In hot water

May's launch of the Surface Water Source Heat Pumps code of practice by CIBSE, and produced in association with the Heat Pump Association (HPA) and the Ground Source Heat Pump Association (GSHPA), marks the second such code released by the Institution in a new venture. To explain the logic behind the launch Phil Jones, Chair of the CIBSE Energy Performance Group, writes on the current situation.

The UK is under huge pressure in the coming years to solve its energy dilemma. As prices rise, security falls – and the effects are being felt in homes and businesses alike: a quarter of the UK’s energy is used by homes, and the majority of that goes on heating them. But rubbing up against this problem is sustainability: the traditional energy sources of oil, gas and coal are great polluters, and the UK Government is rightly attempting to cut its use of these to combat climate change.

Here, the UK has an underutilised secret weapon – its network of rivers, streams, lakes, canals, and its massive coastline. The environment has long been thought of as a largely untapped potential source of heat, with ground and air source heat pumps taking the limelight, but water source systems remain less popular - despite their advantages.

The UK has a large network of rivers, canals and lakes with habitation
suitable for a SWSHP system
As with any engineering solution, the goal is to overcome problems with the best use of the tools available – whether that’s using a closed loop system in a lake, an open loop abstraction approach in a canal or a river-based system to heat or cool a building. The primary consideration for such a system is the sustainability of the project in the long term, which is the technology’s primary advantage. This will bring future cost savings, as well as a positive impact on the environment through fossil fuel savings.

Heat pump systems can also be used to heat and cool simultaneously – this removes the need for separate heating and cooling systems and makes the overall process much more efficient. Rather than generating new energy or wasting surplus energy, the energy that has already been generated can be used again – which raises an important point about sustainability: It is about considering the lifetime cost of a building, not just the short term, and the savings in operating and maintenance that can be achieved with a properly commissioned Surface Water Source Heat Pump (SWSHP) make the system worth the capital cost of installation.

There are also savings to be had in the equipment you don’t have to buy – for example, if used in place of a conventional gas boiler, there is no need for additional infrastructure such as the gas mains supply and the flue. Water also has inherent advantages over other materials for storing heat – it has a much greater capacity for heat storage than air, and the average canal or river’s temperature is greater than the ground, making a water-based system a stand-out option for those with access to a natural supply.

The SWSHP system at Kingston Heights in Surrey
These benefits are all well and good, but the crucial caveat is that they require a well installed system backed by industry knowledge in order to make them work best and provide the greatest benefits to their user. This growing industry has been crying out for concrete guidance and high standards that will cement the status of the SWSHP as a well-regarded and feasible option for buildings new and old going forward.

This new code of practice is a significant step forward, but it will require continuous work to improve and update the document going forward in order to ensure professionals have access to the best and most up to date information. It is also important to remember that we can only do so much with research and paper – the key is to get the information into the hands of professionals through training, and CIBSE and GSHPA have set up training courses to make sure there are trained people are out there pushing good SWSHP installations.

If we can do this, we can ensure that SWSHP systems represent a sustainable solution for the whole life of a building for years to come.


  1. Going to need the active support of the environment agency, harbour masters and waterways authorities. Do we have that ?


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