Madrid, Spain

Multi family house | 48 sqm installation



The present assessment deals with a solar thermal system to be installed on three residential buildings with a total of 140 inhabitants in Bustarviejo, Spain.
The solar thermal installation proposed covers the mandatory solar fraction of 60 % for hot tap water in the zone IV in Spain, according to the new Spanish building code. Its size has been estimated with the SOLARGE tool.
A back-up heating system is needed to ensure the availability of hot tap water during the whole year. The reduction of final energy has been estimated from the energy consumption of a natural gas boiler (η=0,7) for hot water preparation.
Additional building information has been summarised on the Checklist for the estimation of technical parameters of solar thermal installations designed within the SOLARGE framework.



Type of building

Multi family house

Number of dwellings, floors

3 buildings
140 users

Year of construction


Total effective area (heated)

not available 

Hot tap water consumption

1,095 m3/a

Whole energy consumption for heating purpose (present situation)

not available

Proposed CSTS (main variant)

Type of collectors

Flat plate collectors

Thermal power

33.6 kWtherm.

Aperture area of collectors*)

48 m2

Buffer storage

3.0 m3

Hot tap water storage


Total capacity of boilers


Type of hot tap water heating

Natural gas

Type of heating system


Estimated Costs

Total cost solar system

not available

Cost of the CSTS/gross area of collectors

not available 

Available Subsidies

not available

Predicted System Output

Output of solar heat

39,059 kWh/a

Reduction of final energy

55,789 kWh/a

CO2-emissions avoided

13.2 t CO2/a

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


Assessment by

Ecofys SL
Paseo del Ferrocarril, 335, 4o-1a
08860 Castelldefels (Barcelona), Spain
Phone: +34 93 6455-458
Fax: +34 93 6455-184




This assessment summary (English)

479 K


Detailed assessment report, 8 pages (Spanish)

236 K