellations often do not benefit from it. On the other hand, the actors who determine consumption (such as employees) are rarely also the cost bearers (employers). In the private sector, too, many costs, such as water or heating, are simply distributed to users according to square meters. In such situations, there is little incentive to save energy.

In the case of rented apartments, the problem under German law is that the tenant pays the heating costs and the landlord does not even find out the current consumption values ​​promptly in the event of direct billing with the energy provider, while structural measures are the landlord's responsibility (see user-investor dilemma ).

In an ideal market, the price of a commodity includes all costs involved in producing that commodity. The exploitation of natural resources, and in particular the consumption of fossil primary energy, incurs costs that are not included in the business calculations and therefore cannot be identified from the price. These include health risks, long-term costs of destroyed biotopes , accidents such as oil spills and core meltdowns , global costs from climate change and much more. The societies concerned bear these costs as a whole. As a result, the market signal that emanates from high energy consumption is greatly weakened. The energy price does not reflect all costs, energy is too cheap. Conversely, there is also usability that is not included in energy prices, which makes energy too expensive. In order to obtain energy prices that correspond to the actual costs, most economists recommend "internalizing" these positive and negative external effects through appropriate taxation using incentive taxes .

Environmental certificates

The expenses incurred by the company for damage to the environment and health resulting from energy consumption are so-called external costs that the emitters do not take into account in their production. One example is air pollution from lignite power stations and the associated “free” use of air as a resource.

In the context of environmental economics one tries to internalize these external costs by trying to evaluate the physical consumption of resources in monetary terms. This can be done through so-called environmental certificates or targeted taxes, such as the eco-tax in the Federal Republic of Germany. Environmental certificates authorize the use of a previously scarce resource, e.g. the emission of exhaust gases in a certain amount. However, they only fulfill their purpose optimally if the costs of the certificate correspond to the monetary valued consumption of resources, so that the polluters take into account the costs of environmental and health damage during production like any other production factor. In the model, trading with maximum profit leads to the use of more cost-effective production processes, which are reflected in energy-saving measures or the use of alternative energies.

Technical incentives to save energy

Mobile devices

Lithium-ion battery Nokia BL-5B

Many mobile devices use batteries or accumulators as energy storage . These have a limited size and mass and therefore a limited capacity. Saving energy can therefore primarily increase the service life of these devices. Mobile telephones are a popular example of such devices . In recent years it has been possible to reduce the overall size of these devices despite the increased scope of functions. In addition to the improved accumulators, this is mainly due to the more efficient use of the stored energy. For example, the transmission power is adapted to local conditions and the display lighting has become more efficient. Other portable devices also achieve significantly longer operating times through the use of energy-saving microelectronics .

Motor vehicles

With motor vehicles , especially cars , there are different motivations for saving energy:

  • Lower operating costs
  • A smaller tank leaves more space for the interior and trunk.
  • An economical vehicle has a longer range or a lower fuel mass, and a smaller tank reduces the vehicle weight and can thus lead to further fuel savings.
  • A lower total weight (regardless of which measure) allows better performance with the same engine (keyword: downsizing ).

In recent years, the efficiency of internal combustion engines has improved significantly. The weight of the vehicles increased for a long time, especially in favor of safety (see Euro NCAP ). Only vehicles that are marketed as particularly fuel-efficient or particularly sporty have a weight that reveals the lightweight construction of motor vehicles.

( See also: low energy vehicle ).

Saving opportunities according to energy sector

Average energy consumption of private households in Germany

Against the background of energy policy discussions, in addition to technical energy-saving measures, the conscious use of energy and the reduction of consumption through individual measures are repeatedly called for. According to the EU Commission, 90% of all apartments in the EU are not energy efficient. In this respect, there is considerable potential for savings.

The actual amount of energy consumed by households is around 30% of total energy without the consumption of cars in Germany. The energy saving potential is considered to be high, since the “typical” household technology is often constructed in an energy-technically inefficient manner for price reasons.

Building heating and water heating (around 25 to 33% of the total German primary energy household ) and electrical energy, of which part is for lighting energy (around 2% of total German primary energy consumption), but a large part also for electrical household appliances, have the largest share of individual energy consumption .

In order to make the purchase decision process for energy-efficient devices easier for the consumer , the labeling of the energy efficiency class was introduced.

In a study in Great Britain, the "top ten" (ten most common) "energy saving sins" were found in English households:

  • 71% run electrical appliances in standby mode ,
  • 67% boil more tea water than they need,
  • 65% leave unused chargers in the socket,
  • 63% leave lights on in empty rooms,
  • 48% take the car even for short distances,
  • 44% wash the laundry too hot,
  • 32% run the engine when the car is stationary,
  • 32% use clothes dryers instead of clotheslines,
  • 28% heat the empty house,
  • 22% prefer to turn up the heating instead of putting on a sweater

Heat utilization

Heating energy

Today in Germany around 40% of energy is consumed in the building sector. Around 70% of this (28% in absolute terms) is accounted for by domestic private energy consumption. Private households consume most of the energy for heating or cooling living spaces. In Central Europe, heating is particularly important.

