Hobby Greenhouse with savENRG PCM Pipes

These are pictures of an excellent hobby greenhouse built by Robert Diken from the New England area.  He installed savENRG pipes on his walls to stabilize inside temperatures during times of fluctuating hot and cold conditions.  Thank you for sharing your great pictures!

savENRG at the WNC Home, Garden and Green Living Show, 2014

Learn about passive heating and cooling in greenhouses, sun rooms, and buildings using phase change materials for thermal energy storage.

savENRG by RGEES, LLC
WNC Home, Garden, and Green Living Show
US Cellular Center
March 21-23, 2014
Asheville, NC 

All passive-heat storage is not created equal: The case for phase-change materials

By Nina Reinhart on 03/13/2013

 

Hot and cold: Andy Reinhart installs PCM pipes at A-B Tech’s Sycamore greenhouse. The thermal-mass system helps heat the greenhouse in winter and cool it in the summer. Photos courtesy of RGEES 

Anyone who has sat on a sun-warmed rock on a cold night has experienced the effects of passive-heat storage. The effect occurs regularly in nature with anything that collects solar heat during the day and releases it at night. In this case, rock is a type of thermal mass — material that absorbs and retains heat for release later. With indoor spaces, many different types of thermal mass can be utilized.

Good passive-solar building design means that the walls, floors and windows can collect, store and give off heat during cold temperatures and repel heat during warm periods. Examples of commonly used thermal mass are brick, rock, concrete, tile and, more recently, various types of phase-change materials.

In poorly insulated structures such as greenhouses, thermal mass is used to trap solar heat during the day for night release, preventing damage and promoting growth in plants and veggies. It also is used to decrease overheating by providing a place for the sun’s energy to accumulate, creating a more stable thermal environment. A typical thermal mass found in greenhouses is a Trombe wall of dirt, concrete, brick and/or barrels of water. 

Normally, the larger the thermal mass in a space, the greater its ability to store heat and stabilize temperatures, resulting in less energy consumption, and savings on heating and cooling costs.  Any thermal mass is good for heat storage, but some work better than others. 

Phase-change materials as thermal mass

Phase-change denotes materials that change from a solid to a liquid and liquid to a solid while absorbing and releasing thermal energy. Some commonly utilized PCMs are water, paraffins, fatty acids and salt hydrates. PCMs are an ideal solution for passive temperature control, especially when there are large variations between outside day and night temperatures.  PCMs made from salt hydrates serve as practical and efficient thermal mass in buildings, homes and greenhouses because they are nontoxic and nonflammable, require less space than other types of thermal mass, and are simple to employ.

A good example of how a 72-degree-Fahrenheit salt-hydrate PCM works can be observed at Sycamore greenhouse at A-B Tech’s main campus in Asheville. The installation process was simple. The PCM was poured into 5-foot-long, 1.24-inch PVC pipes. Wooden supports were drilled into the existing cinder-block wall inside the greenhouse, and the pipes were horizontally bound. The rows of pipe were framed with wood and covered in a half-inch insulation board. An attic fan was attached beneath the row of pipes for thorough air circulation. The fans pull the air from above, through the PCM pipes, releasing the heated or cooled air below. This ultimately stabilizes the temperatures inside the greenhouse.

A total of 274 pipes were installed, with each pipe containing 5 pounds of PCM, for a total of 1,370 pounds. This system provides 30 kilowatt-hours of heat-storage capacity. During the day (the heat-gain cycle), the PCM pipes absorb 30 kwh of heat, reducing its cooling load by 30 kwh. At night, during the heat-loss cycle, the system will release the PCM’s absorbed heat and reduce the heating load by 30 kwh. This provides 60 kwh of free energy within a 24-hour day.

All the materials above, excluding the PCM, can be bought locally. This 72-degree, salt-hydrate PCM can fill any container made from HDPE, PP plastic or stainless steel. Placement inside a space can be against, on or inside a wall; above the ceiling; in between floors; or independently standing. The PCM is melted by warm daytime temperatures and begins to release the absorbed heat as the temperature falls below 70 degrees. The PCM then solidifies. During solidification, a constant temperature of 72 degrees is maintained. Once it’s completely solid, it acts as a heat sink as temperatures rise above 74 degrees and continue the cycle of absorbing heat.

Without the PCM installation, the greenhouse would have been intolerably warm during the summer months. The temperatures inside the greenhouse are consistently 15-20 degrees lower with the PCM than without it. The phase-change material in the greenhouse eliminates temperature extremes that would normally occur with our changing seasons, not to mention that it retains optimal conditions for plant growth.

Due to the simple nature of phase-change materials, there are numerous methods of storing heat in both passive and active solar applications. All types of buildings and enclosed spaces can benefit from incorporating PCMs. Computer and communications facilities already utilize PCMs to absorb heat and maintain the recommended temperatures to protect their electronics. Thermal heat storage can, at the same time, shift the load on heating and cooling equipment and serve as backup during power failures. The possibilities of heat storage for enhancing active solar applications are currently being explored and implemented by professionals in various industries worldwide. Thermal heat-storage solutions will become an important objective of future energy-conservation efforts with the goal of preserving natural resources and lowering energy consumption and costs.

