Smart Thermostat vs TRV: Which Saves More Money in the UK?

Great British Insulation Scheme update: The Great British Insulation Scheme closed on 31 March 2026. For insulation funding, check the Warm Homes Plan via your local council, or ECO4 (until 31 December 2026) via an obligated supplier.

Energy Company Obligation (ECO4) update: ECO4 is scheduled to end on 31 December 2026. If you may be eligible, start the referral now — applications received close to the deadline may not complete in time.

Introduction: Two Approaches to Smart Heating#

If you are looking to cut your heating bills without a full system overhaul, smart heating controls are one of the fastest ways to see results. But the choice between a smart thermostat and smart thermostatic radiator valves (TRVs) is not always obvious, and getting it wrong means leaving money on the table.

A smart thermostat controls your entire heating system from a single point. Smart TRVs control individual radiators, letting you set different temperatures in different rooms. Both connect to your phone, both promise energy savings, and both work with most UK central heating systems.

So which one actually saves more? The answer depends on your home, your habits, and your budget. This guide breaks down the differences with real costs and savings data so you can make the right call.

For a broader overview of smart heating technologies, see our complete smart heating guide.

What Is a Smart Thermostat?#

A smart thermostat replaces your existing wall-mounted thermostat and connects to your home Wi-Fi. It gives you app-based control over your entire heating system: you can set schedules, adjust temperatures remotely, and receive energy usage reports from your phone.

The leading models in the UK market are:

• Google Nest Learning Thermostat (opens in new tab) (£200-£250), which learns your routine and programs itself automatically.
• Hive Active Heating 2 (opens in new tab) (£180-£230), which integrates tightly with British Gas services and other Hive smart home products.
• Tado Smart Thermostat V3+ (opens in new tab) (£150-£200), which provides geofencing, weather adaptation, and OpenTherm boiler modulation.

Key features across all three include remote app control, smart scheduling, integration with voice assistants (Alexa, Google Assistant), and energy usage insights. Some models also offer geofencing (heating adjusts when you leave or approach home) and open window detection.

For a full breakdown of these models, read our best smart thermostats for 2026 guide.

What Are Smart TRVs?#

Smart thermostatic radiator valves replace the manual twist-top valves on individual radiators. Each valve connects wirelessly to a hub and can be controlled through an app, giving you room-by-room temperature control.

The main smart TRV brands in the UK are:

• Tado Smart Radiator Thermostat (opens in new tab), from approximately £76 per valve, or around £113 for a three-pack. Requires a Tado Internet Bridge (included in starter kits).
• Drayton Wiser Smart Radiator Thermostat (opens in new tab), from approximately £40-£50 per valve. Requires a Wiser Hub (1st or 2nd generation). Won the Red Dot Design Award and fits 90% of existing radiator valves.
• Igenius (Eve Thermo), from approximately £50-£70 per valve. Works with Apple HomeKit for iPhone and Siri control.

Smart TRVs let you heat only the rooms you are using. You might keep the living room at 21°C in the evening while bedrooms sit at 16°C, then reverse that at night. This targeted approach avoids wasting energy heating empty rooms, which is where the real savings come from.

For detailed reviews of each model, see our guide to the best smart radiator valves in 2026.

Head-to-Head Comparison#

The table below compares the two technologies across the factors that matter most to UK homeowners.

Which Saves More Money?#

This is the question everyone asks, and the honest answer is: it depends on how you heat your home today.

Smart Thermostat Savings#

The Energy Saving Trust estimates that smart thermostats save 10-15% on heating bills for most households. Hive's own data from 2025 shows an average 6% reduction in gas consumption after installation, translating to roughly £190 per year at current gas prices. Households that previously had no programmable controls tend to see the largest gains — up to £300 per year.

The savings come from three mechanisms: not heating an empty house (geofencing and scheduling), not overheating (precise temperature control), and not heating when it is mild outside (weather compensation).

Smart TRV Savings#

Smart TRVs save money by eliminating heating in rooms you are not using. A BEAMA study on thermostatic radiator valves found that adding TRVs to a home that already has a thermostat saves around £35 per year with basic manual TRVs. Smart TRVs with proper scheduling deliver considerably more. Real-world tests in a three-bedroom Victorian house with eight smart TRVs showed a 22% reduction in heating costs.

The savings scale with your home. A couple living in a four-bedroom house who only use two rooms regularly will save far more than a family of five that uses every room.

The Numbers in Context#

For a typical three-bedroom semi-detached house spending £1,200 per year on gas:

• Smart thermostat alone: saves roughly £120-£180 per year
• Smart TRVs alone: saves roughly £80-£150 per year
• Both combined: saves roughly £200-£360 per year

The combined approach delivers the best results because the thermostat handles system-level optimisation (scheduling, away detection) while the TRVs handle room-level optimisation (only heating occupied spaces).

