Heat Pumps: Will this Old Technology Be the Future of Green Heating?

In the quest for sustainable solutions, heat pumps have emerged as a game-changer in the built environment. Heat pumps offer a promising alternative as the world grapples with the pressing need to reduce carbon emissions and minimise energy consumption.

The concept of heat pumps isn’t new, dating back to the 19th century. However, their evolution and technological advancements over the years have propelled them to the forefront of sustainable heating solutions.

The origins of heat pumps can be traced to the work of Lord Kelvin in the mid-1800s, who conceptualised the principle of heat transfer through mechanical means. It wasn’t until the 1940s that the first practical heat pump was developed. Since then, these systems have undergone transformative changes, becoming pivotal in sustainable heating for the modern built environment.

Depiction of an original-style heat pump from the 1800s
Depiction of an original-style heat pump from the 1800s
Modern installation of an air source heat pump
Modern installation of an air source heat pump

How do Heat Pumps Work?

At its core, a heat pump operates on the principles of thermodynamics, leveraging the transfer of heat from one location to another. Unlike traditional heating systems that generate heat, a heat pump extracts warmth from the surrounding environment, making them highly energy-efficient.

Air Source Heat Pumps (ASHP) mechanism illustration
Air Source Heat Pump mechanism Illustration

The heart of a heat pump system is the refrigerant cycle, which comprises four main components: the evaporator, compressor, condenser, and expansion valve.

The cycle begins with the evaporator absorbing heat from a low-temperature source, such as the outdoor air or the ground. The compressor then pressurises the low-temperature vapour, raising its temperature. The heated vapour passes through the condenser, where it releases heat into the indoor space. Finally, the expansion valve lowers the pressure of the refrigerant, preparing it for the next cycle.

This mechanism can also be reversed to provide an efficient cooling system. The reversing valve switches the symmetry of the hot and cold fluid in the system so that the indoor piping is cooler than the ambient temperature. The air that circulates through the system and your home cools as it comes into contact with the lower-temperature coils. The heat absorbed is then released outdoors, cooling the fluid once again and thus, the cycle continues.

Recent Technological Advancements

In recent decades, technological progress has significantly enhanced the efficiency and versatility of heat pump systems. One notable development is the introduction of variable-speed compressors, which allow heat pumps to modulate their output based on the heating or cooling needs of the space. This not only improves comfort but also minimises energy wastage.

The further integration of smart and programmable thermostats empowers users to optimise their heat pump’s operation, adapting it to their lifestyle and schedule. These advancements not only elevate user experience but also contribute to greater energy savings.

Advantages over Conventional Heating Systems

Heat pumps offer a myriad of advantages over conventional heating systems, making them a compelling choice for the built environment:

Energy Efficiency: Heat pumps are remarkably energy-efficient, typically delivering more energy in the form of heat than the electrical energy they consume. The primary source of consumption from the system comes from the compressor, which doesn’t use that much electricity.  Heat pumps are so efficient because they take advantage of basic physics. These systems essentially transfer pre-existing heat around, using the force of compression to heat fluid instead of using large quantities of energy to inefficiently generate heat.

Average heat pumps have a coefficient of performance (COP) of 2.5. Compared to a high-efficiency natural gas boiler, which typically has a COP of 1 or below, they produce far more heat for their energy requirement. This translates to lower utility bills and reduced carbon emissions.

Versatility: Heat pumps can provide both heating and cooling, making them a year-round solution for maintaining indoor comfort and avoiding the need for installing two different systems.

Safety: Unlike combustion-based systems, heat pumps do not involve burning fossil fuels, eliminating the risk of carbon monoxide leaks and improving indoor air quality.

Low Operating Costs: With their high efficiency, heat pumps substantially lower operating costs than traditional heating systems, offering long-term financial benefits. They can potentially reduce operating costs by $300 or more over a gas boiler. However, this is highly dependent on the circumstance.

Minimal Environmental Impact: By relying on renewable energy sources like the outdoor air, ground, or water bodies, heat pumps have a significantly lower environmental footprint compared to systems dependent on fossil fuels.

Longevity: Heat pumps have a longer lifespan than many traditional heating systems, contributing to reduced waste and resource consumption over time.

Environmental Benefits and Net-Zero Goals

The environmental advantages of heat pumps extend beyond individual buildings. On a larger scale, the widespread adoption of heat pump systems aligns with global sustainability objectives. As nations strive to achieve net-zero emissions, transitioning to heat pumps could be pivotal in curbing greenhouse gas emissions. By reducing the demand for fossil fuels, heat pumps contribute to cleaner air, reduced pollution, and a more sustainable planet.

Furthermore, the integration of renewable energy sources, such as solar panels or wind turbines, with heat pump systems creates a powerful synergy. The surplus energy generated can be utilised to power the heat pumps, further minimising the reliance on non-renewable resources.

What are the drawbacks?

Installation costs for a 3-bedroom house range from £8000-£15000 for an air source heat pump system (ASHP). This price may include the cost of having a new water tank and compatible radiators installed. Ground source heat pumps (GSHP) typically cost much more, with prices exceeding £15000 and sometimes up to £45000.

The UK government does provide grants to alleviate some of this financial pressure in an attempt to promote the use of more environmentally positive heating systems. They offer up to £5000 per household for ASHPs and up to £6000 for GSHPs. The initial expense is still significant but is more manageable with this government contribution.

Insulation is a highly influential factor in the viability of ASHP installations. Poorly insulated housing reduces the efficiency and increases the operating cost of having an ASHP. The energy provider Octopus has stated that in a poorly insulated home ASHPs may cost 40% more to run than a traditional boiler system.

Cold climates could also be another deciding factor on the overall benefit of a heat pump system. ASHPs are less efficient in lower temperatures, whereas more expensive GSHPs are more consistent in varying conditions.

Graph of Heat Pump Efficiencies
Ecovative’s grow-it-yourself Mycelium material kit

The building in question could also be another barrier to acquiring a heat pump. GSHPs require compatible infrastructure to be installed and so are out of the question for many living in apartments or shared buildings. ASHPs can also be challenging to install in confined spaces and whilst retrofitting is possible, it is often a costly and laborious process that is unappealing to many homeowners.

Are heat pumps worth the switch?

If the building structure is suitable for heat pumps or a new heating system is being fitted anyway, then the switch is definitely worth it, assuming the initial expenses can be covered. GSHPs tend to be the most effective system to have but are more expensive and more invasive to install as they require drilling and boreholes.

The environmental benefits are unquestionable, with lower carbon output and greater reliance on renewable energy, they’re an ideal alternative. The UK government already supports heat pump installations and the future may well see further government incentivisation.

In most eligible cases, a heat pump will offer financial savings over traditional heating systems in the long term. These savings are also likely to improve as fossil fuel energy prices increase over time due to resource depletion and climate consciousness.

There are many hopes for a future in which complementary synergistic energy systems work together for greener energy and heating that is economically viable. Widespread adoption of heat pump systems would make them more compatible with homes and reduce installation costs. They also work well in tandem with independent energy production in the form of solar or wind power and would be a big step toward a self-sustaining built environment. It is very likely that in years to come, conventional heating systems as we know them will be obsolete, replaced by more sustainable alternatives. Heat pumps are the most likely substitute in this heating system revolution.

To discover other solutions to a more sustainable future, have a look at the Firstplanit website and blog to learn about the most recent developments for the built environment.

Learn More on Firstplanit

Click here to read about the heat pump race heating up in Europe.

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