Heat Pumps

WHY ARE HEAT PUMPS SO HOT RIGHT NOW?

Vital Energi’s Elliott Sharpe explains all.

Air, ground, and water source heat pumps are one of the most effective technologies for reducing carbon, and with a potential 500% efficiency, they are a great solution for projects of all sizes.

With almost 15 years’ experience in the industry, Elliott Sharpe, Vital Energi’s Design Director in London, leads the design and CAD departments to deliver high quality design solutions that set new standards in best practice. Elliott is helping Vital remain at the forefront of renewable technologies, driving continuous improvement and energy efficiency, with a strong focus on heat pump technology, which is helping the UK’s journey to net zero.

Elliott gives us an insight into heat pump technology, covering the benefits, for businesses and the environment alike, the factors that have to be considered when thinking about heat pumps, and he tells us about some of the large scale heat pump projects he’s worked on, including the UK’s largest water source heat pump. What types of heat pump are there and how do they work?

Heat pumps can appear quite complicated at first glance, but the technology has been around for quite some time. Think about your fridge at home or an air conditioning system for an office - these are using heat pump technology.

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. What are the key benefits of heat pumps?

Efficiency! In the right conditions, a heat pump can operate at 300, 400, dare I say 500% efficiency. What this means is for 1 unit of consumed electrical energy, the heat pump is producing 5 units of energy. Are there any other renewable technologies that work well alongside heat pumps?

Yes, heat pumps are 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. What factors have to be observed if considering a heat pump?

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.

Tell us about some of the heat pump projects you’ve worked on…

We are currently developing and delivering seven heat pump projects, with the most recent completion being the UK’s largest district heating connected water source heat pump project at Queens Quay, Clydebank, where we installed two 2.65MW heat pumps to extract energy from the River Clyde, providing heat and hot water to surrounding homes and businesses.

We’re also really proud of our recent work with Southwark Council to provide a more efficient low carbon heat supply using water source heat pumps to supply and decarbonise over 2,000 properties, using ground water abstracted from and reinjected into locally drilled boreholes. Can you explain the difference between an open and closed loop system?

Let’s take a couple of examples to explain. 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. What type of businesses can benefit from heat pump technology?

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. Of course, each case has to be looked into to determine the feasibility of applying this technology. What size network can a heat pump power?

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.

How easy is it to retrofit heat pumps into an existing network?

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, so 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. Why are heat pumps becoming more popular?

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.

How are heat pumps renewable if they rely on electricity for power?

Good question! We’ve talked about how heat pumps can use energy from water, the ground, or air, but quite rightly, they need 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.

With over 30 years’ industry experience, Vital Energi specialise in the design and installation of the latest renewable and low carbon energy generation, distribution and consumption technologies.

If you have an energy project in mind, or would like more information about how we can help decarbonise your business, please contact us today. www.vitalenergi.co.uk

HEAT PUMPS

GAS BOILERS VS. GROUND SOURCE HEAT PUMPS

Around 85% of UK homes use gas-fired central heating. To reduce carbon emissions, combat air pollution and help stop climate change, there must be a radical shift in how we heat our buildings. But how does the lesser-known heat pump compare to the familiar boiler? Kensa Heat Pumps looks at how the two technologies compete in efficiency, emissions and more.

THE FUTURE OF GAS VS. GROUND SOURCE HEATING

WHY ARE GAS BOILERS BEING PHASED OUT?

To achieve the UK’s legally binding target of net-zero carbon emissions by 2050, it’s vital that fossil fuels, including natural gas, are phased out and replaced with renewable alternatives.

Ground source heat pumps future-proof properties - both in terms of sustainability and conforming to regulation. From 2025, the government has confirmed that gas boilers will no longer be an option for new builds. They are even set to commit to cutting carbon emissions by 78% by 2035, meaning a significant amount of gas boilers will have to be ripped and replaced. HOW THEY WORK

GAS BOILER

A gas boiler heats water by pumping it into pipework over a series of gas flames. Just like liquid in a pan, the water is heated up as it passes the flames. It is then used to deliver central heating and hot water to the home. There are different types of boilers, such as combi boilers, which give you instant hot water – meaning you don’t need a hot water tank. GROUND SOURCE HEAT PUMP

A ground source heat pump is an electrically-powered heating system. Using buried pipework filled with a heat transfer fluid (usually glycol), the system absorbs low-grade heat energy from a renewable energy source, such as the ground or water. The heat pump then compresses this heat energy to raise its temperature.

Heat exchangers transfer the additional heat energy from the glycol fluid to the water piped through the home’s heating distribution system, upgrading this to a higher temperature. The newly heated hot water can be used for space heating delivered by radiators or underfloor heating, and also for domestic hot water stored within a cylinder.

