Protected Ornamentals: Investigation into the potential savings available from adopting energy optimisation principals in UK glasshouse production

Poinsettia:

Temperature Integration used in poinsettia production under experimental conditions showed the potential to save as much as 30% of energy for heating, although the temperature limits and humidity control strategies need further evaluation in order to avoid adverse effects on shelf-life.

Conclusions

• Temperature integration was used and demonstrated the potential to save 30% of the energy used for heating a poinsettia crop; £221,000 per annum for the UK production area.
• 11 varieties were evaluated and no variety was delayed more than 1½ days to show colour or visible cyathia. No variety was delayed at marketing and the expert assessment was that all plants were of excellent quality.
• Both the fresh and dry weights of all varieties were increased in the integrated compartment, confirming a similar result in pot mums in 2001.
• Some varieties, including Sonora, Eurostar, Marblestar, Elegance Pink, Elegance White and Red Elf, grown under temperature integration lost more leaves and bracts in shelf life than the control plants.
• The reduced shelf life quality for some varieties and increased plant losses suggest that the method of temperature integration used was not optimum for these varieties. Either not using temperature integration for the last month of production or trying an alternative humidity control strategy should be evaluated.

Chrysanthemums:

The use of temperature integration in the production of protected ornamentals can save up to 25% of the energy for heating during the winter period (November to March).

Conclusions

• The use of temperature integration in the production of protected ornamentals can save up to 25% of energy for heating during the winter period (November to March).
• The quality and post harvest performance of eight varieties of pot chrysanthemum grown in two temperature integration treatments were as good as the plants in the commercial control.
• The scheduling of crops in the integration treatments was delayed by as much as three days, but compared to the potential financial saving this is hardly significant.
• Temperature integration had no significant effect on the agronomy of the pot chrysanthemum crop, there was no increased incidence of pest or disease and no additional plant growth regulators were required.
• Additional uses of heat for disease control or minimum pipe temperatures will reduce the potential energy savings, but good housekeeping could reduce these to only essential use.
• A potential problem in the reduction in heat demand with the use of temperature integration is the reduced supply of CO2 from boilers. However, growers using heat storage tanks will suffer less.
• The use of higher ventilation temperatures would appear to reduce the amount of CO2 lost from venting, this may also reduce the CO2 demand on a nursery.
• Alternative CO2 sources have often been thought of as cost prohibitive. This may not be the case in the future when other technologies come on line.
• There is now scope to apply the findings from the pot chrysanthemum work to other energy intensive ornamental crops such as poinsettia, begonia, and cut flower chrysanthemum.
• A package of commercial-scale demonstration trials together with adequate education and training of growers in the use of climate control computers, should assist the widespread uptake and use of temperature integration to save energy.

Poinsettia:

• To evaluate the potential energy savings of a temperature integration regime compared to a commercial control
• To quantify crop speed, quality and shelf life of the poinsettia crops grown under two temperature regimes.

This trial did not aim to produce a blueprint for poinsettia production using temperature integration, but to determine whether temperature integration could be used to produce a poinsettia crop and contribute towards energy savings. Further work will be required to improve confidence in the temperature and humidity limits as well as to continue to develop new and challenging ways to save energy.

Chrysanthemums:

• Potential energy savings of two modest temperature integration regimes will be determined for an important pot plant crop grown under semi-commercial conditions
• The effects of temperature integration on crop speed, quality and shelf life will be assessed for a range of pot mum cultivars.

This trial would be unlikely to produce a blueprint or advice for every crop grown under protection, but would prove whether the principles of temperature integration could contribute towards energy savings. Further work may well be required to improve confidence in the principles over many seasons or crops as well as to continue to develop new and challenging ways to save energy.