How do Air Source Heat Pumps Compare to Alternatives?

If you’re wondering whether air source heat pumps are any good, then wonder no more – they’re great.

In fact, they’re so good for the UK’s climate that we’re confident they’ll be the most common method of heating radiators and hot water within the next two decades.

After all, if they work so well for a country as cold as Norway (where over 60% of households have heat pumps), then we’re confident the UK’s homeowners are going to love them in no time.

But how do they compare to alternative heating methods, and what comparisons can we make? Let’s learn about heating.

Here is everything we discuss:

• The main sources of heating
• Electric storage heaters
• Biomass heating
• Ground & water source heat pumps
• Air source heat pumps
• Are air source heat pumps more expensive?

Most domestic properties in the UK rely on gas-powered boilers to heat their water and radiators – but this is quickly being phased out as the world moves away from fossil fuels.

So what alternatives are available to you if you’re thinking about cutting the gas off at your home?

The current viable forms of heating are:

• Electric storage heaters
• Biomass heating
• Ground and water source heat pumps
• Air source heat pumps

Let’s look at these in some more detail.

Electric storage heaters are more common in apartment buildings and houses built around the 1970s.

In theory, they’re a great way to heat your home because you can get electricity from renewable sources and you can control them in a much more precise way than you can control, say, every radiator in your home. 

While it’s true that energy can come from renewable sources, the main downside to storage heaters is that they’re incredibly inefficient. Because they have to heat up heating elements which then release heat into your spaces, they need to use a lot of electricity to output that heat.

What’s more, other than a few very new models, electric storage heaters tend to be much harder to control accurately because they take so long to heat up in the first place.

In all, electric storage heaters tend to be some of the least efficient (and therefore most expensive) ways to heat a home – especially when accounting for radiators and hot water.

“Biomass” is promoted as another way of heating your home with a “renewable” resource, but that resource is essentially trees. Rather than logs on a roaring fire, biomass heaters use refined wood pellets to reduce the amount of soot that gets produced. By starting with drier wood, the pellets burn quickly and reach a high heat, so less heavy carbon (soot) gets emitted.

They create less emissions than gas or oil boilers, but they’re still burning a fuel – so therefore creating emissions. It’s also worth bearing in mind that a lot of energy needs to be used to cut down the trees, dry them out, chip them, and turn them into pellets. So while homeowners don’t have as many emissions at their boiler, it’s essentially passing the buck elsewhere.

Heat pumps are currently the only viable alternative to heating a home than gas or oil-powered systems – both financially and from an environmental perspective. A better alternative may yet be developed but at least you can get consistent, dependable, sustainable heat for your home and water in the meantime.

Heat pumps don’t “generate” heat themselves but actually move heat from one place to another – what this source of heat is depends (and is included in the name).

We go into more detail about how they work and what types are available here but, essentially ground and water source heat pumps use a long loop of coolant to pull heat out of a source. 

Ground source systems usually have to have a really deep borehole drilled into the ground (sometimes as deep as 150m) and can be unsuitable for many geological locations, and water source heat pumps need to be near an aquifer to extract heat from them.

While these are seen as more “consistent” sources of energy, they’re much more costly to install and have quite a detrimental impact on their immediate environment.

Ground source boreholes, for example, can freeze the ground around them during cold weather (which renders them inoperable) – and if everyone taps into the heat of underground aquifers, there’s no telling what the knock-on consequences would be for numerous ecosystems further down the line.

The three main ways to maximise system efficiency through the way you use the system are:

1. Get the weather compensation right
2. Check that your hot water’s not set too hot
3. Make sure all radiator valves are turned on (even in rooms that don’t need to be heated)

Air source heat pumps get the energy benefits of heat pump innovations but without the complicated installations and detrimental environmental impacts. They’re actually as consistent (if not more consistent at times) than ground and water sources because they don’t have the possible problems of freezing their source.

They’re so effective, in fact, that they’re usually expected to work at between 300-400% efficiency when averaged over the year – which means they often work at a lot more than 400% efficiency!

This means that you only need to use 2.5kWh of electricity for every 10kWh of heat produced! If you were relying on an average older gas boiler working at 75% efficiency, you’d have to use 12.5kWh of energy to get the same heat. So you’re saving a lot – which is great for the planet without having to make any sacrifices.

The topic of “how expensive are air source heat pumps” is actually quite a sticky one – not because they’re significantly more expensive but because the cost varies so much based on the efficiency of the system and the current unit prices available on your tariff. So the difficulty is in giving figures that are almost immediately outdated.

If you’re curious, we go into great detail about heat pump installation and operation cost here. According to Energy Saving Trust data, however, an air source heat pump can provide significant savings on your energy bills compared to electric storage heaters or older inefficient boilers – and often comparable running costs to a brand-new high efficiency gas boiler.

If you’re looking at investing in your home’s future while keeping the planet happy, get in touch with a heat pump expert to answer any questions and even get a free no-obligation quote.