What are heat pumps?

Heat pumps are a huge topic these days. Not only are household heat pumps becoming more popular than ever thanks to increasingly efficient designs and relatively impressive environmental impact, but they are quickly becoming a fundamental part of how your car works as well.

Heat pumps aren’t fitted to all electric cars, but they are offered as an optional extra on many models, and higher-end EVs like Teslas and Porsches have them fitted as standard. But what exactly is a heat pump, how does it work, and why would you want to add one as an (often expensive) optional extra to your electric car? 

We’ll answer each of these questions in detail below, but the short version is that heat pumps are a really efficient way to both heat the cabin and cool the battery pack in an electric car. They’re also able to work in reverse to warm the battery on a cold day – especially useful given that electric car batteries are significantly impacted by extreme temperatures.

Read on to find out all you need to know about heat pumps and their applications in electric cars.

How do heat pumps work?

Heat pumps work like air-conditioning systems or refrigerators. There’s a compressor and a series of tubes full of refrigerant. The compressor turns it from a gas into a liquid and thanks to the laws of thermodynamics, the liquid absorbs heat from the air around it. When it turns back into a gas, it releases the heat back into the air. By controlling where the heat is absorbed and released, you can heat one place by cooling another.

In an electric car this means you can warm the cabin in winter while also keeping the battery, which produces heat while being used, at an optimum temperature. It can also be used to heat the battery when charging, which allows it to perform better and be charged up faster. Since it’s reversible, the heat pump can remove hot air from the cabin in summer as well, although your EV will also have a separate air-conditioning system to supplement this (which actually works in a similar way, but is more effective at cooling in particular).

Of course, the compressor requires energy to run, which can be a drain on your electric car’s battery. However the process is really efficient and adding a heat pump is certainly a net benefit because it takes more energy to heat the cabin in cars without one.

The reason normal petrol and diesel cars don’t have heat pumps is because the engine produces an extraordinary amount of heat –it’s exploding fuel to make energy, after all. This means they heat the cabin simply using this excess heat, and a complex heat pump isn’t needed.

Should I choose an electric car with a heat pump?

Electric cars have batteries that produce a bit of heat, but it’s nothing like the warmth from an engine. This means they can’t rely on the power source to heat the cabin and make them comfortable to drive in – they need something extra. Electric cars without heat pumps simply rely on electric fan heaters, and anyone who has lived somewhere without central heating knows how inefficient those can be.

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Most high-end electric cars like Teslas and Porsches have heat pumps as standard, but some models such as the Volkswagen ID.3, Skoda Enyaq iV and Hyundai Ioniq 5 don’t get one unless you shell out £1,000-odd to add it. The BMW i4, Polestar 2, Tesla Model 3 and even the Peugeot e-208 all come with heat pumps as standard – and we reckon it will become as basic as air-conditioning as electric cars mature. 

It can seem expensive but it’s one of the best options you can add to your EV if you care about efficiency. Not only are heat pumps able to keep the cabin warmer in winter with less energy penalty, they also keep the battery in better condition when it’s cold, which increases the amount of range available to you. It depends on what model you choose, but in general you can expect about 10 per cent more range from a car fitted with a heat pump over the same model without.

Electric cars are significantly more efficient and have a longer driving range with heat pumps fitted. They’re also really useful for pre-conditioning, where you can use an app to get the cabin to a comfortable temperature before you even step inside.

There are some reasons to choose a car without a heat pump, of course. You’ll save some money on models where it’s an optional extra, and it’s likely that used examples will be quite a bit less desirable and therefore cheaper to buy in the future. 

Further to this, if you are buying an electric car to do local trips and won’t need to maximise use of the battery, or live somewhere with mild weather all year, you might feel it’s simply not needed and can use the money elsewhere.