How Do Ground Source Heat Pumps Work?

December 5th, 2024

Last updated: December 5th, 2024

Ground source heat pumps (GSHPs) are becoming a popular choice in the UK for businesses looking to cut heating costs and reduce their carbon footprint. But people have a lot of questions about them. How do ground source heat pumps work? And are they worth it for businesses?

With energy efficiency and sustainability high on the agenda, these systems offer an innovative way to keep buildings warm during the colder months and cool in summer. But how exactly do they warm your building? Let’s dive into the basics and explore the mechanics behind these clever devices.

Using Earth’s Natural Heat

The concept behind ground source heat pumps is simple: they harness the natural heat stored in the ground. Even during winter, the soil a few metres below the surface remains at a relatively constant temperature, usually between 10 and 15 degrees Celsius in the UK. This stable heat provides a reliable energy source that the pump can extract and amplify.

A GSHP system works by circulating a special liquid, often a mix of water and a substance that is effectively antifreeze. It travels through a network of underground pipes. These pipes, called ground loops, absorb the heat from the earth and carry it back to the pump. Once inside the system, the heat pump does its job…

The Role of the Heat Pump

The heat pump itself is the beating heart of the system. After the ground loop fluid delivers the absorbed heat, the pump uses a process involving compression and expansion to boost the temperature to a level suitable for heating. People often hear that the temperature below the ground is and assume this is the maximum that the heat pump can achieve. This is not the case.

This process relies on a refrigerant, a substance that changes from a liquid to a gas and back again at low temperatures.

Here’s how it works in simple terms:

1. Heat Absorption: The fluid in the ground loop transfers the earth’s heat to the refrigerant inside the heat pump.
   Compression: The refrigerant is compressed, raising its temperature significantly.
2. Heat Transfer: The heat from the now-hot refrigerant is transferred to a water-based system that heats radiators, underfloor heating, or hot water.
3. Cooling and Expansion: The refrigerant cools back down, ready to repeat the process.
   It’s an efficient, closed-loop system that keeps things running smoothly while making the most of renewable energy.

Types of Ground Loop Systems

Not all ground source heat pumps are the same. The type of ground loop used depends on the available land, budget, and heating needs. There are two main designs: horizontal and vertical.

• Horizontal Loops. These are laid out in shallow trenches, typically about 1 to 2 metres deep. Horizontal systems are ideal for properties with plenty of outdoor space since the loops require a significant amount of land.
• Vertical Loops. For spaces with limited space, vertical systems are a better option. These involve drilling boreholes 50 to 150 metres deep to house the loops. While more expensive to install, they’re just as effective and take up far less surface area.

Some systems even use nearby water sources, such as ponds or lakes, to draw heat instead of ground loops. These variations are less common but can be an option in the right circumstances.

Heating Your Building

Once the heat pump has done its job, the warm water is circulated through your heating system. Whether it’s radiators or underfloor heating, the result is a cosy space without relying on gas or oil. Ground source heat pumps are particularly well-suited to underfloor systems, which operate at lower temperatures than traditional radiators.

The system also provides hot water, although a backup electric heater may be installed for peak demand, especially in large buildings. This makes GSHPs a versatile solution for both heating and water needs.

What About Cooling?

When people ask “how do ground source heat pumps work?” they may not even realise that they can cool. In addition to heating, ground source heat pumps can also provide cooling during the summer. By reversing the process, the system extracts heat from your building and transfers it back into the ground. This feature isn’t always included but can be a valuable bonus for those hot spells the UK sometimes experiences.

Efficiency and Benefits

Ground source heat pumps are impressively efficient. For every unit of electricity used to power the system, it can generate three to four units of heat. This high efficiency translates to lower energy bills, especially for those who currently rely on expensive fuels like oil or LPG.

There’s also the environmental benefit to consider. GSHPs use renewable energy, which means they produce far fewer greenhouse gas emissions than conventional heating systems. For business owners looking to reduce their carbon footprint, this makes them a strong contender.

Moreover, with the UK government offering financial incentives like the Boiler Upgrade Scheme, installing a GSHP has become more affordable. These schemes aim to help cover the upfront costs of technologies like heat pumps and biomass boilers which can otherwise be a barrier for some.

A Sustainable Future

Ground source heat pumps represent an exciting step forward in sustainable heating technology. By using the earth’s natural heat, they offer an efficient, eco-friendly alternative to fossil fuels. Their long-term benefits make them an appealing option for those looking to future-proof their businesses.

With the UK aiming for net-zero carbon emissions, ground source heat pumps as well as air source heat pumps are likely to play a growing role in how commercial buildings are heated. For those considering a switch, understanding how these systems work is the first step towards a warmer, greener future.