Case Studies

Cartagena50 residential building renovation

Madrid, Spain

Code: OP19

Original building
© Díaz Rojo Arquitectos
Retrofitted floor plan
© Díaz Rojo Arquitectos
DesignPH model
© VAND arquitectura
Airtightness concept
© VAND arquitectura
Heat generation with heat pumps in common area
© VAND arquitectura
Airtight connections
© Díaz Rojo Arquitectos
Ventilated facade
© Díaz Rojo Arquitectos
Retrofitted building
© Nuria Díaz Antón / VAND
The official plague is installed
© Díaz Rojo Arquitectos
The rooftop space above Madrid
© Díaz Rojo Arquitectos

Original situation

The original building, located in the city of Madrid, consists of eight floors above ground for offices, and two more below ground, for parking, storage rooms and building services rooms. Two facades, located in the corner of the plot, are orientated to north and west, and the other two are party walls. In the southeast corner there is a courtyard for lighting and ventilation of the common areas.

It was built in 1972 using a traditional construction system: concrete floors and pillars, a double-leaf brick facade, flat roof without insulation, and anodized aluminium exterior framing with double glazing.

Renovation approach

The tenants have moved in and the monitoring is about to start.

Modernisation proposal

In this retrofit, the EnerPHit standard will be achieved through the Energy Demand Method. It is a complete renovation including the following actions:

-Building envelope insulation (facades, roof, floor towards basement and interior walls between apartments and staircase)

-Ventilated facade installation

-Windows, doors, and roller shutter replacement

-Airtightness improvement

-Ventilation system with heat recovery installation

-Heating and cooling systems renovation

-Existing thermal bridges improvement

-Accessibility improvement

-Orientation improvement by means of removing the service staircase located next to the courtyard, in order to several apartments have a south-facing facade

-Photovoltaic system installation

After the retrofit there will be six floors above ground for apartments, ground floor for access, storage rooms and building services rooms, and three floors more below ground for parking.

Efficiency improvement

No calculations available for the existing building. A comparison is not possible as the main use of the building has changed, and therefore the occupancy, schedule, internal heat gains, etc.

The reference values of efficiency improvement of EnerPHit standard can be taken into account.

PHPP verification sheet after retrofit

TFA existing treated floor area (usable floor space)

2860.0 m2

Space heating Heating demand

20.0 kWh/(m2a)

Heating load

11.0  W/m2

Space cooling Cooling & dehum. demand

4.0 kWh/(m2a)

Cooling load

7.0 W/m2

Frequency of overheating (> 25 °C)

0.0 %

Frequency of excessively high humidity (> 12 g/kg)

0.0 %

Airtightness Pressurization test result n50

1.0 /h

Non-renewable Primary Energy (PE) PE demand

105.0 kWh/(m2a)

Primary Energy Renewable (PER) PER demand

67.0 kWh/(m2a)

Generation of renewable energy (in relation to projected building footprint area)

– kWh/(m2a)

EnerPHit classic



Click to view via Youtube (Google)

Key facts

Building typology

Apartment house

Existing treated floor area (usable floor space)

2 860 m2

Building owner


Consulting outphit partner


Project status



Nuria Díaz Antón
VAND arquitectura
Téléphone: +34 917751267