Climate control & energy > Tips for energy saving
Introduction
Below follows a long list of possible energy saving measures in greenhouses. These measures are commonly appleid in the Netherlands, where the winters are relatively cold. In other regions these measures are not necessarily cost-effective, due to other climatic conditions and cost structures. It is impossible to say anything about the percentage energy saving, as that varies between locations. Some actions have only an indirect effect on energy use. For instance, improving the light level in the greenhouses improves the production and hence indirectly enhances the energy efficiency. The list shows an indication for significance of the energy saving actions: I = indirect, S = significant, VS = very significant, U = unknown.
Heating system
• Replace hot-air heating with hot-water pipe heating system (VS)
• Lower the heating pipes to bring them closer to the plants (VS)
• Install adequate heating along the greenhouse walls (VS)
• Insulate the transport pipes and distribution ducts of the heating system (VS)
• Insulate the supply and return pipes near compartment boundaries (VS)
• Have enough space around heating pipes along the walls (S
• Have enough distance between heating pipes and the ground (S
• Paint the heating pipes white (I)
• If needed re-design and adjust the heating system (VS)
Burner
• Ensure regular burner maintenance (VS)
• Get a burner efficiency test done (U)
• Repair any shortcomings (VS)
• Switch the burner off when not in use for some weeks (VS)
• Investigate the cost-effectiveness of a more energy efficient burner (U)
Condensor
• Install a condensor (VS)
• Connect the condensor to the heat buffer (S)
• Check all valves in the lines to and from the condensor, as well as the shunt pipe (U)
• Check the temperature of the water stream that goes to the condensor and act on it (U)
• Check the effectiveness of the condensor (U)
• Clean the inside of the condensor (S)
Boiler and boiler house
• Insulate the burner/boiler and transport pipes (S)
• Place the boiler in a boiler house instead of outside (VS)
• Insulate the walls and roof of the boiler house (S)
• Adjust the shunt control (S)
• Check the bricks in the boiler (U)
• Install retarders in the combustion chamber (S)
Heat storage tank (heat buffer)
• Consider a buffer, taking into account the heat requirement at night (U)
• Check if the connection of heat buffer and heating system is optimal (U)
• Improve the control of heat transport and the connection to the heating nets (S-VS)
• Optimise the heat buffer control (S-VS)
Thermal screen
• Installing a thermal screen (consider the economics first) (VVS)
• Improve the sealing of the thermal screen (VS)
• Minimise the size of the thermal screen package to improve light level (I, S)
• Replace an existing thermal screen timely (S)
• Optimise the control of a thermal screen (VS)
Wall insulation
• Insulate the wall, or at least the south wall (S)
• Or install a moveable thermal screen along the walls (S)
Climate control
• Calibrate the temperature and humidity measurement (S-VS)
• Check, maintain and clean the sensors in the measuring boxes (S-VS)
• Check the weather station (location, maintenance, cleanness) (S)
• Check the climate control very accurately: use a checklist and study the graphs (VS)
• Apply temperature integration and other energy-wise control approaches (VS)
• Check the safety alarm setting (S)
CO2-enrichment
• Consider options for CO2 enrichment including installing a heat buffer (U)
• Place the CO2 meter and the inlet of it on the right locations (S)
• Calibrate the CO2 meter (VS)
• Check the pressure in the CO2 distribution system (S)
• Avoid condensation in the CO2 transport duct (S)
• Use the correct CO2-tubes (S)
• Check the lay-flat CO2 ducts (S)
• Check the carbon monoxide-detector (S)
• Check the start and stop time of CO2 enrichment: do not enrich at night (S)
• Do not aim for too high CO2 levels (S, VS)
• Optimise the CO2 control, e.g. make the setpoint depending on vent opening (S)
Pumps
• Use pumps with variable speed or frequency controlled pumps (where relevant) (S)
• Switch the circulation pumps off (automatically) when not in use (S)
Natural light
• Clean the greenhouse roof (S-VS)
• Measure the light transmission of the greenhouse and consider improvement (U)
• Minimise the presence of any light blocking devices above the crop (S)
Temperature gradients
• Measure temperature gradients. Find the cause and choose the best remedy (U)
• Greenhouse maintenance
• Close the gaps and leaks in the greenhouse foundation (S)
• Repair broken glass panes or tears in plastic (S)
• Tune the vents opening (VS)
Future: co-generation (combined heat and power)
• Investigate cogeneration, including selling power to energy company (U)
• Investigate the feasibility of a flue gas treatment plant for a co-generator (U)
Publication
Elly Nederhoff. ‘Energy saving measures in greenhouses’. Short report to CRL Energy Ltd. September 2004.
