What is Lot 20? An Expert Guide to Save on UK Electric Heating Bills 

Worried your electric heating is costing more than it should? You are not alone. With space heating making up 61% of energy used in UK homes, according to the House of Commons Library, the kind of heater you buy has a real say in your bills. That is the job of Lot 20. It is the rule that sets the minimum energy efficiency standards an electric radiator must meet before it can be sold in the UK, keeping the worst energy wasters off the shelves.

Not sure if your current radiator is up to scratch? This guide breaks down what Lot 20 means, why the rule exists, and how to check if a heater meets it before you buy.

What is LOT 20?

Lot 20 is the rule that sets minimum energy standards for electric room heaters and radiators sold in the UK and EU. Formally known as Commission Regulation (EU) 2015/1188, it came into force on 1 January 2018, and any new electric room heater entering the UK market from that date has to meet it. 

The rule sits inside a much bigger framework called the Ecodesign Directive (2009/125/EC), which covers a wide range of energy-related products sold across the UK and EU. The Directive groups products into smaller categories called Lots, so each type can be regulated in a way that fits it. Boilers sit under Lot 1. Lighting sits under Lot 19. Electric room heaters sit under Lot 20.

Lot 20 specifically covers electric local space heaters, including panel heaters, electric radiators, storage heaters, infrared heaters, and electric underfloor heating. 

What Does Lot 20 Compliant Mean?

A Lot 20 compliant radiator is one that meets the rules set out in Commission Regulation (EU) 2015/1188. Every electric radiator is given an energy score, and to pass Lot 20, it has to reach a set minimum.

The minimum score depends on the type of heater:

• Fixed electric radiators above 250W (such as wall-mounted electric radiators): at least 38
• Portable electric radiators : at least 36
• Storage electric heaters: at least 38.5
• Underfloor electric heating: at least 38
• Radiant electric heaters: at least 35

A heater that reaches its minimum score can be sold in the UK. If it does not, it cannot.

Does Lot 20 Still Apply After Brexit? 

Yes. Lot 20 came into force on 1 January 2018, before the UK formally left the EU on 31 January 2020. It was retained in UK law after Brexit, so the same minimum standards still apply to electric heaters sold in Great Britain.

Northern Ireland follows EU product rules under the Windsor Framework, which means electric heaters sold there continue to meet the original EU version of Lot 20.

So whether you are buying a new electric heater in Belfast, Birmingham, or Bristol, the same energy standards apply.

What Features Must a Lot 20 Compliant Electric Heater Have 

To reach the energy score required to pass Lot 20, a heater needs smart controls built in. The regulation lists each control as a scoring option, and each one adds points toward the heater’s total. The more controls a heater has, the higher its score.

The main controls you will find on a Lot 20-compliant heater are the following:

• An electronic thermostat: Holds the room at the exact temperature you set, so the heater stops drawing power once it reaches that point.
• 24/7 timer: Lets you schedule when the heater turns on and off, so it does not run when nobody is home.
• Open window sensor: Detects a sudden drop in room temperature, usually from an open window, and switches the heater off until the room warms up again.
• Adaptive start control: Learns how long the room takes to warm up, so the heater turns on at the right time and reaches your target temperature when you want it.
• Distance control or Wi-Fi app: Some Lot 20 heaters can be controlled from your phone, anywhere in the home or even when you are out.

Most modern electric radiators sold today come with these controls built in as standard. UK suppliers like Best Electric Radiators, for example, fit their core range with a digital thermostat, a 7-day programmable timer, and Wi-Fi compatibility, all of which help the heater hit its Lot 20 score. 

The mix of controls a heater needs depends on its type. Wall-mounted electric radiators usually need a thermostat, a timer, and either open window detection or adaptive start to score enough. Portable heaters and storage heaters have their own combinations.

How to Check if Your Heater is Lot 20 Compliant 

If you are buying a new electric heater or you want to know whether an existing one meets the rules, there are a few easy checks you can do.

1. Look for “Lot 20” or “EcoDesign compliant” on the product page or packaging. Most UK retailers state this clearly on the product listing and the box. If a heater is compliant, the seller will say so. If you cannot find any mention at all, that itself is a red flag.
2. Check the manufacturer date. Lot 20 came into force on 1 January 2018. A heater made before that date does not need to meet the rules. You can usually find the manufacturer’s date on the back or underside of the unit or in the product manual.
3. Check the features listed in the product description. A compliant heater should include the smart controls covered earlier, including an electronic thermostat, a 24-hour or 7-day timer, and either an open window sensor or adaptive start. If the heater is missing one of these, it may not score high enough to pass. 
4. Ask the retailer for the seasonal energy efficiency rating. Lot 20 sets a minimum seasonal energy efficiency for each heater type. A reputable retailer will be able to share this number on request. For electric fixed space heaters, the minimum is 38%. 
5. Ask the retailer if you are unsure. A reputable UK retailer will be able to confirm Lot 20 compliance and share the product’s energy data on request. If they cannot, that is a sign to walk away.

How is Lot 20 Efficiency Calculated? 

Working out the exact energy use of every electric heater on the market would be slow and impractical. So Lot 20 uses a points-based system instead. Every heater starts with a base energy score, and each smart control or feature on the unit adds a small percentage on top. The final score has to clear the minimum for that heater type, which is 38% for fixed electric heaters (like wall-mounted radiators).

The extra points come from two correction factors, called F(2) and F(3) in the regulation. F(2) covers the heater’s main temperature control. F(3) covers extra features that add even more credit on top. The values below come straight from Annex II of Commission Regulation (EU) 2015/1188.

