Politecnico di Torino
Master of Architecture for Sustainability
From Performance-Based Passive Envelope to Façade Engineering
A Case Study of the Intersection Hotel Tower in Turin, Italy
Figure 1 Overall Unitized system drawings 1/50
Figure 3: Details section – Scale 1/20
.
Figure 4: Detail sections - Scale 1/5
1. Design for Assembly & Disassembly. 6
1.1. Overall façade technology distribution. 6
1.2. Unitized façade system (system 2). 7
1.4. Design for Assembly and Disassembly. 9
2. Optimizing Thermal Transmittance. 11
2.1. Methodology. 11
2.2. Thermal Tranmittance Budgeting. 11
2.3. Thermal Transmittance Calculation. 12
(a) Unitized frame design for thermal transmittance. 13
(b) Glazing unit design for thermal transmitance. 16
(c) Opaque Component Design for thermal transmittance. 16
3. Embodied Carbon, Fire safety & Acoustic performance. 17
4.1. Optimizing Embodied Carbon. 17
4.2. Optimizing Acoustic Performance. 19
4.3. Enhancing Fire Safety. 19
3. Optimizing Solar Radiation.. 21
3.1 Solar equivalent area (Asol,est) vertification. 21
3.2 Solar radiation reduction efficiency in summer period. 22
4. Discussion.. 22
Project Overview and Acknowledgements
This report presents a comprehensive synthesis of work conducted across two last consecutive Master’s design studios at Politecnico di Torino the Advanced Parametric Design Studio (14 credits) and the Façade Engineering Studio (8 credits). It focuses on the "Intersection Project", a high-rise hotel building located in Turin, Italy.
The core objective of this work is to bridge the gap between parametric architectural form-finding, performance-based passive envelopes, and performance-driven engineering. The study evaluates relevant performance metrics through three main pillars:
· Building Physics (including passive façade design and thermal performance)
· Structural Design (façade engineering and system verification)
· Architectural Conceptual to Designing (parametric conceptual forming and detailing)
Collaborative Foundation and Individual Synthesis
The foundational phases of this project were developed collaboratively within highly multidisciplinary teams, bringing together expertise from Architecture for Sustainability, Architectural Engineering, and Civil Engineering.
Architecture Conceptual Team: Maitane Bilbao Barrera, Sara Cantone, Ruochen Li, and Van Hieu Nguyen.
Façade Engineering Team: Clément Charron, Aleksandra Shelepova, and Van Hieu Nguyen.
Following the final exam discussions of both studios, this document was reconstructed, combined, and further developed individually by me (Van Hieu Nguyen). It represents an integrated personal touch that consolidates the collective research into a unified, high-performance architectural and engineering framework.
Van Hieu Nguyen
Master of Sience in Architecture for Sustainability
The initial phase of the Façade Engineering Studio focuses on advanced Design for Disassembly (DfD). The goal is to design a building envelope that ensures ease of maintenance, disassembly, and component replacement to enable future recycling. The core strategy utilizes dry-assembly methods, mechanical interlocking fasteners, and hook-type connections.
1.1. Overall façade technology distribution
The hotel landmark consists of two main building volumes: a two-storey podium, accommodating public spaces and hotel service functions, and a 100 m high-rise tower, containing hotel guest rooms and private service areas. Consequently, the façade design is divided into two principal groups: the podium façade and the tower façade, comprising six main façade systems below:
Type
Name
Area
Position
Description
1
Podium stick curtain wall
3469 m2
Level 1, 2
(Podium)
Alluminium stick curtain wall system with red aluminium vertical louvers
2
Tower Unitized curtain wall
5057 m2
Level 4, 5, 25
(Room floors)
Aluminium unitized curtain wall system incorporating red aluminium vertical shading louvers and horizontal overhangs
3
Tower Stick curtain wall
0737 m2
Level 3, 8, 15, 21
(Service floors)
Dark-coloured aluminium stick curtain wall system with dark-color glazing
4
Green roof
2444 m2
Level 1, 2
(Roof)
Walkable intensive green roof with high-performance thermal insulation
5
Tower roof
0318 m2
Level 26
(Roof)
Insulated pitched roof with integrated photovoltaic (PV) panels
6
Ground floor
3392 m2
Level 1
Basement
Highly insulated façade system with advanced thermal technology
Table: Hypothesised overall façade technology and distribution
Among these systems, System 2 (Tower Unitized Curtain Wall) is selected as the focus of this report due to its predominance on the building envelope as well as its structural and thermal complexity.
