Case Study: nZEC - Energy refurbishment of 38 dwellings in Via dei Querci, Firenze, Italy (UNDER MONITORING)

Short Description

This study case is interesting since it represent an example of application of Energy Performance Contract by a Social Housing company. Social Housing companies made an energy assessment based on the heatinconsumption data and following the prescription of national regulation. The assessment included proposals for energy retrofit of the building, which was in need of maintenance work of the façades. The total cost for this maintenance work was equal to € 361.000,00.


The Social Housing company has proposed to add extra energy retrofitting measures to those already planned for the façades, with the following methodology:

• the Social Housing company makes the tender specifications, which include the thermal insulation of walls with external cladding and the substitution of the existing gas boiler with a new, energy efficient one. The costs related to those two have been considered as extra-costs

• the Social Housing technicians provide technical/administrative services: selection of the supplier, supervision of retrofitting works, assistance provision to the flat owners to access financial subsides.
These services are considered as an extra-cost, and they are equal to 107.000,00 €.


Then, the Social Housing company finances the extra- costs for the energy retrofit measures, as an ESCO, so the technicians estimated energy savings basing on the results of the building energy audit, accounting for 20-22 %, with reference to the gas consumption for the past two years prior to the intervention. This datum is set in the Energy Performance contract signed between the Social Housing company and the condominium, and it corresponds to 46.000 gas mc/year. It is possible to envisage an annual economic saving of approximately 9.200 €, with a payback period which stood at 12 years, considerably less than the average life times of the boiler and of the façades.


Concerning the Energy Performance Contract:
If the fuel savings will be greater than 20%, the payback will be shorter and the condominium will begin to enjoy the savings directly before the end of the twelfth year. In the meantime, flat owners keep paying for energy as in 2010: 46.000 mc natural gas/ year.

The energy savings, that means the difference between the actual consumption and 46.000 mc and the average gas consumption for the past two years prior to the intervention are measured through periodic monitoring and is billed by the Social Housing company to the condominium. The savings will be always considered in terms of energy savings (gas mc) and not in terms of economic savings, because the gas tariff varies quarterly.

The flat owner doesn’t have extra costs for the energy retrofit, but will benefit of better comfort from the beginning and of lower energy costs after the extra investment has been repaid. The extra-costs represent about the 22% of the investment.


Update December 2014:
During the first heating season, due to some shortcomings in the management of central heat and a general misuse of the central itself, the gas savings was only 14,70% compared to pre-intervention, while in the second year was of 22,50%, and in the third year (October 2014) they are around 25%.

Key Elements

Certification

Before the renovation:

• External walls U value: 1,078 W/m2K
• Annual heating demand: 95,22 kWh/m2.a
•  Energy Class: G

After the renovation:

• External walls U value: 0,261 W/m2K
• Annual heating demand: 46,46 kWh/m2.a
• Energy Class: D
  
  
  

Project Management

Unica made an energy assessment based on the heating consumption data and following the prescription of national regulation. The assessment included proposals for energy retrofit of the building, which was in need of maintenance work of the facades.

Unica has proposed to add extra energy retrofitting measures to those already planned for the facades, with the following methodology:

• Unica makes the tender specifications, which include the thermal insulation of walls with external cladding and the substitution ot the existing gas boiler with a new, energy efficient one; these two are the energy retrofit measures;
• Select the supplier;
• Supervise retrofitting works;
• Provides assistance to the flat owners to access financial subsides;
• Finance the extra cost for the energy retrofit measures.

For what concern the payback of the investment:

• Flat owners keep paying for energy as in 2010: 46.000 mc natural gas/ year;
• Unica keeps for itself the difference between the real consumption and the consumption in 2010, which was estimated being larger than 30%;
• The agreement will last until Unica finish paying back the extra investment costs for energy efficiency measures.

This way the flat owner doesn’t have extra costs for the energy retrofit, but will benefit of better comfort from the beginning and of lower energy costs after the extra investment has been repaid.

Since in Italy there is not much experience of this type of energy services, signing the agreement required a long preparation work with many meetings with the flat owners.

Thermal Insulation

External walls have been cladded with Graphite-EPS (lamda = 0,031 W/mK), thickness 9 cm. The entire system has been insured.

Heating and Hot Water

The old heat generator (gas boiler) hab been replaced with a new one (3 star, 190,4 kW of nominal power, thermal performance 94,5 – 97,5%). The work included the renovation of all the accessories; new exhausted fumes duct in stainless steel; new electric system in the heater room.

Monitoring

Click here to access the monitoring data on the HIVE Database!

Funding

Energy efficient measures table:

Main Results

• The savings in energy consumption was estimated based on the results of the energy audit, accounting for 20-22%. The payback time of the investment is estimated in 12 years (with reference to the consumption of gas for the past 2 years prior to the intervention). If energy savings will be greater 20%, the Social Housing company will recover in a shorter time the investment and the owners will begin to benefit the savings directly before the end of the twelfth year.
• The energy retrofit works were completed in October 2011, so at present consumption data are available for two heating seasons. During the first season, gas savings were around 14.70%, while during in the second year they were around 22.50%. The significant improvement has been possible due not only to some minor technical adjustments on the boiler but in large part to the information and training performed by the Social Housing staff at the households. They focused especially on a correct use of the heating regulation equipment in order to avoid excessive indoor temperatures.
• The households were very satisfied, not only for the good results of heating during winter but also, for the significant improvement of thermal comfort during summer.
  
  
  

Lessons learned

• The Assembly should be already oriented to undertake a renovation project, so in spending money, this could facilitate the decision making process.
• Importance of the energy audit: more precise it will be, more trustable will be with advantage both for owners and for the Social Housing company in terms of respecting  the payback time of the investment.
• Importance of the meetings with technicians who are in charge of the renovation project: direct explanations to owners contribute to solve doubts and gain trust in the intervention, facilitating the decision making process.
• Social Housing company supported the owners both in administrative issues (e.g., tax deduction practices) and, if necessary, they accompanied them to banks in order to facilitate the request of funding.
• Importance of monitoring the energy consumption after the works. Monitoring consumption is crucial not only for the financial partner (in this specific case, the Social Housing company) in order to check the economic return of the investment, but also for the beneficiaries, in order to inform about their consumption and, if necessary - as in this case was - correct energy behaviour and make a little training about energy savings at home, such as use of thermostatic valves, how to ventilate by opening windows, etc.
  
  
  

Additional Information

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