Via Tovo

Olgiate Olona (Varese), Italia

Multi-family house | 40 sqm installation



The present assessment deals with a solar thermal system to be installed on a new residential building with twelve dwellings in northern Italy.

The investor is sensible to renewable energy sources and has already had a positive experience with a small self-built system.

The new building is suitable for a solar thermal plant for domestic hot water. Two systems with different collector and storage sizes have been proposed (21 and 28 kWth). The system with 28 kWth leads to 55 % energy savings and solar heat costs lower than those for conventional heat. In addition, six tons of CO2-emissions are avoided per year.



Type of building

Multi-family house

Number of dwellings, floors

12 dwellings
45 persons

Year of construction


Total effective area (heated)

not available 

Hot tap water consumption

730 m3/a

Whole energy consumption for heating purpose (present situation)

not available

Proposed CSTS (main variant)

Type of collectors

Flat plate collectors

Thermal power

28 kWtherm.

Aperture area of collectors*)

40 m2

Buffer storage

2.0 m3

Hot tap water storage

1.2 m3

Total capacity of boilers

187 kW

Type of hot tap water heating


Type of heating system


Estimated Costs

Total cost solar system

21,850 Euro

Cost of the CSTS/gross area of collectors

460 Euro/m2

Available Subsidies

55 %

Predicted System Output

Output of solar heat

22,500 kWh/a

Reduction of final energy

30,000 kWh/a

CO2-emissions avoided

6 t CO2/a

*) Aperture area = light transmitting area of the front glass


Proposed System Scheme



Piero Balossi
Olgiate Olona (VA)

Assessment by 

Ambiente Italia srl
Via Carlo Poerio 39
20129 Milano, Italy
Tel.: +39 02 27744-0



Assessment summary (English)

355 K


Detailed assessment report, 13 pages (Italian)

393 K