1.2. Unitized façade system (system 2)
System 2 consists of several types of unitized curtain wall panels, each measuring approximately 1500 mm × 3500 mm. The panels are installed on top of each others with a 750mm shift, resulting in the two typical façade floor plans. One called odd and another called oven typical:
Figure 2: Unitized system (system 2) distribution
Considering the hotel's functional requirements and architectural geometry, different panel configurations are required. Some panels incorporate operable windows to provide natural ventilation, while others are designed with 30° and 60° inclined geometries to accommodate the building form. The different panel types in System 2 are summarized in the table below:
Color
Type
Name
Area
Description
1a
Unitized Typical fixed panel
66%
- Typical technology:
- Frame: Wicona Witec EL60 aluminium unitized frame
- Glazing: Guardian LowE- Float UltraClear DGU
- Spandral: High insulation aluminium opaque panel
- Aluminium overhangs and vertical louvers, with dimensions optimized according to solar radiation exposure
1b
Unitized Typical openable panel
22%
2a
Unitized 120-Angle opaque panel
4%
2b
Unitized 120-Angle glazing panel
2%
3a
Unitized 60-Angle opaque panel
2%
3b
Unitized 60-Angle glazing panel
2%
Table 1: Different Unitized Panel Distribution
1.4. Design for Assembly and Disassembly
1.4.1. Manufacture and Installation
Principle of the design is manufacturing separately unitized panels and their external shading. These elements will be transferred to the site and attach here off-site. Thanks to the hook connection, specific louvers can be atttached dirrectly. Then lift to the position using cranes, and attached to the site by brackets,…
The general logic described above is illustrated in the reference construction details reported in Figure 1.7. Figure 1.7 presents the full vertical and horizontal sections at a typical floor level, showing the unitized panel build-up (mullion/transom frame, insulation, composite cladding, glazing) together with its connection to the primary structure and the slab-edge firestop assembly. Figure 1.8 zooms into the hook-up interfaces identified in Section 4.3.1: the vertical connection between stacked unitized panels, and the two hook-type connections used to suspend the external louvre and the external shading overhang from the panel frame, allowing tool-light removal without disturbing adjacent components. The bracket shown "waiting for connection" corresponds to the anchor point onto which the shading elements are hooked during installation.
1.4.2. Accessing and Maintainance
The maintenance strategy is adopted for the unitized façade system, covering the selection of the building maintenance unit (BMU), the overall façade access strategy, and the inspection and replacement provisions to be followed over the building’s service life.
The replacement strategy for façade panels and components is based on external access via the roof-mounted BMU following a defined sequence of component removal. Access to the façade unit is achieved from the exterior face using the BMU. Components are removed in the following order: Local External louvres → Local External shading Ovehang → Unitized façade panel.
The external shading devices are supported on a hook-type connection, allowing them to be lifted vertically by approximately 1 cm to disengage the hooks before being removed from the supporting structure. This avoids the need for bolted or mechanically fastened connections at the shading interface, simplifying both installation and future replacement.
2.1. Methodology
Budgeting (Overal to Detail) → Calculate (Frame + Glazing + Opaque + Thermal Bridge) and go back (loop)
2.2. Thermal Tranmittance Budgeting
a. Overall Building Thermal Requirements
The assessment complies with the Italian Decree of June 26, 2015. The scope focuses exclusively on single envelop components and the overall thermal envelope parameter ( ), omitting whole-building energy performance indices.