The underground pipework, known as a ground array, can be installed on an individual or communal level - providing a sustainable source of heat for either a single home or a whole street. Kensa has pioneered an infrastructure that facilitates the installation of ground source heat pumps on a larger scale. This is known as a Shared Ground Loop Array. CARBON EMISSIONS & ENVIRONMENTAL IMPACT

GAS

Some 37% of the UK’s carbon emissions come from demand for heat (of which 17% is space heating and 4% hot water), which is mostly met by burning natural gas.1 The typical emissions from a gas boiler are 226g/kWh, which add up to 2.7 tonnes per year for an average house. This level of emissions equates to travelling 12,000 miles in an average family car – that’s enough to get you from London to Auckland with miles to spare.2

As gas is a fossil fuel, it releases carbon dioxide (CO2) – a greenhouse gas that contributes to climate change. Fossil fuel heating systems also contribute to air pollution. GROUND SOURCE

Ground source heating is certainly the winner when it comes to reducing carbon emissions. By its very nature, the system is sustainable, as the ground or water from which the heat energy is extracted are renewable heat sources.

Ground source heating uses some electricity which creates some emissions, but the emission levels of a ground source heat pump is just 53g/kWh, delivering a whopping 77% saving on emissions versus gas.3 One of the main reasons the emissions are so low is due to the heat pump’s high efficiency.

And it gets even better. As the electrical grid continues to rapidly decarbonise due to generation from renewable sources such as solar or wind farms, so does that small amount of electricity consumed by the ground source heat pump – meaning the heat pump you install today will emit fewer carbon emissions in the future.

EFFICIENCY

GAS

Modern condensing gas boilers can be around 90% efficient. This means that 90% of the energy used by the boiler goes to heating the home, while the remaining 10% is waste heat that is passed through the flue to the outside. The heating system isn’t as efficient as it could be because of this wasted heat.

GROUND SOURCE

Ground source heat pumps can be 300 – 400% efficient, which means they can deliver three to four times the amount of energy they consume from

1 Rethinking Heat: a utility based approach for ground source heat pumps, Regen, 2021 2 Based on 12,000 kWh of heat. Gas boiler carbon intensity calculated using

SAP figure, which has been divided by typical gas boiler efficiency. 3 An average carbon intensity of 181 g/kWh for electricity, which has been divided by typical heat pump efficiency of 3.5. Gas boiler carbon intensity calculated using SAP figure, divided by typical gas boiler efficiency.

electricity. When multiple properties are linked to a shared ground array system, there is a chance to increase this performance by utilising waste heat from applications such as server rooms and supermarkets. UPFRONT COST

The upfront cost of a gas boiler installation is cheaper than a ground source heat pump. This is to do with the fact that around 1.6 million gas boilers are installed each year, compared to around 30,000 heat pumps.

While the upfront costs of a gas boiler may seem appealing, it’s important to think about the impact fossil fuel heating has on the environment. A 2021 report by Regen on ‘rethinking heat’ recommends that the government changes the environmental levies on the electricity bill into a carbon levy on electricity, gas and oil bills, based on their carbon impacts. If implemented, this could see gas bills rise substantially. GROUND SOURCE

Like many renewable heating technologies, installing a ground source heat pump requires a capital outlay that is significantly higher than a gas boiler.

However, as deployment volumes increase in line with government ambitions to install 600,000 heat pumps per year by 2028, we expect to see significant drops in prices for heat pumps and the provision of the ground array. RUNNING & REPLACEMENT COSTS

Gas heating has been long recognised as a cheap source of heat, but the running cost of gas fluctuates with many factors, such as market reforms or world events that affect the availability of gas. GROUND SOURCE

Ground source heat pumps compare favourably with gas and were very similar until recent gas price drops. However, we expect the running costs of ground source heating to further drop with the adoption of methods such as load shifting. This means, using smart controls and time-of-use tariffs, the heat pump can automatically run when electricity is low in cost and carbon.

Load shifting means you can avoid expensive times, and even take advantage of the fabric of the building. For example, if you like to have your heating on at 20ºC by 5 pm, most heating systems would turn on at 4.30 pm and gradually bring your house up to temperature for, say, when you get home from work. However, if this system looks ahead at energy prices and realises it will be expensive between 4.306.30 pm, it might turn the heating on at 2 pm – bringing the temperature up to 22ºC and cooling down to the perfect 20ºC when you return.

Smart controls learn your heating preferences and devise a customised heating schedule for your home that provides optimum comfort, while saving money. Projects such as Energy Superhub Oxford estimate that this could deliver savings of up to 25% compared to a standard ground source system. On average, this means that ground source heating can be cheaper than gas.

The savings can increase even further when using physical energy storage, which means you can store the heat following consumption at offpeak times and use it when required.

As for lifetime costs, an average boiler will need replacing every 10 to 15 years, whereas ground source heat pumps will typically last 25 years and do not require annual servicing. The ground array pipework used to extract the heat energy will last for 100 years, so installing this infrastructure is a one-off investment to provide heat for generations.

INSTALLATION

Unlike a gas boiler system, a ground source heat pump has no flue or ventilation requirements, no more landlord gas safety checks, and simple and clean servicing. It can be installed inside the home.

The groundwork part of the installation is completed outside, minimising disruption. Once the ground has been restored, they are visually unobtrusive.

