Peak Demand Reduction in a Heat Pump Environment

Peak demand reduction in a heat pump environment is the controlled lowering of the highest electrical power drawn by a heat pump system or complete building during a defined time interval. It keeps heating, cooling and domestic hot water available while preventing compressors, electric heaters, pumps, electric vehicle chargers and other large loads from operating at maximum power at the same time.

Peak demand reduction uses compressor modulation, thermal storage, preheating, load prioritisation, staged operation and energy management. Its purpose is to reduce peak kilowatts without creating unacceptable comfort, hygiene or operational problems. It matters because peak power can determine electrical connection size, network charges, equipment capacity and local grid stress.

Peak demand reduction at a glance

• What it is: A measurable reduction in maximum electrical demand, expressed in kilowatts.
• What it does: It flattens the electricity demand profile while maintaining the required thermal service.
• How it is achieved: The system limits, delays, shifts or coordinates heat pump operation and other electrical loads.
• Why it matters: It can reduce connection requirements, demand-related costs, backup-heater use and pressure on the electricity network.

The International Energy Agency reports that heat pumps represented between 2% and 16% of annual peak electricity demand across major markets in 2024. The same analysis identifies thermal storage, digital controls and integration with other heating systems as important sources of demand flexibility.

Definition of peak demand reduction

Peak demand reduction is the reduction of the maximum average electrical power drawn during a specified measurement interval. The measurement point may be the heat pump, the complete heating plant or the building’s grid connection. The measurement interval may be 15 minutes, 30 minutes, one hour or another period defined by a tariff, meter or grid operator.

A complete definition must therefore state three elements:

1. The system boundary: What equipment is included?
2. The measurement interval: Over what period is demand averaged?
3. The baseline: What uncontrolled or previous peak is used for comparison?

A claim such as “the system reduces peaks” has little technical value unless these three elements are defined.

Peak demand at different system boundaries

Heat pump equipment peak

This is the maximum electrical input of the heat pump unit and its directly associated components. It may include the compressor, fan, source pump, circulation pump and internal electric heater.

This boundary is useful for heat pump product control. It does not show the complete load on the building connection.

Heating plant peak

This is the combined electrical demand of the heat pump plant. It can include multiple heat pumps, external circulation pumps, electric heaters, domestic hot-water equipment and hydraulic auxiliaries.

This boundary is important for plant-room electrical design and cascade control.

Building or site peak

This is the maximum import measured at the building’s point of connection. It includes the heat pump, lighting, appliances, ventilation, electric vehicle charging and other building loads. Photovoltaic generation and battery discharge can reduce the measured grid import.

This is usually the most relevant boundary for contracted power, demand charges, main-fuse capacity and grid connection studies.

Grid-level coincident peak

This is the combined demand of many buildings at the same time. A control action can reduce the peak of one building without reducing the wider network peak. Large-scale peak demand reduction therefore requires coordination, diversity and appropriate grid signals.

Peak demand is measured in kW, not kWh

A kilowatt measures power. It describes how fast electricity is being used at a given time.

A kilowatt-hour measures energy. It describes the total quantity of electricity consumed over time.

A heat pump can use the same number of kilowatt-hours per day while producing a lower peak in kilowatts. The control system achieves this result by spreading consumption across a longer period.

Basic peak demand calculation

Peak demand for a defined interval can be represented as:

Peak demand = maximum interval energy ÷ interval duration

For example, a building that imports 3.6 kWh during a 15-minute interval has an average demand of:

3.6 kWh ÷ 0.25 hours = 14.4 kW

A five-second compressor or motor surge is not the same as a 15-minute demand peak. Starting current remains important for cables, protection and voltage quality, but it may have little effect on a tariff based on average 15-minute demand.

Basic site-demand relationship

A simplified building power balance is:

Grid import = heat pump demand + auxiliary heating + other building demand + EV charging + battery charging − PV production − battery discharge

Peak reduction can then be calculated as:

Peak reduction in kW = baseline peak − controlled peak

Peak reduction in % = peak reduction ÷ baseline peak × 100

The baseline should represent comparable weather, occupancy, hot-water use and operating conditions.

Core purpose of peak demand reduction

The core purpose is to deliver the required heating, cooling and domestic hot water with a lower maximum electrical draw. The system changes when and how thermal energy is produced. It does not simply remove the thermal service.

A well-designed strategy follows a clear priority order:

1. Protect people, equipment and the building.
2. Maintain minimum comfort and domestic hot-water requirements.
3. Keep the heat pump within its permitted operating range.
4. Respect the building or grid power limit.
5. Optimise electricity cost, renewable energy use and system efficiency.

The control system should therefore distinguish between essential and flexible demand. Space heating may be temporarily reduced within a narrow comfort range. A domestic hot-water hygiene cycle, frost-protection function or safety-related process may have higher priority.

What peak demand reduction is intended to achieve

• Lower maximum grid import.
• Prevent avoidable electrical connection overload.
• Reduce simultaneous operation of large loads.
• Limit unnecessary electric resistance heating.
• Shift flexible heat production to suitable periods.
• improve the use of existing electrical infrastructure.
• Support dynamic tariffs and demand-response programmes.
• Preserve acceptable indoor conditions.

Peak demand reduction is successful only when the lower peak does not create a larger rebound peak later.

Why peak demand reduction is needed

A heat pump may be efficient over the year and still create a high electrical peak for a short period. Annual energy performance and maximum electrical demand are separate design questions. Both must be evaluated.

Cold weather increases electrical demand

The heating requirement of a building usually rises as outdoor temperature falls. At the same time, the efficiency of an air-source heat pump can decrease because the temperature difference between the heat source and heating system becomes larger.

The heat pump may therefore need more electrical input during the same period in which the building needs more heat. If an electric backup heater also starts, the electrical peak can rise sharply.

