Case Study: nZEC - New construction of 18 dwellings in Via Fenil Nuovo Molini, Lonato del Garda, Italy (UNDER MONITORING)
Name of organisation: Coop Casa Brescia
Stage of development: completed
Year of finalization: 2012
Type of project: construction
Area: rural
Scale: individual buildings
Type of building: Apartment in a block of five or less stories
Number of units/dwellings: 18
Tenure: social rental
Street: Via Fenil Novo Molini
Postcode: 25017
City: Lonato del Garda, Brescia
Region/ County: Lombardia
Country: Italy
Last Update: 03.03.2015
Short Description
The development, constructed near the city centre, between a public park and an agricultural area, is comprised of two buildings, each with three floors and with three units on each floor. The first two floors are made of concrete and bricks and the last floor of is prefabricated wood construction. The building also features an underground basement and a technical room with a centralised heat pump system on the roof. Construction works were completed in 2011 and the apartments have all been assigned to low-income families in 2012.
Casa Light in Lonato del Garda, Brescia, developed by Coop Casa Brescia, is the only example of a multifamily building certified to Passivhaus standard in Italy (the project is published on the Passive House database with ID 2416). Casa Light combines passive solutions with solar photovoltaic and heating-cooling ventilation systems that are simple to operate and easy to maintain. The project was designed to test a concept for multi-storey residential buildings with zero energy balance, suitable for north Italy.
Key Elements
Certification
One of the 2 building has been granted of the passive house quality assurance certificate issued by the Darmstadt Passive House Institute. Only case of certified multifamily building in Italy. The 2 buildings are classified as “A+” according to the local certification procedure, Cened+. First real data monitoring results show that the energy produced by the PV system is by far greater than the one used for space heating, cooling, production of how water and building services including ventilation. Electrical appliances inside the dwellings are responsible for the higher consumption share. If also this are considered, the PV system cover 70% of total consumption.
Funding
Total construction costs amounted to € 1.887.000. The regional authority Regione Lombardia co-funded this project as part of a social housing support scheme. In addition, the photovoltaic systems benefit from a feed-in tariff through the national Conto Energia programme. The feed-in tariff is paid for by the electricity generated by photovoltaic plants and will cover a period of 20 years, starting from the plant commissioning date.
Components included in cost of construction:
It is not possible to separate materials from labour. Total cost: 1.886.903,62 € divided as follow: Construction 1.307.244,66 €; Windows and entrance doors: 227.826 €; PV: 129.000 €; Connections to electricity and water supplies: 17.306,07 €; Contract: 5.526.89 €; Design and technical costs: 200.000€.
The only non included costs are those of the housing cooperative staff which managed the entire process.
Thermal Insulation
“Extreme” insulation, for this location, has been used: 15 cm on the external walls, 40 under the floor and on top of the roof. But more than the thickness, the installation details are important to avoid gaps in the thermal envelope and thermal bridge. For the balconies, specially designed elements have been used to minimize the contact between the balconies and the structure of the building.
Air Tightness
Air tightness is very good in this building as it is a Passive House requirement to have a max n50 of 0,6 h-1. This has been achieved using special tapes and sealing, and adopting a two stage blowerdoor test procedure: one to identify imperfections, and a final one to measure the real air tightness. Measures have been taken in all the dwellings and all have a maximum n50 of 0,6.
Windows and Shading
Windows are the most important component of the low energy house in this climate. Wooden frame, triple glazing windows have been used. The windows come together with a pre-constructed installation box, perfectly insulated and designed to provide excellent air tightness and continuity with the thermal insulation of the walls. This “box” also host an external, rolling obscuration system. Big window face south, where a continuous balcony plus sun shading tends offer an effective protection from overheating. Much smaller windows on all the other facades. Windows and entrance doors account for the 12% of the total project costs.
Ventilation
Each dwelling has its own ventilation unit with high efficiency heat recover. The units are installed in the staircase in order to facilitate maintenance (periodic filter replacement). Each dwelling has a simple control for setting the operation: 0- stop, 1- low, 2- normal and 3- high flow.
Heating and Hot Water
Each flat has its own ait to air heat pump, which provide heating and cooling. The air distribution system is separated by the ventilation one and is extremely easy to operate. DOW is provided by a centralized system for each of the 2 buildings. There is a compact heat pump on the flat roof and a 1000 liters storage in a well insulated technical room, also on the roof.
Solar Photovoltaic
20 kWp for each of the 2 building. On average, 2.2 kWp per dwelling.
Environmental Design
Passive design has been adopted: compact volumes, optimal orientation with the main facade toward south. Windows on opposite walls in each dwelling, with the exception of the small, 2 rooms central apartments.
Monitoring
Click here to access the monitoring data on the HIVE Database!
Work with Residents
After the handover of the dwelling to residents, each family was briefed about the correct use of the technical services and of the building. The results of a survey, undertaken with 16 out of the 18 families during the second week of January 2013, showed a generally high degree of satisfaction among the residents.
Main Results
The success of this project depended on meeting two important requirements: affordability and low energy consumption, while considering the comfort and needs of the final users of the building. These were achieved by:
- combining passive design techniques to contain heat losses in winter (external wall insulation) and solar gains in summer (passive climate control);
- photovoltaic (PV) models installed on the roof, with a focus on maximised PV integration (each of the two buildings is equipped by 20 kWp PV systems);
- adopting a thermal system for heating and cooling with a simple means of operation and maintenance.
Lessons learned
It is possible to make a low cost multifamily passive house, but quality and special design is vital. New technology has to be adopted, but it is essential to think of the user: systems must be easy to operate! Windows, windows shadings, good insulation techniques, air tightness, ventilation with heat recovery solar PV and or solar thermal are the essential elements of a successful nearly zero project in this temperate climate area.
The housing company already manages several PV systems. Below, there is a list of lesson learned they kept in mind when designing this new PV systems:
- attention in the PV modules orientation/tilt in order to maximize energy production;
- monitoring the PV energy production, in order to act promptly in case of breakdown and/or malfunctioning;
- PV systems on multi-family buildings are characterized by little maintenance, and generally this is due mainly to weathering (lightning and power surges resulting).
Suggestions for the future:
Since Feed-in tariff incentives are going to finance self- consumption instead of energy production, the sizing of PV systems should be done considering this aspect. It could be useful to deliver the energy produced by the PV modules not only to common spaces uses (e.g. lighting, lift) but also to all the flats, in order to maximize the self-consumption by all the families. This should be achieved both by divided and cooperative property.
Additional Information
Ms Rossana Zaccaria
Legacoop Abitanti - The Italian Federation of Housing Cooperatives
E-mail: r.zaccaria@ancab.coop
Web: www.legacoopabitanti.coop