Types of heat generators in Germany in 2008
       7.9 million gas boilers (41%)  2.7 million gas condensing boilers (14%)  6.0 million oil boilers (31%)  0.2 million oil condensing boilers (1%)  0.7 million biomass boilers (4%)  1 , 3 million thermal solar systems (7%)  0.3 million heat pumps (2%). For data for Austria and Switzerland, see Boiler # Boiler types by fuel         

A lot of energy can be saved by a well-planned installation and control of the heating system as well as by good thermal insulation of the building.

Many outdated heating systems only have a degree of utilization (measure of efficiency) of 64%, newer low-temperature heating systems up to 94% and modern condensing heating systems up to 104% (values ​​related to the calorific value ). Replacing an old heating system with a condensing system can save up to 40% energy and thus also reduce carbon dioxide emissions. Renewing the heating system is one of the energy-saving measures that pays for itself economically the fastest.

The average age of heating devices in Germany is 17.6 years, more than a third (36%) is even older than 20 years. Over 70% of the installed heating devices would only achieve efficiency class C, D or E. In August 2015, the federal government adopted the legal basis for implementing the "national efficiency label for old heating systems". The new efficiency label is to apply from January 1, 2016 to boilers that are more than 15 years old.

In the 1980s, the waste of energy as a result of possible heat losses in wood-burning stoves used as single room heating was estimated to be around 70% of the calorific value.

20% waste
even with
new boilers
80% useful heat
up to 50% waste
with outdated fuel oil boilers
50% useful heat
up to 70% waste
for wood-burning stoves
30% useful heat

Almost all single stoves installed in rooms ( heated with coal, oil, wood or biogenic pellets ) make poor use of the fuel due to their simple construction - a large part of the heat generated is lost through the exhaust pipe . Even with inexpensive fuels, this type of heating is uneconomical. This is especially true for open fireplaces. In 1986 there were 2.6 million tiled stoves, open fireplaces and wood-burning stoves in German households with an annual growth rate of around 10%. Most solid fuel stoves pollute the environment with increased fine dust emissions .

In a study from 2003 on heating optimization, the savings potential for the Federal Republic of Germany was estimated at between 20,000 and 28,000 GWh per year (for comparison: the Brokdorf nuclear power plant fed 11,360 GWh of electricity into the grid in 2010). The countermeasures (2003) were comparatively inexpensive with costs of 2 € / m² to 7 € / m² living space. A lot of heating energy (and therefore heating costs) can be saved at low cost by optimizing the return flow from radiators . With (central) boilers, even of modern design, standstill losses can occur, which (depending on the age of the heating system and fuel) can account for up to 50% of the total fuel costs (see Boiler # Energy Waste ).

Condensing boilers have a high degree of fuel efficiency in that the flue gases are cooled down to below the condensation temperature of the water vapor they contain, which means that less heat escapes through the chimney. With condensing technology, the flue gases should be cooled as much as possible in order to use the thermal energy bound in the enthalpy of vaporization of the water vapor through condensation of the vapor. To do this, the circulating water returning to the boiler must have the lowest possible temperature in order to fall below the lowest smoke gas dew point and thus achieve a lot of condensation . This is achieved through low-temperature radiators, underfloor heating or warming the cold fresh air in the building.

Further measures are:

  • improved burner construction and guidance

A heat saving can also be achieved by heating u. a. the heating supply air with the flue gas in double-walled stainless steel chimney tubes ( air-exhaust system ).

Electric heaters

Electric heating converts the electrical energy completely into thermal heat, but since in thermal power plants only about 30% and in photovoltaic systems only about 15% of the primary energy can be converted into electricity, this type of heating is extremely inefficient in terms of energy and only useful in terms of energy if heating is only required very seldom or when the electrical energy required for heating comes from surplus renewable energies . For this it can be useful to store the electrically generated thermal energy. Ideally, electrical storage heaters should be charged when there is an excess supply of electrical energy. This is possible with ripple control relays which, controlled by the energy supplier, can switch consumers on and off.


Radiant heating is considered to be more efficient than convection heating (see thermal insulation # criticism and controversy ), especially if it is operated hydraulically (with low-temperature pipe coils).

