As the world looks towards utilizing more renewable sources of energy, air source heat pumps are proving to be a great way to extract heat naturally stored within the outside air.
While air source heat pumps can be a fantastic way to provide heating and hot water to a home, there can be a number of downsides to using heat pumps and they may not be suitable for every home, but can air source heat pumps be considered to be the future of heating a home?
Air source heat pumps can be seen as the best alternative to traditional heating systems for the foreseeable future. However, their disadvantages, such as a lower heat supply and efficiency in cold weather, can hinder their implementation into buildings and homes.
Our air source heat pump was installed when our house was built over 5 years ago.
While relatively expensive to purchase and install compared to more conventional heating systems, a lack of gas supply in the local area meant that this air source heat pump was considered the most viable solution for generating heating and hot water for our home for the foreseeable future.
In this article we discuss this topic in more detail by explaining how air source heat pumps work, their considerable benefits, and the disadvantages holding them back.
How Air Source Heat Pumps Work
An air source heat pump (ASHP) extracts heat energy stored naturally within the outside air and transfers that heat indoors for use as heating, and potentially also domestic hot water if needed.
Instead of generating heat like most conventional home heating systems, an air source heat pump simply transfers heat from one place to another.
As a result, ASHPs can have lower running costs than a conventional home heating system because they don’t have to consume as much energy to produce the heat.
However, as air source heat pumps run solely on electricity and require no other form of energy such as gas or oil, local electricity prices can dictate how much they can cost to run. See our article on air source heat pump electrical requirements for more information.
Air source heat pumps can also provide cooling as well as heating, depending on the model and setup.
When the heat pump needs to provide cooling, it simply takes the cycle of moving outside heat inside and reverses it. Instead, it takes the heat from indoors and transfers it outdoors.
See our main article on how air source heat pumps work for more information.
Why Air Source Heat Pumps May Be The Future
Air Source Heat Pumps Can Use Less Electrical Energy
Air source heat pumps can require a less amount of electrical energy to run compared to other electrical heating systems. Using one can require as little as 1/5th of the energy that ordinary electrical heating systems use.
According to The Department of Energy, air source heat pumps can also use approximately 50% less electricity than electric resistance heaters like electric furnaces, baseboard heaters, and wall heaters.
Air Source Heat Pumps Are More Energy Efficient
ASHPs can have a coefficient of performance (COP) ranging from 2-3, depending on the outdoor temperature. This means that, in ideal conditions (when the temperature is above 40°F or 4.44°C), for every single kilowatt of energy the heat pump uses to run, it produces 2-3 kilowatts of energy back.
Thus, they produce 2-3 times more heat energy than the electrical energy they consume. Sometimes it can produce over five times more or even up to 7 times in mild climates such as the Mediterranean and Southern or Central China.
The COP for our own air source heat pump is over 3 in the most ideal scenario.
See our articles explaining air source heat pump COP and overall air source heat pump efficiency for more information.
Air source heat pumps can also be more efficient for cooling.
While typical air conditioning units run into issues when the outside temperature is very high, ASHPs have no problem with high outdoor temperatures. They can typically deliver efficient cooling no matter the indoor and outdoor temperature difference.
Air Source Heat Pumps Have a Low Carbon Footprint
ASHPs heat and cool homes by moving energy in and out of homes rather than by burning fossil fuels. This is in contrast with most heating systems which depend on burning natural gas, electricity, or heating oil to heat the air or water home.
These conventional heating systems can leave a pretty big carbon footprint. Accordingly, commercial and residential buildings accounted for 13% of greenhouse gas emissions from fossil fuels burned for heat in 2019.
In contrast, according to Columbia SIPA, when powered by zero-carbon electricity, ASPHs provide heating without any greenhouse gas emissions at all.
According to IEA.org, heat pumps could supply 90% of global space and water heating needs in the future and do it with a lower carbon footprint than gas-fired condensing boilers. Given this, ASHPs could be a powerful tool for a more sustainable future in the race to reduce greenhouse gas emissions.
Air Source Heat Pumps Can Have A Lower Running Cost
Since ASHPs can produce up to 5 times as much heat energy as they consume in electricity, their electrical cost for the amount of energy produced can be low.
According to a study done by the Northeast Energy Efficiency Partnerships, ASHPs savings are around 3,000 kWh or $459 a year compared to electrical resistance heaters and 6,200kWh (or $948) compared to oil heating systems in the US Northeast and Mid-Atlantic region.
Replacement of electric resistance heaters with ASHPs in these regions could save approximately $1.2 billion annually, while replacing home oil heating systems with ASHPs could save $1 billion. The adoption of ASHPs in other regions could result in similar savings.
Furthermore, The Renewable Heat Incentive (RHI) offered home and business owners fixed payments using air source heat pumps in the UK, meaning that UK citizens can actually make up the cost of owning an air source heat pump because they do good for the environment.
While our own air source heat pump may not currently cost much less to run than a gas heating system would (because electrical energy prices are much higher than gas in our area), we’re not directly burning any fossil fuels and gas prices may continue to climb for the foreseeable future.
Disadvantages Of Air Source Heat Pumps
Air Source Heat Pumps Can Have a Lower Heat Supply
While ASHPs are typically more energy-efficient, they can produce less heat than other alternatives such as oil and gas boilers.
Air source heat pumps can’t deliver the same on-demand heat as conventional heating systems can and so must be used over longer periods of time to provide the same heating effect.
This allows time for an ASHP to extract heat from outside air over time and deliver that heat indoors. When using an air to water heat pump (such as the type we have), using underfloor radiant heating and large numerous radiators with large surface area helps to release the lower temperature heat more effectively.
This can also mean that if your home isn’t already well insulated, you’ll most likely have to pay to have it insulated alongside your ASHP to ensure that the heat stays in for long enough.
Air Source Heat Pumps Can Have Lower Efficiency In Cold Weather
In freezing temperatures below 15°F (-9°C) or so, ASHPs can have a harder time producing heat.
At these low temperatures, there is less heat energy in the air and air source heat pumps can need to work for longer and harder to produce the same indoor temperatures.
The image below shows how our air source heat pump has a lower COP and higher energy input when outdoor air temperatures are lower (A2 compared to A7).
However, air source heat pumps can still work very well in even the coldest of temperatures, they can just be less efficient.
Our air source heat pump is guaranteed to work down to low temperatures as shown below.
As outdoor temperatures reach this minimum operating temperature the output temperatures can fall.
See our article on how air source heat pumps can still work in winter for more information.
Are Air Source Heat Pumps The Future?
Air source heat pumps come with amazing benefits for your home and the environment, including potential:
- Higher energy efficiencies
- Lower electricity usages
- Lower running costs
- Low to zero greenhouse gas emissions
However, nothing is perfect, and ASHPs do come with some disadvantages. Nonetheless, their negatives may not outweigh the positives in many situations.
Air source heat pumps are a powerful and efficient choice of technology towards creating a more sustainable future and can be considered to be one of the best choices for providing heating and hot water for a home for the foreseeable future, alongside other technologies such as ground source heat pumps.
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