Demand Response · Glossary

Demand response (German: Nachfragereaktion) refers to the targeted adjustment of electricity consumption. It is triggered by price signals, grid signals or contractually agreed control requirements. The consumption side is thus no longer entirely passive. It provides the power system with a controllable, or at least influenceable, load. Demand response is therefore a form of demand-side flexibility.

In European law, the German-language version uses the term "Laststeuerung". Electricity Market Directive (EU) 2019/944 understands this as final customers changing their electricity consumption relative to their usual or current pattern. This can be a response to market signals, such as time-varying electricity prices or incentive payments. It can also mean that a final customer, alone or through an aggregator, offers to reduce or increase its demand at a certain price on an organised electricity market. Important: under this definition, not only reducing but also deliberately increasing consumption counts as demand response.

Power, energy and timing

Usually it concerns a change in electrical power over a certain period. Power is the amount of electricity drawn at a given moment per unit of time and is expressed in kilowatts or megawatts. Energy, by contrast, is measured in kilowatt-hours or megawatt-hours. For demand response this distinction is central. A heat pump can reduce its power for an hour and reheat later without lowering the daily heat demand. An electric car can shift charging from 6 p.m. to 2 a.m. and still charges the same amount of energy into the battery. An industrial process, on the other hand, can offer a load reduction: production is postponed, throttled or, in individual cases, skipped entirely.

Demand response is therefore not the same as saving energy. With energy efficiency, the same service for the user is provided with less energy, for example through a more efficient motor or a better-insulated building envelope. With demand response, the benefit to the consumer often stays the same; only the timing of consumption changes. Load shifting can leave total electricity consumption unchanged and still be very valuable. This applies when it avoids expensive demand peaks, reduces grid congestion or uses periods with plenty of wind and solar power.

Demand response should also be distinguished from classic load management. Load management is a broad term for the technical and organisational control of consuming devices and installations. Demand response more precisely means the reaction to an external signal or to a contractual requirement. An example: a business that internally sequences its machines so that its own peak load falls is practising load management. If this reaction is additionally used on the electricity market, for system services or for relieving the grid, it is demand response in the narrower sense.

Price, grid and control

Demand response can be triggered by different signals. Dynamic electricity tariffs link the energy price, i.e. the price per kilowatt-hour, to exchange prices. The price then changes with fluctuations on the spot market. Other price components such as grid charges, taxes and levies generally do not follow the exchange price. At low prices it pays to increase flexible loads, such as charging or heat generation. At high prices, consumption is shifted or reduced. This form suits above all consumers who can automatically link their load to prices and whose comfort or production does not suffer directly as a result.

Grid-related signals follow a different logic. A distribution system operator may have a bottleneck on a particular line or transformer even when the wholesale price is currently low. Additional local consumption can then burden the grid even though it would be worthwhile on the market. Conversely, it can relieve a grid if a lot of solar power is consumed directly on site, even if the market price gives no strong signal for this. Anyone who wants to understand demand response must therefore distinguish between scarcity on the market and scarcity in the grid. The two can coincide, but do not have to.

A third form is direct or automatic control according to contractual or statutory rules. This includes controllable devices such as private charging points, heat pumps or battery storage, whose power consumption may be limited under defined conditions. For consumers, it matters not only whether the device is technically controllable. Also important are what they receive in return, which interventions are permitted, how long they may last and what minimum supply remains guaranteed.

Legal framework in the EU and Germany (as of November 2026)

At EU level, Directive (EU) 2019/944 obliges Member States to permit and promote demand response, including through aggregation. Final customers, alongside generators, are to be able to participate in all electricity markets without discrimination. Distribution system operators are to be able to procure flexibility services, including from providers of demand response, where this cost-effectively replaces or defers grid expansion. Member States may provide for financial compensation toward suppliers or balance responsible parties that are directly affected by the activation of demand response. How this is implemented in detail is regulated by each country itself.