High flow temperatures increase compressor input

A heat pump generally requires more electrical power when it must produce a higher water temperature. This issue is common in renovations with small radiators, high heating curves or poorly balanced heat emitters.

Improving the building envelope, increasing emitter area and lowering the required flow temperature can reduce both energy use and peak electrical demand.

Electric backup heaters create large peaks

An electric resistance heater converts electricity to heat at approximately a one-to-one relationship. A 6 kW heater can therefore add almost 6 kW to the electrical demand.

The heater may start during very cold conditions, domestic hot-water charging, fault operation or an aggressive temperature recovery. Incorrect bivalence settings can allow the heater to operate when the compressor could still meet the load.

Morning recovery can create an avoidable peak

A large night-time temperature setback may appear to save energy. The subsequent morning recovery can force the heat pump, circulation system and electric heater to operate at high output together.

A flatter temperature schedule often produces a lower peak. It may also allow the heat pump to run at a lower flow temperature.

Domestic hot-water production can coincide with space heating

Domestic hot water normally requires a higher temperature than space heating. The heat pump may increase compressor speed or use an electric heater during tank charging.

A peak can occur when hot-water charging starts during a cold-weather heating period. Scheduling and storage can separate these demands.

Multiple electrified loads compete for the same connection

A modern building may contain a heat pump, electric vehicle charger, battery, ventilation system, cooking appliances and other large electrical loads. Each device may be acceptable on its own.

The problem occurs when several devices operate at maximum power together. Whole-building load coordination is therefore often more effective than heat pump control alone.

Commercial tariffs may include a power component

Some electricity and network tariffs charge partly for the highest measured demand. In these cases, a single high interval can influence costs for a month or longer.

Peak demand reduction addresses the kilowatt component. Energy efficiency addresses the kilowatt-hour component. A complete cost strategy should address both.

Grid connection capacity can limit a project

A high calculated peak may require a larger service cable, main distribution board, transformer or contracted connection. The upgrade may increase capital cost or delay the project.

A verified peak-control strategy may allow the building to use existing capacity more effectively. Acceptance depends on the network operator, protection design and local connection rules.

Renewable electricity requires flexible demand

Wind and solar production change over time. Heat pumps can move some electricity use to periods with greater renewable production by storing energy in water, a floor slab or the building structure.

This flexibility helps connect the electricity and heating sectors. It does not mean that every low-price period is automatically a low-grid-stress period.

Common causes of heat pump demand peaks

• Low outdoor temperature.
• High heating flow temperature.
• Electric backup-heater activation.
• Morning temperature recovery.
• Domestic hot-water charging.
• Defrost and post-defrost recovery.
• Simultaneous start of multiple heat pumps.
• Simultaneous EV or battery charging.
• Incorrectly configured bivalence points.
• Poor hydraulic balancing.
• Excessive setpoint changes.
• Emergency or fault operating modes.

Key features of effective peak demand reduction

Peak demand reduction is not one control command. It is a coordinated set of design, measurement and operating functions.

The main features are:

1. Peak measurement and baseline definition.
2. Correct heat pump and distribution-system sizing.
3. Dynamic power limiting.
4. Variable-speed compressor control.
5. Electric backup-heater management.
6. Thermal storage management.
7. Preheating and precooling.
8. Domestic hot-water scheduling.
9. Cascade and stage coordination.
10. Whole-building load management.
11. Forecasting and demand-response capability.
12. Rebound prevention and fail-safe control.

Detailed explanation of key features

Peak measurement and baseline definition

Definition: Peak measurement records electrical demand at a defined point and interval. The baseline represents the demand profile before a new control strategy is applied.

Purpose: It identifies when peaks occur and which devices create them. It also provides a reference for verifying the result.

Benefits: Accurate data prevents the system from solving the wrong problem. It separates heat pump peaks from whole-building peaks.

Example: A site may show a 20 kW main-meter peak even though the heat pump itself never exceeds 6 kW. The remaining peak may come from an 11 kW EV charger and other building loads.

The measurement interval should match the relevant tariff or connection requirement. A controller that reacts to instantaneous power may still need a rolling interval calculation to manage a 15-minute billing peak.

Correct sizing and low-temperature heat distribution

Definition: Correct sizing matches heat pump capacity, heat emitters and thermal storage to the building’s design heat requirement.

Purpose: It prevents both excessive cycling from oversizing and excessive backup-heater use from undersizing.

Benefits: Lower flow temperatures improve compressor efficiency and can reduce peak electrical input. Accurate sizing also produces more stable operation.

Example: Replacing undersized radiators in a renovation may allow the heating curve to fall from a high-temperature regime to a lower-temperature regime. The heat pump can then produce the same room heat with less electrical input.

The applicable national edition of EN 12831 provides a recognised basis for design heat-load calculation. Manufacturer data under standards such as EN 14825 should then be checked at the relevant source and sink temperatures, not only at a favourable nominal condition.

Dynamic power limiting

Definition: Dynamic power limiting sets a maximum permitted electrical demand for the heat pump plant or complete site.

Purpose: It prevents the measured demand from crossing a defined connection, tariff or operating threshold.

Benefits: It provides a direct and measurable peak-control function. A site-level limit can coordinate several flexible devices.

Example: A building has an 18 kW grid-import limit. When total import reaches 16.5 kW, the energy manager reduces EV charging and postpones non-essential hot-water reheating.

A hard limit reacts before the threshold is exceeded. A soft limit attempts to remain below the target but permits temporary exceptions for safety or essential service.

Variable-speed compressor control

Definition: A variable-speed compressor adjusts heat pump output instead of operating only at full output or stopping completely.

Purpose: It matches thermal production more closely to current building demand.

Benefits: Modulation can lower electrical demand, reduce unnecessary starts and produce a smoother load profile.

Example: Instead of running at 5 kW electrical input for short periods, a heat pump may operate for longer at 2.5 kW when the building requires only part load.