Is the perfect complement of a condensing boiler as an environmentally friendly and energy-saving heating system, a low-temperature heating in the form of a (at least by convection losing overhead heater or other radiant heating . The low supply temperature as a low-temperature radiation heating (up to 40 ° C) corresponding to the optimum operating temperature of a condensing boiler or solar thermal heating. underfloor heating systems provide approximately two-thirds of their heat as radiant heat, ceiling heaters about 90%. the increase in temperature space surrounding surfaces and Nichterw # ärmung of air leads to lowering of the room temperature and a further energy saving (6% energy saving per lowered Kelvin room temperature are possible In well- insulated houses, conventional wall- mounted radiators can also be operated with low hot water temperatures from a condensing boiler, which promises a similar level of comfort with a lower room temperature Heating strips installed on the outer walls , which first heat the wall surface with rising warm air, which then releases the heat to the room via the physiologically beneficial thermal radiation . As with wall and floor heating, the room air can stay a little cooler and heat build-up on the ceiling is avoided.

Wall and baseboard heating should not be shielded by curtains or cupboards.
Normal radiators also work more efficiently if existing cladding and, if necessary, curtains, which obstruct the air flow around the radiator, are removed. It also makes sense to insulate the wall surface behind the radiator particularly well. If the radiator is in a wall niche, a particularly large amount of heat will be lost through the outer wall in an uninsulated building due to the reduced wall thickness. If thicker insulation is not possible, a three to five millimeter thick layer of styrofoam with laminated aluminum foil, available as a roll at the hardware store, helps to reflect the heat radiation of the radiator directed towards the outer wall back into the room.

When selecting the floor covering for underfloor heating, both the thickness and the thermal conductivity are the decisive criteria. Thinner and better heat-conducting coatings (ceramics) reduce the temperature difference. Well insulating and thick coverings (carpets) are less cheap.

Thermostats on radiators and heating devices regulate the room temperature and thus control the energy demand. A temperature of 20 to 21 ° C is standard for living spaces. A reduced room temperature leads to an average energy saving of 6% per 1 ° C.

Another structural means to save energy is to avoid unnecessarily high rooms. The temperature difference between floor and ceiling can be over 10 ° C. However, a slowly running ceiling fan is sufficient to distribute the heat evenly in the room.

Stairways should also be separated from the living rooms by doors.

Further information on buildings under energy standard , low-energy house and passive house .

District heating

District heating is provided by heating plants . With combined heat and power , the energy efficiency is significantly increased. Combined heat and power is a way of saving primary energy in generating electricity and heating. In addition to the large-scale variant of the thermal power station, there are also technical solutions for the household ( combined heat and power station and micro-CHP ). Due to the block size of heating plants, increased technical effort is economical there in order to increase energy efficiency. This is offset by heat losses during transmission. District heating networks also help to reduce individual exhaust gas emissions .

Process heat

Waste heat from process heat , as it occurs in some industrial plants, is rather limited to the spatial environment.

Heat pump

A heat pump heating system generates heat by cooling the outside air, the surface or groundwater or layers of earth close to the surface. Heat pumps can balance the efficiency of electricity generation using fossil fuels or nuclear fission and are therefore competitive with firing systems. The cooling of the outside air as a heat source is heavily dependent on the outside temperature and becomes uneconomical at low temperatures. If, on the other hand, favorable conditions are available (e.g. heat from surface water or groundwater-bearing layers) and if low tariff periods and surpluses of sustainably generated electrical energy are used, heat pumps combined with heat storage systems are among the most efficient heating systems. The high investment costs are disadvantageous.

Geothermal energy

The geothermal energy is almost always associated in Germany with the use of heat pumps since hardly any deposits accessible to high-temperature. Geothermal energy enables efficient, environmentally friendly heating, but requires high investments.

Solar panels

Solar collectors can cover essential parts of the heating energy requirement and the hot water requirement. Not only effective solar collectors contribute to this, but also heat storage systems with up to seasonal capacities. Combined with low-energy houses , solar heat can completely replace active heating.

Nitric oxide avoidance

Through the endothermic formation of nitrogen oxide (NO x ) in all combustion processes, energy is chemically bound again (see also enthalpy of reaction ). Combustion temperatures below 1,000 ° C, such as those possible with catalyst- supported pore burners (so-called “cold flame” technology), can avoid this type of energy loss. This method is used both for industrial systems (for heating workpieces) and for building heating.

Ventilation / ventilation

Energy-efficient ventilation requires the residents' attention. Manual ventilation during the heating season leads to a loss of energy. In houses without automatic ventilation with heat recovery that is airing superior both for achieving good indoor air quality and to save heating energy to the continuous ventilation (z. B. by tilting the window). This is due to the fact that with St + ´ventilation only the air is exchanged and there is hardly any time for objects and walls to cool down.

Warm air rises and cold air sinks. A ceiling fan can achieve a better mixing of the air and thus a faster temperature adjustment. Ceiling heating leads to the lowest heat and air convection from all radiator systems. Permanent ventilation openings should be located near the floor of the room and not on the ceiling, so that warm air cushions do not escape into the open air (which also happens when windows are tilted). A similar energy-saving function is fulfilled by an air siphon for basement rooms, with which fresh air is led to an outlet opening near the floor . A lot of heat is also lost as latent heat bound in water vapor, air dehumidifiers can recover heat there (see also condensing boilers # use latent heat ).

