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Heat pump without an outdoor unit: does it exist and what does it cost?

The dream of a sustainable home without a conspicuous unit in the garden or on the facade is something many Dutch people are concerned about. While the heat pump is emerging as *the* solution for a fossil-free future, many homeowners encounter the aesthetic question: does that large outdoor unit *really* have to be there? The term “heat pump without an outdoor unit“ is appearing more and more frequently, promising a solution for those who want to keep their home’s appearance intact. But does such a system truly exist, how does it work, and what are the costs in the Dutch market?

In this article, we delve deep into the world of heat pump technology to unravel the mystery surrounding the heat pump without an outdoor unit. We highlight the various options that come close to this ideal vision, their advantages and disadvantages, and provide you with a realistic picture of the investment involved. This way, you can make a well-informed decision on your path to a more sustainable and comfortable home.

1. Heat Pump Without an Outdoor Unit: A Misconception or Reality?

Let’s get straight to the point: an air-to-water heat pump that absolutely no contact with the outside air does not exist. A heat pump draws its energy from an external source – air, ground, or water – and then releases it to your home’s heating system. For most popular (air-to-water) heat pumps, the outside air is the energy source. This means there must always be a mechanism to draw in and discharge this air.

However, there are systems that come very close to creating the illusion of a “heat pump without an outdoor unit“. These innovations focus on minimising the visibility and noise of the outdoor components. The most common options that fall under this category are:

Compact monoblock indoor heat pumps: These are air-to-water heat pumps where all components (compressor, fan, heat exchanger) are placed in a single unit inside the home. The connection to the outside air is made via two relatively small air ducts through the wall.
Geothermal (ground source) heat pumps: These systems extract heat from the earth. Although there is indeed an outdoor part (the ground source), this is completely invisible because it is installed underground. There is therefore no visible unit in your garden or on your facade.
Hybrid heat pumps (to a certain extent): Some very compact hybrid systems, which work in conjunction with a central heating boiler, have a small outdoor unit. However, the focus of this article is on heat pumps that supply the majority of the heat.

The term “heat pump without an outdoor unit“ therefore usually refers to solutions that either make the external components invisible or integrate them into the home. The focus here is on aesthetics and preventing noise pollution for yourself and your neighbours.

2. The Monoblock Indoor Heat Pump: Aesthetics and Functionality

The monoblock indoor heat pump is one of the most concrete answers to the demand for a “heat pump without an outdoor unit“. With this type of heat pump, as the name suggests, the complete heat pump unit is installed inside your house. This is often in a utility room, storage room, technical area, or in the attic. The unit extracts the necessary heat from the outside air via two discreetly concealed ventilation openings (air ducts) that pass through the outer wall. These ducts are often fitted with grilles that are barely noticeable.

How does it work?
The monoblock indoor heat pump draws in outside air through one of the ducts. Inside the unit, heat is extracted from this air using a refrigerant. The cooled air is then blown back outside through the second duct. The generated heat is internally transferred to the water of your heating system.

Advantages of a monoblock indoor heat pump:

Aesthetics: This is the primary driver. You don’t have a large, conspicuous unit in your garden or on your facade, which is ideal for smaller gardens, terraced houses, or protected urban landscapes.
Less external noise pollution: Although the unit produces noise, this sound remains indoors. This is a significant advantage for relations with your neighbours, especially in densely populated areas. However, internal noise pollution must be considered, although most modern units are designed to be as quiet as possible.
No issues with permits (often): As there is no unit hanging outside, there are often fewer to no discussions with the municipality or VvE about placement and appearance. You should check whether the wall penetrations are permit-free.
Protection against weather influences: The heat pump is located indoors, meaning it is less exposed to the elements, which can benefit its lifespan.

Points for consideration:

Indoor space requirement: The unit is relatively large and requires suitable indoor space.
Installation complexity: Drilling the air ducts through the outer wall can be a more complex job than installing an outdoor unit.
Indoor noise: Despite the quietness of modern units, the presence of a heat pump indoors may be more audible than a remote outdoor unit. Placement in an uninhabited space is therefore advisable.
Efficiency: Depending on the specific model and installation, the efficiency may be slightly lower than with an optimally placed split-unit air-to-water heat pump.

3. Geothermal Heat Pumps: The Ultimate Invisible Solution

If you are truly looking for a heat pump without a visible outdoor unit, then a geothermal (ground-to-water) heat pump is the ultimate solution. These systems extract heat from the earth, which remains at a constant temperature regardless of the season. The ‘outdoor unit’ here consists of a closed circuit of pipes (collectors) laid in the ground. This can be done horizontally at a shallow depth (provided sufficient garden space) or vertically via deep boreholes.

