Heating, Ventilating & Plumbing
The great source
Published:  30 June, 2014

Groundwater, which is widely available in the UK, has great potential for energy saving and CO2 reduction. An integrated heat pump technology may help to harness its sustainability and profitability, says Andrea Bertelle, communications manager at Climaveneta.

With energy security issues and carbon reduction targets on the top of the agenda for country and urban authorities, groundwater as a renewable energy source for heating and cooling through heat pumps is enjoying renewed popularity in the UK and in the whole of Europe. 

This is no surprise - water source heat pumps offer an ideal answer to many energy and sustainability challenges relating to built environment heating and cooling.

A bigger surprise is that groundwater is actually more available and more easily accessible than we think.  Research from London University and the Environment Agency shows the existence of a rich aquifer at a relatively reduced depth in most of the city. The UK Groundwater Forum explains that the importance of groundwater is only likely to increase in the future. Its buffering capacity should help to reduce the impact of extended dry periods that may result from climate change. However, the groundwater can also contribute directly to the provision of renewable energy via geothermal technology, in combination with heat pumps.

In fact, ground source use with heat pump systems is not new in the city. Many landmark buildings such as the Portcullis House, the Royal Festival Hall, the Queen’s Gallery in Buckingham Palace, the Sadler’s Wells Theatre, the Zetter Hotel and the City Hall by Norman Foster are already using groundwater for heating and cooling, either from the aquifer or from the Thames. 

The use of ground source heat pump (GSHP) systems for heating or cooling is already widespread in Germany, France, Switzerland and Sweden. In the UK, it is an emerging technology. The number of UK installations has increased rapidly since 2000, from about 12 systems installed between 1970 and 1994 to approximately 2,000 systems (of all system types) in 2013. The reasons for this rapid development include the increased awareness of climate change issues, rising fuel prices as well as the introduction of the Merton Rule and similar policies in 2003.

Currently, open-loop systems are a relatively small sector in the overall GSHP market in the UK, but demand for use in larger scale commercial/public buildings in urban environments is expected to increase. Market growth scenarios published by the Environment Agency predict that between 7,750 - 29,000 open-loop systems will be operational in the UK by 2020.

As the Milan case shows, at the moment we are still far from reaching its real potential. In fact, it was almost a problem especially in recent times when offices replaced many water-intensive industries in the area and the water level was rising. The city found a way to make the best of this resource, using ground source heat pumps as a standard solution, which helps to control the aquifer level and improve building energy performance. As groundwater floods are caused by the emergence of water from sub-surface permeable strata, through the use of open-loop GSHP it is possible to take the water from a wide aquifer and after using it, to pump it into an aquifer that is not as rich in water to create a sort of balance between the aquifers and avoid any flooding.

Despite all the enthusiasm and positive examples, critics say that an excessive use of groundwater may cause a temperature increase in the aquifer, with dramatic effects on the local flora and fauna. Yet by using the aquifer to exchange rejected heat, the amount of water used by the system must be well proportioned to the total amount of available water, so that the temperature increase has no effects on the total.  

Again, critics point out that the efficiency increase of water source systems would barely compensate the additional initial investment for boreholes and pumps required by these systems.  

The debate is flourishing.  As often happens, a responsible, pragmatic approach combining careful environmental considerations and sound economics can help to find a balance and identify the best way to harness the opportunity of this technology.  

With reference to green buildings and sustainable policy, George Adams, the CIBSE president said: “The built environment is hugely important to UK business and to our social requirements. Equally so are the essential reductions in carbon emissions required by the Government’s target of 80% within the next 36 years. Buildings affect people’s health, security, productivity and overall lifestyles. As they become increasingly complex and modern systems and operators become more focused on in-use performance levels, then building services engineers must play an important part in ensuring their efficient operation and helping to optimise facilities management delivery and energy efficiency”. 

In this context a specific heat pump technology, Integra, may help to make a difference for a more effective, sustainable and profitable use of ground source. Developed by Climaveneta, Integra heat pumps provide for simultaneous and independent heating and cooling production. By synergistically integrating heating and cooling production in one single unit, they offer very high efficiencies especially in case of a simultaneous heating and cooling request, when either heating or cooling is provided for free.  This is a very common request in modern buildings with glass facades.

The advantages of this technological approach are sound and thanks to the wide application of this technology by Climaveneta in hundreds of successful projects, figures can be referred to real cases and studies. A recent study developed by Climaveneta, British Land, Broadgate Estates, Studio Planning and the University of Padua on 350 Euston Road - a building in British Land’s West End portfolio - demonstrates a 30% energy reduction, by using Integra air source heat pumps instead of a chillers and boilers. An even more stunning result has been achieved in the CIBSE Awards shortlisted Aporti Palace, a major regeneration project in Milan. Here the air source Integra system, enhanced by a ClimaPRO optimization solutions results in a 17% energy reduction in the early operating months.

As expected, water source offers even higher efficiency. The case of Porta Nuova, Italy’s highest skyscraper developed by Hines in Milan, shows a 40% energy reduction compared to chillers and boilers. In this case the system uses the underground rivers that flow under the city. The romantic Garda Lake was the water source for the Klima Hotel Bardolino. The research carried out for the environmental certification demonstrates how in this case Integra units allowed an operating cost reduction by 50% and an aquifer water use reduction by 75% compared to high efficiency cooling only units. Climaveneta’s experience in water source applications with Integra is not limited to ground, lake and river water. In its portfolio we can also find successful projects using seawater, such as the iconic Foredeck in Valencia.

The debate on the real potential of groundwater and on the most effective and responsible way to harness it is just at the beginning - it  will involve civil society, governments and industries and is very likely to lead to different outcomes in different countries according to specific groundwater availability and climate conditions.