Mercator is the leading retailer company in the south east Europe. It owns more than 1300 shops and hypermarkets of different sizes with total floor area 921.374 m2. It is obvious that the energy costs are becoming more and more significant and they have a direct influence on profit and loss of the company. Therefore we started with the systematic approach of the energy reduction in the shops. Project SARA is most beneficial for the Mercator Company because we are able to check and implement technical solutions which we should use in our future development. We invest 250 M Euros per year for building new shopping centers and we shall definitely use the findings of the SARA project in our new buildings. Apart from the energy benefits the principles of energy saving and environmental protection in building Mercator centers there is also a responsibility for the community to which Mercator belongs with its 20.000 employees. Everybody needs to contribute to the environmental aspects of life.
Construction works are finished and building was opened for the public on December 4, 2007.
The building is finished an occupied
Presented Mercator Center Ljubljana is following typical Mercator design and has 43.397 m2 gross area, 27.696 m2 heated area, ground floor, first floor partly with mezzanine, underground parking facilities. Mercator centre consists of 25.258 m2 gross area (16.188 m2 heated area) of retrofitted building old centre and 18.139 m2 gross area of new building (11.508 m2 heated area).
Expected Energy Demand (kWh/m2/yr)
Renewable Energy Systems contribution
28.000 - 36.000 (PV, solar tubes)
Building is connected to the district heating, the power of heating station is 1200 kW. Building is equipped with advanced cooling system with COP 3 and installed power 1754 kW.
The energy strategy is based on :
low temperature floor cooling/heating system
solar protection automation.
Total predicted thermal energy saving is consequence of low temperature floor cooling/heating system and displacement ventilation intervention: 225 MWh/year, or separately:
predicted heating energy savings because of use of floor heating: 94 MWh/year
predicted heating energy savings because of use of displacement ventilation: 131 MWh/year
Total predicted electrical energy savings: 62 MWh/year
Expected annual reduction of CO2 emissions: 110 t/year.
Solar tubes for daylight capture will significantly reduce energy consumption due to artificial lighting.
High insulation levels have been incorporated into the building design, with an average U value = 0.2 W/m2K.
|Constructional complex||Slovenian Regulations|
U-values (W/m2·K) (on design)
|Installed U-values (W/m2·K)|
Project deliverables reference:
Other U values : Roof (R1): Ug-value 0.3 ; Other glazing: Ug-value 0.58
Project deliverables reference:
Design for Daylighting
Priority daylight illumination through windows, glazed roof and solar tubes.
The artificial lighting: energy saving lamps.
A testing real scale model was made in order to measure the daylight influence using solar tubes. ULFGG developed the innovative lighting control strategy for Mercator center project in Slovenia. The use of innovative light tubes to bring natural daylight to areas of the supermarket that would otherwise rely exclusively on electrical lighting has been extensively studied. Their use should result in a 40% reduction of energy needed for artificial lighting.
Expected energy savings are 21.000 kWh/year - 28.000 kWh/year, or 24-32 kWh/m2.year
Expected annual reduction of CO2 emissions are 11800 kg/year - 15700 kg/year.
The illumination strategy, with a priority for natural daylight stressed a combination of glazed surfaces with solar radiation control and use of solar tubes. In the spaces with solar tubes separated DALI system for daylighting harmonization was introduced. In other places with daylighting possibility artificial illumination is controlled with installed BMS based on illumination levels.
Factors taken into consideration include
See Project deliverables reference:
An innovative heating and cooling system was built in, using a CO2 demand based ventilation system with a displacement system (0-2m), harmonized with floor heating (winter) and floor cooling (summer).
Due to more favorable temperature gradient achieved with floor heating compared to classical systems (convector or radiator), comfort dwelling conditions in a room are achieved with lower air temperatures, about 2 °C lower than those needed for the conventional heating.
Floor heating or cooling also significantly reduces levels of air temperature supplied by the ventilation system.
The decisive factor for displacement ventilation is the diffuser. These are mainly built into the walls or are placed by the structural columns of the building. Diffusers are designed in such way to allow mainly stable air flow, without the unnecessary effects of draught on the floor, mixing of air in the room or suction effects along the perforated surface. The exit surface of the diffuser is made of perforated wood or stainless material.