When to Choose a Smart Thermostat#

A smart thermostat is the right starting point if:

• You have a smaller home or flat where most rooms are used regularly. Room-by-room control adds less value when you only have two or three rooms.
• You currently have no programmable controls. Upgrading from a basic on/off timer to a smart thermostat delivers the single biggest jump in efficiency.
• You want a simple, low-cost upgrade. One device, one installation, immediate savings.
• You are often away from home at irregular times. Geofencing and remote control mean you never heat an empty house.
• You want a single point of control. One app, one schedule, no complexity.

A smart thermostat is the foundation of any smart heating setup. Even if you plan to add TRVs later, starting with a thermostat gives you immediate savings and a platform to build on.

When to Choose Smart TRVs#

Smart TRVs are the better choice if:

• You already have a smart thermostat and want to squeeze more savings from your system. TRVs are the natural next step.
• You have a larger home with rooms that are often empty — spare bedrooms, a home office only used on weekdays, or a dining room used only at mealtimes.
• Different household members prefer different temperatures. TRVs let you keep the living room at 21°C and the bedroom at 18°C without compromise.
• You have a multi-storey house where heat rises and upper floors are naturally warmer. TRVs can reduce heating upstairs while maintaining comfort downstairs.
• You want to start small. You can buy one or two TRVs for the rooms that matter most and add more over time. A single Drayton Wiser valve costs around £40.

Can You Use Both Together?#

Yes — and this is the setup that delivers the highest savings. A combined smart thermostat and TRV system gives you whole-house control and room-level precision in a single app.

Here is how it works in practice:

1. The smart thermostat manages overall scheduling and away-mode detection. It tells the boiler when to fire and for how long.
2. The smart TRVs control individual radiators within that schedule. Even when the boiler is running, TRVs close off radiators in rooms that have reached their target temperature or are not in use.

Tado and Drayton Wiser both offer integrated ecosystems where their thermostat and TRVs work together in a single app. If you buy a Tado thermostat, adding Tado TRVs is straightforward — they share the same hub and app. The same applies to Wiser.

The Energy Saving Trust notes that zonal heating control (which is exactly what a thermostat-plus-TRV setup provides) can reduce heating costs by up to 30% compared to a home with no smart controls.

The main trade-off is cost. Equipping a three-bedroom house with a smart thermostat (£150-£250) and six TRVs (£240-£480) means an upfront investment of £390-£730. At typical savings of £200-£360 per year, the payback period is still under three years for most households.

Our Recommendation: Scenario-Based Advice#

There is no single right answer. The best choice depends on your situation. Here is our advice for the most common scenarios:

One-bedroom flat or small terrace#

Get a smart thermostat only. Room-by-room control adds little value when you have two or three radiators. A Tado V3+ or Hive Active Heating will deliver strong savings for under £200.

Three-bedroom family home, all rooms used daily#

Start with a smart thermostat, then add TRVs to bedrooms. The thermostat handles scheduling and away detection. Adding TRVs to bedrooms lets you drop temperatures overnight without affecting the living areas.

Three- or four-bedroom home with spare rooms#

Get both from the start. This is where TRVs deliver their biggest savings. Keeping spare bedrooms at 16°C instead of 21°C while you are in the living room makes a meaningful difference on a yearly bill.

Older, larger property (Victorian or Edwardian)#

Prioritise TRVs across all radiators alongside a thermostat. Older homes often have uneven heating and poor insulation in some rooms. TRVs let you compensate by directing heat where it is needed and reducing waste where it is not.

Already have a smart thermostat and want more savings#

Add TRVs to the rooms with the biggest temperature mismatches. Start with the rooms you heat but rarely use, or rooms that overheat because of their position in the house. Even two or three TRVs at £40-£80 each can make a noticeable difference.

For more product comparisons across heating, insulation, and renewable energy, visit our product comparisons hub.

Practical Next Steps#

1. Assess your current controls — if you have no programmable thermostat at all, that is the priority upgrade.
2. Count your radiators and rooms — work out how many TRVs you would need and whether the investment makes sense for your home layout.
3. Check compatibility — most smart thermostats and TRVs work with standard UK combi and system boilers, but verify before purchasing. Tado and Wiser both have online compatibility checkers.
4. Start with one technology — if budget is tight, a smart thermostat gives the best single-device return. Add TRVs later as budget allows.
5. Look into grants — some smart heating controls may be covered under the ECO4 scheme or the Great British Insulation Scheme for eligible households.

Sources#

• Energy Saving Trust — Thermostats and Heating Controls
• BEAMA — Assessing Energy Savings from TRVs
• Centrica — Hive Smart Thermostat Savings Data 2025
• Tado UK Shop
• Drayton Wiser — Smart Radiator Thermostat