SimBuild 2008, 3 rd National Conference of IBPSA-USA, July 30- August 1, 2008, Berkeley, CA Seminar: Lighting and Daylighting High-Performance Commercial Building Façade Solutions Eleanor Lee, PI, Staff Scientist
Where do we want to go? Public Agency Objectives US Department of Energy EERE: Zero-energy buildings (ZEB) by the year 2025 using leap-frog technologies such as dynamic façade systems + renewable energy sources California Energy Commission (CEC) PIER: Improve affordability, reliability, health and safety, California's economy, environmental outcomes, and consumer choices relevant to electricity supply and use in California, particularly in hot inland areas of high growth. http://www.time.com/time/specials/2007/ environment/
How do we get there? Buildings consume 39% of total U.S. energy, 71% of electricity and 54% of natural gas 57%
Energy/ Demand Management with Integrated Facades + Daylighting Controls
Integrated Facades Approach Ideal: Integrated approach to façadelighting-hvac building systems to achieve optimum energy-efficiency and comfort. Energy Use Slopes vary depending on efficiency of lighting and HVAC systems Increased lighting energy use and heat gains Minimum energy use Increased solar heat gains
Quantifying solar heat gains versus daylighting trade-offs Source: http://gaia.lbl.gov/btec h/papers/32931.pdf
ASHRAE 90.1-1999 (& 2004) Appendix C: Building Envelope Trade-off Option explicitly defines relationship between façade, lighting and HVAC
Integrated solutions via ASHRAE 90.1 and LEED? Thermal and daylighting impacts on energy use regulated in different sections of the code ASHRAE 90.1-2004 and CA Title-24-2008 - Envelope: Limits on SHGC and U-factors by glazing area (<50% of gross wall area) and facade orientation - Lighting: Lighting controls and available daylight from façade not linked in code (e.g., no Tv requirements) USGBC LEED - Minimum illuminance in 75% of occupied zones via Daylight Factor > 2% (IEQ) overly daylit spaces - Mandatory (6/07): 2 points in EAc1 14% energy cost savings below ASHRAE 90.1-2004 (7% for existing construction) - Indirect impact Energy budget can put a ceiling on daylight factor requirement
ASHRAE/ USGBC/ IESNA Standard 189.1 (draft) Trade-offs between façade-lighting-hvac system made more explicit Thermal: - Stringent solar heat gain requirements - No direct sun penetration - Minimum shading projection factors (attached exterior shading) Lighting: - Prescriptive approach: minimum effective aperture (Tv* WWR) for daylighting - Performance approach: minimum illuminance target, proof via physical or simulation model
Integrated Façade Design Process Existing practice: Designers rarely (i.e., never) design a façade using the codes Façade design typically defined by end of concepts phase Architect subcontracts out HVAC and lighting systems design Architect subcontracts out proof of energy code compliance Simulation tools used after the fact, rarely before Ideal practice: Recognizes synergistic impacts of design on lighting and HVAC systems over 30- to 50-year life of building Analysis focused on quantifying magnitude of trade-offs between façade-lighting-hvac designs energy and non-energy trade-offs that affect occupant comfort
Commercial Window Website
Source: Carmody, J., S. Selkowitz, E.S. Lee, D. Arasteh, T. Wilmert. 2004. Window Systems for High Performance Commercial Buildings. New York: W.W. Norton and Company, Inc.
http://www.commercialwindows.umn.edu/
COMFEN Tool (see Session TS12)
High performance building façade solutions Sponsors: Marc LaFrance, US Department of Energy Michael Seaman, California Energy Commission Public Interest Energy Research (CEC PIER) Project Objectives To evaluate, optimize and develop, as needed, integrated, high performance building façade systems To facilitate the widespread deployment of such systems into the U.S. commercial buildings market To provide designers and owners with the data and tools needed to achieve these performance objectives. Scope: Systems engineering, field tests, showcase demonstrations, simulation tools
Optically-complex systems Source: St. Gobain/ Eckelt DLS COOLSHADE HR 32/9 South North
WINDOW+ Suite of Tools New: WINDOW6! IGDB (Specular Glass Data Source) Optics (Window Glass) THERM (Window Frame) calculation CGDB (Complex Glazing Data Base) WINDOW (Whole Window) Design / Simulation Tools DOE-2, EnergyPlus Radiance COMFEN (Whole Building Commercial) RESFEN (Whole Building Residential)
Background: Optics of Glazing and Shading Layer types specular?? diffuse Shading device
Scanning radiometers Goniophotometers measure the angular light distribution of lamps and the angular transmittance/reflectance of arbitrary materials. Hemispherical measurement made in RGB and SOL spectra.