To determine the target thermal transmittance ( ) for the façade, the process involves defining the allowable limit, establishing assumed U-values for non-façade components, and allocating a specific thermal budget. Given the building's location in Climatic Zone E and its compact form with a shape ratio (S/V) of , the maximum allowable global heat transfer coefficient ( ) is strictly capped at in accordance with regulatory standards.
b. Whole system budget Estimate
Table 2.2 below summarizes these hypothesised design values to meet this global heat transfer coefficient technical justifications for these parameters follow the table:
Opt 2
Surface
Area
U_value
Description
1
Podium stick curtain wall
3469 m2
1.10 W/m2K
Wicona Stick El60 + Double Glazing
2
Tower Unitized curtain wall
5057 m2
1.20 W/m2K
Unitized Wicona EL60 frame + Double glazing
3
Tower Stick curtain wall
0737 m2
1.20 W/m2K
Wicona Stick EL60 + Double glazing
4
Green roof
2444 m2
0.15 W/m2K
Intensive green roof + insulation
5
Tower roof
0318 m2
0.20 W/m2K
Insulated roof + PV panel
6
Ground floor
3392 m2
0.40 W/m2K
Insulated ground floor
Table 2 Overall Building Thermal Requirements option 2 (chosen one)
Opt 1
Surface
Area
U_value
Description
1
Podium stick curtain wall
3469 m2
1.60 W/m2K
Wicona Stick EL50 + Double glazing
2
Tower Unitized curtain wall
5057 m2
0.80 W/m2K
Unitized Wicona Evo frame + Triple glazing
3
Tower Stick curtain wall
0737 m2
1.60 W/m2K
Wicona Stick EL50 + Double glazing
4
Green roof
2444 m2
0.15 W/m2K
Intensive green roof + insulation
5
Tower roof
0318 m2
0.20 W/m2K
Insulated roof + PV panel
6
Ground floor
3392 m2
0.40 W/m2K
Insulated ground floor
Table 3 Overall Building Thermal Requirements option 1 (alternative)
The design analysis in the next chapter shows that option 2 is more reasonable than option 1, since the main façade is made by double glazing and an advanced technological frame, while option 1 is a lot more expensive because the concentration in the main façade with triple glazing unit and top-norch technology of frame.
c. Unitized system budget Estimate
While the thermal assessment was conducted on a baseline functional unit, the actual execution of the System 2 envelope inherently includes localized geometric variations. These deviations consist primarily of corner modules, terminal edge panels, and dimensionally adjusted fit-in modules required to align with the primary structural grid of the building. Because these atypical panels possess slightly different frame-to-glass and frame-to-spandrel area ratios, their individual thermal transmittances will experience minor deviations from the calculated baseline.
System
Area
U_value
Description
Type 1a: Typical fix panel
3469 m2 (66%)
1.03 W/m2K
Stick El50 + Double Glazing
Type 1b: Typical openable panel
5057 m2 (22%)
1.53 W/m2K
Unitized EL60 frame + Double glazing
Type 2a: 120-Degree-Corner panel a
0737 m2 (04%)
1.10 W/m2K
Stick EL60 + Double glazing
Type 2b: 120-Degree-Corner panel b (Opaque)
2444 m2 (02%)
1.02 W/m2K
Intensive green roof + insulation
Type 3a: 60-Degree-Corner panel a
0318 m2 (04%)
1.07 W/m2K
Insulated roof + PV panel
Type 3b: 60-Degree-Corner panel b (Opaque)
3392 m2 (02%)
1.02 W/m2K
Insulated ground floor
Table: Overall Building Thermal Requirements
The panel type 1a is chosen to be deep analysis in the next chapter. This result sets a U_value target for Type 1a
2.3. Thermal Transmittance Calculation
In accordance with EN 13947, the overall thermal transmittance of a single unitized module is determined by the area-weighted thermal transmittances of its transparent and opaque elements, combined with the linear thermal transmittances of the frame. The U-value of the functional unit is calculated using the area-weight formula:
• is the overall thermal transmittance of the unitized facade module, expressed in ;
• is the surface area of the insulated glass unit (IGU), expressed in ;
• is the center-of-glass thermal transmittance of the IGU, expressed in ;
• is the surface area of the opaque spandrel panel, expressed in ;
• is the center-of-panel thermal transmittance of the opaque spandrel section, expressed in ;
• is the projected surface area of all the components of the frame, expressed in ;
• is the weighted average thermal transmittance of the frame components, derived from 2-D FEM simulations, expressed in ;
• is the total visible perimeter length of the glazing unit, expressed in ;
• is the linear thermal bridge coefficient at the glass edge, accounting for the localized heat flow interaction between the IGU spacer and the aluminium frame, expressed in ;
• is the total projected surface area of the functional unitized module, expressed in .