Passive house scheme

Additional ventilation is counterproductive in houses with a ventilation system with heat recovery . Ventilation systems with heat recovery are sophisticated technical systems that have hygienic, energetic and indoor climate quality features.

Thermal insulation

A lot of energy is also saved by good thermal insulation of the building. Examples are the thermal insulation of all external surfaces (walls, floors, roofs, doors and windows).

The heat loss through the windows, by e glazing and tightly closing windows are reduced.

When modernizing buildings, thermal insulation is very important. Should the facade not or cannot be changed, there are now insulation systems that can also be attached to the inside of the exterior walls. Insulating the top floor ceilings or the roof is mandatory for buyers of buildings within 2 years in the German Energy Saving Ordinance. An insulation value of 0.24 W / m²K must be achieved.

It is essential that the building is largely impermeable to air. Even small drafts in an effectively insulated building can carry significantly more heat out of the building than the heat conduction through the external surfaces. Drafts can also be caused by kitchen extractor hoods , unused room stoves and poorly closing attic doors. The blower door test is used to test the air permeability of buildings .

Building thermography - uninsulated exterior wall

Another way to save energy is to close the shutters or shutters in the dark. The air between the window and the shop acts as additional thermal insulation.

Industrial processes

The thermal insulation in the industrial environment above 700 ° C is done using high-temperature wool . Compared to classic thermal insulation materials such as lightweight refractory bricks (calcium silicate and microporous materials), heavy bricks (fireclay bricks and masses) and refractory concrete, high-temperature wool (HTW) as thermal insulation materials can lead to energy savings in many heating processes:

  • in the production and processing of steel and non-ferrous metals.
  • in industrial furnace, furnace and heating construction
  • in the ceramic and porcelain industry
  • in hot gas filtration
  • in appliance technology (e.g. thermal insulation of ceramic hobs, microwaves and ovens).

In some areas, energy savings of up to 50% compared to conventional stone / concrete linings are possible. Industrial ovens and systems with HTW thermal insulation need to be heated up and cooled down more quickly because of their lower heat capacities. This reduces energy consumption, especially in the case of discontinuous processes.

Use of hot water

The second place in the energy consumption of a household is hot water preparation.

As with room heating, there are three paths

  • Reduction in consumption
  • more efficient delivery
  • Recovery of thermal energy
Reduction in consumption

The highest consumption of hot water in the household is caused by personal hygiene (bathing, showering). A shower bath requires approx. 40 to 75 liters of warm water, depending on the duration, a bathtub requires an average of 160 liters, i.e. about three times as much (the warmth of this can, however, help to heat the room by allowing it to cool, which is hardly practiced when showering with the water in the shower tray ). With water-saving shower heads, the exit speed of the water jet is significantly increased, which creates the feeling of a richer jet despite the reduction in the flow rate. Savings of up to 50% are possible. Ultimately, however, the behavior of the user is also decisive here.

Efficient deployment

The production of hot water using electricity is ineffective and expensive, because the primary energy consumption in the production (and transport) of this electricity is about three times as high as the useful energy. However, a solar or heat pump heated water storage tank can be connected upstream of the (electrically heated) hot water tank.

However, there are also hot water storage tanks on heat pumps that use their hot gas energy to create the temperature level of 70 ° C in the upper part.

The losses of the hot water storage tank itself and its drainage can be reduced by better insulation and lowering the storage tank temperature.

The temperature must not fall below 60 ° C permanently, as otherwise there is a risk of dangerous legionella multiplying . These bacteria can cause pneumonia or flu-like illnesses ( Legionnaires' disease , Pontiac fever). Alternatively, a legionella switch can be used, which heats the boiler to over 70 ° C once a week at boiler temperatures <60 ° C. The lime deposit in the pipes is greatly increased at temperatures above 60 ° C and, depending on the material of the pipes, narrows the pipe cross-section.

The circulation pump of a hot water network can be switched off when there is potentially little demand (e.g. late at night). This partially eliminates the heat losses in the circulation line.

As an alternative to the hot water network with a circulation pipe , a flow heater near the tap can prevent idle and pipe losses. Electric instantaneous water heaters are easy to install, but are only worthwhile for remote tapping points with low hot water requirements. Gas water heaters do not have these disadvantages, but gas is not available everywhere. If possible, better thermal insulation of the pipe is the solution of choice.

Some washing machines can draw their washing water from the hot water network instead of heating it themselves electrically.

Recovery of thermal energy

See also the article on waste water heat recovery .

Warm wastewater is produced in the shower / bathtub and in the washing machine and dishwasher.

If the shower has a flow heater, the incoming water can be heated with the outgoing shower water via a heat exchanger .

If a heat storage with stratification is available, the warm wastewater can be used directly after filtering to heat the water in the colder layers. However, this requires a separate, well-insulated pipe for the warm wastewater and a layer storage tank, which is provided for this.

