2500 specially adapted PV panels adorn the facade
Integrated into three of the hotels’s facades 2,500 custom-made silicium PV modules make up the largest facade integrated PV installation in Denmark. The installation consists of approx.1.700 m2 PV modules distributed along the east, west and south facing facades of the South Tower. As a matter of fact the modules replace the entire facing on the south side of the tower. The PV modules are tailored into 38 different designs to accompany the architecture of the building. This kind of facade integration is the speciality of the Danish company Gaia Solar, the contractor on the assignment.
On the roof of the South Wing, a more traditional 70 kWp roof top installation covering 500m2 contribute to the production of energy. The total installed PV capacity is 270 kW and the silicium modules have an efficiency of up to 17.2%.
Utilising the flexibility and narrow tracking of the TripleLynx inverters
A total of 14 Danfoss TripleLynx inverters ensure that the energy from each section of the solar cell installation is converted to AC power for the hotel's mains supply. As facade integration exact very different conditions for the PV modules very precise tracking is required. The three Mpp trackers per inverter thus ensure optimum yield. Integrating PV modules into a facade, thereby diverging from the optimum angle to the sun can result in a reduction of module performance by 25%. It is therefore imperative that the inverter utilises the energy to the fullest. The inverters run in individual configuration deploying approx. 6.2kWp per Mpp tracker. All inverters are connected in an RS485 network enabling monitoring of performance.
With an annual production of 170,000 kWh the facade integrated system, the roof top installation and the inverters make up one of the largest building-integrated solar cell systems in Europe. The energy generated equals 10% of the hotel’s power consumption or what corresponds to the electricity consumption of 55 average-sized detached houses.
Green energy produced by wind turbines covers the remaining need for electricity.
Saving 90% of the energy used for heating and cooling
The idea behind the hotel was not only to generate a large part of the energy used, but also to save as much energy as possible.
One of the key energy saving initiatives is the installation of a groundwater based system, which provides both heating and cooling to all 366 hotel rooms, the conference room section, kitchen, restaurant and the ancillary office building. The system is based on the idea of recycling energy.
Cold water stored underground is drawn during the summer and directed to the hotel’s basement where it cools the water in the internal cooling-heating system. The now warm water is then returned into the ground, accumulating heat over summer. During winter, the warm water is re-drawn and distributed through the heating system. The water is sent through two heat pumps that raise the temperature to reach comfort warmth. Danfoss frequency converters adjust the heat pump capacity by regulating the speed. This system is the first of its kind in Denmark, and it saves up to 90% of the energy used for indoor climate control in the hotel.
“The combination of groundwater cooling and heat pumps is an innovative solution. With this, we can reuse the heat accumulated during the summer and use it in the winter,” says Peter Andersen, real estate director at Copenhagen Towers.
Moreover, a whole range of other pumps in the building, circulate water in the hotel’s internal heating and cooling system. They are variably speed controlled by frequency converters from Danfoss and contribute to major energy savings on the pump system.
Lots of energy-saving initiatives
A lot of additional energy-saving and environmentally-friendly measures are applied such as the intelligent control of lighting and low-energy light sources, LED flat screens in every hotel room and computer-control of all electronic equipment. This ensures the consumption is kept as low as possible especially when rooms are vacant. Furthermore, all of the components of the hotel’s IT infrastructure were chosen on grounds of energy-efficiency and degree of reusability.
“It is our basic principle to be a sustainable hotel, without compromising quality and the comfort of the guests. I think we obtain both,” says Peter Andersen.
Facts:
Copenhagen Towers complies with the Green Building standard, as required by the EU. It is also the first hotel in Denmark to have joined the UN’s Global Compact. The hotel was built in accordance with the Danish Low Energy Class 2 standard, which means that the energy consumption must not exceed 42.6 kWh per m2 per year. This corresponds to savings of 53% when compared with conventional buildings. Copenhagen Towers is estimated to save 1,373 tons of CO2 on an annual basis and it received the award "det gyldne søm" (the golden nail) for the most innovative environmentally friendly construction.