Case Study: nZEC - New construction of 142 dwellings in Bazzana Inferiore, Assago, Italy

Name of organisation: Coop Ferruccio Degradi

Stage of development: in progress

Year of finalization: 2013

Type of project: construction

Area: suburban

Scale: group of buildings

Type of building: Apartment in a block of five or less stories

Number of units/dwellings: 142

Tenure: private ownership by individual households

Street: Bazzana Inferiore

Postcode: 20090

City: Assago

Region/ County: Lombardia

Country: Italy

Last Update: 03.03.2015

Funding Windows and Shading Environmental Design Heating and Hot Water Cooling Ventilation Water Saving Solar Photovoltaic

Short Description

Cascina Bazzana, a development of Coop Ferruccio Degradi, is a new residential complex of 142 dwellings in four buildings completed in 2013. Each building has 4 floors plus attic and an underground level for car park and storage.

Cascina Bazzana was designed in such a way that it creates a connection between the existing historical centre, with the typical rural court buildings, and the new residential and commercial blocks. The buildings are L-shaped, one opposite the other, with the main façade exposed towards the south and with two large courts in between to create large urban gardens. These green spaces are intended to enhance increased interconnectedness among residents; the multifunctional common spaces of the buildings are directly accessible from the courts.

The construction elements are inspired by the local building traditions but technologically advanced materials and components are used to enhance energy efficiency. Heating of spaces and water is done through the use of geothermal heat pumps which extract heat from the underground water. During the summer, the heat pumps operate with an inverted cycle and provide space cooling through the floor “heating” circuits which use underground water as the cold source.

A 20 kWp PV system was installed, the modules being positioned on the tilt roof. Part of the energy is used for the heat pumps and some is released into the electricity grid. The system benefits from a feed-in tariff.


Key Elements

Windows and Shading

Triple glazing windows, with low conductivity spacers, Uw = 0.79 W/m2.K. Solar shading is provided by wooden blind and a line of tall trees in front of the facade. The largest windows have in front a balcony to prevent direct solar radiation in summer. Each flat has openings on opposed sides, to facilitate natural ventilation in summer. Trees have been thought to provide additional cooling in summer thanks to evapo/transpiration. During the winter, lives are lost and more solar radiation can reach the buildings and the ground.


Ventilation

A mechanical ventilation system has been installed to provide always a good air quality level. The ventilation system is double flux with heat recovery (up to 80%).


Heating and Hot Water

Space and water heating is done by mean of geothermal heat pumps, which during the summer also provide for space cooling. The heat pump are water / water, using as cold source the superficial underground water. Once the heat has been taken from the water, the water goes back to the environment by mean of a re-injection bore. Each heat pump has a double compressor which allows to operate at 50% power. The system is fully automated to balance operation time of each compressor and reduce maintenance work. Low temperature floor heating provides enhance comfort and allow the heat pumps to operate with optimal Coefficient of Performance COP. Each dwelling has its own metering system to correctly divide energy costs on the bases of real consumption.


Cooling

In summer the heat pumps operates with an inverted cycle and provide space cooling through the floor “heating” circuits.


Solar Photovoltaic

A 20 kWp system has been installed, the modules being positioned on the tilt roof. Part of the energy is used for the heat pumps; part is released into the grid. The system benefits of a feed/in tariff.


Water Saving

Typical water saving accessories has been used such as double flux toilets and flux redactor on the water tubs. Superficial underground water is used for the toilets and for watering the green areas.


Environmental Design

The disposition of the buildings and of the different spaces within each flat has been done to optimally exploit the solar radiation in all the seasons. The external finishing materials have a low reflection index. Materials and components have a high ecology index: at least 94% of the materials can be disposed and recycled. Materials used fulfil the tighter requirements for non-toxic content. Fibrous materials, pre-treated wood panels etc. Have been avoided.


Funding

The PV system will benefit from a tariff scheme which applies to systems with a capacity of at least 1 kW, in operation since August 2012. The PV systems are to be connected to the grid. The feed-in tariff is based on the electricity produced and varies depending on the capacity and type of system. The tariff is place for a period of 20 years.

For systems commissioned by 31 December 2012, the scheme (called Feed-in Premium) provides a tariff for the electricity produced. The electricity fed into the grid may be purchased by the Gestore Servizi Energetici (GSE)  or offset against the value of electricity withdrawn from the grid (net metering) service.


Funding

Energy efficient measures table:

Energy efficiency measure

Ir

Iee,brutto [€]

Iee,netto [€]

Life time [years]

[€]

Thermal insulation

-

760 000

100 000

30

Windows

-

1 600 000

460 000

30

PV System

-

60 000

60 000

20

Mechanical Ventilation with Heat Recovery

-

360 000

360 000

20

Heating Pumps

-

60 000

60 000

20

Total

40 800 000

2 840 000

1 040 000

 

Running costs (savings estimated)

47 121

47 121

47 121

 

Simple payback time

 

60

22

24




Main Results

Finabita has contacted the technicians responsible of the project in December 2014 and asked them some updates regarding energy savings . The dwellings started to be occupied in November/December 2013. The Social Housing company is not yet able to quantify the potential savings of this building comparing to a traditional building, since the first year of operation has not been completed yet . In addition, the energy supplier does not read the meters regularly, hence the bills received by the SH company are not in line with the actual production. The annual savings was estimated comparing the minimum energy standard currently in force (60 kWh/m2 per year ) with that of the building (14 kWh/ m2 per year).


Lessons learned

Potential buyers are interested in “energy saving” dwellings, therefore an A+ class energy certificate gives an added value to the building itself and constitutes a “marketing lever”. Since Cascina Bazzana was built in an area which is not traditionally "competence" of the Social Housing companies, therefore it could represent a good example of its construction activity, even if this type of construction implies extra costs for high quality energy efficiency measures. Nevertheless, the cooperative decided to reduce the economical expected margin (consider that the buildings belong to subsidized housing and people will buy at a fixed price per m2).


As for the operation and management of the Heating system (heating pumps and other devices), the SH company states that it has been necessary a transitional period in which they are sought initial optimal adjustments of the various technical components and different settings with respect to those carried out by the installer, especially concerning the dehumidifiers. Even the calibration of the flow temperature was carried out manually and weekly by the technician in order to obtain an optimum performance. In this type of system a transitional period of settling should be provided in order to obtain good yields: we must consider that this transitional could cause discomfort to the inhabitants (eg, lack of heating and / or DHW), who therefore should be informed about it and about any kind of possible malfunctioning deriving from it.


In addition this typology of heating systems is rather complex and their management / maintenance is often tied to the manufacturing company. This can be a problem especially in the case of system shutdown, because the repair could not be timely, thus causing inconvenience to the households.


The heating pumps produce both heating and cooling. Households should be informed about the fact that the radiant cooling produces a cool feeling different from that produced by traditional split: there is not a flow of cold air coming out of the vents, but radiant system creates a cool feeling widespread, much more comfortable but also less direct. Since the service can be set on per apartment, the SH company stressed the importance to the inhabitants of closing the service when the apartment is unoccupied in order to avoid energy waste. Despite all the difficulties in the transitional period due to the technical adjustments, residents are satisfied especially for the comfort.


Additional Information

Ms Rossana Zaccaria
Legacoop Abitanti - The Italian Federation of Housing Cooperatives
E-mail: r.zaccaria@ancab.coop
Web: www.legacoopabitanti.coop


Source: http://www.powerhouseeurope.eu/nc/cases_resources/case_studies/single_view/?tx_phecasestudies_pi3%5Bid%5D=187&tx_phecasestudies_pi3%5Bdisplaytype%5D=overview&cHash=