Heat pump in the garden: hidden costs for homeowners

Many homeowners simply place their heat pump in the garden – only to be surprised later by bills nobody anticipated.

When upgrading their heating, most people focus on grants, noise levels and efficiency. Few realise that the precise location of the outdoor unit in the garden can bring the planning authority into the picture and create additional costs running into four figures. A recent case in Stuttgart illustrates how a supposedly straightforward replacement can rapidly turn into an expensive bureaucratic delay.

The Stuttgart case: a heat pump in its old position, but new problems

A homeowner in Stuttgart-Bad Cannstatt planned to replace his ageing heat pump. The new system was intended for the same place as the old one: at the rear of the garden, on his own land, where it had apparently caused no issues for years. He believed it would be a routine project.

Instead of a simple replacement, however, the building control authority got in touch. The authorities suddenly requested comprehensive documentation, including up-to-date site plans, land registry extracts, details of the unit’s exact location and dimensions, and potentially even information about its noise emissions. The owner estimates that obtaining these documents alone added around €1,600 to the cost.

“The same location, but a different set of rules: even replacing an existing heat pump can trigger new obligations and costs.”

At first, the case may appear to be an exceptional approach by a particularly strict authority. In reality, much of it is based on rules that apply across Germany and can become relevant in any local authority area whenever a heat pump is positioned in the garden outside the designated building area.

Exempt from planning permission does not mean “it can be installed anywhere”

Many installers and property owners hear that heat pumps are exempt from planning permission. This can sound like no application, no authority and no hassle. Legally, though, it means something different.

Exempt from planning permission essentially means only that, in many German federal states, the unit itself does not require a conventional planning consent. The heat pump is classified as an ancillary structure and benefits from certain relaxations in planning law.

Heat pumps and development plan requirements

What exemption from planning permission explicitly does not determine is:

• Whether the unit sits within the permitted building area of the plot
• Whether required distances from neighbouring properties are observed
• Whether noise protection requirements are met
• Whether the development plan permits ancillary structures at that location

This is where the development plan becomes important. It defines the so-called buildable area of the plot.