Nina Reinhart is a partner at RGEES. To find out more about phase-change materials, visit www.rgees.com.

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.

Greenhouse at Asheville-Buncombe Technical Community College

South-side of greenhouse
-located at Sycamore Bldg., A-B Tech
-approximately 1200 sq. ft.
-construction with 1 ft. thick cement blocks and single layer glass
-heated with 2 steam unit heaters
-forced air ventilation on outside west wall, windows open and shut

Winter CSAs'

    Is there anything bad about being part of a CSA?  You receive a variety of super fresh, locally grown, vegetables and fruits, directly from the farm to the consumer.

   The only part that takes a little bit of thought, at least for me, is having to come up with new recipes for veggies and fruits that I don’t normally buy and eat.  But really, is adding variety and vitamins to our diets a negative thing?  How terrific would it be to have CSA’s all year round even in winter?  Winter Sun Farms is doing this through Blue Ridge Food Ventures and local farms.  Check them out at http://www.wintersunfarmsnc.com/

   A great way to to grow winter vegies in WNC is to grow indoors in greenhouses.  WNC winters can be harsh and we often experience snow, frigid winds and temperatures.  Greenhouses provide shelter, heat and a controlled environment.  So, why don’t all farmers do this?  I assume it’s due to the difficulty and cost of building and maintaining greenhouses with heating as its highest energy expense.

    RGEES, LLC is currently working on developing a procedure for heat storage solutions in greenhouses by maximizing the thermal mass and using latent heat storage through phase change materials.  What is thermal mass and latent heat storage?  It is anything that absorbs solar heat and energy during the day when the sun is out and then releases it at a later time.  Our main purpose is to design a practical and useful system that will dramatically reduce overall energy costs by decreasing fossil fuel consumption.

   We welcome any and all input from farmers, greenhouse owners/operators and experts on greenhouse heating and cooling.

--We’d like to know what your biggest challenge is concerning temperature?
--What kind of return on investment you expect (less than 5 years, 5-10 years)    

If you already have a greenhouse, we’d like to know about:  location in relation to seasonal temps, square footage of gh, structural layout, coverings, insulation materials, thermal mass, time/seasons of operation, desired gh temperatures for summer and winter months, heat/cooling systems, fossil fuel consumption, annual energy costs.

   Please feel free to contact me at nina@rgees.com

Heating at Huckleberry Ridge Farm's Greenhouse

     Recently, I’ve been visiting local farms and nurseries to check out the how the locals have constructed their greenhouses and the creative ways in which they are heating and cooling them.

    My first visit was to a lovely, little dwelling in Old Fort called Huckleberry Ridge Farm.  The owners, Ken and Judy, have built a small greenhouse that they use to grow greens during the winter months.  There is an infrared system that heats the dirt the on table beds where the greens grow.  They supplement with a wood stove and small fan to circulate the warm air on cold winter nights which has substantially, lowered their heating bills.  They’ve cleverly, placed bubble wrap on the inside of the roof covering for added insulation as well as insulating the backwall and using bagged leaves on the edges of the greenhouse.  They’re always seeking more efficient ways to heat the space and to increase temperatures during winter to grow more food.  A phase change material of 70 to 80 degrees F would be a perfect fit to store the heat for later use,  for decreasing fossil fuel consumption and burning less wood.   

    Judy and Ken’s specialty is fine rabbit meat.  They have beautiful, healthy rabbits which they process themselves at the farm, chickens for eggs, various greens and vegetables and lively ducks and geese that roam the property!  I can attest that their rabbit meat is delicious and they’ve got the best tasting eggs we’ve had thus far!

Thank you for the visit, Judy!  
Huckleberryridgefarm@hughes.net

Indoor Agriculture

 The importance of temperature control:

    The science and practice of producing high quality, high quantity plants and veggies indoors is better understood and precisely controlled more today, than ever in the past.  I’ve been reading quite a bit on controlled environment agriculture (CEA) or hydroponically-based agriculture.  Although it may seem unnatural to grow plants in a such a manipulated manner, there are irrefutable advantages to hydroponics.  

PCM Trees at Das Tropenhaus, Berlin

   This is by far the most creative usage of phase change material in a greenhouse application, I’ve ever seen.

   Just a quick bit of history... Construction of the botanical gardens in Berlin began in 1897 with the purpose of exhibiting exotic plants brought back from the German colonies.  ”Das Grosse Tropenhaus”, a main feature of the botanical gardens, is currently the largest, self supporting, glass structure in the world.  

   This gigantic tropical greenhouse maintains a temperature of 30 degrees Celsius with high humidity.  Before its recent renovation, it utilized approximately 1,500 tons of coal a year.  After recent renovation, energy consumption levels are one-fifth of previous usage.  Wallboards, tiles and concrete containing PCM, were considered for energy storage inside the structure.