Air speed drops with increasing distance from the diffuser, while air speed next to the diffuser reach 0.2 m/s. Air speed is also higher in the floor area. Air speed limits may be higher in summer than in winter time. The limit is determined by the temperature gradient that should not exceed 3 K/m height between 0.1 and 1.1 m above floor level.
The efficiency of the system is reduced by shopping shelves, placed near the diffusers or sources of air. This is true for the supermarket area, while in the shopping alley the situation is in this respect considerably more efficient.
Low temperature distribution is achieved through two methods, slab floor exchange (heating 40/30°C and cooling 14/19°C) and displacement ventilation. Both techniques diminish the energy requirements for heating and cooling by reducing the temperature for heating requirements and increasing the temperature for cooling requirements.
Project deliverables reference:
With heat recovery ventilation system 5% reduction in energy costs is expected. Volume flow of input air is 316.000 m3/h, of exhaust air 281.450 m3/h.
Sanitary water in the building (hypermarket) is heated by using waste condensation heat from the operation of the devices for technological cooling.
50 m2 area
7 kWp installed power
6.800 - 7.800 kWh/yr energy production
all energy will be sold to the grid
Mono-crystalline cell, opaque modules
South East (azimuth), 30º inclination
32 modules: Bisol 215 Wp
1 invertor: Sunny Minicentral 7000
Project deliverables reference: D12, 20/12/2005
Beside heating, cooling and lighting system management and control a comfort control system is used.
Information technology elements are included for on-line presentation of real time data on energy consumption and costs. An environmental impacts information system on three levels of access to data for users, building manager, general public and for selected partners for research purposes are available through internet.
The main goal of the BMS project is the establishment of permanent real-time control system in the framework of a global information control system of the building.
Measured data include: 1. Microclimate with ambient air temperature, ambient air humidity, global solar radiation and wind speed; 2. Energy systems with heating consumption (district heating), cooling consumption (electricity, thermal energy), lighting consumption (electricity, parts of the building) and total electricity consumption. 3. Indoor comfort with indoor air temperature, CO2 concentration levels, indoor air humidity and lighting levels (selected spaces).
Data acquisition and monitoring strategy: All monitored data in the building are collected by the installed BMS.
Microclimate: sensors for ambient air temperature and ambient air humidity are mounted on the north elevation of the building, while sensors for global solar radiation and wind speed are mounted on the roof of the building. Energy Systems: heating: building is supplied with several heat meters connected to the BMS. They will enable metering of heating/cooling consumption of the whole building and selected zones. Electricity: several conventional electricity meters enabling metering of electricity consumption of the whole building, cooling devices, ventilation and lighting for selected zones are installed. Indoor Comfort: for selected zones indoor air temperature, CO2 concentration, indoor air humidity and illumination levels are registered.
The design has been modelled and analysed by the University of Ljubljana. Of note, the performance data of the “light tubes” that are to be installed in the Mercator centre to increase the penetration of daylight to some areas of the building, reducing the buildings energy consumption. This work has been disseminated to technical audiences at various conferences. Interest generated locally by the project is high; the University of Ljubljana have produced a Slovenian language version of the project web site and bulletin. http://kske.fgg.uni-lj.si/sara/
Touch screen and large display are installed in the main entrance hall of the centre informing visitors and users about sustainability, weather conditions, installed measures and energy performance of the building, etc.
Heat recovery system :
Energy system cost reduction of 5%
Reduction of electric energy by more than 30%,
Reduction of thermal energy up to 40%.
40% reduction of energy needed for artificial lighting
up to 40% overall saving on energy costs
GEOGRAPHICAL AND METEOROLOGICAL DATA
Mercator Centre Ljubljana is situated in the North-Western suburb of SI capital Ljubljana.
Elevation: 298 m, Latitude: 46° 04’, Longitude: 14° 31’
Partner Nº9 Poslovni Sistem Mercator, MERCATOR
Partner Nº10 University of Ljubljana, ULFGG