Why are heat pumps attracting so much attention? Discover how the technology works, the benefits it can deliver, the answers to the questions we hear most often.
A heat pump takes energy from a source such as water, the ground, or surrounding air, and then using a refrigerant and power from an electrical supply, this heat is transferred into your home, at a higher temperature than the source.
I know what you’re thinking, how does water from a lake or cold air outside turn into hot heating water coming out of the heat pump?
This is the clever part inside, the heat pump is compressing and expanding a refrigerant in a cycle, and it’s this process that is able to take water from that cold lake and turn it into heat for your radiators.
Efficiency! In the right conditions, a heat pump can operate at up to 600% efficiency. What this means is for 1 unit of consumed electrical energy, the heat pump is producing 6 units of energy.
Other benefits can include:
Heat pumps can be a key part of a wider technology mix, that when combined together can provide a low carbon solution. This might be solar thermal panels that are adding heat into the ground to recharge the thermal energy taken out by the heat pump, or a biofuel CHP engine that’s used to feed electricity to the
heat pump.
You should consider where you’re going to source energy for the heat pump, do you have a river nearby or can you drill deep into the ground on your site?
Maybe you have lots of outdoor space for an air source solution. Then think about your local electrical infrastructure, depending on how large your heat pump installation is, this could be a significant factor to consider. When it comes to water source heat pumps, there is also the potential to drill down and utilise aquifers, which are bodies of water that lie under the surface.
We’ve delivered some of the UK’s most ambitious schemes, including:
An open loop system is where we are directly extracting energy from the source, such as taking water from a river. We pump water from the river, extract energy back at the heat pump and we pump this water back into the river, so because we are interacting directly with the river water, this is an open loop system.
For a closed loop system, let’s take pipework installed in boreholes deep into the ground as our example. Within this pipework, we have a fluid that is transferring energy from the ground, which we then pump back to the heat pump, extract this energy and pump it back into the ground around this closed loop.
So unlike in our first open loop example where we directly pumped the river water, here we are transferring energy from the ground via a heat transfer fluid inside a close pipework circuit.
Heat pumps come in a huge variety of sizes, from one heat pump in your back garden serving that single dwelling, all the way up to large centralised district heating production serving thousands of end users
connected to a heat network.
Anyone looking to decarbonise energy production can benefit, whether you have an existing installation and are looking to come away from gas, for example. Or you have waste heat or waste electricity which could be used alongside a heat pump installation. Each case has to be looked into to determine the feasibility of applying this technology.
It comes with its challenges of course. First, we have to determine the appropriate source of energy for the retrofit heat pump, is this water, ground or air source?
Then we have to consider how hard are we asking the heat pump to work, what I mean is, the temperature we are asking the heat pump to produce. Older systems often operate at higher temperatures, which heat pumps can achieve - the trade-off is a reduction in efficiency, it’s about finding a balance between modifications to the existing network to lower temperatures and the heat pump selection. So, it depends on a project by project bases how easy it is, but it’s certainly possible.
Changes in planning policy and the decarbonisation of the electrical grid are major factors. With the electrical grid becoming less carbon intensive, people are turning to electricity as a source of fuel - remember heat
pumps require an electrical supply.
In some cases, it could be that this electrical supply is coming directly from a renewable source itself, such a
PV panels. However, for the majority of installations this electrical supply will come from the grid, so we have to consider how clean is this electricity supplying the heat pump. Some may argue that the grid isn’t quite as low carbon as future planning policy is indicating, but generally speaking, we can see that the grid is on a path of decarbonisation, so the electricity we power the heat pumps with is coming from a greener source each day. Combine this with the efficiency a heat pump can operate at and you start to see why a heat pump is a low carbon technology.