In Germany, § 41a of the Energy Industry Act (Energiewirtschaftsgesetz, EnWG) is particularly important for price-based demand response. Under it, electricity suppliers must, where technically feasible and economically reasonable, offer a tariff that creates an incentive to save or to steer consumption, for example a load-variable or time-of-day tariff. Since 1 January 2025, all electricity suppliers must offer customers with an intelligent metering system a contract with a dynamic tariff. Previously this applied only to large suppliers. In addition, suppliers must provide information on the costs, advantages, disadvantages and risks of such contracts.

For grid-oriented control of smaller installations, § 14a EnWG applies together with the determinations of the Federal Network Agency (Bundesnetzagentur). The law names as controllable consumption devices in particular heat pumps, non-publicly accessible charging points for electric vehicles, cooling installations, electricity storage and electric night storage heaters. Since 1 January 2024, newly commissioned installations in the low-voltage grid with more than 4.2 kilowatts of grid connection capacity fall under the new rules. The grid operator may temporarily "dim" their electricity draw when the local grid is at risk of overload. With direct control, a minimum power of 4.2 kilowatts per installation must in principle be maintained. The operator may not switch them off completely. The remaining household electricity is not affected, and feed-in, for example from a photovoltaic system, is not limited either. In return, operators receive a reduced grid charge. The grid operator may also no longer refuse or delay the connection of such installations by citing possible local overload.

There are transitional rules for older installations. Installations that went into operation before 2024 and already have a control agreement keep the old conditions until 31 December 2028 and then move to the new regime. Existing installations without such an agreement remain permanently exempt but can switch voluntarily. For night storage heaters, the previous rules continue to apply permanently. These controllable consumption devices are thus a statutorily regulated special case of grid-oriented demand response. It is not voluntary and market-driven but an exchange: connection and a cheaper grid charge in return for limited interventions.

Why demand response is becoming more important in the power system

In the power system, generation and consumption must be in balance at every moment. In the past, this was solved mainly on the generation side: power plants were ramped up or down, reserves were held and load forecasts were matched with controllable generation. With more wind and solar power, this changes. Part of generation follows the weather rather than demand. As a result, the value of consumption that can shift in time rises.

Demand response can smooth the residual load. This is the demand that remains after deducting feed-in from wind and solar. If many flexible consumers draw more in hours with plenty of renewable electricity and less in scarce hours, the need for expensive peaking power plants, for storage and for curtailment of renewable installations falls. How large the effect is depends on the scale, the response speed and the reliability of the loads.

Demand response becomes particularly important through electrification. Heat pumps, electric vehicles, electrolysers and electric industrial processes increase electricity consumption but at the same time bring new controllable loads. An electric car often stands for many hours but needs only part of that time for charging. A heat pump can step aside for a limited time using the thermal mass of the building or a buffer tank. Electrolysers can link their production to electricity prices, provided hydrogen demand, storage and economics allow it. This flexibility does not arise automatically with the connection of the installations, however. It requires metering systems, communication channels, suitable tariffs, control technology and rules on access.

Common misconceptions

Demand response is not a programme of going without. In many applications nobody sits in the dark, and no production is lost without replacement. The room for manoeuvre often lies in heat storage, battery capacity, intermediate buffers in processes or time tolerances. The comfort limit nevertheless remains a real limit. A household accepts different interventions than a cold store, a data centre or a chemical plant. Demand response is reliable only if product, contract and control take these limits into account.
Not every flexible consumer automatically helps the grid. Anyone who responds only to exchange prices may ramp up in a low-price hour at the same time as many others. If these loads are concentrated in the same distribution grid, a local bottleneck can arise. The Federal Network Agency expressly cites as an example electricity storage units that are charged simultaneously under favourable dynamic tariffs. The problem is less flexibility itself than the lack of coordination between market price, grid state and local connection capacity.
Demand response is not the same as digital meters. A smart meter can be a prerequisite because it records consumption more precisely in time and makes variable tariffs billable. In Germany, an intelligent metering system is, for example, a prerequisite for the entitlement to a dynamic tariff. The meter itself does not create flexibility, however. A washing machine that runs at a different time of day brings little to the system. A charging park, a heat pump with storage or an industrial process can achieve considerably more if power, duration and callability are plannable.
The term "consumer" is also blurry here. Many actors are at the same time consumers, generators and storage operators. A household with a photovoltaic system, battery storage, heat pump and electric car can draw electricity, feed in, store temporarily and shift load. An industrial company can buy on the spot market, offer balancing power and optimise its connection capacity.