Modulation range matters. A nominally variable-speed unit may still have a relatively high minimum output. The designer should compare the minimum and maximum electrical input with the building’s actual operating range.

Electric backup-heater management

Definition: Backup-heater management controls when an internal or external resistance heater may operate and how much power it may use.

Purpose: It reserves resistance heating for conditions in which it is genuinely required.

Benefits: It can remove one of the largest avoidable contributors to peak demand. It can also improve operating-cost transparency.

Example: A controller blocks the heater during normal domestic hot-water recovery but allows it during a defined hygiene cycle or a compressor fault.

Important settings include the bivalence point, maximum heater stage, delay time, emergency override and domestic hot-water priority. A permanent heater lockout can be unsafe or unsuitable. The correct strategy is controlled availability.

Thermal storage management

Definition: Thermal storage holds useful heat or cooling for later use. It may consist of a buffer tank, domestic hot-water cylinder, floor slab, building mass or process store.

Purpose: It separates the time of heat production from the time of heat delivery.

Benefits: The heat pump can run before a peak period and reduce output during the peak. Storage can also support longer, more stable compressor operation.

Example: A buffer is charged before an evening tariff or connection peak. The heating circuits then draw stored heat while heat pump output is limited.

The approximate heat stored in water is:

Stored heat = water volume × 1.163 kWh/m³K × usable temperature difference

A 500-litre tank with a usable 10 K temperature range contains approximately:

0.5 m³ × 1.163 × 10 = 5.8 kWh of thermal energy

At a 4 kW building heat load, this idealised quantity represents about 1.45 hours of heat. Actual usable storage is lower because of stratification, temperature limits, losses and hydraulic requirements.

Storage should not be charged to an unnecessarily high temperature. Higher storage temperatures can reduce heat pump efficiency and may cancel part of the expected benefit.

Preheating and precooling

Definition: Preheating or precooling changes the building temperature slightly before a predicted peak period.

Purpose: It uses the building structure and heat-emission system as short-term thermal storage.

Benefits: It reduces the need for heat pump operation during the restricted period without requiring a very large water tank.

Example: An underfloor-heated building is raised by a small, controlled temperature margin before an evening peak. The heat pump then operates at reduced output while the slab releases heat.

The permitted temperature change should be small and occupancy-sensitive. Large setpoint increases can cause discomfort, excessive heat loss or reduced COP.

Domestic hot-water scheduling

Definition: Domestic hot-water scheduling controls when the storage tank is charged and which heat source may be used.

Purpose: It prevents hot-water production from coinciding with another predictable electrical peak.

Benefits: It separates a high-temperature load from space heating, EV charging or commercial process demand.

Example: A residential system completes its main tank charge before the morning household peak. A hotel uses demand forecasting to charge storage between occupancy-driven draw-off periods.

Hot-water control must preserve hygiene, minimum availability and local regulatory requirements. A peak strategy must never disable required hygiene functions without an approved alternative.

Cascade and stage coordination

Definition: Cascade control coordinates multiple heat pumps, compressor stages or heat sources.

Purpose: It activates only the capacity required for the current thermal load and electrical limit.

Benefits: It prevents several units from starting together. It can also select the most efficient available unit or source.

Example: A three-unit plant starts one heat pump at low load. The second unit starts only after the first reaches a defined operating point and the third remains available for design conditions or redundancy.

Stage delays, minimum run times and start sequencing should be coordinated with the peak interval. Poor staging can create a short but expensive simultaneous demand peak.

Whole-building load coordination

Definition: Whole-building load coordination manages the heat pump together with other flexible electrical devices.

Purpose: It protects the main connection rather than optimising each device independently.

Benefits: It addresses coincident demand from EV charging, batteries, ventilation, cooking equipment and other loads.

Example: A home energy management system gives space heating priority during a cold period. It reduces EV charging from 11 kW to 3.7 kW and delays battery charging.

The priority matrix should reflect the building’s function. A care facility, food process or hotel may apply different priorities from a single-family home.

Forecast-based control

Definition: Forecast-based control uses predicted weather, occupancy, hot-water demand, electricity price or PV production.

Purpose: It takes action before the expected peak rather than reacting after the threshold has been reached.

Benefits: It can charge storage gradually and avoid abrupt shutdowns. It also reduces the risk of a rebound peak.

Example: A controller detects a forecast cold front and pre-charges thermal storage during a moderate-temperature period when the heat pump can operate more efficiently.

A forecast is not a guarantee. The controller needs real-time correction and conservative fallback logic when the forecast is wrong.

Demand response and external grid signals

Definition: Demand response is an intentional change in electricity consumption following a price, grid or flexibility signal.

Purpose: It allows a heat pump to support the wider energy system within defined user and equipment limits.

Benefits: The building may receive tariff savings or flexibility payments while helping manage congestion and system balance.

Example: An aggregator requests a temporary 2 kW reduction from a portfolio of heat pumps. Each controller decides how much flexibility is available without violating local comfort constraints.

Demand response is one way to produce peak demand reduction. It is not the same as peak demand reduction itself. ACER defines demand response as an intentional adjustment of consumption in response to price changes or financial incentives for balancing or congestion management.

Rebound prevention and fail-safe control

Definition: Rebound prevention controls how the system returns to normal operation after a restricted period.

Purpose: It stops delayed loads from restarting at maximum power together.

Benefits: It prevents the system from moving the original peak to a later interval.

Example: After a one-hour demand-response event, the heat pump, water heater and EV charger restart in stages instead of simultaneously.

Fallback control should also define what happens after a lost meter signal, communication failure or invalid forecast. The heat pump should return to a safe local mode rather than remain indefinitely restricted.

Types and control models

The following classification is a practical engineering model. It is not a formal regulatory standard.

