Heating Systems and Building Design
In Finland, nearly all homes are designed for low-temperature heating, typically underfloor systems or large radiators that work efficiently with heat pumps. Buildings are well insulated and airtight, which is essential in sub-zero winters. Finnish construction emphasizes high thermal performance from the outset, ensuring heat losses are minimal and systems can operate efficiently at flow temperatures of 30-45 °C.
In contrast, much of the UK’s housing stock predates modern insulation standards. Older brick homes often lack cavity wall insulation, have draughty windows, and use small-bore copper pipework connected to compact radiators designed for high-temperature gas boilers. These systems expect flow temperatures of 60-80 °C, levels at which air-source heat pumps perform poorly. Simply replacing a gas boiler with a heat pump is therefore rarely straightforward.
The physical characteristics of homes, including insulation, airtightness, and heating surface area, determine how viable heat pumps can be. Finland’s success stems from aligning these aspects decades ago, while the UK now faces the challenge of retrofitting them simultaneously.
Energy Prices and Policy Context
In Finland, electricity prices are relatively stable and increasingly reflect the growing share of renewables. District heating systems, often powered by biomass, heat pumps, or waste heat recovery, provide affordable warmth. Electricity tariffs are increasingly time-based, rewarding consumption that avoids peak hours or aligns with renewable generation.
In the UK, electricity prices remain coupled to gas. The wholesale electricity market is set by the marginal cost of the most expensive generator, which is almost always a gas-fired power station. This means that even as renewable generation expands, the cost of electricity remains tied to volatile gas prices. Meanwhile, natural gas is piped directly into most homes, creating both a technological and psychological lock-in, as gas is convenient, familiar, and often still cheaper.
The policy challenge for the UK is therefore twofold: decouple electricity prices from gas and make low-carbon heating systems economically rational for households.
Using Hot Water as a Thermal Battery
A practical way to increase flexibility and reduce costs is through the domestic hot water cylinder. In both Finland and the UK, cylinders can act as flexible storage, heated during low-tariff periods or when solar generation is available, and supplying hot water later when electricity is expensive or unavailable.
In a system with a heat pump, solar PV, and smart controls, the cylinder becomes a key part of a home’s energy strategy. By treating the cylinder as a thermal battery, households can reduce grid demand during peaks and improve the self-consumption of renewable energy. This approach reflects common Nordic practice, combining efficiency with flexibility rather than relying on high-intensity heating at any time of day.
Variable Tariffs and Smart Operation
Variable or time-of-use tariffs further enable these strategies. Finnish households often have access to electricity prices that change hourly, reflecting real-time market conditions. Smart thermostats and automation systems adjust heating schedules to take advantage of low-price periods without compromising comfort.
The UK is now beginning to see similar tariff models, such as Octopus Agile or Intelligent Octopus, where electricity can cost a fraction of the peak rate during off-peak hours or periods of high renewable generation. Heat pumps, electric vehicle chargers, immersion heaters, and even dishwashers can all be coordinated to operate when power is cheapest and greenest.
For this system to work effectively, homes benefit from some form of storage, either thermal, electrical, or ideally both.
Solar Self-Consumption and Battery Integration
Rooftop solar is becoming increasingly common in both Finland and the UK, but the way it integrates with heating differs.
In Finland, solar PV contributes modestly to space heating but is often paired with heat pumps to offset electricity costs. Smart systems automatically prioritize self-consumption, using excess solar generation to run the heat pump, charge a hot water cylinder, or power home batteries.
In the UK, self-consumption is critical because exported electricity is often compensated at a much lower rate than retail import prices. A battery system can bridge that gap, storing excess solar output for later use in the evening or for pre-heating the home before the sun sets. When combined with time-of-use tariffs, batteries can also perform energy arbitrage, charging during cheap hours and discharging during peak pricing, reducing both emissions and costs.
Toward Smarter, More Resilient Homes
Finland shows what is possible when heating, building design, and energy policy evolve together. Homes are efficient, heat pumps are standard, and electricity markets reward flexibility. The UK’s path is more complicated: a legacy gas infrastructure, older buildings, and market distortions make electrification harder.
Yet the direction is clear. With improving insulation, larger radiators or underfloor systems, and smarter controls, heat pumps can thrive in the UK climate. By embracing time-based tariffs and storage (both thermal and electrical), homes can become active participants in the energy system rather than passive consumers.
As the energy transition accelerates, the difference between Finland and the UK may soon narrow, not through copying, but through adapting: combining Nordic efficiency with British ingenuity.
