Temperature Management through Phase Change Materials

Installation of PCM22P (72 Fahrenheit) at AB-Tech Sycamore Greenhouse

These are the most recent temperature recordings we've received from our PCM fittings at the greenhouse.  The PCM pipes were originally installed earlier this year.  On the left side, it is clear that the inside temperatures (green) far exceeded the outside temperatures (red) during the day.  Starting in April, after the phase change materials were added to the North wall, the indoor climate stabilizes and remains consistently cooler during the day and warmer at night than the outdoor thermal readings.  We'll continue to monitor the temperatures over the winter and will share the results as we collect them.

Come visit savENRG in Asheville

Please come by our "savENRG by RGEES" booth at the Southern Green Living Expo at the  US Cellular Center in Asheville, NC.  Learn about passive heating and cooling in greenhouses, sun rooms, and buildings using phase change materials for thermal energy storage.  The Expo will be today, tomorrow and Sunday (Sept. 14-16).

Greenhouse Temperature Control Using Phase Change Materials

Passive heating and cooling in greenhouse using PCM 22P.

The green color represents the inside temperatures of the Sycamore greenhouse at AB-Tech.  The red color represents the temperatures outside of the greenhouse.  The left side of the graph exhibits temperatures inside and out of the greenhouse before the PCM installation. From the end of January to mid-April, 2012, when its hot outside, its even hotter inside the greenhouse.  There is little visible red.

PCM 22P was installed at the end of April.  The graph on the right illustrates how phase change materials passively control temperature inside the greenhouse.   Pretty impressive results considering that temperatures from January to April are cooler than in mid-summer.  Without the PCM installation, greenhouse temperatures would've been much hotter during the summer months.  The fact that temperatures inside the greenhouse are consistently 15-20 degrees lower with the PCM than without it, is significant and exciting.

The phase change material in the greenhouse eliminates temperature extremes that would normally occur with our changing seasons, not to mention it retains optimal temperatures for plant growth.

PCM Bottles, Panel and Ball

Frost:  PCM00P; phase change materials made from hydrated salts; non-toxic, non-flammable

1.2 liter bottle; 300x235x30 mm

75 mm ball filled with PCM

Flat panel; 450x200x20 mm

For the whole range of our PCM temperatures and products, please go to:   http://rgees.com/products.php

Another visit to Huckleberry Ridge Farm

road to Huckleberry Ridge Farm

Judy, you're very gracious!  Thank you!

hedgerow of Hemlock trees on the Northside of the vegetable garden

"gorgeous garlic"

baby geese

spotted Mama

what an enjoyable morning!

"so sweet and all scrunched up"

old Moravian house on the Farm

Judy and Emilie are at the Black Mountain Farmers' Market on Saturday mornings from 8-12 with farm fresh produce, eggs and delicious meats (rabbit, duck, and geese) which you can also buy directly from the Farm.  She'll be using our savENRG PCM packs in her coolers to keep her frozen meats frozen and her produce, cold at the market during the hot summer months!

Installation of phase change materials at AB-Tech greenhouse

A 72 degree Fahrenheit phase change material was filled into 5 ft. long, 1.25" PVC pipes and sealed.  

Wooden supports were drilled into the cinder block wall and the PCM pipes were horizontally bound.  Three rows with 72 and one row with 58; totaling 274 pipes.  Each pipe holds approximately 5 lbs. of PCM 22P; amounting to 1370 pounds.  This system provides 30 kWh of heat storage capacity.  During the day (heat gain cycle), the PCM pipes absorb 30 kWh of heat, reducing it's cooling load by 30 kWh.  Reversely, at night, during the heat loss cycle, the system will release the absorbed heat by the PCM, and reduce the heating load by 30 kWh.  This provides 60 kWh of free energy within a 24 hour day.

The rows of pipe were framed with wood and attic fans (1300 CFM) attached beneath for thorough air circulation.

Finally, the pipes are covered in 1/2 inch, extruded, polystyrene, insulation board, R-value-3.  The fans pull the air from the upper levels of the gh, passes over the PCM pipes and releases at the bottom, circulating the air and stabilizing the temperature inside the greenhouse.  More to come...