Reactive versus predictive control

Reactive control acts after demand approaches a threshold. It is simpler and depends mainly on reliable real-time metering.

Predictive control acts before the expected peak. It requires forecasts, thermal models or learned building behaviour. The strongest systems normally combine both methods.

Direct control versus EMS control

Direct control sends a limit or operating state to the heat pump. It is suitable when the heat pump is the main flexible load.

Energy management system control applies one site-level limit and distributes the available power between several devices. This method is more suitable for buildings with PV, batteries, EV charging or multiple heat pumps.

Peak demand reduction use cases

Single-family home with a heat pump and EV charger

Definition: A dwelling has several large electrical loads behind one residential connection.

Purpose: Prevent the heat pump and EV charger from producing an excessive coincident peak.

Benefits: The household may avoid main-fuse problems, use connection capacity more effectively and maintain heating priority.

Example: The energy manager reduces EV charging during domestic hot-water production and restores charging gradually after the tank reaches its target.

Home with photovoltaic generation

Definition: The heat pump shares the connection with an on-site PV system.

Purpose: Move flexible heating demand toward periods of local solar production.

Benefits: Grid import can fall, PV self-consumption can rise and thermal storage can replace some electrical storage demand.

Example: The system increases the buffer or domestic hot-water setpoint within defined limits when genuine PV surplus is available.

PV alone does not guarantee a lower winter peak. The coldest heating periods may occur before sunrise, after sunset or during low solar production.

Multi-family residential building

Definition: One central or cascaded heat pump system serves several dwellings.

Purpose: Manage morning and evening hot-water demand without excessive plant or connection power.

Benefits: Shared storage and diversity can reduce the required coincident capacity.

Example: The controller forecasts domestic hot-water draw-off and stages tank charging across lower-demand periods.

The strategy must preserve tenant comfort and transparent cost allocation. Individual room conditions and hot-water availability should remain within agreed limits.

Hotel, hospital or care facility

Definition: The building has continuous occupancy, high hot-water demand and strict service requirements.

Purpose: Reduce peak power without compromising hygiene, care functions or guest comfort.

Benefits: The operator can control demand charges and reduce simultaneous plant operation.

Example: A BEMS coordinates heat pumps, hot-water storage, laundry equipment and ventilation according to an operational priority schedule.

These buildings require conservative fallback logic. Critical service should take priority over tariff optimisation.

Office, school or retail building

Definition: Occupancy and HVAC demand follow a relatively predictable daily schedule.

Purpose: Reduce morning warm-up and simultaneous heating, ventilation and lighting peaks.

Benefits: Preconditioning and staged start-up can produce a flatter demand profile.

Example: Ventilation and heating circuits start sequentially before occupancy instead of all equipment starting at the same time.

Aggressive night setbacks should be evaluated carefully. The recovery peak may be more costly than the small overnight saving.

Commercial or industrial heat pump plant

Definition: A large heat pump supplies process heat, commercial hot water or a local heat network.

Purpose: Keep the plant within contracted capacity and coordinate production with process schedules.

Benefits: Thermal storage can separate electricity consumption from process heat delivery.

Example: A food-production site charges a hot-water store before a production shift and limits compressor stages during the site’s main electrical peak.

The business case may depend on capacity charges, connection reinforcement, operational flexibility and lost-production risk.

District heating or energy centre

Definition: One or more large heat pumps supply a heat network.

Purpose: Coordinate heat generation with grid conditions, electricity prices and storage availability.

Benefits: Large thermal stores can provide substantial operating flexibility.

Example: The plant increases output during high renewable production and reduces output during a network-constrained interval while storage maintains heat supply.

Connection-constrained new development

Definition: A project cannot obtain the full unconstrained electrical capacity within the required time or budget.

Purpose: Design the building around a verifiable import limit.

Benefits: The project may use a smaller agreed connection or avoid simultaneous load assumptions.

Example: The development uses a central site controller, staged EV charging, thermal storage and a heat pump power limit.

The grid operator must accept the proposed control and protection arrangement. A software promise alone is not a substitute for a connection study.

Cold-climate heat pump system

Definition: The heat pump operates in a climate with prolonged low outdoor temperatures, such as Finland or Alpine regions.

Purpose: Control the combined effect of high building load, lower source temperature and backup-heater demand.

Benefits: Correct sizing and heater management can prevent extreme winter peaks.

Example: The system reserves a limited heater stage for design conditions and blocks unnecessary heater use during normal hot-water recovery.

Reversible heat pump in a cooling-dominant period

Definition: The heat pump supplies cooling during warm conditions, as may occur in Spain, northern Italy or mixed-use buildings.

Purpose: Prevent cooling demand from coinciding with other afternoon or evening loads.

Benefits: Precooling, PV coordination and variable compressor control can reduce the cooling peak.

Example: The building is precooled slightly during strong PV production and then maintains comfort at reduced compressor output.

Benefits of peak demand reduction

Peak demand reduction can create value for the building owner, installer, facility manager and electricity network. The benefit depends on the site boundary, tariff and control quality.

Lower electrical connection requirements

A lower verified peak may reduce the required service capacity. This can affect cables, protective devices, switchgear, transformers and contracted power.

The benefit is strongest where a connection upgrade would otherwise be required.

Lower demand-related electricity costs

A capacity or demand tariff charges partly according to kilowatts. Reducing the highest measured interval can lower this part of the bill.

The controller must target the actual billing method. Reducing a peak outside the chargeable window may create no financial benefit.

Better use of existing infrastructure

A flatter demand profile increases the utilisation of existing electrical assets. The same cable or transformer serves more useful energy without being designed around a short, avoidable peak.

This benefit is relevant to both individual buildings and distribution networks.

Reduced reliance on electric resistance heating

Good heater control can prevent unnecessary resistance operation. This may reduce both peak demand and electricity consumption.

The heater should remain available for approved emergency, hygiene and design functions.

