Table of Contents

In modern Swiss architectural engineering, external dynamic solar shading forms the primary barrier against summer overheating across commercial office towers and residential buildings. Coupled with smart building automation infrastructure (KNX, SMI, BACnet), external venetian blinds, coupled louvers, zip-guided fabric screens, and roller shutters dictate compliance with cantonal energy laws (MuKEn / SIA 380/1) without relying on energy-intensive mechanical chillers. Severe wind gusts in exposed alpine regions and narrow structural window reveals demand extreme fabrication precision. Specialized trade software coordinates site measurements, actuator drive controls, and final billing in real time.

1. Statutory Foundations: SIA 342 (Solar Shading Systems) and Product Standard EN 13659

The engineering, manufacturing, and installation of external blinds and shading systems are governed by Standard SIA 342 (Solar Shading Systems – Requirements and Test Procedures) and European standard SN EN 13659:

  • Functional Classification: Delineation between glare protection (limiting desktop VDT luminance to < 2'000 cd/m2 pursuant to SUVA/SECO workplace safety rules) and thermal solar radiation rejection.
  • CE Marking & Declaration of Performance (DoP): Statutory requirement to document mechanical stability, pull-out forces on lateral guide channels, and corrosion resistance of marine-grade aluminum profiles.
  • Operational Cycle Endurance: Verification of mechanical endurance through testing (10'000 certified operation cycles per EN 14201).

2. Thermal Energy Verification: Total Solar Energy Transmittance (gtot) per SIA 380/1

The total solar energy transmittance of the combined glazing (g-value) and shading assembly (gtot) governs summer thermal protection under SIA 180 and SIA 380/1:

gtot = g \cdot (1 - Fc)

(where Fc represents the solar protection reduction factor).

  1. Minergie & MuKEn Target Thresholds: Maximum permissible design value of gtot ≤ 0.10 \dots 0.15 in fully deployed shading positions for exposed facades.
  2. **Automated Louver Angle Tracking (Cut-Off Function):** Motorized solar tracking adjusting slat tilt according to solar azimuth and elevation to block direct beam radiation while maximizing daylight autonomy.
  3. Cavity Air Ventilation: Mandatory 30 mm to 50 mm clear air gap between glass surface and blind louver to eliminate heat traps that trigger thermal glass stress.
Thermal Stress Glass Breakage Liability

Installing internal blinds or unventilated external screens causes severe thermal differentials across the glass pane (Δ T > 40 K), causing spontaneous fracture of annealed float glass. The installer is fully liable unless pre-existing tempered safety glass was verified or formal written reservations were submitted per SIA 118.

3. Mechanical Engineering: Wind Resistance Classes (0–6), Sensors, and KNX/SMI Motorization

Wind load engineering ensures the structural integrity of venetian louvers and vertical fabric zip screens:

  • Wind Resistance Classes per SN EN 13659:
Class 3 (400 Pa ≈ 90 km/h):* Baseline specification for beaded venetian blinds across the Swiss Plateau. Class 6 (800 Pa ≈ 130 km/h):* High-wind zip screens and heavy extruded architectural louvers for high-rise towers and exposed alpine valleys.
  • Wind Safety Sensors: Mandatory integration of certified wind and rain sensors programmed for automatic emergency retraction prior to storm gust thresholds.
  • SMI Digital Motors (Standard Motor Interface): High-precision stepper drives providing bidirectional status feedback, millimeter position accuracy, and diagnostic codes to the building management system.

4. Tendering, BKP 228, NPK 374, and Work Contract Installation under SIA 118

Commercial administration adheres to Swiss building classification structures:

  1. Building Cost Plan BKP 228 (External Closures and Solar Shading): Breakdown into venetian blinds (BKP 228.1), fabric drop-arm/zip awnings (BKP 228.2), roller shutters (BKP 228.3), and automated controls (BKP 228.8).
  2. Standard Position Catalog NPK 374 (Solar Shading and Blackout Systems): CRB tender positions detailing recessed headbox casings, sheet metal pelmets, slat geometries (70/80/90 mm rolled edges, Z-shaped, flat slats), motors, and guide rails.
  3. SIA 118 Takeoff Rules: Blinds are invoiced on a per-unit basis (pcs.) indicating nominal width and height. Formed pelmets, insulation backing, and power feed lines are invoiced separately per linear meter (m) or daywork.

5. System Comparison: Manual Paper Schedules vs. ACCSoft Solar Shading ERP

Workflow Manual Paper Job Sheets / Excel ACCSoft Solar Shading Module
Site Takeoff & Sizing Transcription errors on reveal deductions Mobile tablet takeoff automatically generating exact fabrication sizes
g_tot & MuKEn Verification Tedious manual calculations with glass charts Integrated SIA 380/1 simulator for glass-blind pairings
NPK 374 Tendering Laborious manual lookup of hardware codes Automated CRB export interface with accessory options
Motor Drive Sizing Omitted radio receivers and relay modules Automated torque (Nm) sizing based on curtain weight and friction
Field Service & Repairs Misplaced paper maintenance work cards Digital service logs with barcode component scanning and e-signatures

6. Swiss Statutory Sources, Trade Associations, and Technical Standards