Zero Energy Cool Chamber (ZECC) Training, 19 February, 2013, PSTC, AVRDC, Arusha, Tanzania. www.sonorapacific.com

1. ZECC Training Day, 19 February, 2013,
PSTC, AVRDC, Arusha, Tanzania

2. Zero Energy Cool Chamber: Introduction and
Construction for Small-scale Horticultural
Farmers and Marketers
One Day Training led by Lizanne E Wheeler

3. Cool Chambers can reduce temperatures by 10-15oC and
maintain a high humidity of 95%. This can increase the
shelf life and retain quality of horticultural products.
Small and marginal farmers can store a few days harvest
to avoid middlemen.

4. So, ..lets prepare for the Training Day and the Participants
Arrival! First, confirm the 600 wet bricks….

5. …and the CLEAN SAND for the pad and filling the
channel between the inner and outer chamber walls

6. Proper measurements for the chamber and walkway space!

7. ….measuring the chamber size

8. ..and …Check the measurements once more!

9. Preparing a level pad is important for drainage…

10. …adding a soft sand bed to align and maintain the brick
floor and walkway…

11. Hurrah! Ready with a level foundation for the days
training to build on!

12. Preparing the PSTC for the Training 20 Farmer
Participants from nearby Ndutu

13. Prepare the produce temperature demo. During the day, we
will discuss the differences in temperature and RH: sun, shade
and ZECC. ZECC reduces food loss by maintaining cooler
temperatures and higher RH! (even more than shade!)

14. All is set for the day…and here come the participants!

15. We started under the traditional shade structure, with introductions
of ourselves and the PSTC. Then we asked the farmers questions
about their crops , postharvest programs, and markets. We wanted
to better understood their needs, and address these during the day.

16. Because we were learning about the ZECC today, a
cooling postharvest technology, we reviewed the various
shade structures on the PSTC training grounds…
Here is simple structure covered with 60% shade cloth,
easy to make, and often found in India.

17. Already! the farmers had curiosities of how they could
better their own postharvest practices.

18. We returned to the cool shade of the PSTC and
reviewed the training and services that were available to
them. Inside the PSTC we would tour the….

19. …Cool Room! We passed under the heavy plastic heat
barrier curtain strips and into 15oC temperature. For
some, it was a first time going into a Cool Room!

20. Outside the Cool Room
is the PSTC Store: sales
of useful postharvest
tools and knowledge

21. At the Store we found PSTC Information brochures
and Small Scale Postharvest Technology books: the
Small Scale Technology book is in Swahili!

22. Next to the Store was the Educational Poster Board, with
innovation plans, produce tips, and the PSTC Research
Specialist and Manager contact information.

23. We reviewed the Harvesting Tools Demo table.
This was useful as we would later be speaking about
proper harvesting practices when we discussed the
produce that would be stored in the ZECC.

24. Harvest and Market Containers Demo table

25. At this demo table we discussed:
why a traditional roughly made wooden crate can cause
produce losses, and why plastic crates are used in the ZECC.

26. Next, a Food Safety discussion: why washing hands
and tools before harvesting, sorting and packing
produce is a must!

27. ….and now, the ZECC! ..our learning focus for the rest of
the day . Here we see the Zero Energy Cool Chamber with
the plastic crates, shade structure, chamber cover and
water source

28. The ZECC, can keep 100kg of produce (6 plastic crates), fresh
and alive! for several days, allowing a small farmer to have
more control as to when she must sell her produce. Options
include waiting until the market price is higher, or perhaps
selling their produce on days when no else has such produce!

29. So… let’s take a look inside the Zero Energy Cool Chamber!

30. Inside we find 6 plastic crates, each can hold 15 to 20kg of
fresh and alive produce!

31. To protect our produce from water
contamination, we place a plastic sheet cover
over the top layer of crates

32. Then we put the lightweight cover on…

33. ..and place a wet sisal cloth over the cover to
help keep the moisture and coolness inside
the chamber…

34. Sooo…just what is the ZECC? It is a low cost cooling
technology that does not require electricity and is easy
and inexpensive to build with local materials.

