The SCIENCE of Automated Shading CONTEMPORARY SHADING SYSTEMS ROLLER SHADES + LOUVER SYSTEMS WINDOW MANAGEMENT DAYLIGHT HARVESTING Joel Berman The SCIENCE of Automated Shading CONTEMPORARY SHADING SYSTEMS ROLLER SHADES + LOUVER SYSTEMS WINDOW MANAGEMENT DAYLIGHT HARVESTING Joel Berman CONTENTS 1 EXECUTIVE SUMMARY 6 2 INTRODUCTION 6 2.1 Background: The Case for Automated Shading Systems ....................................................................................................................... 6 2.2 Energy Savings with Automated Lighting and Shading Systems: The New York Times Building ................................................................ 7 2.3 Energy Savings with Daylighting and Automated Shading: A 2014 Study by TRC Energy Services and PG&E ............................................. 8 2.4 21st-Century Building Design ............................................................................................................................................................. 8 2.5 20th- and 21st-Century Window Glazing Design ................................................................................................................................... 9 2.6 Automated Shading with BMS and BAS Systems ................................................................................................................................. 9 2.7 Communication and Interaction Between Systems ............................................................................................................................... 9 3 HUMAN FACTORS 10 3.1 Human Factors: Definition ................................................................................................................................................................ 10 3.2 Solar Radiation and Human Factors ................................................................................................................................................. 10 3.3 Human Factors in Automated Shading Design ................................................................................................................................... 11 4 SKY EVALUATION AND CLOUD TRACKING 12 4.1 SolarEvaluation®: The Most Precise Method for Automated Shading .................................................................................................. 12 4.2 MechoShade’s SolarEvaluation System ............................................................................................................................................ 13 4.2.1 The ASHRAE Clear Sky Algorithim..................................................................................................................................... 13 4.2.2 The ASHRAE Clear Sky Radiation Curves .......................................................................................................................... 14 4.2.3 The SolarTrac® Modeling Program: A Sample Analysis ....................................................................................................... 15 4.3 Solar Penetration: Allowing or Avoiding the Direct Solar Ray ................................................................................................................ 19 4.4 Control of Heat on the Glazing with SolarEvaluation .......................................................................................................................... 20 4.5 SolarEvaluation Programs for Skylights and Atriums .......................................................................................................................... 20 4.6 Traditional Shade Control with Daylight Measuring ............................................................................................................................ 20 4.7 Daylight Measuring and Lookup Tables .............................................................................................................................................. 21 4.8 Advantages of SolarEvaluation Compared to Daylight Measuring ........................................................................................................ 22 4.9 The Thermodynamics of Solar Radiation: Understanding Radiation, Heat Gain and BTUs ..................................................................... 23 5 WINDOW-COVERING SYSTEMS 24 5.1 Venetian Blinds ............................................................................................................................................................................... 24 5.2 Louvered Blinds for Clerestory Windows ............................................................................................................................................ 24 5.3 Perforated Louvers .......................................................................................................................................................................... 24 5.4 Fabric Roller Shades ........................................................................................................................................................................ 24 6 SHADE CLOTHS 25 6.1 Characteristics of Shade Cloths ...................................................................................................................................................... 25 6.2 PVC-Free Shade Cloths ................................................................................................................................................................... 26 6.2.1 Polyester Shade Cloths with Translucent Yarns ................................................................................................................. 27 6.2.2 Contents of Recycled Polyester Shade Cloths ................................................................................................................... 27 6.3 Selection Criteria for Shade Cloths .................................................................................................................................................. 27 6.3.1 Solar Optical Properties of Shade Cloths .......................................................................................................................... 27 6.3.2 Selection Criteria for Glazing with a Screen Cloth ............................................................................................................. 29 6.3.3 Selection of Shade Cloths for Transparency and Color Selection ........................................................................................ 29 7 AUTOMATED SHADING SYSTEMS 30 7.1 Requirements for Automated Shade Performance ............................................................................................................................. 31 7.2 SolarEvaluation Systems with Louver Blinds ...................................................................................................................................... 31 7.2.1 Traditional Daylight Measuring Systems with Louver Blinds ................................................................................................ 31 7.3 SolarEvaluation Systems with Roller Shades ..................................................................................................................................... 31 7.3.1 Automating Top-Down Roller Shades ................................................................................................................................ 32 7.3.2 Using Bottom-Up Roller Shades ....................................................................................................................................... 32 7.4 Emerging Technologies: Electrochromic Glazing ................................................................................................................................. 32 7.5 Emerging Technologies: Predictive Sky Analysis ................................................................................................................................. 33 8 SOLAREVALUATION: SOLAR SCIENCE APPLIED 33 8.1 The SolarTrac® SolarEvaluation® Program .......................................................................................................................................... 33 8.2 The SolarTrac® Window Management® System ................................................................................................................................... 33 8.3 SolarTrac® Performance Factors ........................................................................................................................................................ 35 8.4 Solar Data ...................................................................................................................................................................................... 35 8.5 SolarTrac’s Performance and Repeatability ........................................................................................................................................ 35 8.5.1 SolarTrac’s Browser Interface .......................................................................................................................................... 35 8.5.2 Mobile Device Application ............................................................................................................................................... 36 8.5.3 BMS Interaction ............................................................................................................................................................. 36 8.5.4 Interaction and Communication with Third-Party Systems ..................................................................................................