Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 381

pump (GHP) is integrated with the DHW production and covers the heating
and cooling needs.
The building envelope (Cellura et al. , 2011b) is comprised of

Walls : Plaster 0.02 m, light weight brick 0.30 m, polystyrene 0.18 m
and plaster 0.02 m;
Roof : Plasterboard 0.03 m, vapor barrier 0.001 mm, wood fiber (170
kg/m 3 ) 0.10 m, rock wool 0.10 m, sheathing 0.001 m, air space, and
pinewood 0.02 m;
Floor : Terracotta tiles 0.02 m, concrete subfloor 0.05 m, polyurethane
foam 0.04 m, lightweight concrete 0.05 m, bitumen 0.005 m, concrete
0.20 m, air cavity 0.19 m, gravel 0.115 m. Table 7.5 lists the calculated
U -values of the opaque structures.

Table 7.5 External structures U -values

External structures U -value (W/(m 2 K))
Walls 0.15

Floor 0.30

Roof 0.25

The south-facing window area-to-wall ratio is about 24%, while the rest of
the orientations are kept below 10%. The windows are made of a double
panel insulated glazing ( U = 1.1 W/(m 2 K)) with 0.006 m external glass,
0.14 m gap filled with argon and 0.004 m internal glass; the average global
window U -value is 1.40 W/m 2 K. The solar heat gain coefficient (SHGC) is
0.6.

7.3.2 Description of the Design Process

The idea of creating a case study in the field of carbon neutral buildings was
first developed in June 2004 by the Architetture Sostenibili s.r.l. and the
Loccioni group. The first target was later modified and recalibrated toward
the Nearly Net ZEB objective.
The preliminary design took place over 1 year (October 2004 - October
2005)andwasprolongedinordertoincludeinthedesignthefeedbackfrom
theearlydesignsimulations.Thislatterphase(November2005-December