Greater renewable energy integration

Thermal storage allows heat pump demand to move toward periods with available wind, solar or local PV production. The building becomes a flexible electricity consumer rather than a completely fixed load.

The control should use actual surplus or system signals. A fixed midday schedule may not match renewable production every day.

Improved operational stability

Controlled staging and modulation can prevent abrupt demand changes. The heating plant operates with clearer priorities and fewer simultaneous starts.

Stable operation can also make faults and incorrect settings easier to identify.

Greater cost predictability

Monitoring reveals which operating modes create the largest peaks. Facility managers can connect technical events with tariff outcomes.

This information supports maintenance, optimisation and future investment decisions.

Increased grid hosting capacity

At aggregate scale, coordinated flexible loads can reduce local congestion and defer some network reinforcement. This requires many devices to respond at the right time and location.

Uncoordinated price response can have the opposite effect by causing many devices to restart together.

Potential equipment benefits

Peak control may reduce compressor cycling and backup-heater runtime when it promotes longer, stable operation. It can also distribute operating hours across a cascade.

Poor control can increase cycling or force operation at inefficient temperatures. Equipment benefits are therefore conditional, not automatic.

Selection criteria for a peak demand reduction system

The system should be selected from the required outcome backwards. The first question is not which controller to buy. The first question is which peak must be reduced.

Define the control objective

Specify whether the target is:

• Heat pump input power.
• Heating plant power.
• Whole-building grid import.
• Contracted capacity.
• A tariff demand peak.
• A grid-operator limit.
• An aggregator flexibility commitment.

One control strategy may not satisfy every objective.

Define the measurement interval

Determine whether the relevant peak is:

• Instantaneous power.
• A rolling 15-minute average.
• A fixed 15-minute meter interval.
• A 30-minute average.
• An hourly average.
• A daily, monthly or annual maximum.
• A peak within specific tariff hours.

The controller’s data resolution and response time must support the applicable method.

Identify the baseline

Use interval data from a representative period. Adjust for outdoor temperature, occupancy, production and domestic hot-water use where necessary.

For a new building, create a simulation that includes realistic simultaneity rather than adding every nameplate maximum.

Analyse the maximum electrical input

Review more than nominal compressor power. Include:

• Maximum compressor input at relevant conditions.
• Internal electric heater.
• External heater.
• Source pumps and fans.
• Circulation pumps.
• Defrost-related components.
• Domestic hot-water immersion heater.
• Multiple-unit simultaneity.
• Emergency operating modes.

Evaluate thermal flexibility

Determine how long heat production can be reduced without violating constraints.

Assess:

• Buffer volume.
• Domestic hot-water storage.
• Floor-slab capacity.
• Building thermal mass.
• Indoor temperature tolerance.
• Process storage.
• Occupancy schedule.
• Heat-loss rate.
• Required recovery time.

Check the heating distribution system

Low-temperature emitters improve heat pump performance. High-temperature radiators or poorly balanced circuits can reduce available flexibility.

A building that loses temperature quickly may require more storage or a smaller control event.

Review compressor modulation

Check minimum and maximum input at actual operating temperatures. A wide modulation range normally provides more control options.

Also verify minimum run time, restart delay and permitted ramp rate.

Specify backup-heater logic

The control specification should state:

• Permitted operating conditions.
• Maximum stage or input.
• Delay before activation.
• Emergency override.
• Hygiene-cycle behaviour.
• Fault-mode behaviour.
• Interaction with the site power limit.

Verify meter and communication interfaces

The system may require data from a smart meter, inverter, battery, EV charger or building management system.

Verify protocol, update rate, data quality, cybersecurity, ownership and fallback behaviour. “Compatible” should mean tested at the required functional level.

Check regional tariff and DSO rules

Tariff structures and control obligations differ between Germany, Austria, Switzerland, Italy, Spain, Poland, Finland and other markets. The design should follow the rules at the specific connection point.

Do not copy a German power limit or Austrian tariff assumption into another jurisdiction.

Define priority and comfort rules

The control specification should state which loads may be reduced first.

A typical residential order may be:

1. Battery charging.
2. EV charging.
3. Optional hot-water boost.
4. Space-heating setpoint adjustment.
5. Compressor limitation.
6. Safety or emergency functions remain protected.

The correct order depends on the building.

Include rebound control

The controller should stagger the return of delayed loads. It should not release every restriction at the same time.

A ramped return is particularly important after a tariff period or grid event that affects many buildings.

Require commissioning and data access

A peak-control function should be tested under realistic conditions. The operator should be able to review interval power, control commands, temperatures, heater operation and alarms.

Without data access, underperformance can remain invisible.

Evaluate lifecycle support

Check whether software updates, remote diagnostics, spare parts and integration support will remain available.

Peak control is an operational function. Its value depends on long-term configuration and maintenance, not only initial installation.

Peak demand reduction compared with related concepts

Peak demand reduction versus peak load management

Peak demand reduction is the result. It is the measured decrease in maximum kilowatts.

Peak load management is the process. It includes the controls, schedules and operating rules used to achieve that result.

A peak load management system can be installed without producing a meaningful reduction if it is poorly configured.

Peak demand reduction versus energy efficiency

Energy efficiency reduces the energy required to deliver a service. It is normally measured in kilowatt-hours, seasonal performance or useful heat per unit of input.

Peak demand reduction reduces the highest rate of electricity use. It is measured in kilowatts.

A strategy can improve both. However, preheating to a high temperature may reduce the peak while increasing total energy consumption.

Peak demand reduction versus load shifting

Load shifting moves electricity consumption from one time to another. It may reduce the original peak.

It does not guarantee a lower maximum. Delayed loads can create a new rebound peak.

Peak demand reduction versus demand response

Demand response starts with an external price, grid or market signal. Peak demand reduction may be the requested outcome.

