The new Aquaticum Waterpark of Debrecen is not only unique regarding its architectural solutions but due to its high demand of capacity it is also one of BORD HVAC Engineering’s most outstanding projects. The studio considers renewable energy solutions as top priority at all times which was particularly important in the case of such an immense aquatic institution.


How big is the heating requirement of the spa and what does it comprise of?

In order to understand this, more factors need to be taken into consideration. The spa has several units that need to be heated even during the summer (and in certain cases during the winter too). Such are the hot water pools, the changing rooms, the showers, the shops, the restaurants and the like, but the biggest “consumers” are the pools.


Performance demand depends on several other factors too, for example the number of visitors (i.e.: people using the pools), the weather, the time of day, etc. Considering the maximum number of visitors a total number of 8 domestic hot water containers – 2 m3 per piece – were placed in the heating centre on the cellar level of the main building.  Producing domestic hot water also needs a great deal of heating.

Numerically speaking the heating requirement of the spa is ~6000 kW during the summer and ~393 kW during the winter. By comparison the neighbouring Nagyerdei Stadium with its football pitch heating requires ~2500 kW energy. The summer heating of the spa: ~6000 kW could provide enough heating for ~1700 70nm2 newly built, insulated apartments.


How does the heating system of the waterpark work?

The district heating system of the city can actually provide the necessary capacity but since the heating requirements of the spa are immense the team of BORD HVAC Engineering did its best to install as many renewable energy options for heating as they possibly could in order to ensure the most economic operation possible. Here are some examples:


  • utilizing the heat of the thermal water that comes from the thermal water well
  • cooling further down the 50°C thermal water with a heat pump and recycling the heat created during this process in the heating system
  • cooling further the thermal water drained from the thermal water pools into a reservoir with a heat pump
  • using water-water heat pumps to cool vents and fan coils on the entire venue and utilizing the excess heat in the heating system
  • utilizing the actual waste heat of the gas engine


In all cases utilizable heat can be recycled with parallelly bound heating exchangers to preheat the heating return piping of the central heating of the spa. In other words the heating exchangers of the district heating can be hydraulically bound into the system serially.

BORD HVAC Engineering considers utilizing renewable energy top priority at all times. Nowadays, regulations demand that 25% of the entire energy need must comprise of renewables. In the case of the waterpark this at the moment is ~50%, which is fitting to the energy consumption of a modern building that is fitted with a heat pump. In case the heating requirement of the waterpark decreases - on a very hot summer day for instance - renewable energy consumption would proportionally grow further, up to even an extraordinary 70%.


How exactly do renewable energy resources support a “greener” operation?


  • The mostly 60°C water arriving from the direction of thermal wells can provide a maximum amount of 1.500 kW heating capacity. The heat content of the thermal water that is cooled to 50°C can be further utilized, in other words can be cooled to a further 45°C with the help of installing 2 water-water heat pumps and a plate heat exchanger. The gained excess heat capacity to be utilized this way is between 300-600 kW.
  • Because of the high temperature of thermal water it was necessary to install a three way mixing valve in front of the plate heat exchangers on the side of the water-water heat pump in the case of each heating circuit in order to protect the equipments.
  • The lowest limit of thermal water heat when regaining necessary heat from thermal water is 45°C. This is the lowest heat necessary to maintain thermal water pools during summer months in case of minimum water refill requirements. Out of the two heat pumps that are installed to gain heat from thermal water, the second one gains heat either from the thermal water that is refilling the pools or the thermal water that is drained from them in order to avoid overheating.
  • The central building management system controls the motor exchange valves positioned on the cooling side of the heat pump and decides in what direction the heat should be utilized based on the temperature of the water going towards the pools.
  • The 32-34°C water drained from the thermal pools are directed into a 84 m3 reservoir right next to the main building block. The capacity of the reservoir is suitable for retaining the drained water of the three thermal water pools while adjusting to the minimum amount of auxiliary thermal water.
  • With the help of the thermal water pump the water gets from the reservoir into the plate heat exchangers on the cellar level of the main building where it utilizes heat in the central heating system using two water-water heat pumps that are partially shared with and partially independent from the previous system. The utilized heating capacity here is also 300-600 kW.
  • More heat can be utilized from the water-water heat exchanger heat pump used for cooling the areas of the property. This capacity is variable, the planned maximum is 200 kW. The capacity varies based on the level of operation of the restaurants and outside temperature.
  • There is also a gas engine on the premises of the spa, the excess heat of which is also recycled to increase the temperature of the return water. The total capacity of the excess heat provided by the gas engine is 200 kW.

Based on the above it is clear that with maximizing the usage of renewable energy resources alternative heating solutions can provide 2.800 kW  capacity ideally, which equals 50% of the total heating capacity. Maximum demand   occurs very rarely so most of the time renewable energy exceeds 50 %.  Thus we can say that BORD HVAC Engineering has implemented the ‘green concept’ of the building from a technical point of view too and with its solutions it greatly contributed to the waterpark’s representing the mission statement of BORD Architectural Studio.