The building, a residential construction designed by DMDV Arquitectos and built in 2020, represents an exemplary nZEB with that reached also the certification of Passivhaus Plus.
It has a useful area of 2.475,54 m2 shared between common spaces and 14 apartments, constructed on a rectangular building site of 1287,85 m2. The architectural concept is defined as a dynamic prism with great compactness, and the facades present the same finishing forming a zigzag stripe between the windows of each floor, looking for a clear formal singularity within the simplicity of its concept The ground floor opens to the outside and includes spaces for a community room aimed at coworking. It has underfloor heating and cooling, Mechanical Ventilation Heat Recovery System and photovoltaic installation. All energy production for heating and cooling is through individual aerothermal heat pumps.
The exterior wall façade presents a U-value of 0.202 W/(m2K), and it is insulated with External Thermal Insulation Composite System (ETICS) with 15 cm of EPS panels . Continuity in the insulation in the whole envelope avoids the thermal bridges in forged edges and encounters with floor and deck as well as in correspondence with the ground floor The interior of the enclosure has been made with a self-supporting laminated gypsum board with mineral wool of 0.031 W/(mK) and 40 mm. of thickness.
The basements has a U-value accounting for 0.195 W/(m2K), and it is insulated with a mineral rock layer 150 mm thick applied on a reinforced concrete slab. Moreover, on the inside, an underfloor heating system with a 35 mm thick XPS sheet and 0.043 W/(mK) is installed.
The flat roof has a U-value of 0.153 W/(m2K). It is not passable, and it is formed by a unidirectional slab on which slope mortar, waterproofing, thermal insulation XPS 20 cm thick, with a thermal conductivity of 0.035 W/(mK). A layer of gravel protects the construction system. An air chamber and a false ceiling with thermal insulation of mineral rock wool 20 mm thick and a thermal conductivity of 0.038 W/(mK) are arranged on the lower face of the slab.
The windows have a PVC frame with a thermal transmittance of 1.2 / m2K and the glasses present a U g-value of 0.64 W/(m2K) and a g -value of 49 %.
The overall air tightness value of the envelope is n50 = 0.6/h.
The ventilation is supplied by a double mechanical flow ventilation system with heat recovery, whose heat exchanger has an efficiency up to 82%. The housing are permanently ventilated through insulated ducts in each apartment.
The heating and the cooling are provided by decentralised aerothermal systems with an air heat pump, while the domestic hot water is produced by a centralised heat pump with a heating capacity of 30kW and a COP of 4.3 . The heat pump is connected directly to the water supply circuit system, has a two insulated tank of 1000 litres and 2000 litres to storage the hot water.
The building has also integrated a PV system of 61 panels having an estimated yearly production of 32973 kWh (according to PHPP evaluations)
OVERALL ENERGY FIGURES
The energy performance was assessed through PHPP tool and the overall results are:
- Annual heating demand = 14 kWh /(m2a ),
- Primary energy requirement 60 kWh /(m2a ) on heating installation, domestic hot water, household electricity and auxiliary electricity calculated according to PHPP, while for this building the PER demand accounts for 38 kWh /(m2a )
- Generation of renewable energy 67 kWh /(m2a ) based on the projected area
- Cooling load 7 W/m2
- Cooling and dehumidification demand 9 kWh /(m2a )