How to Heat a Greenhouse Without Electricity
Summary
TLDRIn this video, Gardener Scott addresses the common myth that greenhouses stay warm with little effort, especially in cold regions. He explains the importance of thermal mass for retaining heat in unheated greenhouses and demonstrates how to calculate the amount of water needed for this purpose. Scott uses concrete pavers, gravel, and water-filled containers to increase thermal mass, aiming for a 260-gallon target. He also adds Styrofoam insulation to retain heat and reflects on the greenhouse's improved nighttime temperatures, promising a future analysis of its impact on both heating and cooling.
Takeaways
- 🌡️ Greenhouses in cold regions like Colorado can lose heat at night despite warming up during the day.
- 🏡 Insulation in a greenhouse helps retain heat but can also trap cold without proper measures.
- 🔥 Thermal mass is crucial for retaining heat in unheated greenhouses, with materials like concrete, rock, and water being effective.
- 💧 Water is the most efficient thermal mass for warming an unheated greenhouse due to its heat absorption and release capabilities.
- 📏 Determining the amount of water needed involves calculating the greenhouse's square footage and adjusting based on regional climate.
- 🏞️ The video suggests a formula for calculating water volume based on sun exposure or floor area, multiplied by a factor related to climate harshness.
- 📦 The use of 55-gallon drums, totes, and other containers is practical for storing water to serve as thermal mass.
- 🎨 Painting containers black enhances their heat absorption and retention, aiding in the greenhouse's thermal regulation.
- 🌡️ The addition of Styrofoam insulation and reflective surfaces helps to minimize heat loss and radiate warmth back into the growing area.
- 🌡️ The video documents a noticeable increase in nighttime temperatures, indicating the effectiveness of the thermal mass strategy.
- 🌤️ The potential dual benefit of thermal mass is highlighted, suggesting it can also help moderate temperatures during hot summer days.
Q & A
Why do greenhouses lose heat at night even if they get hot during the day?
-Greenhouses can lose heat at night because the insulation that helps retain heat during the day can also hold in the cold when it gets cold outside. Without supplemental heating, the heat can be easily lost.
What is thermal mass and how does it relate to greenhouse heating?
-Thermal mass is the ability of a material to absorb, retain, and then release heat. In the context of a greenhouse, materials with high thermal mass, like water, can help retain heat and keep the greenhouse warm.
Why is water considered the most efficient thermal mass for an unheated greenhouse?
-Water is the most efficient thermal mass for an unheated greenhouse because it has a high specific heat capacity, meaning it can absorb and store a lot of heat before it starts to increase in temperature.
How can one determine the amount of water needed in a greenhouse for thermal mass?
-The amount of water needed can be determined by calculating the square footage of the greenhouse's floor or the surface area exposed to sunlight, then multiplying it by a factor based on the region's climate and winter length.
What are the target ranges for water storage in the greenhouse mentioned in the script?
-The target ranges for water storage in the greenhouse are between 260 gallons (using the lower factor) and 390 gallons (using the higher factor).
How does the use of concrete pavers and gravel contribute to thermal mass in a greenhouse?
-Concrete pavers and gravel contribute to thermal mass because they can absorb, retain, and release heat, helping to maintain a warmer temperature inside the greenhouse.
What is the role of Styrofoam insulation on the north side of the greenhouse?
-The Styrofoam insulation helps to reduce heat loss by providing an extra layer of protection against the cold. It also has a reflective surface that can help radiate heat back towards the plants.
How does the thermal mass affect the greenhouse's temperature during the day and night?
-During the day, the thermal mass absorbs heat from the sun, preventing the greenhouse from overheating. At night, it releases the stored heat, keeping the greenhouse warmer than the outside air temperature.
What other considerations are there when determining the amount of water needed for thermal mass?
-Other considerations include the presence of other thermal mass materials like concrete or gravel, how much the greenhouse is used during the coldest months, and the desired temperature range.
What are some practical ways to store water in a greenhouse for thermal mass?
-Practical ways to store water include using 55-gallon drums, 27-gallon totes, gallon jugs, and even repurposed containers like four-gallon cake frosting containers, which can be painted black to absorb and hold heat.
What is the expected outcome of using thermal mass in the greenhouse as described in the script?
-The expected outcome is that the greenhouse will maintain a warmer temperature at night compared to the outside air, and potentially help moderate temperatures during hot summer days by absorbing excess heat.
