1. New covering materials – how far can we go in energy saving? A look into the future Seminar 23 rd of October 2012, Gjennestad, Norwegen Silke Hemming

2. (Sensible and Latent heat by ventilation, leakage and dehumidfication) Convection and radiation from cover 1500 MJ Soil 150 MJ Total energy loss: 3950 MJ Total by ventilation: 2300 MJ 2400 MJ Boiler or CHP Inside 1600 MJ Total energy in: 4000 MJ Photosynthesis: 50 MJ Background

3. 2400 MJ Boiler or CHP Inside 1600 MJ Total energy in: 4000 MJ Photosynthesis: 50 MJ Background

4. Energy input by solar radiation  Importance of PAR  Rule of thumb: 1% more light means 1% higher yield Crop Yield increase at 1% more light Lettuce0.8% Radish1% Cucumber0.7-1% Tomato0.7-1% Rose0.8-1% Chrysanthemum0.6% Pointsettia0.5-0.7% Ficus benjamina0.6% Source: Marcelis et al., 2006

5. Energy input by solar radiation =PAR+NIR  More PAR by:  Advanced covering material ● Low iron glass (+1-2%) ● New plastic films ETFE (+1-3%) ● Modern coatings on glass, AR (+5-8%) ● New surface structures (+5-8%)  Lighter greenhouse construction (+1-5%)  Less installations (+1-3%)  Greenhouse orientation / shape  Cleaning

6. Energy input by solar radiation  Filtering out NIR radiation Effects:  Lower greenhouse temperature  Reduction in transpiration  Less humidity control needed  No effect on crop production In summer:  Reduction heat load  More efficient use of CO 2 In winter:  More energy needed Source: Kempkes et al., 2008

7. (Sensible and Latent heat by ventilation, leakage and dehumidfication) Convection and radiation from cover 1500 MJ Soil 150 MJ Total energy loss: 3950 MJ Total by ventilation: 2300 MJ Photosynthesis: 50 MJ Background

8. Reduction of energy losses  Double covering materials  High insulation = less convection losses  Specific coatings (low-) = less radiation losses

9. Reduction of energy losses Double covering materials Humidity:  Humidity is an increasing problem with increasing insulation  Decrease of condensation from 100l/m 2 /yr to about 10l/m 2 /yr  Search for alternative dehumidification system Plant reactions:  High light transmission necessary  Less CO 2 available  Increase of crop temperature in top of plant  New climate control strategies possible (temperature integration, nbo minimum pipe...)

10. Innovative energy saving coverings

11. ETFE (F-Clean)  Plastic film material  Long lifetime (20 years)  Lighttransmission 93% (86%) clear film  Lichttransmission 93% (82%) diffuse film, high diffusion 75%  UV transparant  Ca. 20% Energy saving double materials

12. PMMA (Plexiglas Alltop)  U-value 2.5 W/m 2 /K  16 mm space  Lighttransmission 91% UV transparant material  Lighttranmission 86% Plexiglas Resist, UV-bloc material  Ca. 25 energy saving

13. Glass with modern surface treatments/coatings  New covering materials with different surface treatments/coatings ● Diffuse structure  light scattering ● Low-iron  increase light transmission (PAR) ● Anti-reflection  increase light transmission (PAR) ● NIR-reflection  decrease solar transmission (NIR) ● Low-emission  decrease solar transmission (NIR), decrease heat losses  Single and double glass  Effect on energy saving, greenhouse climate (temperature, humidity, CO 2 ), light transmission, crop response

14. Diffuse glass Spring crop 2008 Kg/m2 +6.5%+9.2% Autumn crop 2008 Kg/m2 +8.8%+9.7% Reference clear Low diffusion 27% High diffusion 74%

15. Diffuse glass - crop  Diffuse light is positive because…  Photosynthesis ● Horizontal light distribution more equally (Hemming et al., 2006) ● Changed light penetration in crop vertically (Hemming et al., 2007) ● Diffuse light is absorbed more by middle leaf layers (Hemming et al., 2007; Dueck et al. 2009, 2012) ● Higher photosynthesis in those leaf layers (Hemming et al., 2006, 2007; Dueck et al. 2009, 2012) ● Higher dry matter in those leaves (Dueck et al. 2012)