   

The Eden Project

   Last week, a friend of mine who lives in England, sent me a link to this outrageous park in Cornwall, called the Eden Project.  It’s basically an elaborate construction of domes (Yes, I’ve fallen in love with dome sturctures) transformed into gigantic greenhouses that sustain a global collection of plants; some, very peculiar.  It is a multi-purpose park that holds gardening and educational courses for all ages to music festivals, theatre productions, art exhibits, etc.

   These biomes sit on a foundation of granite.  Eden’s plan is to build the UK’s first geo-thermal power plant  utilizing the heat from the radioactive decay in the granite, deep inside the earth’s crust.  Although, drilling a hole 3 miles deep into the Earth must have an outrageous cost, the park experts are estimating that Eden, itself will need only a quarter of the green power generated.  The other three-quarters would feed back into the local community/National grid and possibly, supplying 10% of England’s future electricity needs.

   I wasn’t able to find information about the actual construction of the biomes or how they maintain suitable temperatures for plants and people.  And having no knowledge of power generation, I don’t know if there is even a need for thermal energy storage  in such a park that’s powered geo-thermally.  But I’m sure the power needs for Eden are immense and they seem to be headed in the right direction.

http://rgees.com/index.php

dome, di dome, dome

     I’ve been looking at a lot of greenhouses.  I’ve decided my favorite ones on the market are “Growing Spaces,” created by a couple in Colorado who began their venture 20 something years ago.  These greenhouses are beautiful.  They are essentially dome structures, well built and well insulated.   I assume the majority of people who own these greenhouses are using their indoor pool of water as their thermal mass to store the sun’s heat.

    So, I was recently reading one of the articles on their blog and someone asked what winter temps the dome would be able to endure if one were to install solar water heat exchangers.  They answered that with the solar hot water addition, the inside of the greenhouse could maintain temps 50 degrees (Farenheit) warmer inside than out.  This is truly significant when you’re talking about growing plants and veggies.  Think you can’t make this any better?  But you can.

    Regardless of whether you feed the hot water into piping underneath the dome or back into the indoor pool itself, using PCM in the hot water tanks can store the heated water for longer periods of time and you could probably downsize to smaller storage tank as well.

    This is how it would work.  Your solar hot water heat exchanger heats the water during the day when the sun is out.  I’ve seen solar collectors that follow the direction of the sun to receive optimal light.  But as soon as the sun goes down and the water cools, there is some kind of backup generator that switches on or other alternative heating source to keep the water warm in order to heat the greenhouse.  If you put PCM of an appropriate temperature  into the storage tanks, it will conserve the sun’s heat for a longer duration.  And to top it off, you’d be saving money and fuel due to less usage of your backup heating source.  Again, totally advertising here, but this basic idea of utilizing PCM to store heat is feasible with ANY solar hot water system.

    Check out these geodesic domes.  Wish I had an extra $15,000 laying around…

    This doesn’t have anything to do with greenhouses although I’m sure you could use some of his micro-houses for the purpose of a greenhouse (heat storage would still be an issue).  This guy’s clever.  Goes to prove, you can pretty much recycle anything.  

Derek "Deek" Diedricksen featured in the New York Times gives a tour of his “gypsy junker”.

storing the sun's heat...

    I recently developed a personal interest in Greenhouses which led me into a world of structural, glazing, binding, and sealing materials.  Not being much of the builder/designer type, I then, gravitated towards the thousands of different kinds of pre-fab kits.  Most curiously though, my on-line research of greenhouses, directed me straight back into my area of work, which is, thermal energy storage using phase change materials or PCM.
   
    My desire was to build our greenhouse on Mom’s property in Haywood County that currently flourishes with tasty veggies that grow from Spring to early Fall.  So, I thought “how great would it be if we could grow tomatoes and other summer edibles during the cold months”.  I found that if you’re in an area with mild enough winter temperatures and can get away with just a passive solar system, you still need some sort of thermal mass to keep the warmth through the night.  A greenhouse is just a big solar collector.  And as with all solar heating systems, they share the same problem.  How do you store the sun’s heat for later use at night?  PCM based thermal energy storage systems is the answer, of course.  Back to greenhouses.  Savvy gardeners have been successfully using all sorts of materials for thermal mass; the most common being, barrels of water, rocks, concrete, bricks, tiles, wet dirt and basically, any mass that stores heat.  These materials are all heavy, bulky and take up a lot of the greenhouse space that could be utilized for growing space instead.
   
    If I were not a small business partner of a company that produces PCM, and just wanted to build a greenhouse for my family, I would probably ask such questions as:

--how does the PCM store thermal energy?
--how much PCM is needed?
--what temperatures would be appropriate?
--what is the cost?
--how is it installed?
--what are the advantages and disadvantages of PCM next to the other types of thermal mass?

    There are many factors and variables to consider.