In addition, the thermal energy of the wastewater can be raised to a higher, more usable temperature level with a heat pump and fed into the hot water storage tank.

The residual heat from a hotplate that has been switched off after cooking can heat the water in a saucepan placed on it. The heated water can be used, for example, for rinsing, thus saving energy for water heating.

Many dishwashers use a cold water supply in the inlet for condensation drying of the wash cabinet. The heat that is partially transferred into this can be saved in a subsequent wash cycle.

Food heating

Gas-operated stoves and ovens are more efficient because of the conversion losses when converting primary energy into electricity in the power plant and the high electricity price per kWh.

Pots that go with the stove are helpful for electric stoves with single plates to save energy. Thermostats and boiling aids also facilitate efficient cooking. A closed metallic lid prevents heat loss.

Egg boilers are more efficient and save water than boiling eggs in a pot.

Electric kettles or immersion heaters are energy-efficient because the radiator heats the water directly. Energy can also be saved if only the amount of water that is actually required is heated to the temperature that is actually required (for example, hot beverages often do not need hot water at 100 ° C).

With coffee machines , energy can be saved by pouring the finished coffee into a thermos .

For longer cooking times, the hotplate can be set so low that the water just simmers - as long as there is water in the pot, a higher cooking temperature cannot be reached except with the pressure cooker. When water boils, the additional energy supplied is released into the environment through evaporation without reducing the cooking time.

Fast cooking, on the other hand, is possible in the pressure cooker , in which the cooking temperature is well above 100 ° C due to the higher pressure. The shorter cooking time saves energy, and the pot whistles when it is boiling.

Getting products and food out of the freezer in good time for thawing before preparation saves energy for thawing, but it is lost to the room heat. Therefore, it is better to thaw in the refrigerator in winter and use the cold for this. Cooked food should cool down first before putting it in the refrigerator.

Devices and systems in household and business

Household appliances make up the second largest item in a household's energy needs. The largest shares of total consumption are made up of refrigerators and heating devices (i.e. stove and oven ), washing machines and, if available, tumble dryers and dishwashers .

Despite more energy-efficient technology, the average electricity and energy consumption in German households has remained almost unchanged. Compared to older household appliances from the 1980s, modern devices consume between a quarter and a half less electricity. This saving is almost completely offset by new electricity applications and negligence. Many households are not aware of their unnecessary energy consumption. Consumer advice centers offer free energy advice.

Washing machine

With hygienic restrictions, washing machines can also be sufficiently clean without pre-wash and at low temperatures from 20 ° C, which reduces water and electricity consumption. Despite automatic quantity control, a washing machine works most efficiently with its nominal washing quantity - it is optimized for this.


The air drying the laundry outside on the clothesline avoids any Ergieaufwand for drying. The spin helps : the higher the speed, the greater the effect. A speed that is too high for the textile can lead to increased effort when ironing / mangling. Wind drying can reduce wrinkles.

Drying with the tumble dryer also requires a lot of energy with the condenser dryers . Dryers with heat pumps are another 50% more efficient.

Drying laundry on the line indoors removes energy from the air in the room and can cause condensation in colder places in the home.

Wash the dishes

Fully filled dishwashers make better use of the energy per wash cycle. Some dishwashers can also use the usually more efficiently heated domestic hot water and then require less electrical energy for the built-in heating. Zeolite technology is currently considered to be the most energy-saving variant, with around 11 liters of water and 1 kWh of energy consumption, 160 dishes can be cleaned, other devices use twice as much and more.

Hand washing is most energy and water efficient when using a wash and rinse bath, and most inefficient when washing under running water.

Cooling and keeping fresh

Despite a relatively low electrical connection load, cooling devices also require a lot of energy because their motors (thermostat-controlled) start over and over again. A cooling device needs all the more energy, the more difficult it is to release its waste heat into the ambient air. Therefore, good ventilation on the rear side, where the heat exchanger is located, improves the efficiency. Iced heat exchangers inside the devices also reduce the efficiency of the cooling circuit. Regular defrosting can help here.

Replacing a refrigerator is usually only worthwhile when the old one is 10 to 15 years old and the new one has the highest energy efficiency class. In the case of freezers, buying new ones pays for itself even less often. Chest freezers are about 12% more efficient than freezers. Refrigerators work more efficiently when they are cool. Manufacturers specify a minimum ambient temperature.

Some cooling devices consume so much electricity that replacing them can save money because the annual electricity costs of the new cooling device plus the proportional purchase price (so-called depreciation ) are lower than the electricity costs of the old device. With the old device cooling check, this can be checked for most of the devices currently used in Germany.

If frozen food is placed in the refrigerator for defrosting in good time before preparation, the energy requirements for cooling and subsequent heating are reduced.


LED lamps require about 15 to 112 the energy of incandescent lamps . An incandescent lamp only emits 3… 5% of its energy as light, the rest becomes heat.

