December 6, 2018 Optimizing Solutions through Superior Dehumidification Technology SM

Humidity Control and Heating and Cooling Applications December 6, 2018 Optimizing Solutions through Superior Dehumidification Technology SM

Today s Discussion Discussion of cooling, heating and dehumidification loads. Importance of zone condition selection on efficiency. Airflow energy impact through HVAC equipment and room. Basic equipment options and energy use. Critical importance of commissioning. 2

ROOM LOADS Lights and Water (and others)

Relative Intensity of Lighting

Relative Intensity of Lighting at Specific Wavelengths

Lighting Summary Even with 45-65 watts / sq. ft. the PAR value is less than full noon summer sun. Although plants use a small amount of the light energy in the process of converting water into sugars, starches, and O 2, virtually all lighting energy becomes sensible heat load. Total input (including ballasts or drivers) is important.

Latent loads. Evapotranspiration Evaporation + Plant Transpiration Evaporation highly dependant on irrigation method. Drip Irrigation Low evaporation. Flood or Trough Irrigation Higher rate. Spray Irrigation Extremely high evaporation. As much as 300 Btu/hr for large plant in high light. Perhaps best estimated by (water in) (water out); if known.

Plant Physiology Water Transport

Transpiration

Evaporative Cooling Effect As water evaporates energy is converted. 1060 Btu/lb at typical conditions. Plants also use this effect in the transpiration process to cool themselves. Through conduction and convection this in turn cools the air. Care must be observed if used to offset loads. If plants are just emerging, water use and evaporative cooling effect are small.

Facilities Construction Can vary significantly. Room within room. Structurally insulated panels (or similar). Partitioned room. Open warehouse.

Typical Rooms

Load Details Building Skin Loss/Gain If Applicable Insulated (or uninsulated) walls, floors, and ceilings. Heat loss as ambient temperature decreases. Heat gain as ambient temperature increases. Concrete floors create a heating load. Doors and windows have different losses and gains than the walls. Solar load has major impact if it exists.

Ventilation for Plants Outdoor air exchange may be required to maintain CO 2 levels for plants. Adds (or subtracts) sensible and latent load. Alternative in a Closed (Sealed) Growing Environment is CO 2 supplementation. Rooms may be kept at higher temperature.

Relative Humidity is relative It represents the ratio of moisture in the air relative to when no more can be held in the air. (Saturated) but..

Relative Humidity Relative humidity is relative to temperature! Higher temperature air is able to hold more moisture. Lower temperature hold lesser amounts before saturation. Therefore, RH changes with temperature!

Relative Humidity is Relative Changes in Dew Point Affect Relative Humidity Changes in Dry Bulb Temperature Affect Relative Humidity

Higher Enthalpy (More Energy Rich) Lower Enthalpy (Lower Total Energy) Lines of Constant Enthalpy

Transpiration Rates Lights On Leaf temperature determines the vapor pressure in the leaf. Air temperature and humidity determines the vapor pressure in the air. Vapor Pressure Deficit (VPD) drives transpiration regulated rates are important for plant growth and health.

Transpiration Rates Lights Off Stomata closed as no light is being received. Evapotranspiration continues at a lower rate during lights off. Slowly decreases over 60-90 minutes. Roughly 30% of full light moisture rate when full dark. This latent load can still be relatively high as sensible load is negligible.

VPD at 1.3 kpa (0.39 Hg) at various DB/WB/RH Different operation, but same drive for growth

Larger Equipment/Higher Energy Use Smaller Equipment/Lower Energy Use

Calculation Methods for Latent Load Derivations of Penman-Monteith equation or similar Net Watering Rate given or calculations

Total Loads and Control - HID Design Conditions 3,500 ft 2, 2,000 plants, 63 watts/sq ft. (85% BE), 318 gal/day net water Early Veg 500 CFM Ventilation - Lights On Description Sensible (Btu/hr) Latent (Btu/hr) Lighting and Appliance 852,500 0 Doors 445 0 Ceiling 5,331 0 Walls 4,564 0 Infiltration -320-199 Ventilation -6,510-7,770 Evapotranspiration 0 150,404 Evaporative Cooling Effect -150,404 - Total 705,606 142,435 705,606/(142,435 + 705,606) = 0.83 SHR Compiled using ACCA Manual N Form N1 and ASHRAE Dehumidification Weather Data

Total Loads and Control - LED Design Conditions 3,500 ft 2, 2,000 plants, 25 watts/sq ft. (95% DE), 318 gal/day net water Early Veg 500 CFM Ventilation - Lights On Description Sensible (Btu/hr) Latent (Btu/hr) Lighting and Appliance 314,078 0 Doors 445 0 Ceiling 5,331 0 Walls 4,564 0 Infiltration -320-199 Ventilation -6,510-7,770 Evapotranspiration 0 150,404 Evaporative Cooling Effect -150,404 - Total 167,184 142,435 167,184/(142,435 + 167,184) = 0.54 SHR Compiled using ACCA Manual N Form N1 and ASHRAE Dehumidification Weather Data