Outlines
🌡️ Maintaining Warmth in an Unheated Greenhouse
The script begins by dispelling the myth that greenhouses stay warm with little effort, especially in cold regions like Colorado. Gardener Scott introduces the concept of thermal mass, which is the ability of materials to absorb, retain, and release heat. He explains the importance of retaining heat in an unheated greenhouse and how thermal mass, such as concrete pavers and water, can be used to achieve this. The video also discusses the calculation of the required amount of water for thermal mass, based on the greenhouse's square footage and the severity of the winter. Scott shares his personal greenhouse measurements and his method for determining the amount of water needed to maintain warmth, emphasizing the trade-off between space and thermal mass effectiveness.
💧 Utilizing Water as Thermal Mass in Greenhouse Heating
In this segment, Gardener Scott elaborates on his use of water as a thermal mass to heat his greenhouse during the cold months. He discusses the practical aspects of using water, including the space it occupies and the impact on plant growth areas. Scott details his approach to storing water in various containers, such as 55-gallon drums and 27-gallon totes, to reach his target of 260 gallons. He also mentions the use of black-painted containers to enhance heat absorption. The video highlights the benefits of thermal mass in not only warming the greenhouse during cold nights but also potentially cooling it during hot summer days. Scott concludes by sharing his observations of the greenhouse's nighttime temperatures being warmer by about 10 degrees Fahrenheit compared to the outside air, indicating the effectiveness of his thermal mass strategy.
Mindmap
Keywords
💡Greenhouse
💡Insulation
💡Thermal Mass
💡Water as Thermal Mass
💡Square Footage
💡Gallons of Water
💡Styrofoam Insulation
💡Temperature Fluctuations
💡Reflective Surface
💡Gallon Jugs and Containers
Highlights
Greenhouses in cold regions like Colorado can lose heat at night despite warming up during the day.
Insulation in a greenhouse helps retain heat but can also hold in cold without proper measures.
Thermal mass is key to retaining heat in an unheated greenhouse.
Concrete, gravel, and water are effective materials for thermal mass.
Water is the most efficient thermal mass for unheated greenhouses.
Calculating the amount of water needed involves considering the greenhouse's square footage and sun exposure.
The amount of water needed also depends on the region's climate and the length of the winter season.
For a greenhouse with a floor area of 130 square feet, the target range of water storage is 260 to 390 gallons.
Other thermal mass materials like concrete and gravel can reduce the amount of water needed.
The use of the greenhouse during the coldest months affects the amount of thermal mass required.
Using 55-gallon drums and 27-gallon totes for water storage helps reach the target thermal mass.
Water as a thermal mass can take up significant space in the greenhouse.
Painted black containers can absorb and hold heat, contributing to the greenhouse's thermal mass.
Adding Styrofoam insulation on the north side of the greenhouse helps retain heat.
The greenhouse's nighttime temperatures are warmer by at least 10 degrees Fahrenheit compared to outside air.
The thermal mass effect on cooling the greenhouse during hot summer days is yet to be analyzed.
The video series will continue with more analysis on the impact of thermal mass on greenhouse temperatures.
Transcripts
it's a common misconception that
greenhouses get hot and stay hot with
very little effort but that's not the
case especially in a cold region like
mine in Colorado my Greenhouse warms up
just fine during the day
and then it's easy to lose all of that
heat at night join me today as I show
you how to keep an unheated Greenhouse
warm
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thank you
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hi I'm Gardener Scott and as I showed in
an earlier video
a greenhouse that most of us would have
in our garden is just an insulated
structure if it gets hot the insulation
like these polycarbonate panels of mine
will help hold in that heat to a point
but when it gets cold in the greenhouse
that same insulation can help hold in
the cold and for those of us that don't
have electricity in our greenhouse and
don't have any type of supplemental
heating we have to do all we can to try
to retain the heat that we do have and
that's when we start talking about
thermal Mass
thermal mass is simply the ability of a
material to absorb retain and then
release heat and we can see examples of
this all around us you've probably
walked Barefoot on a concrete sidewalk
during the middle of summer
and burns your feet because it's so hot
concrete is pretty effective at
absorbing and retaining and releasing
heat that's one reason why I've got
these concrete pavers in the greenhouse
it's for the purpose of that thermal
Mass warming the greenhouse gravel is
also pretty effective Rock will absorb
retain and release heat but the most
efficient thermal mass that we can put
in our Greenhouse is water
knowing that water is the most efficient
thermal Mass to have in an unheated
Greenhouse to help keep it warm
it's just the first part of the solution