A building can also reduce its own peak without participating in a formal demand-response programme.

Peak demand reduction versus PV self-consumption

PV self-consumption uses locally generated solar electricity inside the building. It can reduce grid import while the sun is available.

Peak demand reduction focuses on the highest grid or equipment demand. The annual maximum may occur when PV production is low.

Peak demand reduction versus battery peak shaving

A battery can discharge during a peak and reduce grid import. The heat pump may continue operating at the same electrical input.

Battery peak shaving is therefore an electrical storage method for achieving site-level peak demand reduction.

Peak demand reduction versus load shedding

Load shedding disconnects or reduces loads when necessary. It can be abrupt and may affect service.

Peak demand reduction normally uses thermal flexibility, modulation and prioritisation to avoid unnecessary loss of comfort.

Peak demand versus design heat load

Design heat load is the thermal power required to keep a building warm at defined outdoor conditions. It is expressed in thermal kilowatts.

Peak electrical demand is the electrical input drawn by the heating system or building. The two values are related through heat pump efficiency, but they are not interchangeable.

Integration with other systems

Integration with photovoltaic systems

Definition: PV integration links heat pump operation with measured on-site solar production.

Purpose: It shifts flexible heating, cooling or hot-water production to periods of genuine PV surplus.

Benefits: It can reduce grid import, increase self-consumption and charge thermal storage.

Example: The controller starts buffer charging only when export at the main meter exceeds a defined threshold.

The system should use net site flow rather than inverter production alone. A building may produce solar electricity while still importing power because other loads are larger.

Integration with battery storage

Definition: Battery integration coordinates electrical charging and discharging with heat pump demand.

Purpose: It prevents the battery and heat pump from charging from the grid at full power together and allows battery discharge during a site peak.

Benefits: Batteries provide faster electrical response than most thermal systems.

Example: The battery discharges when the heat pump enters domestic hot-water mode and the site approaches its import limit.

Battery state of charge must be considered. A battery cannot provide peak support when it is empty or reserved for backup power.

Integration with electric vehicle charging

Definition: EV integration treats charging power as a controllable building load.

Purpose: It coordinates two high-power electrified technologies behind one connection.

Benefits: Charging can often be reduced temporarily with little effect on mobility.

Example: The EV charger accepts a variable current setpoint from the HEMS and increases power again after the heating peak.

The control should consider required departure time and minimum charge level.

Integration with a smart meter

Definition: A smart meter supplies interval or near-real-time data at the electrical connection.

Purpose: It gives the controller an accurate view of net grid import.

Benefits: The system can manage the complete site rather than estimate demand from individual devices.

Example: A meter reports import every few seconds while the controller maintains a rolling demand value for the tariff interval.

The available update rate and data interface vary by meter and country. Billing data access may be slower than operational control requires.

Integration with a HEMS, BEMS or BMS

Definition: An energy or building management system coordinates the heat pump with the wider building.

Purpose: It applies site priorities, schedules, limits and optimisation rules.

Benefits: It provides one control layer for multiple energy assets.

Example: A BEMS allocates available grid power between a heat pump cascade, ventilation plant, EV chargers and battery.

The heat pump should retain its local equipment-protection functions. The higher-level system should request an operating state or limit, not bypass compressor safety.

Integration with dynamic electricity tariffs

Definition: Dynamic tariff integration changes operation according to time-varying electricity prices.

Purpose: It moves flexible demand toward lower-price periods.

Benefits: It can reduce energy cost and create an economic incentive for thermal storage.

Example: The system prepares domestic hot water before an expensive evening period.

The cheapest period is not always the period with the lowest local grid load. Price optimisation and peak limiting should therefore be separate control constraints.

Integration with grid operators or aggregators

Definition: The heat pump or site controller receives an external flexibility or power-limit signal.

Purpose: It provides congestion management, balancing or another grid service.

Benefits: Flexible demand can support network operation and may earn a tariff reduction or payment.

Example: A DSO sends a temporary site-import limit and the EMS distributes the available power between controllable devices.

Participation rules, baselines and communication standards vary by jurisdiction.

Integration with weather forecasts

Definition: Weather integration uses forecast outdoor temperature, solar radiation and other relevant conditions.

Purpose: It predicts building heat demand and likely heat pump performance.

Benefits: The controller can prepare storage before a cold period and avoid excessive preheating during mild weather.

Example: The heating curve is adjusted gradually before a forecast temperature drop.

Forecast-based decisions should be corrected by measured indoor and outdoor conditions.

Integration with room control

Definition: Room control supplies temperature, humidity and occupancy information.

Purpose: It defines the real comfort margin available for preheating, precooling or temporary reduction.

Benefits: Flexibility can be allocated without applying the same temperature change to every room.

Example: South-facing rooms with solar gains receive less preheating than north-facing rooms.

Room control can also identify zones that are already overheated and should not be used as additional thermal storage.

Integration with thermal storage

Definition: Storage integration combines tank temperatures, available capacity and predicted load in the control decision.

Purpose: It ensures that stored heat is available before the peak period starts.

Benefits: The system can estimate the duration and magnitude of available flexibility.

Example: The controller calculates that a buffer contains enough usable energy to reduce heat pump power for 45 minutes.

Storage temperature alone may not describe usable capacity. Stratification, return temperature and required flow temperature also matter.

How to implement peak demand reduction

A successful project begins with the electrical and thermal problem. Control settings are selected only after the peak source and required service have been defined.

Step 1: Define the system boundary

Decide whether the target applies to the heat pump, heating plant or complete site. Identify the exact meter or measurement point.

Step 2: Define the peak metric

Document the interval, tariff window, contracted limit or grid-control requirement. State whether the target is instantaneous, rolling or fixed-interval demand.

Step 3: Collect representative data

Measure site import, heat pump input, heater operation, temperatures and major flexible loads. Include cold weather, hot-water peaks and relevant production periods.