Element
Area [m2]
U_value
Technology
(a) Transparent (glass)
2.40
1.060 W/m2K
Guardian LowE- Float UltraClear DGU
(b) Opaque (op)
2.23
0.164 W/m2K
High insulation Rockwool+ aluminium opaque panel
(c) Panel Frame (f,avg)
0.62
2.462 W/m2K
Wicona Witec EL60 aluminium unitized frame
(d) Thermal Bridges
6.8 Length [m]
0.143 W/mK
Between Glass + Frame
Total
1.030 W/m2K
Reach the target!
Table 4 U_value calculation
(a) Unitized frame design for thermal transmittance
To accurately evaluate the thermal performance of the unitized module, the localized thermal transmittances ( ) of the various extruded frame profiles, as well as the linear thermal bridge coefficient ( ) induced by the IGU spacer, were calculated using two-dimensional finite element method (FEM) simulations in BISCO.
Type of junction
ID
Length (L) [m]
Uf [W/(m²K)]
Uf⋅L [W/mK]
Opaque to Glazing
Point 1
2.00
2.158
4.3160
Break point (with external shading)
Point 1'
0.40
6.321
2.5284
Opaque to Opaque
Point 2
1.10
1.938
2.1318
Opaque to Opaque
Point 3
1.50
2.075
3.1125
Opaque to Glazing
Point 4
4.20
2.328
9.7776
Break point (with external shading)
Point 4'
0.20
7.741
1.5482
Mullion junction
Point 5
0.95
2.179
2.0701
Total frame
-
10.35
= 2.462
= 25.485
Table 5
The frame's length-weighted average thermal transmittance ( ) is the value carried forward into the module U-value calculation in previous chapter.
Figure 5 Frame Thermal Transmittance Analysis by BISCO
(b) Glazing unit design for thermal transmitance
General characteristics of reasonable glazing are explored above, all of them must have a U_value of around 1.06W/m2K. The proposed baseline stratigraphy was simulated using GlassAdvisor software to extract precise luminous, thermal, and mechanical properties.
Design Parameter
Constant Value
Unit
Outer Panel Thickness
8mm
Toughened & Polished
Gas Cavity Width & Fill
22mm
Fill with Argon 90%, make place for the cavitied blind inside
Inner Pane Stratigraphy
4 mm + 0.76 mm PVB + 4 mm
Trosifol Clear Interlayer
Total Glass System Thickness
38.8mm
Table: Overall Building Thermal Requirements
However, to determine the specific manufacturer, and determine the optimal insulated glass unit (IGU), a comparative analysis was conducted evaluating high-performance glazing products from four leading manufacturers: AGC, Guardian, Pilkington, and Saint-Gobain. Table 2.7 below summarizes these performance metrics:
Parameter
AGC
Guardian
Pilkington
Saint-Gobain
Low-Iron Float Glass
Planibel Clearvision
Float UltraClear
Optiwhite
SGG DIAMANT
Solar Control Coating
Stopray Neutral 50/27
SG SNX 50
Suncool 50/25 Pro T
Cool lite SKN 154
Light Transmittance (Tv)
51%
49%
51%
52%
Solar factor (g_value)
28%
24%
28%
28%
Selectivity Ratio (Tv/g)
1.82
2.04
1.82
1.86
References
https://app.glassadvisor.com/configurator/308c223f6303b8169dc33557939f
https://app.glassadvisor.com/configurator/60eeeee7a0ce76e3014610f298d6
https://app.glassadvisor.com/configurator/22dca0b32d3020576988fbf9ed48
https://app.glassadvisor.com/configurator/0579cb2c91e3bc7308762927d267
Table 7
Guardian was selected as the optimal glazing provider for the unitized facade system, utilizing the Float UltraClear substrate paired with the SG SNX 50 solar control coating. By providing the lowest solar factor (g = 24%), the Guardian configuration minimizes solar heat gain on the highly exposed southeast (SE) and southwest (SW) orientations, directly reducing summertime peak cooling loads and thermal discomfort.
