In the first part of this series, we examined the running costs of various heating systems.
In Part 2, we now remove the fuel cost and analyse how much energy they use, as well as their efficiency.
As with part 1, we are comparing common UK heating options using a standard 100m² home with typical heat loss. Each situation will vary, but this example illustrates the trends in the amount of energy different heating systems consume.
Log Burner
Traditional, potentially cheap but inefficient.
- Pros: Relatively inexpensive fuel, works off-grid
- Cons: Inefficient and localised heat typically to the room it’s in.
Log burners are a common sight throughout the UK, and many people have access to cheap or even free logs. The downside is that they are one of the least efficient methods of heating a home from burning a fuel. They can heat up a room quickly as they are very powerful, using radiant heat to make the space feel warm. However, compared to a biomass boiler, less of the energy in the wood is converted into useful heat for your room.
Oil Boiler
Common off-grid option.
- Pros: Good efficiency, widely available off-grid
- Cons: Price is still volatile, carbon emissions
Now we are moving into the boilers that burn things in a contained environment to heat water for a central heating system. Newer condensing type boilers are more efficient, extracting upwards of 90% of the energy available in the kerosene. Older boilers are usually non-condensing, which are less efficient. All of the following modern boiler types have very similar efficiencies.
Biomass Boiler
Renewable option with reasonable running costs
- Pros: Renewable, lower running cost
- Cons: Needs storage space, frequent deliveries
Biomass boilers commonly use wood chips or similar for fuel. Much more efficient than a log burner and has similar efficiency to other boilers. The disadvantage of biomass boilers is that the fuel is less energy-dense, and thus, it commonly requires more frequent deliveries of fuel.
LPG Boiler Central Heating System
Off-grid solution, but pricey fuel
- Pros: Suitable for off-grid homes
- Cons: Expensive fuel
Liquefied Petroleum Gas (LPG) boilers are typically the most expensive to run of the boilers due to the fuel price, but have a similar burning efficiency to other boilers. Commonly used in more remote locations as it can be stored in tanks.
Gas Boiler
The UK standard for good reason
- Pros: Affordable, reliable, widely available
- Cons: Still a fossil fuel
The most common boiler fuel in the UK is natural gas. These are now achieving around 95% efficiency and burn very cleanly, which has helped reduce pollution in urban environments.
Hydrogen Boiler Central Heating System
Future-friendly but still similar efficiency to other boilers
- Pros: No emissions from your building, potential for the future
- Cons: Is still burning a fuel to create heat with high current hydrogen prices
Hydrogen is likely to have a role to play in our net zero journey but projections are suggesting it is not going to be the boiler of choice for most future homes. It may become a more off grid solution or an option in places where electricity generation, storage and supply have challenges.
Electric Storage Heaters
Simple but costly for larger spaces
- Pros: Easy to install and efficient, good for small, well-insulated spaces
- Cons: Expensive to run in bigger or draughtier homes
We now move into the heating systems powered by electricity. Electric heating is often considered to be close to 100% efficient, which is why it is used in kettles, stoves, and other appliances. The downside is that the current market price of electricity is considerably higher than that of burnable fuels, and hence can be expensive to run. An interesting side note is that the vast majority of the electricity your appliances use within your home ultimately ends up as heat that helps heat your home.
Electric Infrared Heaters
Targeted heating that needs careful management
- Pros: Cheap to install, heat specific areas directly
- Cons: Can cause damp problems if used incorrectly
The efficiency of infrared heaters is similar to that of storage heaters and very close to 100%. The reason it uses less energy compared to storage heaters is that it can often be timed and targeted better.
It is worth noting that other building issues can occur with infrared heating, as people tend to heat the building less to save costs. A common one we see is colder spots where the heat isn’t targeted, creating condensation and damp in these areas. Another issue is owners turning the heating on when they are in the building and then off when leaving, commonly trapping moisture inside. With no heating to keep the water in the air, it condenses on surfaces and can create mould.
In certain scenarios, it can be a great heating scenario, but in the wrong scenario, it can be expensive or create expensive building problems.
Air Source Heat Pumps
Modern, efficient, but needs good installation
- Pros: Lower running costs than gas (when installed properly), government grants available
- Cons: Expensive to install, less efficient in very cold weather
Now we move into the heat pumps, where they really start to show their benefits. Modern air source heat pumps are capable of efficiencies of 400% plus. This means that for every 1 unit of electricity, you will get 4 units of heat out, as the heat pump uses that electricity to extract heat from the air surrounding the building. This is why there is a big push from the Government to migrate to heat pumps. The country has a plan to reduce the emissions it takes to make electricity, and moving consumers to electrical heating systems is a huge part of the country’s net-zero plan. The current issue is that the National Grid is limited in the amount of electricity it can reasonably supply, and electricity is currently expensive. Heat Pumps solve this by reducing the required electricity from the grid, and have now managed to reduce their running costs to below that of gas.
If the Government achieves its goal of reducing the electricity price relative to fossil fuels, then heat pumps will become significantly cheaper to run than boilers.
This is why the Government has the £7500 Boiler Upgrade Scheme grant in place to incentivise switching to a heat pump.
Ground Source Heat Pumps
The most efficient but most expensive to install
- Pros: Low energy consumption
- Cons: Costly and complex installation
As with the cost comparison, the ground source heat pump tops the list of the most efficient heating systems. It is, however, likely to be the most costly and complex to install. The reason it is the most efficient is that during the coldest winter months, the ground is warmer than the air; thus, the ground-source heat pump is more efficient in these months.
Air source heat pumps have been closing the gap quite quickly, and it is conceivable that the efficiency of smaller systems may overtake ground source systems in the not-so-distant future.
Summary
In efficiency terms, the heat pumps hugely outperform their boiler equivalents. They demonstrate the amount of energy available in the environments immediately surrounding our buildings, and it’s clear why this is the heating technology being incentivised by the Government.
In our next and final blog, we’ll examine the emissions of each system to provide insight into how the country can achieve its net-zero targets.