Feel-good indoor climate in the Citti-Park Flensburg shopping centre, thanks to the Roth floor cooling system – Underfloor cooling system in the shopping centre with the Roth Original Tacker system

20/04/2015

The Citti-Park shopping centre in Flensburg, which has around 60 shops and a total sales area of some 22,300 square metres, also offers a feel-good indoor climate. Floor cooling in the malls, the areas set aside for special promotional activities and the shops ensures well-balanced temperatures and makes shopping a pleasant experience.

The Citti-Park is also home to a health centre and a creche, and has over 2000 free parking spaces for customers. With around 600 employees, the company is one of the biggest employers in the region.

Together with the Roth Key Account Manager, Thorsten Wolf, the Kiel-based planning office IBK Kaeding & Rust planned the energy concept which included some 11,000 square metres of Roth floor cooling. The specialist companies IBS from Haldensleben and Betona from Hamburg installed around 77,000 metres of 20-millimetre Roth System Pipe X-PERT S5+. The system pipe was fitted on the perimeter insulation using Roth Original Tacker Ex Clips with installation spacing of 15 centimetres.
The pressure- and water-resistant insulation against the soil was installed underneath the foundation slab of the building. In order to provide protection against moisture through the roller-compacted concrete used, the insulation panels were covered with overlapping polyethylene film before the pipes were installed.
The Roth Original Tacker Ex Clip with lift-up pipe-raising function guarantees a defined penetration depth into the insulating layer regardless of the pipe dimensions. Optimum energy efficiency is also ensured because the screed always fully surrounds the pipe. This permits better transmission of the heating and cooling power.

The energy concept
In keeping with the building owner’s requirements, the planning consultants IBK Kaeding & Rust drew up plans for a cooling output of 80 Watts per square metre in all sales areas. The basic cooling for the whole of the ground floor is provided by means of underfloor cooling. The cooling and heating for the specialist stores and shops is provided via ventilation and air-conditioning systems. A total of 24 of these systems have been installed with variable volume flows to a maximum of 300,000 cubic metres per hour, controlled on the basis of the temperature and air quality. Heat is supplied in the form of district heating by the Flensburg public utilities, while the energy for the cooling system is provided by two 750-kilowatt chilled water units.

Why floor cooling?
Planning expert Jürgen Kaeding explains: “Since the entire floor area in contact with the soil needed to be insulated, the decision was taken, in consultation with the building owner, to opt for underfloor cooling. This is designed to cover the basic cooling load. The volume of air – an expensive way of transporting energy – is therefore reduced and the time needed to generate the required cooling is also lowered. Based on a temperature of 16 to 18 degrees Celsius, partial free cooling without using the chilled water unit is also possible at night by using the heat exchanger.”
The large floor surfaces available for use for cooling purposes enable the room air temperature to be raised in cooling mode without any loss of comfort for the user.
When it comes to assessing the level of comfort experienced by the user, the important parameter is the operative room temperature (resultant temperature). The operative room temperature includes the interaction of the air temperature and the average temperature of radiation from the various surfaces of the room, such as the floor or walls, and it is the key factor in the level of thermal comfort experienced by the occupants of the room.

“In the case of cooling systems, it therefore makes sense to consider the operative temperature when designing the system. Regardless of which heating or cooling system is considered, the absolute level of thermal comfort is always achieved at the same operative temperature. The only possible differences are the air temperature and the temperature of radiation. Compared to other system solutions, floor heating systems need lower air temperatures in order to achieve the same operative room temperature. With floor cooling systems, the situation is reversed,” explains Jürgen Kaeding.
The combination of the underfloor cooling system and the ventilation and air-conditioning system in the Citti-Park guarantees feel-good temperatures for both customers and staff.

Summary: The outcome of the specialist planning work satisfies the building owner’s requirements in terms of comfort in an exemplary fashion. The solution is also cost-effective and efficient, resulting in lower ancillary costs for the operator due to the configuration of the system on the basis of temperatures of 16-18 degrees Celsius.

BREEAM certification
In June 2014, the Citti-Park was awarded BREEAM certification for sustainable construction. BREEAM stands for "Building Research Establishment Environmental Assessment Method”. It is the world’s foremost certification system for sustainable construction and was developed in the UK in 1990.
BREEAM awards four different levels of quality seal in eight assessment categories. The criteria relate to the impact at a global, regional and local level, as well as on the interior spaces. It assesses a range of factors, including ecological aspects, materials, health and wellbeing.

The operator of the shopping centre has hailed the project a success. Harald Rottes, Director of the Real Estate Department at Citti-Park, explains: “The Roth floor cooling system ensures a pleasant temperature profile in the shopping centre. We are delighted that we are able to offer our customers a feel-good climate.