Lake Source Heating – Complete Guide to Technology, Installation and Costs

Lake source heating is a heating solution where a lake is used as the heat source for a heat pump. The energy stored in the water is captured and used to heat the house and produce domestic hot water. Everything takes place in a closed-loop system where energy is transferred from the lake into the house.

1. A collector pipe is placed on the lakebed and filled with brine (a heat transfer fluid).
2. The fluid circulates in a closed system between the lake and the house.
3. As the fluid passes through the pipe, it absorbs heat from the surrounding water.
4. The warmed fluid is then transferred to the heat pump in the house.
5. Inside the heat pump, the temperature is increased so it can be used for heating and domestic hot water.
6. The heat is distributed to radiators, underfloor heating, and hot water taps.
7. The fluid is returned to the lake and the process repeats.

The closed-loop system allows the energy to be used efficiently all year round. In some systems, the same energy source can also be used for comfort cooling during summer, depending on how the system is designed.

For lake source heating to work in practice, several basic conditions need to be met. Before proceeding, it is important to check the following:

• There is a lake or large body of water in direct connection to the property.
• You have the right to use the water area where the pipe will be placed.
• The water is deep enough for the pipe to lie securely.

The pipe also needs to be positioned so it is not affected by factors such as boat traffic or heavy ice formation during winter.

Other important considerations include:

• The distance between the lake and the house is reasonable.
• The house has a heating system compatible with a heat pump, such as radiators or underfloor heating.
• The property has a stable heating demand that justifies the installation.

If these basic conditions are met, lake source heating may be a viable option to consider.

Since lake source heating involves placing a collector pipe in a body of water, it affects the physical environment of the lake. The installation therefore requires notification and permits. A permit must always be applied for.

Regulations vary between municipalities, making it important to contact the local environmental authority early to clarify what rules apply in the specific area.

Installing lake source heating connects the energy source in the lake with the building’s heating system through a designed and properly dimensioned solution. The exact work depends on local conditions but normally includes the following steps:

• Dimensioning the system based on the property’s energy demand
• Laying the collector pipe on the lakebed
• Installing pipe connections between the lake and the house
• Installing and connecting the heat pump

Commissioning and testing the entire system.

The cost of installing lake source heating varies due to below factors. The exact price depends on the specific conditions of the property and how the installation can be carried out.

Factors affecting the cost include:

• Distance between the lake and the house
• Length of the collector pipe
• Water depth and lakebed conditions
• The property’s energy demand and required output
• Ground work on land
• Choice of heat pump

Operating costs are generally low compared to direct electric heating or older heating systems, since the lake acts as a stable energy source year-round. The actual savings are depending on electricity prices and how well the system is dimensioned.

Advantages of lake source heating

Stable temperature in the energy source

Water maintains a relatively stable temperature throughout the year, providing reliable operating conditions even during cold periods.

No drilling required

Unlike ground source heating, no borehole drilling is required, which can be beneficial where drilling is difficult or expensive.

Less land area required than ground source heating

Compared with horizontal ground source systems, no large land areas are needed to place collector pipes on the property.

Low ongoing energy consumption

Once installed, energy is drawn from the lake, reducing electricity use for heating.

Requires access to a lake or water body

The system is only possible for properties with access to a lake or large body of water.

Permits may be required

Because installation takes place in a water area, notifications or permits may be necessary.

High initial investment

Like ground source heating, lake source heating involves a significant upfront investment.

Installation depends on local conditions

Water depth, lakebed conditions, and distance to the house can affect how the installation is carried out. 

Lake source heating works best when the conditions of the property and the location near the water align. It is not suitable everywhere, but it can be highly efficient where installation is practically feasible.

Lake source heating is particularly relevant when:

• The property has direct access to a lake or large body of water
• Installation can be carried out without extensive ground work
• Heating demand is stable throughout the year
• A long-term and reliable heating solution is desired

In other situations, alternatives such as ground source heating, ground collectors, or air-to-water heat pumps may be more suitable.

Like other heat pump systems, lifespan depends on installation quality, proper sizing, and ongoing maintenance. Read more in our guide about heat pump lifespan.

Lake source heating is an efficient heating solution where the right conditions exist. When the energy source, installation, and property requirements align, the system can provide stable and long-term operation.

At CTC, we work with complete heat pump systems where the entire solution – from energy source to indoor comfort – is carefully designed. For properties with access to a lake, our lake source heat pumps can be part of such a complete solution.

If you want to learn more about how lake source heating could work for your property, you are welcome to contact one of our retailers for advice.