Efficient ac brings BREEAM award

ITALY: Efficient air conditioning equipment has helped the new Nave de Vero hypermarket near Venice to achieve BREEAM certification – a first for an Italian shopping mall.  

Opened last month, the Nave de Vero in Marghera offers 120 commercial units and a wide range of dining areas and has a total volume of 500,000m3, 55,000m2 of retail space, including a 4,000 m2 hypermarket and galleries of over 15,000m2.

The project has been ambitious both in the attention to finishing details, as well as in the choice of materials and the plant equipment to guarantee environmental sustainability.

These include mechanical ventilation with heat recovery, the construction of a rainwater collection tank that will be used for the irrigation of green outside areas, a photovoltaic plant and a photocatalytic permeable floor to reduce pollutants in the air. All the above solutions have been employed to ensure the building’s high energy performances and give an A+ energy rating to the mall.

The design and the realisation of the hvac plant was a key part of the certification strategy.

The hypermarket and the shopping mall have separate and independent facilities. The first one consists of a heating plant with condensing boilers, air-cooled chillers and air handling units and the second one is composed of a plant room with high efficiency chillers.

The hvac plant comprises three Climaveneta air-cooled heat pump chillers with FOCS-N/ SL-CA4822 and three high efficiency water-cooled chillers. Four condensing boilers provide 100% of the winter heat loads, and have been designed as a full backup to the heat pumps. The plant sequence operation has been designed to maximise the efficiency in every season and with any kind of load.

During the mid-season, when outside ambients are 20-25° outside, the air cooled units’ operate. If heating is required, it is always possible to use a unit in heat recovery mode.

When  the outside temperature increases, the water-cooled heat pumps kick in. Only in mid-summer, with high external temperatures, will the air cooled units run again.

During the summer, hot water is provided by four out of the six units.

In winter, to maximise the building’s energy efficiency, the units operate in free-cooling mode to ensure the best comfort in the galleries.

As the shops in winter cannot rely on free-cooling, it is necessary to operate a unit giving priority to the air cooled units which are more efficient at low temperatures. With an external temperature of 5°C the power required for heating is covered by only two units operating in heat pump mode, leaving the third free to work as a chiller. Condensing boilers only work in extremely cold temperatures when heat pumps are less efficient. The boilers and heat pumps never operate simultaneously.

Finally, given the low loads compared to the power involved for serving the entire mall and given the possible simultaneous request of cold and hot water, the consultants, Manens-Tifs, decided to equip the offices with an independent multi-purpose unit serving a 4-pipe hvac plant, able to produce simultaneous cooling and heating.

Particular attention has also been given to the air distribution in the upper level of the shopping centre, achieved by high induction nozzle diffusers, with different swirl effect elements, depending on the geometric characteristics of the spaces to serve.

Diffusers suitable for high height environments have been used for the lower levels.

Other design choices include a mixture of high-performance solar cell stained-glass windows and opaque panels with acoustic absorption. These offer good natural light even on the ground floor, significantly reducing solar energy loads.

The use of LED lighting further reduces internal loads with light intensity adjustment linked to the amount of natural light.