we have to figure out how much water we
need in the greenhouse to get that heat
there are a couple ways to do this the
first is to figure out the square
footage that you have the sun shining
through how much polycarbonate or glass
or plastic do you have for the sun's
Rays to heat the greenhouse
another option is to measure the square
footage of the floor of your Greenhouse
now my Greenhouse is three meters wide
by four meters long and that's pretty
close to how much sun exposure I have a
little bit less than three meters by
four meters and I think a lot of us are
going to have similar styles of
greenhouses so either formula will give
me a basic guideline for how much water
I need to put in my Greenhouse to get
that thermal Mass positive effect
I've done the math and the square
footage of my floor is about 130 square
feet the square footage of the wall that
the sun is shining through is a little
bit less than that we're going to take
that square footage and multiply it by
another factor to determine how many
gallons of water we should store in our
greenhouse and that factor is going to
be determined by how cold your region is
and how long your winter is if you're
using the method of the surface area
that the sun is shining through you
multiply the square footage by a factor
of two to three if you're using the
square footage of your floor then you
multiply the factor by two to four in
very mild regions where you might only
have a couple months of winter you use
the lower number in regions where you
have harsher weather in longer Winters
you use the higher number the square
footage of the floor multiplied either
by two 260 gallons or three
390 gallons is the target range of how
much water I should be storing in my
Greenhouse
there are other considerations before
you arrive at a final number do you have
concrete that is also acting as a
thermal Mass do you have gravel that's
also acting as a thermal mask and how
much are you using your Greenhouse if
you're not actively growing in it during
those coldest months then you don't need
as much thermal Mass to heat your
Greenhouse if you're only heating the
greenhouse during the months where the
weather is cool then you don't need as
much water
I'm not growing in my Greenhouse in the
dead of winter so I'm airing on the low
side closer to 260 gallons and I've
started with these 55 gallon drums and
filled them with water
and I've added water to these 27 gallon
totes giving me another 54 gallons of
water
now the biggest problem with using water
as a thermal mass in your Greenhouse is
it can take up an awful lot of space
you've probably already noticed that
this wall is lined with water I can't
grow plants where I have that water
stored but I need it to help heat my
Greenhouse between the three barrels and
these two totes I have
219 gallons of water stored toward my
target of 260 gallons
to give me some of that extra water
storage that I need
I'm using gallon jugs
and these four gallon cake frosting
containers that I got at my supermarket
I've painted these containers black
the black color will help them absorb
and hold the Heat
and then gradually release it when it's
cool inside
I can do the same with the gallon milk
jugs
and then slide them into every nook and
cranny I can find and fill up some of
the space that's not being used
with the jugs and the containers that
I've already painted and filled I'm up
to
234 gallons of water and I have more
containers to paint and fill and should
be able to get up to that 260 gallon
Target
so the water the concrete pavers and the
gravel are all thermal Mass to help keep
my Greenhouse warm I've also added a
layer of Styrofoam insulation on the
north side of this greenhouse one of the
reasons it gets so cold in a greenhouse
at night is that that heat escapes this
extra layer of insulation will help hold
in the Heat and because of this
reflective surface all this water can
radiate its heat back to where the
plants are going to be
you're probably wondering if I've
noticed yet if all of this work is
having its desired effect and yes it is
my Knights are still getting down to 30
degrees to 40 degrees Fahrenheit but
I've noticed even though I don't have as
much water as I would like that the
temperatures at night are at least 10
degrees Fahrenheit warmer than the
outside air temperature so it is staying
warmer in here and not getting as cold
as it did in that earlier video where
this basically becomes a refrigerator
and just keeps everything cold what I
haven't noticed yet is the effect that
this thermal Mass has on cooling the
greenhouse because during the heat of
the day in summer that's yet to come
this water is absorbing the heat that
could otherwise overheat the plants so
not only does it warm up the greenhouse
when it's cold outside but it can
actually cool the greenhouse to a point
when it's hot outside I'll continue to
add water I'd like to get more than that
260 gallon Target and then start doing
some real good analysis to see exactly
what the Improvement is in the daytime
and the nighttime temperatures so you
can expect that that video is coming in
the future if you want to see what else
I've done in my journey towards
Greenhouse growing then go ahead and
watch this video next
I'm Gardener Scott enjoy gardening
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