Advantages of geothermal heat pumps:

Completely invisible: There is absolutely no unit visible in your garden or on your facade. The heat pump unit itself is located indoors.
Very high efficiency: The ground temperature is more stable than the air temperature, resulting in higher and more constant efficiency throughout the year, and thus lower energy costs.
Extremely quiet: As no fan is required to draw in or discharge air, geothermal heat pumps are the quietest option.
Passive cooling possible: Many systems offer the possibility of passive cooling in summer, where the relatively cool ground temperature is used to cool the home, without additional energy costs.

Points for consideration:

High initial investment: The installation of the ground source (especially deep boreholes) is a costly undertaking, making the total investment higher than for air-to-water systems.
Space for installation: Horizontal collectors require a lot of garden space. Vertical boreholes require less, but access for the drilling rig must be possible.
Complex installation and permits: Drilling sources is a specialist job and requires permits from the municipality.
Suitable for new builds or major renovations: Although it can also be implemented in existing buildings, it is often more efficient and less intrusive to consider this for new builds or large-scale renovations.

4. What Do These ‘Invisible’ Heat Pumps Cost in the Netherlands?

The costs of a “heat pump without an outdoor unit“ depend on the chosen system and the specific situation of your home. It is an investment that pays for itself in the long term through lower energy costs and an increase in your home’s value.

Costs for a monoblock indoor heat pump:

Equipment and installation: Expect an investment of between €8,000 and €15,000. This includes the heat pump unit, installation, the necessary air ducts, penetrations, and connection to your heating system. The price varies significantly based on the capacity (suitable for your home), the brand, and the complexity of the installation (e.g., the length and routing of the air ducts).
Subsidies (ISDE): Fortunately, in the Netherlands, you can qualify for the Investment subsidy for sustainable energy and energy saving (ISDE). The amount of this subsidy for air-to-water heat pumps varies but can amount to €2,000 – €3,000 or more, depending on the heat pump’s capacity. This significantly reduces the net investment.
Payback period: With current energy prices and subsidies, the payback period for a well-insulated home with a monoblock indoor heat pump is between 7 and 15 years, depending on your energy consumption and installation costs.

Costs for a geothermal heat pump:

Equipment and installation (including source): This is the most expensive option, with prices ranging from €20,000 to as much as €35,000 or more. The majority of this amount goes towards the installation of the ground source (boreholes). The heat pump unit itself is comparable in price to high-quality air-to-water heat pumps.
Subsidies (ISDE): For geothermal heat pumps, you can also qualify for the ISDE subsidy, which is often higher than for air-to-water systems due to the higher initial costs. You can expect amounts of €4,000 to €6,000 or more.
Long-term benefits: Despite the higher initial costs, geothermal systems offer the highest efficiency and lowest operational costs, plus the advantage of passive cooling, which makes the long-term value proposition very strong.

Important considerations regarding costs:

Insulation: Good insulation of your home is crucial for the efficient functioning of any heat pump and affects the required capacity and thus the costs.
Distribution system: Suitable distribution systems such as underfloor heating or low-temperature radiators are essential for optimal efficiency.
Multiple quotes: Always request multiple quotes from different certified installers. This not only gives you a better price overview but also insight into different solution approaches and advice.

Conclusion: The Invisible Path to Sustainable Heat

A “heat pump without an outdoor unit“ is not a myth but a reality with various nuances. Whether you choose a monoblock indoor heat pump for its aesthetic benefits and the absence of a conspicuous outdoor unit, or for the ultimate sustainability and comfort of a geothermal heat pump with its completely invisible source; there are plenty of options to make your home more sustainable without compromising its appearance.

Each option has its own specific advantages and disadvantages and is suitable for different housing types and budgets. While the monoblock indoor heat pump is an excellent middle ground for those who prioritise aesthetics and have indoor space, the geothermal variant offers the most complete and efficient long-term sustainable heating and cooling solution, provided the budget and ground conditions allow for it.

In the Netherlands, there are plenty of experts who can advise you on the best choice for your situation. Consider your home’s insulation value, your heating system, available space, and, of course, your budget. It is an investment in the future, both for your home and for our planet.

Curious which “heat pump without an outdoor unit“ best suits your Dutch home? Request free advice and quotes from certified installers in your area now and take the step towards a more comfortable and sustainable home!

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Also read: our complete heat pump guide 2026.

Heat pump without an outdoor unit: Does it exist? Options, Costs & Subsidies in NL