When planning buildings, the use of daylight can save a lot of energy for lighting.

Energy-saving lamps such as LED lamps have a higher manufacturing and disposal costs and sales price, but this is offset by the higher efficiency and longer service life. With fluorescent lamps , up to 75% can be saved compared to conventional ballasts by using electronic ballasts in conjunction with motion and light sensors.

Also halogen lamps provide true for the same electrical power consumption a higher luminous flux than conventional incandescent lamps, the high-voltage variations, however, are concerned in the EU are already restrictions of the sale because of inefficiency.

LED lamps are available as an energy-saving replacement for incandescent and halogen lamps. They achieve a high level of efficiency even at low color temperatures of 2700-3000 K, which are equivalent to an incandescent lamp.

The luminous flux in lumens is decisive for comparing the brightness . The electrical output in watts has no meaning because it describes the power consumption and not the brightness. Incandescent lamps achieve luminous efficacies up to 10 lm / W, LED lamps reach 50 to 83 lm / W. Particularly efficient models achieve 110 lm / W.

Computers, consumer electronics and small appliances

Flat screens require less energy than cathode ray tube screens

By completely disconnecting devices with standby mode ( standby function ) from the mains , an average household saves around 3% of electricity. To illustrate the problem: According to the North Rhine-Westphalia consumer advice center, the standby functions of televisions, computers, CD players and co. Unnecessarily consume 20 billion kWh annually in Germany. Conventional plug-in power supplies consume more energy than electronic ones. In entertainment electronics, an operating switch is usually installed that only switches the low-voltage current - just like with devices with a separate power supply unit, the device's transformer is continuously connected to the mains and can usually only be switched off by pulling the mains plug.

Devices should have a power switch. Modern desktop computers are often far oversized for use as a pure writing instrument, so that a large part of the energy is used to supply components that the user rarely or not at all uses. In addition, all of the energy required by the computer is ultimately converted into heat that has to be removed from the device. A notebook is usually much more economical because as a mobile device it is designed for a long battery life and therefore low power consumption. But there are also many ways to save energy for desktop computers and other home electronics (see also: Green IT ).

  • Use of a multiple socket outlet with a switch so that all devices can be disconnected from the power supply with a single movement
  • Master-slave sockets reduce the standby consumption of the peripheral devices
  • Switching off the devices instead of standby mode including switching off the screen (screens run through at night in 23 of all companies)
  • Use of energy-saving components: The processor manufacturers have integrated energy-saving technologies into their processors, see for example Cool'n'Quiet (AMD) and SpeedStep (Intel). The processors normally run at about half the computing power, with only a fraction (mostly 10% to 20%) of the normal energy requirement. If more computing power is required, the operating system automatically switches up the processor.
  • Use energy control systems that are built into software and hardware:
  • Current power supplies have an efficiency of 85% to 95%, cheap and older devices achieve significantly less.
    • Switch off the PC using the power switch on the power supply unit (rear of the housing) - the software-controlled shutdown merely puts the PC in a standby mode in which certain parts are still supplied with energy.
  • Remove unused components such as old analog modem cards.
  • Only switch on peripherals when they are needed (scanner, printer, USB stick, etc.). Remove unneeded data carriers from the drive
  • The transmission power of WLAN devices can be reduced in many cases: with antennas in the same room, 20% transmission power is usually sufficient

Research on the Internet also consumes electricity due to the services used by the servers of the network nodes and search engines.

Building use

In public buildings and schools, 20% energy can be saved through the behavior of the users. Profit-sharing models such as “fifty-fifty” are offered in many places, for example in Frankfurt, Hamburg or Berlin. These projects are a contribution to climate protection and convey these questions of the future to children and young people.

Material usage

Packaging and data carriers, recycling

No energy has to be used for packaging material that is not produced. By reusing ( recycling ), in particular of packaging materials, part of the energy required for production can be saved. The problematic and time-consuming sorting of waste is partly carried out by the consumers. The final sorting is mostly done by waste disposal companies. The DSD ( Duales System Deutschland ), which is responsible for recycling in Germany, has come under fire because there are now (2004) sorting machines that work better, faster and, above all, more economically advantageous than manual waste separation, separate tours and sorting.

Information can often be transported more conveniently, faster and cheaper over the Internet than on fixed media. These are, for example, films, pictures, newspapers, magazines, music, maps and letters. A considerable amount of gray energy is expended in the transport and manufacture of these media, especially in the processing of raw materials (paper, plastic from oil) . The potential for savings through digitization is great, since in many cases more energy is required to manufacture and dispose of pure transport data media than to provide the Internet infrastructure for exchanging the information on them.

