Breaking new ground

The Netherlands is by far the largest voluntary green power market in the world, with Ground Source Heat Pump (GSHP) systems playing a large part in its production of renewable energy. The following installation, at Meerpaal Business Park, demonstrates the benefits of GSHP and how when combined with an energy efficient HVAC system, the ultimate in environmentally friendly climate control can be achieved.
A green space

Houten, a modern municipality in Holland, is world famous for its urban design and green credentials. The area has been designated a GSHP zone, with systems installed by one of the Netherlands largest energy providers, ENECO Energy. All new development plans must incorporate GSHP before local government approval.

In order to receive planning permission, BK Bouw, developers of Meerpaal, had an obligation to source a HVAC solution compatible with GSHP. Based on heat pump technology, Colt-Caloris, the WRF air-conditioning system, was an obvious choice – easily connected to GSHP, while providing considerable environmental benefits through its low refrigerant charge and high efficiency.

GSHP systems are one of the most energy-efficient ways of heating and cooling buildings. Their Coefficient of Performance (CoP) typically ranges from three to four or even higher, which means that for every unit of electricity used, three to four units of heat are produced. Colt Caloris, has a maximum CoP of seven, so combined, these technologies prove an extremely energy efficient partnership.

Ground loops

Using a buried ground loop, GSHPs transfer heat from the ground into a building providing space heating and, in some cases, pre-heating for domestic hot water. The ground loop is buried in either a borehole or a horizontal trench. A mixture of water and anti-freeze is pumped around this pipe, absorbing heat from the ground.

At Meerpaal ground loops are installed vertically, in two 100 metre boreholes, to pump up and inject ground water; one for the storage of cooler water and one for the storage of warmer water. While vertical collectors are more expensive initially, this method offers increased thermal efficiency as ground temperatures are more stable and require less pipe and pumping energy.

The borehole ring main system extends across Meerpaal Business Park, connecting all the buildings on site. This is then connected to a series of 22 Colt-Caloris WRF heat pumps via a heat exchanger.

The Colt-Caloris WRF system is based on reverse cycle water source heat pump technology, and uses water rather than refrigerant as its main energy transfer medium. Local units are linked together by this neutral temperature water loop to form a complete system. Refrigerant charge is minimal and local to the Caloris unit, so it is not dispersed throughout the building. No other refrigerant-based air-conditioning system of equivalent capacity contains a lesser charge of refrigerant, thus reducing its potential environmental impact.

Harnessing thermal mass

In the same way as GSHP systems utilise the heat of the earth, Colt-Caloris uses the building’s thermal mass as an additional energy store. Pipes are laid into the building’s concrete structure, taking advantage of the free thermal energy, which in turn can be stored and re-used later in the day.

During the summer months, the central heat pump operates like a chiller unit but with greater efficiency, dissipating heat. Most water chiller systems operate around 5°C to 14°C, whereas Colt-Caloris only starts when the temperature exceeds 28°C to 30°C. It is much easier to cool water at 28°C than at 6°C, as a result, the heat pump works at a higher efficiency for less time during the day. As soon as the water temperature reaches the normal specified level, the unit stops and waits until the water becomes excessively warm again, thus saving energy.

In winter, most internal rooms will require warm air. The local heat pump takes the heat energy out of the water loop, which eventually causes a heat deficiency within the system. Colt-Caloris copes with this by taking the cold external air and cooling it further, then transferring this heat energy back into the loop.

A versatile solution

In addition to its energy efficient credentials, Colt-Caloris is extremely quiet and offers individual control for heating and cooling. For the 3,500 workers in situ at Meerpaal, this means versatility and individual comfort for all.

This configuration of Colt-Caloris WRF units has achieved significant energy savings and a reduction of CO² emissions. Decentralised control allows occupants to regulate the temperatures of the individual rooms, using energy that is virtually free. The savings are even greater than in a conventional Colt-Caloris installation, where local heat pump units are connected to a water loop and a central, external heat pump. In this instance, the energy input required is nearly half that of such a conventional installation in heating mode, and virtually zero in cooling mode.

With environmental issues featuring high on everyone’s agenda, energy efficient technologies need to be taken seriously. For the UK market, Colt-Caloris provides another benefit – it beats the F-Gas regulation, due to its minimal refrigerant charge. Examples such as Meerpaal show how energy efficient HVAC systems can be implemented to provide users with high standards in climate control and comfort.

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