16. Diffuse glass - crop  Diffuse light is positive because…  Stress: ● Lower crop temperature in upper leaves during high irradiation, higher crop temperature in lower leaves (Dueck et al., 2009)  Morphology and Development ● More generative growth and faster fruit development (Hemming et al., 2007; Dueck et al. 2009, 2012) ● Higher yield, mainly due to heavier fruits (Dueck et al. 2009, 2012) ● Faster development potplants (Hemming et al., 2007)  1% light ≠ 1% growth rule

17. AR glass  Spectral transmission of glass with different anti-reflection coatings from three different producers (SA, CS, GG) Hemming et al., Greensys 2009 Increase of PAR by AR coating  Higher crop production Changed spectrum Possibilities for cooling Possibilities for energy saving with double materials More PAR Cooling

18. Low iron and AR glass Light transmission of different greenhouse glasses (producer CS) with anti-reflection (AR) coatings and/or low-iron treatment

19. AR and low- glass Light transmission and energy saving of different greenhouse glasses (producer GG) with anti-reflection (AR) and/or low- emission (LOW) coatings

20. Modern coatings on glass – energy & CO 2  Year-round energy consumption and CO 2 concentration under different greenhouse glasses calculated by KASPRO, CO 2 use from boiler 33% 25% energy saving need for external CO 2 !

21. Modern coatings on glass - spectrum  Spectral transmission of glass with coatings (anti-reflection, NIR-reflection and low-emission) AR&less NIRAR&low-e AR

22. Summary  Increase light transmission covering  more light  more production  more energy  less fossil fuels needed  Make light diffuse  more production  Increase insulation by double coverings and low-e coatings  use AR / low-iron  compensate light  less energy needed  higher humidity  dehumidification needed  Less CO 2 available  external CO 2 needed

23. Venlow Energy Greenhouse  Double glass  Modern coatings: AR, low-  Low u-value  Lighttransmission ~ single glass  Energy saving tomato 50-60%  New growing strategies! Screen, active dehumidification with heat regain, no minimumpipe, temperatureintegration

24. Venlow Energy Greenhouse – double glass pp hh Single glassAR-AR9891 Single glass AR-Low-  9181 Double AR-AR-Low-  -AR 8980 Single glasstraditional9082 Mohammadkhani et al., 2011

25. Venlow Energy Greenhouse – energy use m 3 gas/year Energy (I) saving (II) VenlowEnergy measured16.348%54% VenlowEnergy estimated15.849%56% commercial(I)31.2 commercial (II)35.5 Kempkes et al., 2011

26. VenlowEnergy Greenhouse – tomato yield Janse et al., 2011

27. A look into the future  New surface structures on covering materials ● Micro V surface ● Micro pyramides ● Micro moth-eye ● Principle: multiple reflection increase light transmission ? Micro pyramides V-grooves Gieling et al.

28. Energy reduction tomato: how far can we go?  Reference: 40 m 3 g.e. per m 2 per year ● Later planting, shorter cultivation: 2.5 m 3 ● Screening strategy: 1 m 3 ● Double screen: 3.7 m 3 ● Temperature integration: 3.2 m 3 ● Humidity control: 2.5 m 3  Reduction by new growing strategies: 27 m 3 g.e. per m 2 per year ● Double glass with modern coatings: 12 m 3 ● Heat exchangers+heat pump+aquifer: replace 10 m 3 gas by solar energy, but use more electricity  Total energy needed: 11 m 3 g.e. per m 2 per year Source: Poot et al., 2011 & Kempkes, 2012

29. Special thanks to my colleagues: Vida Mohammadkhani, Frank Kempkes, Feije de Zwart, Tom Dueck, Jan Janse, Eric Poot, Theo Gieling, Gert-Jan Swinkels et al. Takk skal du ha!