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Heat Pumps or EWI? What To Get First

Deciding between a heat pump and external wall insulation (EWI) for your home can be a bit like trying to solve a classic chicken-or-egg conundrum. Both are essential components in the journey towards a more energy-efficient home, but which one should you prioritise? In this blog, we’ll delve into the pros and cons of each, helping you make an informed decision on what to get first.

It may seem obvious given that we are an external wall insulation company, but the value of heat pumps cannot be understated. Recent ECO statistics show that insulation, and EWI at that, make up a much smaller portion of all energy efficiency measures installed under ECO funding. Whereas heating measures add up to almost half the measures installed. The main reason is seemingly the concentrated drive of the industry to catch up to Europe’s rate of heat pump installs.

What are heat pumps?

Heat pumps are an innovative and sustainable heating solution, growing increasingly popular in the quest for greener living. They work by extracting heat from external sources — such as the air (air source heat pumps), ground (ground source heat pumps), or water (water source heat pumps) — and using it to heat your home. This technology is not only fascinating but also represents a significant shift in how we think about domestic heating.

How do heat pumps work?
  • Air Source Heat Pumps (ASHPs): These extract heat from the outside air in a process that is similar to how a fridge extracts heat from its inside. They can still extract heat when air temperatures are as low as -15°C.
  • Ground Source Heat Pumps (GSHPs): These use pipes buried in the garden to extract heat from the ground. This heat can then be used to heat radiators, underfloor or warm air heating systems, and hot water in your home.
  • Water Source Heat Pumps (WSHPs): Similar to GSHPs, they extract heat from water sources like lakes or rivers.
  • Efficiency: Heat pumps are known for their high efficiency. They typically deliver three to four times more energy in heat than they consume in electricity, making them a highly efficient alternative to conventional boilers.
  • Eco-friendly: They reduce reliance on fossil fuels and decrease carbon emissions. This is crucial in tackling climate change.
  • Consistent Heating: Unlike traditional boilers, heat pumps provide a continuous flow of heat at a consistent temperature, ensuring a comfortable home environment.
  • Cooling Capabilities: Some heat pumps also offer cooling in the summer, making them a versatile choice for year-round climate control.
  • Upfront Costs: The initial installation of a heat pump can be significantly higher than traditional heating systems. This includes the cost of the unit and potential modifications to your home’s heating distribution system.
  • Performance in Extreme Cold: While modern heat pumps are effective in cold climates, their efficiency can decrease as the temperature drops, especially for air-source heat pumps.
  • Space Requirements: Ground source heat pumps require sufficient space for the installation of ground loops.

What is EWI?

External Wall Insulation (EWI) is a key element in enhancing the energy efficiency of homes, especially in climates with significant temperature variations throughout the year. EWI involves applying insulation material to the external walls of a building, which is then covered with a special type of render or cladding. This process not only improves thermal performance but can also revamp the exterior appearance of a property.

How does EWI work?
  • Energy Efficiency: By reducing heat loss through walls, EWI significantly improves the thermal efficiency of a building. This is particularly beneficial for older homes that may not have been built with energy conservation in mind.
  • Cost Savings: Improved insulation leads to reduced energy consumption, which means lower heating bills. This can be a substantial saving over the long term.
  • Comfort Improvement: EWI helps maintain a consistent indoor temperature, making living spaces more comfortable throughout the year.
  • Noise Reduction: Adding insulation to the external walls can also have the added benefit of soundproofing, reducing noise from outside.
  • Aesthetic Enhancement: With a variety of finishes available, EWI can dramatically improve the appearance of a building.
  • Installation Cost: The cost of EWI can be substantial, including the materials and the labour involved in the installation.
  • Planning and Permissions: In some cases, especially in listed buildings or conservation areas, you may need planning permission to install EWI.
  • Professional Installation Required: EWI must be installed by professionals to ensure it meets building regulations and performs effectively. Improper installation can lead to issues like dampness.

What to get first – heat pumps or EWI?

Assessing your home’s insulation

If your home is currently poorly insulated, particularly in the external walls, then prioritising EWI is likely the more strategic choice. Heat pumps are most effective in well-insulated homes, as they operate on the principle of maintaining a consistent temperature. Installing a heat pump in a poorly insulated house can be likened to trying to fill a bathtub with the plug out; the energy efficiency benefits are substantially diminished as the heat escapes through the walls. By first ensuring that your home is well-insulated with EWI, you create an environment where a heat pump can operate at its optimal efficiency, leading to greater energy savings and a more comfortable living space.

Considering the age and efficiency of your current heating system

On the other hand, if your current heating system is outdated or nearing the end of its lifespan, opting for a heat pump might be a wise initial investment. This is particularly relevant if your home already has a reasonable level of insulation. Modern heat pumps not only provide efficient heating (and cooling) but also significantly reduce carbon emissions compared to traditional fossil-fuel-based heating systems. By replacing an inefficient, older heating system with a heat pump, you can immediately start to reap the benefits of lower energy bills and a reduced carbon footprint.

Budget constraints and long-term planning

Budget considerations also play a crucial role in this decision. EWI, while still a significant investment, might be more financially accessible as a first step compared to the higher initial outlay required for a heat pump installation. Furthermore, the immediate energy savings from EWI could help in accumulating funds for a future heat pump installation. It’s a step-by-step approach that can be more manageable for many homeowners.

The bigger picture

Ultimately, the journey towards a fully energy-efficient home is exactly that — a journey. It often involves multiple steps and investments over time. Starting with EWI can prepare your home for the next phase of installing a heat pump, ensuring that when you do make that investment, you’re able to maximise its benefits. Conversely, if your immediate need is a new heating system and your home already has decent insulation, a heat pump could be the right first step.


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