Lightweight construction

Lightweight construction leads to more efficient use of energy and thus to lower energy consumption. The smaller the mass that does not contribute directly to the performance of a work, but still has to be moved, i.e. accelerated and decelerated, or heated and cooled, the higher the proportion of energy used to do the actual work. Another savings effect results from the lower mass of raw materials that is required to manufacture the lightweight construction.


  • A ride on a lightweight bike requires less effort than a heavy bike. This is particularly noticeable when accelerating and when riding uphill.
  • The amount of drinks in a crate with plastic bottles is higher than the amount in a crate with glass bottles for the same mass.
  • A small, light pot needs less heat energy to be heated up than a large, heavy pot made of the same material if the same amount is to be heated in it.
  • For trucks whose gross vehicle weight is limited, lightweight construction can increase the payload while maintaining the same total mass and thus reduce the relative energy consumption per tonne-kilometer .


Choice of transport

When it comes to means of transport, there are several motivations that make economical use of energy (here: fuel ) appear advantageous.

  • high fuel prices
  • Range increase
  • Payload increase
  • Increase in utility
  • Environmental protection

Saving energy in transport for environmental reasons is rarely observed. The negative environmental and health marginal phenomena of energy consumption are fought with mostly technical means and only under political pressure. Measures such as unleaded petrol and catalytic converters do not reduce energy consumption, and diesel particulate filters increase consumption by up to 10%.

Significant increases in efficiency are also possible in the transport sector through improved vehicle and drive technology (for all those who want and can buy these new vehicles). Prototypes show that the 1 to 1.5 liter car is technically and economically possible. Well-engineered concepts for low-energy vehicles have not yet reached the market : Either an investor was missing or the vehicle did not meet the demands of the users.

Transport and traffic

The energy consumption for locomotion now makes up a significant part of the total energy consumption (energetic footprint) of mobile people. This affects most of the commuters who travel longer distances by car every day, or also journeys for training or leisure activities. Roughly calculated, a daily distance of 100 km means approx. 100 kWh per day, with 200 working days this would be 20,000 kWh. Compare this with the energy consumption for electricity of 2300 kWh per year for a two-person household.

In transport, energy can be saved by

  • Avoid unnecessary journeys with motor vehicles
  • Acquisition of vehicles with lower fuel consumption
  • Switching to more energy-efficient means of transport (bicycle, foot traffic , public mass transport )
  • Use of car pools
  • increased expansion of electromobility in local public transport ( trams , trolleybuses , cable cars )
  • Avoidance of goods that are brought to consumers from far away, but that are also produced locally (for example apples from New Zealand , paving stones from China, mineral water from Italy, butter from Ireland, wine from Australia)
  • Waiver of "processing traffic" (pig rearing in Austria, slaughter in Germany, processing in Italy, sales throughout Europe)
  • Increase in the shelf life of products (energy savings in production, transport and disposal)
  • Replacement of travel and driving with video conferencing or working from home
  • Shortening journeys (shopping near your home, choosing an apartment near your workplace, vacationing nearby, etc.)

Transport generates costs in the provision of infrastructure (property purchase, traffic route construction, renovations), in the social area (accident costs) and due to emissions, all of which, however, are not generated by the consumption taxes imposed on fuels .

Theoretically it would be ideal if these external costs could be borne entirely by the polluter instead of the state, social security agencies and municipalities (see “ Polluter Pays Principle ”); d. H. no so-called external costs are passed on to third parties. The cost truth would lead to higher fuel prices, which are expected to have steering effects .

The following rule of thumb applies to air transport: The weight of the product is consumed in fuel per 5,000 km. For products with a low specific weight (e.g. styrofoam ) the ratio is far less favorable.

The reactions to the rising fuel and energy prices show two basic strategies of the providers of all kinds of transport:

  • Increased efficiency: Reduced consumption, for example through increased efficiency, lightweight construction, hybrid drive , Thrust Fin (shipping), ENAflex-S (rail)
  • Alternative energies: cheaper fuels such as gas, hydrogen or electrical energy

Alternative drive technology is described in more detail .

Settlement policy

The settlement structure and the resulting traffic behavior have a major influence on energy consumption in transport . In densely populated areas, journeys are often shorter than in large, sprawled areas, so that many journeys on foot , by bicycle or public transport can be done more cheaply and quickly than by energy-inefficient motor vehicle ( city ​​of short journeys ). Energy-saving means of mass transport can be used to full capacity here and thus achieve a high degree of cost recovery . Only densely populated urban structures make it possible to finance highly attractive public transport offers.

By promoting district and village centers, i.e. upgrading local retailers, smaller cultural institutions, local green and recreational areas and leisure facilities, vehicle kilometers can be reduced and at the same time the spatial mobility of the population increased. If traffic is decelerated, parking is restricted and more space is given to cycling and walking, more life-friendly, less traffic-free, more space-saving and thus more economical urban structures emerge.