Correction Factor F(2) – Control Features 

F(2) is based on the heater’s main room temperature control. Only one option applies per heater, depending on which type of control it has. The exact credit depends on the heater type.

Type of control	Portable	Fixed (e.g., wall-mounted radiator)	Storage
Single-stage heat output, no room temperature control	0.0%	0.0%	0.0%
Two or more manual stages, no temperature control	1.0%	0.0%	0.0%
Mechanic thermostat room temperature control	6.0%	1.0%	0.5%
Electronic room temperature control	7.0%	3.0%	1.5%
Electronic room temperature control plus a day timer	8.0%	5.0%	2.5%
Electronic room temperature control plus a week timer	9.0%	7.0%	3.5%

The more advanced the thermostat and timer, the more points the heater earns. A heater with just an on/off switch gets nothing. A heater with a digital thermostat and a 7-day timer earns 7%, which is often enough on its own to make the difference between passing and failing Lot 20. 

Correction Factor F(3) – Additional Features 

F(3) covers extra controls that earn even more credit on top of F(2). A heater can score points from more than one feature here, and the credit depends on the heater type.

Additional feature	Portable	Fixed (e.g., wall-mounted radiator)	Storage
Room temperature control with presence detection	1.0%	0.0%	0.0%(e.g.,
Room temperature control with open window detection	0.0%	1.0%	0.5%
Distance control option (Wi-Fi or app control)	0.0%	1.0%	0.5%
Adaptive start control	0.0%	1.0%	0.5%
Working time limitation	0.0%	0.0%	0.0%
Black bulb sensor	0.0%	0.0%	0.0%

A wall-mounted electric radiator that has open window detection, adaptive start, and Wi-Fi control picks up an extra 3% on top of its F(2) score. For storage heaters, the same three features add 1.5%. Portable heaters earn most of their credit from F(2) only, so smart features beyond a thermostat and timer add little.

How Much Can a Lot 20 Heater Save You? 

The honest answer: it depends on how you used your old heater.

A heater that ran flat out with no thermostat, no timer, and no way to stop it from heating an empty room was burning through electricity it did not need to. The smart controls now built into every Lot 20-compliant heater are designed to stop exactly that kind of waste.

In real numbers, the current UK electricity price cap sits at around 24.67p per kWh, with average annual energy bills capped at £1,641. At that rate, a 600W electric radiator only needs to draw power for around 25% of the time once the room is warm. That works out to ~3.70p per hour to run. A 2000W model on the same logic runs at approximately 12.34p per hour. Compare that to the always-on cost of an older heater with no controls.

Lot 20 has already done much to improve Britain’s energy output and reduce poorly controlled temperature regulators in favor of smart, energy-efficient heaters:

• Old, uncontrolled electric heaters are off the market
• Smart controls now come built into every compliant heater
• Heaters with proper controls only run when needed
• Many modern heaters now include Wi-Fi, app scheduling, and voice control
• It supports the UK’s wider net-zero target

The exact savings for any individual home depend on how the heater is used, how well the home is insulated, and the electricity tariff. But for anyone still running a pre-2018 electric heater with no proper controls, switching to a Lot 20-compliant model is one of the simpler ways to reduce day-to-day heating costs.

Note: Ofgem reviews and updates these rates every 3 months. Check the latest unit rate before working out your own costs.

Wrapping Up! Choosing the Right Lot 20 Electric Radiator

Every electric radiator on sale in the UK today has to meet Lot 20, but “compliant” is just the starting point. The build quality, the controls, and the speed of heating vary a lot between models. Here is what to look for.

• EU manufacturing: The majority of products from established UK retailers are manufactured in the EU, where build quality tends to be higher than budget Asian imports.
• Smart controls: Look for a digital thermostat, programmable timers, Wi-Fi app control, and voice assistant compatibility.
• Fast, responsive heating: Look for radiators that heat up quickly and react fast to thermostat changes. The quicker the response, the less power the radiator uses to hold the room at a certain temperature.
• Installation: Most electric radiators can be wall-mounted and plugged into a standard socket, making them DIY-friendly. Bathroom radiators are the only exception and need a qualified electrician.

UK retailers like Best Electric Radiators have specialized in heating solutions since 2014, and their full range meets Lot 20 standards.

Whichever heater you choose, check that the supplier is clear about Lot 20 compliance, the controls included, and how responsive the heater is to thermostat changes. If you are still unsure which model is right for your home, the Best Electric Radiators team is ready to help you find the right fit.

FAQs

Is my old electric heater still legal to use?

Yes. Lot 20 applies to the sale of new heaters, not to ones you already own. You can keep using a pre-2018 heater. But heaters from that era often lack thermostats, timers, and other controls, so upgrading to a Lot 20-compliant model can cut day-to-day running costs.

How do I know if a heater I am buying is Lot 20 compliant? 

Most UK retailers state Lot 20 compliance clearly on the product page or packaging. You can also check the manufacture date (post-1 January 2018) and confirm the heater has core smart controls like an electronic thermostat and a programmable timer. If a retailer cannot confirm compliance, that is a sign to walk away.

What size Lot 20 radiator do I need for my room? 

A common starting point is 100W per square meter of floor area for a room you want to heat to 21°C. So a 10m² room would need a 1000W radiator. The figure goes up for rooms with high ceilings, north-facing walls, poor insulation, or open staircases. Use the electric radiator calculator to find the right fit for your room. 

Can I install a Lot 20 electric radiator myself? 

Most Lot 20 electric radiators are designed for DIY installation. Wall-mounted models with a standard plug can be fitted with simple brackets and plugged into a normal socket. The exception is bathroom radiators, which need a qualified electrician under UK wiring regulations for wet zones.