(c) Opaque Component Design for thermal transmittance
To evaluate the thermal performance of the non-vision areas of the unitized module, the center-of-panel thermal transmittance ( ) for the opaque spandrel sections was calculated. This assessment was accordance with EN ISO 6946, which evaluates steady-state heat transfer through the assembly stratigraphy. The overall thermal resistance ( ) of the assembly is determined by summing the internal and external surface thermal resistances ( and ) with the conductive resistances of each material layer:
where is the thickness of the -th material layer (in ) and is its design thermal conductivity (in ). Based on the material thicknesses and surface boundary conditions, the calculation computes a center-of-panel thermal transmittance of , given the table below:
Layers
d
ρ
μ
c
λ
(From extenal to internal)
[cm]
[kg/m³]
[-]
[J/kg°C]
[W/m°C]
Composite Aluminium
0,3
2700
2
960
1,900
Rock Wool (Stone wool)
19,6
125
1
840
0,033
Composite Aluminium
0,3
2700
2
960
1,900
Total
20,0
0.164 W/m2K
Table 8 Opaque Component Thermal Transmittance
4.1. Optimizing Embodied Carbon
Scope of calculation
The embodied carbon associated with the façade system is assessed for life-cycle stages A1–A3 (product stage), following EN 15978 and the RICS Whole Life Carbon Assessment framework. The functional unit is one square metre of assembled unitized curtain wall system (derived from a standard 5.25 m2 functional panel). This assessment incorporates the framing components, Double glazing unit (DGU), opaque spandrel panels, insulation, shading systems, and accessories.
Two options of Embodied Carbon
To quantify the embodied carbon impact of the two façade material specifications, a component-level comparison was carried out for each envelope element (shading, frame, spandrel, and glazing), using Global Warming Potential (GWP) factors sourced directly from manufacturer-published Environmental Product Declarations (EPDs), stage A1–A3 (raw material supply, transport, and manufacturing). For each component, the material volume and density were used to derive the total mass, which was then multiplied by its EPD-declared embodied carbon factor to obtain the total and normalized (per m2 of façade surface area, FSA) CO2e contribution. Tables 2.16 and 2.17 below present this breakdown for Option 1 (Standard Materials) and Option 2 (Low Carbon Materials) respectively.
From left to right
-Unitized anchors and brakets
-Internal cladding
-Insulation
-External cladding
-Internal laminated glass pane
-External single glass pane
-External shading brakets
-External shading structure
-External shading cladding
Figure 6 Typical Unitized Panel Material Explode
Figure 7: Embodied Carbon in two material options
Option 1 Standard Materials
Volume
Weight
CO2
Total CO2
kgCO2e
m3
Kg
kgCO₂e/kg
kgCO₂e
Per m2FSA
Shading
(1) Steel Structural circular hollow Arvedi Tubi Acciai Spa
0.006
43.33
1.94
84.06
16.01
(2) Standard aluminium, alloy 6060 – Gastaldello Sistemi
0.019
50.38
16.70
1382.46
263.33
Frame
(2) Standard aluminium, alloy 6060 – Gastaldello Sistemi
0.012
32.40
16.70
Spandrel
(3) Standard aluminium composite l, A2 – ASAŞ Aluminium
0.018
37.88
9.20
348.46
66.37
(4) Stone wool insulation, λ = 0.033 W/mK – PAROC Cortex
0.436
34.92
4.52
157.77
30.05
Glazing
(5) Standard Guardian ExtraClear™ Float Glass
0.038
96.00
0.96
92.54
17.63
Total
201.20
393.39
Table 9: Option 1 Standard Materials
Option 1 Standard Materials
Volume
Weight
CO2
Total CO2
kgCO2e
m3
Kg
kgCO₂e/kg
kgCO₂e
Per m2FSA
Shading
(6) Recycled and renewably Steel Structural Hollow
0.006
43.33
0.65
27.99
5.33
(7) Low-carbon recycled aluminium – Hydro CIRCAL 75R
0.019
50.38
1.98
163.91
31.22
Frame
(7) Low-carbon recycled aluminium– Hydro CIRCAL 75R
0.012
32.40
1.98
Spandrel
(8) Low-carbon aluminium composite, STACBOND A2PVDF
0.018
40.15
4.52
181.40
34.55
(9) Low-carbon stone wool– ROCKWOOL RED AirBatt
0.436
48.01
1.06
51.07
9.73
Glazing
(10) NEXA™ 6 Flat Glass (Advanced Guardian ExtraClear™)
0.038
96.00
0.64
61.25
11.67
Total
92.50
Table 10: Option 2 Low-Carbon Materials
The comparative analysis evaluates a standard baseline façade build-up (Option 1) against a low-carbon alternative (Option 2), based on the bill of materials for a single unitized panel and the corresponding Environmental Product Declarations (EPDs). Contrary to an earlier draft of this section, all five build-up components, not only the frame and glazing, were substituted with lower-carbon equivalents in Option 2: the steel shading structure, the aluminium frame, the aluminium composite spandrel panel, the stone wool insulation, and the glazing. None of the components remain constant between the two options.
