Delivering excellent energy efficiency with modern air conditioning systems
Energy-efficient air conditioning in a multifunctional building
Karlsruhe, GermanyThe VEMA is Germany’s largest cooperative association for insurance brokers. To meet the high demand for regular training events and continuously adjust its specialist training, the VEMA built a multi-functional building in Karlsruhe in south-west Germany. The new conference centre offers modern meeting rooms with state-of-the-art technology. “All of the rooms are equipped for hybrid events (in-person and online participation). There are a total of five conference rooms, a hall and four meeting rooms with space for up to 180 people across around 700 m2 of floorspace”, explains Silke Weber, authorised officer and manager of the conference centre.
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Requirements:
- Individual heating and air conditioning for all areas
- Continuous supply of fresh air
- Demanding requirements for efficiency and comfort
- High planning reliability
- Maximum flexibility
Background
Background
Alongside event and meeting rooms, the conference centre also houses a restaurant and a hotel floor with 16 business standard and two business comfort rooms. The standard room facilities include air conditioning, high-speed internet and an LED wall. Guests can also book various additional technical or catering options. The VEMA conference centre also has office and administration rooms, an apartment for the caretaker and a fully equipped TV studio for producing live programmes and promotional videos.
Challenges
Challenges
“All of the areas had to be individually, efficiently and comfortably heated, air conditioned and supplied with fresh air. The challenge for the technical building services was therefore developing a flexible and capable system that could meet the demanding efficiency and comfort requirements”, explains Mattias Brunzel, project manager and authorised representative at Wirth Klimatechnik GmbH from Wiesbaden in central Germany, one of the country’s leading providers of technical building services.
Working closely together with the Karlsruhe architecture firm Bahm Architekten + Ingenieure and the planning firm Planing, Wirth Klimatechnik GmbH presented a proposal that ensured planning reliability and maximum flexibility for the combined hotel, seminar (with restaurant/kitchen) and office building. The proposal was based on the idea of equipping the individual areas of the multifunctional building with precisely the right technology for their respective needs in terms of air conditioning and ventilation.
The hotel area
SolutionCombination of air conditioning systems
The solution uses a combination of different systems. In the hotel area, for example, the proposed air conditioning system was sustainable and combined comfort with reliability. The hotel area was therefore fitted with ourHybrid VRF systemfor air conditioning in the 18 rooms, in order to fulfil the demanding efficiency and comfort requirements.
Hybrid VRF system reduces refrigerant charge
The Hybrid VRF system is a heat pump system for simultaneous cooling and heating with only two pipes and an energy-saving heat recovery function. The hybrid two-pipe system combines the benefits of a direct evaporation unit with those of a water-cooled system. Thanks to the separation into a refrigerant-based and a water-based section, this system gets by with a reduced refrigerant charge, as the refrigerant only circulates between the outdoor units and the manifolds known as Hybrid BC controllers.
Fresh air around the clock
Another part of the energy-efficient system concept is the central ventilation system. All office and meeting rooms in the building, including the kitchen area, are continuously supplied with fresh air via the ventilation and air conditioning system. To achieve this, fresh air from the central ventilation system is preconditioned by Mr. Slim series outdoor units. Preconditioning the fresh air follows an energy concept in which no room loads are discharged via the ventilation system and no excess heat or cold is introduced into the building. “We always work with heat recovery in order to achieve a very high level of energy efficiency”, says Brunzel.
Set your own temperature
All 18 hotel rooms are heated or cooled by the Hybrid VRF air conditioning system. The required indoor units (1 for each guest room) are ceiling concealed ducted units located in the entrance areas of the rooms. The Hybrid VRF system allows each individual guest to adjust the temperature as they like (free selection of heating and cooling modes) regardless of time of year, time of day, or outside temperature. The heat recovery function of the Hybrid VRF system ensures that heat extracted from the rooms that require cooling is not released into the environment, but is used instead via the Hybrid BC controllers to heat the rooms that require heating.
Pleasant discharge temperatures
In addition, the extra water circuit enables the system to provide stable and mild discharge temperatures that are considered extremely pleasant. There is a dedicated Hybrid BC controller in a technology room for each outdoor unit, to which the indoor air conditioning units are connected. The heat transfer from refrigerant to water serving as transport medium occurs in the Hybrid BC controllers. Depending on the heating or cooling demands, the controller units forward hot or cold water to the indoor units in the guest rooms and common areas.
Heat pump function included
The outdoor units have a heat pump function that allows for cooling or heating. The control of the outdoor units determines the maximum achievable coefficient of performance (peak COP) based on the capacity requirement, the current cooling or heating capacity and the outdoor temperature. It then adjusts the individual outdoor units to achieve the optimum duty point. PAC-IF013B-E connection kits are used to ensure smooth communication between the Mr. Slim series heat pumps and the on-site heat exchangers of the ventilation units. These kits (one for each outdoor unit) perform the interface function and match the compressors precisely to the output requirements of the centralised ventilation system.
Solutions in other areas of the conference centre
BenefitsHigh energy efficiency with inverter technology
The office and seminar areas, along with the restaurant, are equipped with Mitsubishi Electric City Multi VRF systems from the Y series for cooling or heating. Thanks to its two-pipe system that enables switching between heating and cooling, even the standard version of the Y series delivers high energy efficiency to ensure particularly economical operation. This is because the inverter-controlled compressors in this series adjust their speed to the requirements of the indoor units, so that the system only generates as much capacity as is actually necessary.
Air flow without draughts
The air is distributed throughout the building by means of cassette indoor units, either in Euro grid or as four-way ceiling cassettes. The units in the conference area and office rooms are designed for peak load cooling. Here, the higher-level building control system determines whether the units should heat or cool. The air is recirculated, i.e. the room air is sucked in by the indoor units and sent through a heat exchanger before being returned to the room. The horizontal air discharge ensures an optimum flow of cooled or preheated, filtered air through the rooms to be air-conditioned, with virtually no draughts for users.
Central access for easy monitoring
All air conditioning units in the conference centre are connected to an AE200 system remote control and EW50, and are integrated in the KNX standard for building automation. Integrating the system remote control into the external control system allows the control signals to be forwarded via the interface to the individual units. This makes it possible to control every single unit from one central point. This central access also makes the monitoring and status display of the air conditioning units much easier, providing early notification of high energy consumption and service intervals.
Multisplit system in the caretaker’s apartment
Beyond this, the apartment of the facility manager is equipped with a Multisplit system and wall-mounted units for cooling in the summer months and heating in transitional periods if required. All technology rooms are fitted with wall or chest-mounted units from the Mr. Slim series. This simple and cost-effective option separates the equipment for cooling and comfort air conditioning, while also ensuring reliable temperature control for the particularly sensitive technical areas.
The key points
Summary- The newly constructed multifunctional building at the VEMA conference centre in Karlsruhe places demanding requirements on the building technology systems.
- The best possible air conditioning technology was chosen for each application, including a Hybrid VRF system for the hotel and Y-series City Multi VRF systems for heating and cooling the office and seminar areas.
- The fresh air to be brought into the building from the central ventilation system is pre-conditioned by Mr. Slim outdoor units.
- These outdoor units have a heat pump function that enables both heating and cooling.
- The PAC-IF013B-E connection kit enables smooth communication between the heat pumps and the on-site heat exchangers for the ventilation systems.
- All units are centrally controlled by a KNX controller.