A very big THANK YOU to Harshul and Andy for their hard work!  Great job!

PCM 22P is made from hydrated salts and have large amounts of heat energy.  This energy is stored in the form of latent heat which is absorbed or released when changing from a solid to a liquid or a liquid to a solid.  Phase change materials retain their latent heat without change in physical or chemical properties for over thousands of cycles.  Best of all, PCM 22P is non-toxic and non-flammable.  

If you'd like to learn more about PCM pipes in greenhouses, please contact us at:

info@rgees.com

harshul@rgees.com

nina@rgees.com

elena@rgees.com

Phase Change Materials in Greenhouse at AB-Tech

savENRG Pipes with PCM-HS 22P

PCM pipes are ideal for stabilizing temperature excursions in spaces that experience large temperature swings between day and night temperatures.  These particular pipes are filled with PCM-HS22P and maintains 22C/72F.  Standard size of a pipe is 1.25" x 60".  These are currently being installed in the greenhouse at the Sycamore building at AB-Tech.  More pics to come...

If you'd like to learn more about PCM pipes and how they can work in your greenhouse, please contact us at info@rgees.com or nina@rgees.com.

Outdoor Winter Veggies in Mid-January

This is proof that winter vegetables can tolerate very cold temperatures.  We're in Zone 7 and although we've had an unusually mild winter, we've had cold nights.  Last night was mid-20's and tonight it'll dip down into the upper 10's.  Sara, my neighbor, planted her greens and herbs from Sow True seed last Fall and we've all been enjoying them since.  She has them in the backyard in a sunny spot and has recently began covering them overnight.  Thanks, Sara!!

Temperature Control for Winter Cool Crops

    When asked what greenhouse owners plant over the winter months, the more common responses are that some grow a variety of summer veggies which require high heating and lighting but honestly, who wouldn’t eat ripe tomatoes and cucumbers all year round?  Some don’t grow anything at all due to high fuel and energy costs but interestingly enough, there is a growing group of vegetable growers, private and commercial, that prefer to grow “cool crops.”  For temperature controlled environments such as greenhouses, these cold resilient vegetables are ideal for winter growing not only because they thrive at cold temperatures but also because of the minimal amount of heat energy needed to successfully grow them. Less energy required equals less costs to warm a space that inherently dissipates heat.
    All root vegetables (kohlrabi, turnips, beets, carrots, radishes, potatoes), hardy greens (kale, chard, spinach, mustard greens), anything in the cabbage family (cauliflower, broccoli, brussel sprouts), onions, and various herbs (parsley, cilantro) prefer cold temperatures.  They can grow outdoors in places where average low temperatures are around freezing but they flourish in greenhouses that maintain temperatures right above freezing.  
   Setting your thermostat inside your greenhouse at 35 degrees Fahrenheit will create an efficient temperature to grow cool vegetables as well as keeping your water supply from freezing.  Depending on the weather conditions of where you live and the construction of greenhouse you have, maintaining temperatures right above freezing, may easily be accomplished for the majority of places in the US through passive solar heating.  By simply storing heat from the daytime in some type of thermal mass inside the greenhouse, it can then be released at night when temperatures drop.
    Some different types of thermal mass greenhouse owners use are water, rocks, bricks, concrete, dirt, mulch, manure, straw bales and various types of phase change materials.  Some are better than others.  
   The performance of phase change materials are better solely because it stabilizes temperature while releasing its heat.  A good example is savENRG PCM at 32 degrees F.  This PCM is made from salt hydrates and is non-toxic and non-flammable.   It will consistently release a temperature of 32 degrees F and will require lesser quantities than other forms of thermal mass, providing more growing space inside the greenhouse.
   Regardless of what thermal mass is used and how you heat your growing spaces, keeping temperatures right above or around freezing during the cold season is reasonable and can be achieved with minimal energy costs.  At the same time, planting cool crops provides families and local communities with healthy and seasonal vegetables throughout the winter months.