4.2. Optimizing Acoustic Performance
Based on D.P.C.M. 5/12/1997 sets the minimum façade sound level, the hotel tower falls under Category C (buildings used as hotels, guesthouses, or similar establishments), for which the minimum required façade sound level difference is: D2m,nT,w,req = 40 dB
Component
R_w [dB]
Source
IGU + aluminium frame (system, combined)
40
Frame/system manufacturer data
Glazing alone - double glazing 8-(16)-4-4
33
Reference glazing tables
Glazing alone - Guardian Float Ultra Clear (selected build-up)
34
GlassAdvisor simulation
Opaque spandrel panel (stone wool / ACM, insulated back pan)
60.4
Calculated, see Section 2.4.3
Table 13: Acoustic Performance
The GlassAdvisor value of 34 dB is adopted as the design basis for the glazing, since it reflects the actual selected build-up rather than a generic reference table.
Component Sound Reduction Indices ():
Glazing: The selected Guardian Float Ultra Clear glazing provides an index of 34.0 dB.
Opaque Spandrel Panel: The opaque section (aluminium composite panel, stone wool insulation, and back pan) achieves an impressive 60.4 dB. This high value was calculated by factoring in the mass-air-mass resonance effect caused by the two-skin construction
Acoustic performance in-situ highly depends on the receiving room's sound field dynamics. A small room represents the worst-case scenario because the sound energy gets concentrated within a confined space, producing higher localized acoustic pressure and lowering the apparent insulation performance compared to a larger room
The overall composite façade successfully passed the regulatory check with a result of 40.43 dB in the worst-case small room. However, the passing margin is extremely narrow (0.43 dB) because the glazing is responsible for 99.9% of the transmitted sound energy, whereas the opaque panels are heavily overspecified for acoustics
4.3. Enhancing Fire Safety
The fire classification of the building is established in accordance with D.M. 03/08/2015 - Codice di Prevenzione Incendi, D.M. 30/03/2022, and RTV V.13 “Chiusure d’ambito degli edifici civili”. Given a building height of approximately 100 m, which exceeds the 24 m threshold, the building is classified as a high-rise building (Categoria SC - Sovraffollamento/Complessa). This classification governs the required fire resistance ratings, compartmentation strategy, and reaction-to-fire class of the façade materials adopted throughout the remainder of this section. Fire safety design for curtain wall façades must address three principal paths of fire and smoke propagation across the building envelope:
· Path 1 – Through the façade build-up: propagation through combustible materials within the façade construction itself.
· Path 2 – Across the façade face: vertical fire spread along the external face of the building from floor to floor.
· Path 3 – Through the slab-edge gap: propagation of fire and smoke through the perimeter gap between the edge of the structural floor slab and the inner face of the curtain wall.
Figure 8 Design for Fire Safety
Fire Stop at Slab Edge
A continuous perimeter firestop system is required at the slab-edge gap between the structural floor and the unitized curtain wall, with these characteristics. Position: at every floor level, along the full perimeter of the slab edge, to prevent fire and smoke between floors. Fire resistance: EI 60, consistent with the SC classification of the building. Movement accommodation: must accommodate differential movement between the façade and the structural slab.
The proposed slab-edge firestop solution combines a Hilti CFS-SP WB Firestop Joint Spray with a mineral (stone) wool backing.
· The Hilti CFS-SP WB Firestop Joint Spray seals against smoke leakage, maintains joint integrity, and accommodates movement of up to 50% of the joint width (to be verified by test certification).
· The mineral wool backing is non-combustible and maintains its integrity under high temperatures, providing the primary fire-resistant barrier within the joint.
