Westby-Moss Zero Energy Solar Greenhouse

Transcription

1 Westby-Moss Zero Energy Solar Greenhouse Robert Westby Laboratory Program Manager Federal Energy Management Program NREL Power Lunch Lecture December 4, 2013

2 Contents Problem Statement Design Objective Design Features Overview Salient Design Features Going Forward: Monitoring and Verification Architect/Energy Designer comment

3 Opportunity Food has a large -and largely wasteful- energy/carbon footprint (transportation, field to table ). Local growing using greenhouses to extend the growing season helps address this issue. However, conventional greenhouses typically require considerable auxiliary heat to keep crops from freezing on cold nights (excessive fenestration, poor insulation and insufficient thermal mass). The opportunity is to address these shortcomings with a zero energy SGH integrated design solution.

4 Integrated Design Solution Approach High Solar Heat Gain Glazing & Light Shelves The design minimizes the area of windows needed. Automated Insulating Shutters: Reduces heat loss at night & heat gain in the summer. PV System (with storage) meets all electrical needs. Heavy Wall & Roof Insulation: Minmizes winter-time heat losses; allows for year-round harvests. Thermal Mass: Holds heat & prevents drastic temperature swings. Smart Controls For all sub-system operations (ventilation, thermal storage, shutters, CO 2 levels, etc.) Perimeter Foundation Insulation: Creates a 65º F+ thermal bubble for soil temperatures year-round.

5 Design Objective Zero energy for all thermal and electric uses while supporting year-round local growing at 7,800 feet (Proof of Concept) Design Approach. Based on alpha version of design of SGH located in Boulder, CO which achieved zero energy thermal performance while supporting year round local growing (monitored and verified over a full year of operation). Thermal Energy Performance. Energy engineering assessment: winter losses = 20MBtu, winter solar gains = 27.6MBtu, 125% of load. Thermal storage system conservatively sized to offset any net hourly heat losses. Electric Energy Performance. Off-grid photovoltaic system sized conservatively to exceed all electrical loads. Battery storage capacity facilitates three days + of autonomous SGH operation.

6 Salient Design Features

7 Optimized Window Area Much less glazing then traditional SGH (thermal management) Optimized overall window area (0.45:1 window to floor area ratio) High solar heat gain coefficient (SHGC=0.69) High visible light transmittance (VLT=79%) Conventional greenhouses require significant auxiliary heat to keep crops from freezing on cold nights and to maintain winter growth rates.

8 Insulated Shutters Shutter drive mechanism (low wattage/12 VDC vehicle window motor) All windows and ventilation openings shuttered (R13) Automated operation Microcontroller actuation Input from solar radiation and temperature sensors (solar gain > or < heat loss) Shutter surfaces reflective

9 Thermal Storage System Ground coupled earth storage (80,000 Btu/F capacity) Automated operation (fan operation controlled by microprocessor/temperature sensor (internal air temperature controlled: charges > 75F and discharges < 45F)

10 Thermal Storage Soil Temperature Data Soil Temperature Data (ºF as of 12/01/13) OUTDOOR INDOOR Depth/Sensor East Side A South Bed B North Bed C Surface/T o ft./T 1 42, ft./T ft./T ft./T ft./T Sensor Well Locations C B A Soil Temperature Sensors/Well

11 Intelligent Building Controls Controls enable autonomous automated operation of insulated shutters and thermal storage system. Insulated window shutters actuated by microcontroller based on input from solar radiation and temperature sensors (solar gain > or < heat loss). Thermal Storage system fan operation controlled by microprocessor/temperature sensor (internal air temperature controlled: charges > 75F and discharges < 45F). Ventilation System - Autonomous/automated control system under development. Control box (microcontroller; shutter, thermal storage and ventilation system electronics)

12 Photovoltaic System Stand alone 12 VDC system 750 watts ((3 Lumos LS250 Watt modules), 516 amp hours (Ah) storage capacity (2 Concord PVX258 Sun Xtender Absorbed Glass Matt batteries) Outback Flexmax 60 charge controller Power Brite APS watt inverter for AC powered fans Electrical Loads 120VAC connected: 260 watts (ventilation and thermal storage fans) 12VDC connected: 77 watts (lighting (LED), shutters, electronics, etc.)

13 Increasing Light Availability (Photosynthesis) Light shelves Installed on all south facing windows ( 0.92 reflectance factor) Increases sunlight collected by over 25% Seasonally adjustable Highly reflective interior paint High VLT windows (VLT=0.79) Reflective insulating shutter surfaces

14 Performance Monitoring and Verification M&V Plan Objectives Energy performance verification (LBC certification) SGH performance and operational R&D Comprehensive data acquisition system installed (next slide) One year period of performance (start September, 2013) Measured performance parameters Thermal storage ground temperatures (cross section of depths) Build and calibrate performance models. Thermal model (MatLab) Daylight model (Radiance) Develop ventilation system control algorithms.

15 Data Acquisition System Sensor Sensor Function 4 Campbell Scientific HMP60 Temperature and relative humidity for the interior, exterior, and thermal storage intake and exhaust 4 LI-COR Photosensors Light measurements within the greenhouse 1 LI-COR LI90SB Quantum Sensor 1 Magnetic Reed Switch Insulated shutter position Measures Photosynthetically active radiation. Located next to the front light sensor. Exhaust and thermal storage fan operation Omega FTB4605 Vaisala GMW21 Campbell Scientific CS300 Measure operation of the fans Irrigation water flow Carbon dioxide Exterior global horizontal irradiance

16 Architect: Barrett Studio Architects "One of the things that excited us as architects, was the notion that growing food, year round, at altitude with only natural energy input is so challenging, that it calls for very specific architectural form. In bringing together such a climatically responsive set of integrated systems, systems that sense and control light, heat, temperature and humidity fluctuations, and seasonal variations, form doesn't only follow function, form literally expresses function... not stylized or decorated form, but responsive, unembellished form that is honest and direct. In some ways, this integrated set of functional sensing systems mimics living organisms. In this it is an ecomorphic expression, or what might be termed a Living Architecture. David Barrett, FAIA Barrett Studio Architects th St. Boulder, CO

17 Energy Designer: Synergistic Building Technologies Design of Next Generation of Zero Energy Greenhouses Next Generation Design Directions Further optimization of fenestration area High VT, lower cost glazing materials Reflective insulating louver systems (RILS) Enhanced electronic controls for RILS and other shutter systems Larry Kinney, PhD President & Chief Technology Officer Synergistic Building Technologies 1335 Deer Trail Road Boulder, CO 80302, USA BT.com

18 Conclusions & Audience Questions Robert Westby