Geometric/optical model Create solid geometry of system using CAD or TracePro Assign measured BSDF properties of materials and surfaces to TracePro model Generate system BSDF output file for use in Window6
BSDF: 145x145 matrix of T & R for VIS and SOL spectrum Difference between Window 6 and TracePro BRDF for AoI = (0, 0) ρ dh = 0.0041309 [sr -1 ] 120 105 90 75 60 0.035 0.03 135 45 0.025 150 30 0.02 165 15 0.015 180 195 0 345 0.01 0.005 0 210 330-0.005 225 315-0.01 240 255 300 285 BSDF = Bi-directional scattering Lawrence distribution Berkeley National function Laboratory 270-0.015
Window6
Window6: Definition of Window System
Window6: Complex Glazing Output
WINDOW6 - Complex Glazings Results RESULTS: Venetian Blind Tilt = 40 o, Window Orientation = South (180 o ) EnergyPlus Radiance Thermal and daylighting calculations using BSDF output from Window6 under development
mkillum: Use of BSDF data Full Radiance raytracing simulation of Venetian blinds Second (much quicker) rendering using the supplied BSDF from Window6
rtcontrib: Daylight Coefficients for annual calculations Discrete solar positions at each patch location improve rendering of sharp shadow features. Actual sun position is interpolated from four closest suns. om John Mardaljevic s thesis
Dynamic Systems The New York Times Headquarters If sun orb in view, window luminance > 2000 cd/m 2 for < 30 min/day
Switchable electrochromic windows c b a Direct sun is blocked from the occupant s field of view by the upper zone s Venetian blind (a) or by an overhang (b). This upper EC zone (b) is controlled to admit daylight. The lower EC zone (c) is switched to Tv=0.05 to minimize luminance contrasts between the VDT (e2) and sunlit (e1, d1) surfaces and between paper-based tasks that are sunlit (d1) and shadowed (d2). The luminance of the lower window is controlled (c). View out is preserved (c). e 2 e 1 d d 1 2
Result: optimum transmittance for each window pane Just glass / Equinox 3% 3% 250 nits 26 nits 1300 lx 94 lx
Operation of shades t t At each time-step (t) determine the state of the shade. Select respective luminance image and add to stack. Process stack to determine annual occurrence of high luminance for various control algorithms.
EC Ref Hour Hour 18 16 14 12 10 8 6 18 16 14 12 10 8 6 Max window luminance NO overhang (actually, max big pixel luminance I assume it occurs in the window area) 0 50 100 150 200 250 300 350 Day 0 50 100 150 200 250 300 350 Day 0 1000 2000 3000 4000 5000 6000 Nits
Summary In the near term, A/Es should direct their simulation effort toward identifying solutions that leverage the synergistic impact of the building envelope on thermal loads (HVAC) and daylight availability (lighting energy use). The development of innovative ZEB solutions will require more sophisticated, powerful simulation tools to enable modeling of intelligent façade and daylighting control systems and optically-complex systems. Low-energy cooling strategies peak loads Whole-building integrated systems real-time tradeoffs between lighting and thermal loads
http://windows.lbl.gov/comm_perf/facade-solutions
Acknowledgments Sponsors Marc LaFrance, US Department of Energy Michael Seaman, California Energy Commission PIER Program Software Project Team: Dariush Arasteh, LBNL John Carmody, U Minnesota Luis Fernandes, LBNL Kerry Haglund, U Minnesota Rob Hitchcock, LBNL Tianzhen Hong, LBNL Joe Huang, LBNL Charlie Huizenga, UC Berkeley Jacob Jonsson, LBNL Christian Kohler, LBNL Eleanor Lee, LBNL John Mardaljevic, De Montfort University Robin Mitchell, LBNL Michael Rubin, LBNL Stephen Selkowitz, LBNL Greg Ward, Anyhere Software Mehry Yazdanian, LBNL Links: http://www.commercialwindows.umn.edu/ http://windows.lbl.gov/software/window/6/ http://windows.lbl.gov/software/comfen/1/ http://windows.lbl.gov/comm_perf/newyorktimes.htm http://windows.lbl.gov/comm_perf/electrochromic/ http://windows.lbl.gov/comm_perf/facade-solutions