Step 4: Calculate the thermal requirement

Complete a recognised heat-load calculation. Verify actual flow temperatures, emitter capacity, storage and domestic hot-water demand.

Step 5: Identify the peak causes

Separate structural demand from avoidable simultaneity. Determine whether the main cause is the compressor, backup heater, hot-water charging, EV charging or another load.

Step 6: Define operational constraints

Set acceptable room-temperature variation, minimum tank temperatures, hygiene rules, process requirements and emergency overrides.

Step 7: Select the reduction methods

Choose a suitable combination of:

• Modulation.
• Heater limitation.
• Storage.
• Preconditioning.
• DHW scheduling.
• Load prioritisation.
• Cascade staging.
• Battery discharge.
• EV charging control.
• Demand response.

Step 8: Configure the control hierarchy

Define which controller has authority over each function. Avoid conflicting commands from the heat pump, HEMS, BMS, tariff application and grid interface.

Step 9: Test worst-case operation

Test cold-weather demand, domestic hot-water recovery, defrost, heater activation, communication failure and recovery after a restriction.

Step 10: Verify the result

Compare the controlled peak with the agreed baseline. Check both peak reduction and service quality.

Step 11: Check for rebound

Review the intervals immediately after each event. Tune restart delays and ramp rates where necessary.

Step 12: Monitor and improve

Track seasonal performance, backup-heater energy, comfort deviations and peak demand. Update the strategy when tariffs, occupants or connected equipment change.

Measuring peak demand reduction performance

The main performance indicator is the reduction in maximum electrical power. A complete evaluation should also show whether the result affected energy efficiency, comfort or reliability.

Core performance indicators

• Maximum heat pump electrical input in kW.
• Maximum heating plant input in kW.
• Maximum whole-site grid import in kW.
• Absolute peak reduction in kW.
• Percentage peak reduction.
• Peak duration.
• Demand during the tariff peak window.
• Rebound peak after control release.
• Electric heater energy in kWh.
• Compressor starts.
• Seasonal performance factor.
• Indoor temperature deviation.
• Domestic hot-water availability.
• Number and duration of failed control events.
• Available flexible capacity in kW.
• Available flexibility duration.

Illustrative measurement example

A building has a baseline 15-minute peak of 24 kW. After implementing EV coordination, heater limitation and domestic hot-water scheduling, the maximum comparable interval is 16.5 kW.

The reduction is:

24 kW − 16.5 kW = 7.5 kW

The percentage reduction is:

7.5 ÷ 24 × 100 = 31.25%

This figure is meaningful only when the controlled and baseline periods have comparable outdoor temperature, occupancy and thermal demand.

Illustrative coincident-load example

An uncontrolled building could contain:

• Heat pump compressor: 5 kW.
• Electric backup heater: 6 kW.
• Pumps and fans: 0.5 kW.
• EV charger: 11 kW.
• Other building loads: 3 kW.

The coincident total is 25.5 kW.

A coordinated operating state could contain:

• Modulated compressor: 4 kW.
• Backup heater: 0 kW.
• Pumps and fans: 0.5 kW.
• Reduced EV charging: 3.7 kW.
• Other building loads: 3 kW.

The controlled total is 11.2 kW. This is an illustrative calculation, not a recommended universal limit. The permissible reduction depends on thermal demand and equipment constraints.

Limits, risks and safeguards

Peak demand reduction should improve the energy system without creating hidden operational problems. The main risks arise when the power target is given priority over thermal reality.

Rebound peaks

Delayed heating, hot-water and charging loads may restart together. The new peak can equal or exceed the original peak.

Safeguard: Use staged recovery, ramp limits and minimum restart delays.

Reduced heat pump efficiency

Preheating a tank or building to an unnecessarily high temperature increases compressor lift. The resulting COP reduction can increase total electricity consumption.

Safeguard: Use the smallest effective temperature increase and include predicted COP in the control decision.

Comfort loss

An overly restrictive power limit may allow room temperatures to fall too far during cold weather.

Safeguard: Define minimum room temperatures, event duration and recovery capacity before commissioning.

Domestic hot-water shortage

Moving tank charging without understanding draw-off patterns can reduce availability.

Safeguard: Use minimum storage temperatures, demand forecasting and protected hygiene cycles.

Excessive compressor cycling

A rapidly changing external limit can force repeated starts and stops.

Safeguard: Respect minimum run time, minimum off time, modulation range and ramp-rate limits.

Excessive backup-heater use after an event

A long restriction may leave a large thermal deficit. The heater may then start during recovery.

Safeguard: Predict the post-event load and terminate the event before the deficit exceeds compressor recovery capacity.

Insufficient thermal storage

A buffer tank may be too small or may not have a useful temperature range.

Safeguard: Calculate usable thermal capacity rather than relying on nominal tank volume.

Incorrect dependence on PV

A control strategy may assume that solar generation will be available during the winter peak.

Safeguard: Complete connection and peak calculations without assuming coincident PV unless an accepted control or storage arrangement guarantees the result.

Communication failure

The meter, cloud service, inverter or grid connection may stop providing data.

Safeguard: Use local fallback control, data-quality checks, alarms and a safe default operating mode.

Conflicting optimisation objectives

A tariff controller may request full operation while a site peak controller requests a reduction.

Safeguard: Establish a formal priority order. Safety and connection limits should normally override price optimisation.

Cybersecurity and data protection

Connected controls exchange building, meter and operational data.

Safeguard: Apply controlled access, supported protocols, software updates, logging and relevant national cybersecurity requirements.

Regulatory and standards context

The regulatory context below reflects the position in August 2026. National rules, tariff values and DSO requirements should be checked for each project.

