Heat pumps are one of the most important technologies in the residential energy transition — but they are also significant electricity consumers. A heat pump in a well-insulated Belgian home might consume 3,000-5,000 kWh of electricity per year for heating and hot water. At standard fixed tariff rates, that is a meaningful cost. On a dynamic tariff, with a little intelligence about when to run, it becomes something you can actively manage and reduce.

How Heat Pumps Create Scheduling Flexibility

The key insight is thermal mass. A well-insulated building does not lose heat instantly when the heating source turns off. If you heat your home to a slightly higher target temperature during cheap overnight hours, it will retain that warmth into the morning. Your heat pump does not need to run during the expensive 7-9am peak. It already did the work when energy was cheap.

This pre-heating strategy — sometimes called thermal pre-conditioning — is one of the most established forms of demand-side flexibility in residential energy management. It requires no sacrifice of comfort. The home stays warm. The bill reflects cheaper pricing.

Hot Water Storage: An Underused Asset

Heat pump water heaters are an especially flexible load. Heating a tank of water to 55°C and maintaining it costs relatively little energy across the day. But running the heating cycle during cheap overnight or midday solar hours and holding it through the peak period is an entirely viable strategy.

Smart heat pump controllers can now interface directly with energy management systems that have access to day-ahead prices. The controller instructs the heat pump to run its heating cycle during the cheapest available two-hour window overnight — without any manual input from the homeowner.

System Sizing and Dynamic Interaction

When designing or upgrading a heat pump installation with dynamic pricing in mind, it is worth considering buffer tank sizing. A larger buffer tank increases the thermal storage capacity of the system, giving the heat pump more opportunity to charge when energy is cheap. This is not a significant capital cost at installation time but can have a meaningful impact on the annual optimisation potential.

The Numbers in Practice

Belgian electricity prices regularly see a spread of €80-150/MWh between cheap and expensive hours even in normal market conditions. For a heat pump consuming 4,000 kWh annually, shifting even 50% of that consumption to below-average price periods could yield savings of €150-300 per year at current market structures. For a heat pump that replaced a gas boiler — and is therefore the primary heating system — this is a meaningful optimisation of already-justified investment.