Institutional prerequisites

Demand response rarely fails because of a single missing technology. The more difficult question is usually who is assigned benefits, costs and responsibility. If a household lets its heat pump be controlled in a grid-serving way, the grid operator may save grid expansion or avoid a bottleneck. The household, however, bears the residual risk for its comfort, the costs of controllability and part of the complexity. Tariffs and grid charge rules must pass on this benefit in such a way that participation demonstrably pays off. The grid charge reduction under § 14a EnWG is an example of this.

An aggregator pools many small flexible loads and makes them usable for markets or grid operators. A single electric car is too small and too uncertain for the wholesale market. Thousands of vehicles together can offer relevant load shifting if charging states, departure times and users' wishes are taken into account. This raises new questions: Who may control? Who is liable in the event of faulty control? How are data protected and revenues distributed? And what takes priority when grid security, customer wishes and market optimisation come into conflict? EU law addresses some of these questions, such as compensation toward affected suppliers. The details, however, are left to national rules.

For transmission system operators, demand response can help stabilise the overall system, for example through balancing power or lower scarcity peaks. For distribution system operators, the local loading of lines and transformers is the main concern. Suppliers and electricity traders are interested above all in procurement costs and deviations in their balancing group. These perspectives do not automatically coincide. Conflicts arise where technical possibilities, market rules and political responsibilities diverge.

Classification

Demand response shows that electricity consumption cannot be described by annual energy volume alone. Timing, location, power level, duration and reliability of the response determine its value. A kilowatt-hour on a windy night affects costs and grid operation quite differently from a kilowatt-hour in a cold, low-wind evening peak. Not every demand burdens the system equally, and not every shift helps it. Demand response denotes the part of consumption that, under clear rules, can respond in such a way that market, grid or system security is measurably relieved.

Sources

Richtlinie (EU) 2019/944 mit gemeinsamen Vorschriften für den Elektrizitätsbinnenmarkt (konsolidierte Fassung) — Europäische Union, EUR-Lex; 2019-06-05 (konsolidierte Fassung vom 2024-07-16). Art. 2 Nr. 20 (Begriff Laststeuerung); Art. 17 (Laststeuerung durch Aggregierung); Vorschriften zur Flexibilitätsbeschaffung durch Verteilernetzbetreiber
§ 41a EnWG – Lastvariable, tageszeitabhängige oder dynamische und sonstige Stromtarife sowie Festpreisverträge — Bundesministerium der Justiz / Bundesamt für Justiz (gesetze-im-internet.de); unbekannt (abgerufen 2026-11-11). § 41a Abs. 1, 2, 6
§ 14a EnWG – Netzorientierte Steuerung von steuerbaren Verbrauchseinrichtungen und steuerbaren Netzanschlüssen; Festlegungskompetenzen — Bundesministerium der Justiz / Bundesamt für Justiz (gesetze-im-internet.de); unbekannt. § 14a Abs. 1 und 3 (laut Suchergebnis)
Integration von steuerbaren Verbrauchseinrichtungen — Bundesnetzagentur; unbekannt (abgerufen 2026-11-11). Abschnitte Betroffene Anlagen und Dimm-Regelungen, Bestandsanlagen, Stromspeicher, PV-Anlage
Dynamische Stromtarife — Bundesnetzagentur; unbekannt. Verbraucherportal, Abschnitt zur Kopplung des Arbeitspreises an den Börsenstrompreis

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Edited by eCMS on 11.11.2026 18:49