European Union

The revised Energy Performance of Buildings Directive supports buildings that can sense, interpret and respond to operating conditions, occupant needs and external energy-grid signals. The EU Smart Readiness Indicator specifically evaluates energy flexibility and storage alongside heating, cooling, hot water, electricity and building controls. This supports the policy direction toward grid-interactive buildings, but it does not create one universal peak-demand limit for every heat pump.

The IEA’s 2026 policy toolkit recommends connected heat pump controls that can provide flexibility and contribute to peak-demand reduction. It also identifies dynamic electricity pricing as a method for encouraging flexible demand.

Germany

Germany’s rules under §14a EnWG cover new controllable consumption devices with a grid-connection capacity above 4.2 kW, including heat pumps and associated electric heaters. Since 1 January 2024, affected devices must be controllable. During a specific local network risk, the network operator may temporarily reduce the grid draw to a defined minimum, with a standard 4.2 kW minimum and separate calculation rules for larger or cascaded systems. Operators receive a network-charge reduction in return.

Germany also requires electricity suppliers to offer dynamic electricity tariffs from 2025. Customers need an intelligent metering system to use such a tariff. Dynamic tariffs can support load shifting, but a separate site peak limit may still be required.

Austria

For 2026, E-Control introduced a network-tariff option for eligible network-level 7 customers that reduces the energy-related network charge during defined summer daytime hours. The measure is intended to encourage consumption during periods of high PV production and requires the relevant smart-meter data arrangements.

E-Control’s July 2026 materials also describe a proposed future tariff structure with a stronger capacity component based on the highest 15-minute monthly demand. The published values represent an intended end state and consultation position, not a universal current tariff. The proposal illustrates why short electrical peaks are becoming increasingly important in Austrian system planning.

Switzerland

Swiss rules from 2026 provide a clearer framework for dynamic network tariffs. ElCom states that network operators are increasingly introducing new dynamic models, particularly for network charges, to improve grid utilisation and reduce reinforcement needs. Local products and implementation differ by network operator, and no operator had made a dynamic tariff the standard tariff for 2026 at the time of ElCom’s publication.

SG Ready

The German Heat Pump Association’s SG Ready label identifies heat pumps and compatible components that support a defined control interface. Version 3.1 has applied since 25 February 2026 and describes control through three digital operating states. Compatible components can include inverters, energy managers, FNN control boxes and automation equipment.

SG Ready is an interface capability. It does not by itself prove that a building will achieve a specific peak reduction. The complete hydraulic, electrical and control system must still be engineered and commissioned.

Relevant technical standards

• EN 12831: Applicable national methods for building design heat-load calculation.
• EN 14825: Seasonal performance and declared heat pump performance under defined conditions.
• ISO 52120-1:2021: Framework for the contribution of building automation, controls and building management to building energy performance.
• ISO 50001:2018: Framework for systematic energy management and continual improvement.

Standards support design and measurement. They do not replace project-specific tariff analysis, electrical design or DSO approval.

Peak demand reduction turns a heat pump from an unmanaged electrical load into a coordinated part of the building energy system. It lowers maximum demand by combining correct system sizing, low-temperature heat distribution, compressor modulation, backup-heater control, thermal storage and whole-building energy management.

The target must always be defined in kilowatts, at a specific measurement point and over a specific interval. The result must then be verified against a representative baseline. A good system reduces the peak without creating a rebound, comfort problem or efficiency penalty.

For iDM Energiesysteme GmbH, the strongest product position is a complete, connected heat pump system with a defined peak target. The heat pump, NAVIGATOR control, storage, metering and external integrations should be specified as one operating architecture.

Frequently asked questions

What is peak demand reduction in a heat pump system?

It is the reduction of the highest electrical power drawn by the heat pump plant or complete building during a defined interval. The system achieves it by limiting, shifting or coordinating flexible demand.

Does peak demand reduction save electricity?

It can, but this is not guaranteed. Limiting backup-heater operation or lowering flow temperatures can reduce energy use. Preheating to a higher temperature may reduce the peak while increasing total electricity consumption.

Is a buffer tank required?

Not always. A building may use a floor slab, domestic hot-water tank, building mass or modulating compressor as part of the strategy. A buffer is useful only when its hydraulic function and usable storage capacity match the system requirement.

Can a heat pump simply be switched off during a peak?

Temporary shutdown may be possible, but it is not always the best method. Modulation, storage and load prioritisation normally provide a smoother result. The system must protect comfort, hygiene, frost protection and compressor limits.

How much peak reduction is possible?

There is no universal percentage. The available reduction depends on backup-heater use, storage, building inertia, other electrical loads and the duration of the peak period. A measured baseline and site simulation are required.

Does photovoltaic generation remove the heat pump peak?

Not necessarily. Winter peaks often occur when solar production is low or unavailable. PV can reduce daytime grid import, but connection planning should not assume that PV will always coincide with the maximum heating demand.

Is a dynamic tariff the same as peak demand reduction?

No. A dynamic tariff changes the price of electricity over time. Peak demand reduction limits the maximum power. A low-price schedule can create a new peak if many devices start together.

Does SG Ready guarantee peak reduction?

No. SG Ready confirms a defined interface capability. The controller, meter, hydraulic system, building and operating settings determine the actual result.

Is peak demand reduction relevant for residential buildings?

Yes. Homes increasingly combine heat pumps, EV chargers, PV and batteries. Coordinating these devices can protect the connection and support dynamic tariffs or grid-control requirements.

What data is required?

At minimum, the project needs electrical demand at the relevant measurement point. Better results are possible with heat pump input, electric-heater state, temperatures, weather, domestic hot-water demand and major flexible-load data.

What is a rebound peak?

A rebound peak occurs when delayed loads restart after a restriction and create a new maximum. Staged recovery and predictive control reduce this risk.

Can peak demand reduction affect comfort?

Poorly configured control can affect comfort. Correct control defines minimum temperatures, maximum event duration and protected hot-water functions before reducing demand.