MASS ADOPTION

GAS

For the majority of households connected to the gas grid, a gas boiler is a trusted technology. But the way we heat our homes has to change. If we are to achieve the net-zero target, the UK must adopt another tried-andtested, but renewable, technology. GROUND SOURCE

Switching domestic properties to non-combustion heating systems would significantly reduce harmful emissions and move the UK closer to its net-zero target.

Kensa sees a future where the ground array infrastructure imitates the gas grid and facilitates the mass installation of ground source heat pumps. Deployed on a street-by-street basis, the adoption of this 21st-century network would allow households to simply ‘connect’ their heat pump to the network.

The only cost to the household would be the unit itself, as the ground array can be funded by a separate entity that benefits from a modest ‘standing charge’, similar to when connecting to the gas grid. We call this the split ownership model. www.kensaheatpumps.com

WHY SHARED GSHP LOOP SYSTEMS ARE KEY FOR DECARBONISATION

The UK Government made its intentions clear in March, when it announced its blueprint to deliver the world’s first low-carbon industrial sector. The industrial decarbonisation strategy outlines the government’s goal of cutting the nation’s emissions by two thirds in the next 15 years, with the aim of reaching net zero by 2050.

Decarbonisation has become a top priority for many organisations. Not only would it significantly benefit the environment, but in many cases, the solutions that will help these businesses achieve net zero also prove to be highly cost effective and greatly improve operational efficiency. While much focus is often placed on the decarbonisation of electricity, the true challenges actually lie in heating, ventilation and air cooling (HVAC) systems. However, by optimising existing systems with shared ground source heat pump (GSHP) loops, HVAC technology can be decarbonised effectively. GSHPS MINIMISE CO2 EMISSIONS

GSHPs work by absorbing heat from the ground and transferring that heat into buildings, without the need to burn fossil fuels. By using pipes that are buried underground to extract heat, the system is able to use the extracted heat for radiators, underfloor or warm air heating systems, as well as hot water in homes. With the ground remaining at a fairly constant temperature under the surface across all four seasons, GSHPs provide a viable solution for heating homes year-round.

Defra publishes projections of the carbon grid intensity each year in grams of CO2 emitted for each kWh generated. This includes the relative carbon emissions for different forms of heating, compared to burning natural gas for the same purpose. It shows that combustion methods, such as burning natural gas and coal, produce double the amount of CO2 to that of heat transfer methods like those utilised through GSHPs. It is clear that heating by heat transfer is the attractive alternative.

Steve Wilkinson, Head of Commercial Projects at Cenergist

SCALING THE GSHP

GSHPs can be used at scale in a shared ground loop, a heating network where multiple properties have an individual heat pump that can be controlled and connected to a communal ground loop. A shared GSHP ground loop can serve multiple dwellings at once.

Shared ground loop systems can create highly efficient heating system networks. By using boreholes, over 200 properties could be connected by only 5 communal heating systems. Heat pump boreholes are the vertical pipes used to extract heat energy from rock to a GSHP. They save space and minimise disruption in heat pump installation projects - only requiring approximately 150mm width of per borehole. Each property has its own heat pump that is linked to one of the boreholes, and monitoring data shows that homeowners can potentially save 25% to 50% on their energy bills.

With only 5 boreholes provisioning heat to over 200 heat pumps, shared loops can help contractors reproduce GSHPs at scale. Drilling costs can also be reduced by allowing a smaller number of deeper boreholes, those of which can be positioned flexibly across the site, as there is no specific requirement for a borehole within the curtilage of each plot. This is not only restricted to housing properties, but can also be used in flat clusters, bungalows or apartment blocks.

GREEN ENERGY WITHOUT THE SACRIFICE

These systems are efficient - a welldesigned ground source heat pump installation can provide three or four kilowatts of heat for the consumption of one kilowatt of electricity. Heating is provided without sacrificing comfort, and these efficiency levels provide a significant cost saving.

Before recently, finding a GSHP in the UK was a rare occurrence, this was only because of the taxation and levies that were placed on electricity. Taxes and levies placed on electricity in the UK have received considerable attention in the last decade for their social and distributional impacts. So even though installing and running a GSHP system presented lower upfront costs and running fees than a gas boiler, the taxes were too high to make it sustainable.

It has now become clear these taxations and levies are working against the UK’s need to lower carbon emissions from domestic heating. In response, the government has provided funding and new regulatory measurements in its recent 10 point plan announcement, that counter the taxes and levies. With new government schemes such as the Homes Upgrade Grant and Social Housing Decarbonisation Fund, it is now easier than ever for homeowners and social housing properties to access GSHPs and HVAC systems, benefiting from renewable heating and affordable energy.

With the government making a big push and funding large areas of the country and the industry itself, it is now easier than ever to acquire a GSHP system. Not only are they ecofriendly with low carbon emissions, but they are flexible and scalable to multiple properties, and they have a higher efficiency rate than other methods of heating. Over the coming years, GSHPs will be crucial in the decarbonisation of the housing industry. www.cenergist.com