35. ZECC can reduce the temperature by 10-15C and maintain
high humidity in the chamber…just what keeps your
produce fresh and alive for a longer time and gives you
higher profits!

36. By keeping the bricks and sand channel saturated with
water, you can let nature help to maintain this cool
temperature and high humidity…

37. To keep the bricks and sand wet you can use the
sprinkle can or a drip tubing…or just a hosepipe!

38. Who thinks that they could benefit from using a
ZECC?...Everyone? Great…let’s learn more!...

39. Let’s take another look inside….

40. Hmmmm…how is the ZECC keeping this produce cool and
not wilting when our traditional method of keeping it under
the shade tree cannot?

41. ZECC works on the principle of direct evaporative
cooling…this portable fan demo shows how warm, dry air
will evaporate the water in the wood shavings pillow.
Evaporation needs heat to go from a liquid to water vapor

42. Okay, lets experience evaporative cooling together… We
are in the shade and it is hot outside!
...so……put your right hand out…!

43. Put your right hand in!!…does inside the chamber feel
cooler than outside? YES!

44. ..Put your left hand out…

45. By keeping our produce cool in the ZECC we have longer
shelf life…a great advantage when your buyer does not
come on the day that he said he would! And with some
cooling, we have better quality, and less losses!

46. We need to make sure that we store produce in the ZECC, that is
compatible together…green peppers and amaranth are happy
together…but we would not want to add tomatoes or fruits to the
mix…Check this poster for the kind of produce you have to store…

47. Time for some Questions!

48. Remember our temperature demo that we started early this morning?
The temp @ 8:00am was 23oC under the sun, now at high noon, the
temp is 37oC under the sun, and the ZECC is 15oC cooler, only 22oC!

49. Here, feel the difference in temperature between the peppers in the
sun, shade and ZECC . Observe how much water has been lost in the
leafy greens that were under the sun…now compare these to the
greens in the ZECC. Much fresher…imagine the loss of water in your
green beans…if you can see wilt in a green bean, then at least 20% of
your weight is lost…Do you sell by weight? Yes? Then you are losing
20% of your potential earnings!

50. So…who thinks that a ZECC would be helpful in preventing
your produce losses: giving you more time to market your
produce and maintain better quality and nutrition?

51. Great! Let’s start constructing a ZECC!...and
then you can do this yourself on your farm, or at
the village market place, ….

52. We begin with 600 locally made bricks, the lower the
quality, the more porous they are…and the more water
they will be able to hold, which can then evaporate from
the chamber!

53. Begin by placing the 6 plastic crates on the pad, with a 4 fingers wide
space between each row, (for air circulation and ease of lifting the
crates in and out of the chamber)…
then we will build our chamber to fit around them

54. Start with the corners of the inner and outer walls,… four
finger space between the crates and first inner wall,
the sand channel and the outer wall.

55. Carefully build up the walls, putting the sand in
the channel as we go…

56. The inner wall is 2 bricks higher than the crates and 1 brick
higher than the outer wall…

57. As we build up, we water down the sand channel, it is
easier this way!

58. The ZECC should always be taller than wider, for proper air
circulation and evaporative cooling. The outer wall is level
with the sand channel (better for evaporative cooling!)

59. Ahhh, final quality control by our appointed group member

60. Now, the light weight cover…made of local materials

61. The cover should be just the size of the inner wall, leaving
the sand channel exposed

62. Then the wet, sisal cover to keep the moisture
in the chamber (higher humidity means less
water and weight loss of your produce!)

63. Hands All Together Now….Yeah Team!
We built a Zero Energy Cool Chamber!

64. HURRAH! We will reduce
produce losses and
increase profits!

65. The ZECC is a recommended cooling technology that
allows us to temporarily store our produce in a simple
yet better way than our traditional way under the tree

68. What did we learn today?
We learned that can finally do something to prevent our
produce looses! And have better profits, longer shelf life, and
better quality!

69. Questions? Discussion? Ideas for making
it better fit your postharvest needs?

70. …and don’t forget …the PSTC is here for your continued
learning, as well as for shopping for any needed
postharvest tools and supplies!

71. The completed ZECC
Arusha, Tanzania