The construction of expressways and railways, the identification and promotion of low-density single-family housing estates, the construction of supposedly cheap shopping centers in the outskirts of the cities as well as a car-friendly policy of good accessibility and free parking spaces destroy energy-poor urban structures and promote urban sprawl (" car-friendly city "). Less densely populated settlements can only be insufficiently supplied with local public transport, as their utilization is low. The result of such a policy are costly and energy-consuming urban structures (infrastructure costs per inhabitant). Residents of such regions have to continue to drive for the same or less mobility and are dependent on their own vehicles. As a result, they become heavily dependent on energy sources such as oil and gas and have to raise more money for their daily journeys. People without a car or a driver's license have to suffer significant restrictions on their mobility.

Politicians have many options for influencing the energy consumption of transport through settlement policy:

Further energy saving options

Considerable consumption and investment can save a lot of energy:

  • Avoid unnecessary or half-full chest freezers - all year round or seasonally; For many people, significantly longer shop opening hours make them unnecessary
  • Food from regional cultivation and the corresponding season can avoid transport and other consumption (e.g. for greenhouse heating)
  • New devices save energy compared to old or cheap devices
  • Durable furniture and devices reduce the specific energy consumption for production
  • Modern circulating pumps and hydraulic balancing of the heating save electrical energy
  • Unnecessary new acquisitions should be avoided; so should z. B. functioning devices are only replaced if significant energy savings are achieved, because it often takes a very long time for the somewhat lower energy consumption to manifest itself positively in the overall energy balance (including the energy required for production); A 17-inch TFT screen requires around 70% less energy than a 19-inch CRT monitor with the same resolution, but it is very energy-intensive and environmentally harmful to manufacture
  • You can save energy when operating an aquarium (see also energy saving tips for the aquarium ) by closing the aquarium with a lid
  • The heating energy consumption is reduced in winter if the heating temperature is lowered at night and when leaving the apartment.

See also


Web links

Wikibooks: Saving Energy  - Learning and Teaching Materials
Wiktionary: energy saving  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Law on the Saving of Energy in Buildings (Energy Saving Law - EnEG). Current version. July 4, 2013, accessed July 8, 2014 .
  2. Andersen, Uwe / Wichard Woyke (Hrsg.): Concise dictionary of the political system of the Federal Republic of Germany 5th, actual. Edition Opladen: Leske + Budrich 2003. Licensed edition Bonn: Federal Agency for Civic Education 2003.
  3. ^ BMWi: National Action Plan on Energy Efficiency. PDF, 2014
  4. Research radar Energiewende: Development of energy consumption in Germany. 2014
  5. Energy Efficiency Initiative ( Memento from July 20, 2006 in the Internet Archive ) (PDF)
  6. Wuppertal Institute: ( Memento from September 27, 2007 in the Internet Archive ) Options and potentials for energy efficiency and energy services (PDF)
  7. EU Commission: Starting signal for the European Energy Union. Press release from February 4, 2015
  8. Article Brits practice self-flagellation at , accessed on December 22, 2011
  9. Germany infographic at, private website
  10. Bill of the Federal Government ( Memento of March 4, 2016 in the Internet Archive )
  11. a b Poisonous fire leech. In: Der Spiegel . January 4, 1988. Retrieved July 8, 2014 .
  12. Jagnow, Wolff: OPTIMUS short report, page 7, (PDF; 198 kB) ( Memento from November 27, 2013 in the Internet Archive )
  13. Power Reactor Information System of the International Atomic Energy Agency IAEA (English)
  14. The OPTIMUS project ( Memento from October 2, 2013 in the Internet Archive )
  15. Pore ​​burner technology
  16. 50 tips to save energy at home ( Memento from April 12, 2011 in the Internet Archive )
  17. ^ Association of Energy Consumers - Showers (accessed on October 16, 2007)
  18. Stiftung Warentest : 60 degrees are ideal (accessed on December 11, 2012)
  19. Consistent energy demand despite the latest technology Consumer advice center in North Rhine-Westphalia
  20. Assessment of electricity consumption per household
  22. a b When is the new purchase worthwhile (information at T- Online), accessed April 10, 2020
  23. Zeolite technology dishwasher - Stiftung Warentest
  24. Climate seeks protection: KühlCheck
  25. Survey on energy loss nationwide due to standby operation Stromtipps - consumer center NRW
  26. Savings potential. Office screens are power guzzlers . In: Frankfurter Allgemeine Zeitung , October 17, 2013. Accessed October 17, 2013.
  27. Google upset about a pot of tea
  28. Internet carbon study
  30. See e.g. B. Dirk Asendorpf : Against the separation. - Modern sorting technology has long since made the yellow sack superfluous. Nevertheless, the nonsensical billion dollar business continues. In: Die Zeit No. 12 of March 15, 2007
  31. Hydraulic balance ( Memento from April 7, 2016 in the Internet Archive )
  32. Focus Energiesparen from August 30, 2007
  33. ↑ Saving heating costs in the household (accessed on November 2, 2011)