Façade Separation Band
In accordance with RTV V.13, a horizontal façade separation band of at least 1.0 m is required at each compartment floor level, typically integrated into the spandrel zone, to limit vertical fire spread across the external face of the building. The proposed spandrel configuration provides a total vertical distance of 2300 mm, with a spandrel panel length of 1100 mm, exceeding the 1000 mm minimum required separation distance
Non-Combustible Materials
In accordance with EN 13501-1 (Fire classification of construction products and building elements, Part 1: Classification using data from reaction-to-fire tests) and D.M. 30/03/2022 - RTV V.13, the materials used within the façade build-up, particularly in the spandrel and compartmentation zones, shall be non-combustible or of very limited contribution to fire. The required reaction-to-fire classification is A2-s1,d0 or better, where: A2 – practically non-combustible, or of very limited contribution to fire; s1 – little or no smoke production; d0 – no flaming droplets or particles. The proposed spandrel build-up combines an aluminium composite cladding panel with a non-combustible mineral wool insulation layer:
· Spandrel cladding: an A2-classified aluminium composite panel (e.g. STACBOND® A2 PVDF), achieving reaction-to-fire class A2-s1,d0 in accordance with EN 13501-1.
· Spandrel insulation: non-combustible stone wool insulation (e.g. ROCKWOOL® RED AirBatt / Ventirock Duo), achieving reaction-to-fire class A1 in accordance with UNI EN 13501-1. As Class A1 exceeds the minimum required Class A2-s1,d0, the proposed insulation satisfies the façade material requirement with margin.
Original Architecture conceptual Passive Design sollutions showing very impressive results, with a decrease up to 41% in summer period (in this reseach, from 01/05 to 31/08). However, it could be further developed by enhancing the glazing techonology (G-value). Italian regulations have a very strict guildeline for them, with the g_value must be lower than 0.35, and the ratio between the solar equivalent area (Asol,est) and the useful floor area (Asup,utile) must be lower than 0.04.
3.1 Solar equivalent area (Asol,est) vertification
The legislation requires the verification of the ratio between the solar equivalent area (Asol,est) and the useful floor area (Asup,utile). This parameter evaluates the building’s total solar gain potential relative to its size. The solar equivalent area is calculated for the month of July using the formula provided in the technical specifications:
where:
· : Shading reduction factor derived from external obstacles and overhangs for July.
· : Total solar energy transmittance of the window.
· : Area of the IGU.
· : Correction factor for solar irradiance based on orientation and location
Shading reduction factor is calculated using grasshopper ladybug with the shading devices, the results given here in this table:
North East
North West
South East
South West
Average
Overhang length
350mm
300mm
900mm
900mm
Overhang width
200mm
250mm
500mm
500mm
Shading reduction factor
0.89
0.83
0.59
0.57
0.72
Table 11
The solar equivalent radio is calculated using the above formular is inside the charts below:
Without cavitied blinds
North East
North West
South East
South West
Average
Shading reduction factor
0.89
0.83
0.59
0.57
0.72
Solar window energy trans.
0.24
0.24
0.24
0.24
0.24
Area of the IGU
31.2
31.2
31.2
31.2
31.2
Correction solar factor
0.60
0.75
0.81
0.83
0.75
13.16
/
Not compliance with DM Requisiti Minimi 26/06/2015 <0.04
0.049
Since the glazing has a very good value of G-value 0.240, it is still not possible to commit the Italian regulation. A system of integrated blind is structured inside the cavity of these glazing panels, helping them to significantly reduce the to only 0.096, when blinds is fully close. It represents the ability to shade in peak periods like July:
With cavitied blinds
North East
North West
South East
South West
Average
Shading reduction factor
0.89
0.83
0.59
0.57
0.72
Solar window energy trans.
0.096
0.096
0.096
0.096
0.096
Area of the IGU
31.2
31.2
31.2
31.2
31.2
Correction solar factor
0.60
0.75
0.81
0.83
0.75
7.41
/
Compliance with DM Requisiti Minimi 26/06/2015 <0.04
0.027
Table 12
Figure 8: Solar radiation goes through system 2 in July (kwh/m2)
3.2 Solar radiation reduction efficiency in summer period
A full approach map here in this picture:
It can be observed that while passive design significantly reduces solar gains across all facades, maintaining low levels during several summer months, glazing technology (with a g-value of 0.24) paired with external blinds inside the glazing cavity further enhances this efficiency, successfully meeting the strict limits of Italian regulations ( / <0.04)