1 GREENHOUS MANAGEMENT GREENHOUSE STRUCTURES HEATING, COOLING, AND LIGHTING SYSTEMS

2 Heating systems

3 Types of systems and equipment Boilers that produce steam or hot water Unit heaters Solar energy Infrared heaters Heating cables Heat blankets

4 Calculation of heat requirements Heat lost from a greenhouse depends on: –the glazing material –the exposed surface area of house –the inside desired temperature –wind speed –the condition of the house –the outside design temperature

5 Calculation of heat requirements The heat requirements for a greenhouse can be determined using the formula: –H = K * a * (t1 - t2) H = the heat required in Btu’s per hour K = the heat transfer coefficient of glazing material a = the exposed surface area t1 = desired inside temperature in F t2 = outside design temperature in F

6 Heat transfer coefficients

7 Cooling systems Plant growth decreases at temperatures about 90 degrees Most greenhouses on sunny days are 20 degrees warmer than the outside temperature

8 Cooling systems include Opening side and ridge vents Exhaust fans at one end and louvers at the other end of the greenhouse Swamp coolers Mist systems Fan and pad cooling

9 Supplemental lighting systems It is used to increase photosynthesis It is used to combat cloudy days It will cause or delay flower induction

10 Types of lighting Incandescent lights Fluorescent lights High intensity discharge lights –high-pressure mercury –metal halide –low-pressure sodium –high--pressure sodium

11 Shading systems Reduce the temperature inside the greenhouse Reduce the light intensity or duration

12 Types of shading materials Shading compound –thinned down white latex –applied in spring and removed in fall Shading clothes –There are various degrees of shading with shade clothes depending on use

13 Methods to control temperature, light, and humidity To increase heat –remove shading –turn on heat To decrease heat –use a cooling system –apply a shading cloth or compound

14 Methods to control temperature, light, and humidity To increase light –turn on supplemental lights –remove shading –clean glazing To decrease light –apply shading cloth or compound

15 Methods to control temperature, light, and humidity To increase humidity –turn on overhead watering system –water the sidewalks and under benches To decrease humidity –remove warn moist air and draw in cool air –then heat the cool air to reduce relative humidity