Total Loads and Control - HID Design Conditions 3,500 ft 2, 2,000 plants, 63 watts/sq ft. (85% BE),954 gal/day net water Early Flower 500 CFM Ventilation - Lights On Description Sensible (Btu/hr) Latent (Btu/hr) Lighting and Appliance 852,500 0 Doors 445 0 Ceiling 5,331 0 Walls 4,564 0 Infiltration -320-199 Ventilation -6,510-7,770 Evapotranspiration 0 526,414 Evaporative Cooling Effect -526,414 - Total 326,596 518,445 326,596/(326,596 + 518,445) = 0.32 SHR Compiled using ACCA Manual N Form N1 and ASHRAE Dehumidification Weather Data

Total Loads and Control Design Conditions 3,500 ft 2, 2,000 plants, 954 gal/day net water - Flower 500 CFM Ventilation - Lights Off Description Sensible (Btu/hr) Latent (Btu/hr) Lighting and Appliance 1,203 0 Doors 445 0 Ceiling 5,331 0 Walls 4,564 0 Infiltration -320-199 Ventilation -6,510-7,770 Evapotranspiration 0 175,471 Evaporative Cooling Effect -175,471 - Total -170,758 167,502 No cooling required. Dehumidification Only Load. Compiled using ACCA Manual N Form N1 and ASHRAE Dehumidification Weather Data

Lights On

Lights Off

Air conditioner and dehumidifier Lighting Load

Reheating

Energy use and control Traditional dehumidifiers heat the air when it may not be needed. Cooling needs to work harder. Some equipment has less than full capacity reheat or electric reheat only. New energy needs to be added. Not considered here. All-in-one environmental control is best practice.

Multiple Units Serving a Space

Multiple Units Serving a Space Partial capacity during maintenance/service. Redundancy possible. Footprint and layout advantages. Enhanced staging capability. Energy efficiency. 38

Control coordination is critical

Economizers Number of hours where OA is possible is variable depending on the location and time of year. More care required for filtering with air economizer. May introduce more spores and pests. Both the temperature and humidity are affected if economizer is used. This must be approached carefully. CO 2 Enhanced grows impractical with OA economizer.

Target 76 Dry Bulb 45% RH Outdoor Air too Humid Outdoor Air Too Warm in Lights On May not be able to properly cool or dehumidify Outdoor Air Too Warm Few Hours in Lights Off Will require more energy to heat or humidify.

IMPACTS OF AIRFLOW Affinity Laws Working for Energy Efficiency 42

Affinity Laws (Fan Laws)

Affinity Laws (Fan Laws) For example, reduction in the airflow (shaft speed) to ½ of the peak flow rate in a given system results in 1/8 of the peak power at the fan shaft.

Importance of Air Movement Plant Leaf Boundary Layer Water vapor builds at leaf boundary layer. Creates higher relative humidity and vapor pressure at leaf surface. Buildup can happen under canopy. Dicots have most stomata on underside of leaf. 20-30% higher relative humidity under canopy if airflow is too low. Slowly moving canopy is goal

10-tons Capacity (120,000 Btu) 3400 CFM Moisture Removed = (3400 CFM *17 grains per lb) / 1555 = 37.2 lbs Water Removed Sensible Cooling= (3400 CFM *Δ 22 F TD) * 1.08 = 80,784 Btu/h Δ 7.8 Btu/lb Δ 17 grains/lb Δ 22 F

Δ 15.6 Btu/lb 10-tons Capacity (120,000 Btu) 1700 CFM Moisture Removed = (1700 CFM *44 grains per lb) / 1555 = 48.1 lbs Sensible Cooling= (1700 CFM *Δ 34 F TD) * 1.08 = 62,424 Btu/h Δ 44 grains/lb Δ 34 F

COMMISSIONING Critical Steps in Ensuring Success

Commissioning Startup by factory trained technicians who know the equipment. Equipment and facility in operation. Challenge with this application. A project manager with timeline is key. Have operators/facility people available during startup for Owner Training. Have local Service Technicians aligned for PM and ready in case of any issues.

Continuous Commissioning Periodic Maintenance for this type of equipment is key. Complete a Start-up on a yearly basis. Review trends to determine if there is an issue. An ounce of prevention is worth a pound of cure.

Sensor Locations and Central Control 72 /65% 85 /35% 79 /55% 60 /11% 76 /50% 76 /55%

Controls Tuning Tune Changes

Remote Monitoring Remote monitoring. E-mail and SMS alerts. Cloud-based service. Real-time data and logging. Allows a team to review together quickly.

Thank you! Craig Burg Desert Aire, LLC craig@desert-aire.com 55