November December 2023 - 8

DUETS
process in this column. I'm excited to
discuss the curtain directly with the
manufacturer today - you!
Let's discuss my decision to install
a curtain that serves double duty;
primarily as a winter energy curtain
and secondarily as a summer shade
curtain. It sounded like a perfect
solution to my research greenhouse
needs but I observed something during
the first two winters of operation that
you can help me better understand.
By asking the curtain to perform
double duty I gave back a portion
of its heat retention potential. It all
makes sense to me now, the fabric
needs to be less opaque ... more
light transmission, in order to shade
the greenhouse during the summer
without being too shady. Help me
understand how much winter fuel
savings I gave back by asking the
curtain to serve two masters, so
to speak.
Julie: Thanks for choosing our
curtain system for your study. Using a
single curtain to provide two functions
results in compromises, though
there are still a variety of choices
allowing you to prioritize between
heat retention and the amount of light
passing through the curtain.
Heat retention for curtain fabric
ranges from 15% to 70%, and
shading runs from around 13% to
100%, which is total blackout. Not
surprisingly, a curtain fabric that
shades all light, with an opacity of
100%, has a high potential for the
heat retention. However, blackout
curtains have specific uses like
addressing light pollution and
providing for crops that require a
balance of daylight and darkness to
flower (poinsettia, cannabis). There
are energy curtains that are not
opaque and have the same high
heat retention that might be a
better choice.
Fabric is categorized to address
specific needs: light diffusion, dual
8 NOVEMBER/DECEMBER 2023 GPNMAG.COM
thermal control, energy saving with
maximum light transmission, solar
control, and light restriction. There
are over 100 choices. We offer many
different curtain fabrics to meet the
growers needs.
Fabric manufacturers report
percentage of shading with the first
two numbers of a product's name
and the heat retention value using
the last two numbers. For example,
your greenhouse has Svensson's
Tempa 5557, so 55% of the light is
blocked with heat retention of 57%.
If you'd chosen Tempa 6560, you
would have compromised the amount
of light, from 55% shading to 65%
shading, while gaining 3% in energy
savings. You could have selected a
fabric focused on maximum light
transmission with high energy savings,
like the Luxous 2945, but you would
have lower heat retention. A curtain
fabric in the 50/50 range works well
for single systems. Tempa, the dual
thermal line, is designed for serving
both as a shade and energy curtain.
Your choice was a good one for your
purposes. We have designed systems
with two and sometimes three layers of
curtains to make certain specific needs
are met to the fullest capacity.
Fabric
manufacturers
report percentage
of shading with the
first two numbers
of a product's
name and the heat
retention value
using the last
two numbers.
- Julie Dean
Peter: That's a welcome perspective
Julie, thanks for sharing the bigger
picture. I feel better about my decision
knowing that the opportunity the
shade system gives me to continue
research later in the spring and sooner
in the fall outweighs the fuel savings I
passed on.
Moving on, Wadsworth has
placed a high priority on irrigation
management. Tell us about your
philosophy as a company in this arena
and how your environmental control
products address this challenge.
Julie: We've seen the challenges
growers face, starting with the energy
crisis in the 1970's. Though energy
is still a factor today, water use is
becoming growers' top priority. We're
addressing this by programming
options into the controller.
Watering schedules help growers
make the most informed decisions on
water usage resulting in consistent
crops and watering tailored to the
crop's growth phase.
Peter: First, it's refreshing to write
with someone familiar with the energy
crisis of the 70's Julie...I'm usually
dating myself to next generation
horticulturists when I reference it.
I concur that my top concerns in
managing my greenhouse are energy
consumption for heating, cooling, and
lighting and water use efficiency. Most
of my research for the past decade has
focused on hydroponic systems and
water management. It's affirming to
engage with you in this conversation
to realize that we're both addressing
these concerns from our respective
areas of expertise.
I imagine that as irrigation
controllers evolve with complementary
technology they are only as good as
the sensors that activate irrigation
events. Tell us how Wadsworth is
integrating sensor technology into
irrigation control and how sensor tech
is advancing.
http://www.GPNMAG.COM
November December 2023

Table of Contents for the Digital Edition of November December 2023
