How to Heat a Greenhouse Without Electricity

Summary

In 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

00:00

🌡️ 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.

05:01

💧 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.

Keywords

💡Greenhouse

A greenhouse is a structure made typically of glass or polycarbonate panels, designed to create a controlled environment for growing plants. In the video, the greenhouse serves as the central focus, where the host, Gardener Scott, demonstrates methods to maintain warmth in an unheated greenhouse, especially in cold regions like Colorado.

💡Insulation

Insulation refers to materials or structures that reduce the transfer of heat. In the context of the video, polycarbonate panels are mentioned as a form of insulation that helps retain heat during the day but can also trap cold if not managed properly, highlighting the dual role of insulation in a greenhouse.

💡Thermal Mass

Thermal mass is the ability of a material to absorb, retain, and then release heat. The video explains that materials like concrete pavers, gravel, and water are used for their thermal mass properties to help maintain heat within the unheated greenhouse, showcasing the strategic use of these materials to combat temperature fluctuations.

💡Water as Thermal Mass

Water is highlighted as the most efficient thermal mass due to its high heat capacity. The video details how water can absorb and release heat, thereby helping to keep the greenhouse warm. Gardener Scott calculates the amount of water needed based on the greenhouse's size and the severity of the winter, emphasizing the practical application of this concept.

💡Square Footage

Square footage is a measure of the area within a greenhouse and is used to determine the amount of thermal mass required. The video mentions calculating the square footage of both the floor and the wall area exposed to sunlight to estimate the necessary water volume for effective thermal mass.

💡Gallons of Water

The term 'gallons of water' is used to quantify the amount of water needed to achieve the desired thermal mass effect. Gardener Scott calculates and aims for a target of 260 gallons of water, using various containers to store it within the greenhouse, demonstrating a practical approach to thermal mass implementation.

💡Styrofoam Insulation

Styrofoam insulation is an additional layer of insulation mentioned in the video, used to further retain heat within the greenhouse. It is applied to the north side of the structure to minimize heat loss, illustrating a multi-layered strategy to manage temperature in an unheated greenhouse.

💡Temperature Fluctuations

Temperature fluctuations refer to the changes in temperature within the greenhouse, particularly the loss of heat at night. The video discusses how the use of thermal mass materials can mitigate these fluctuations, aiming to keep the greenhouse warmer during cold nights.

💡Reflective Surface

A reflective surface, in the context of the video, is used to describe how the water can radiate heat back into the greenhouse. The video suggests that the reflective properties can help distribute the heat more evenly, contributing to the overall thermal management strategy.

💡Gallon Jugs and Containers

Gallon jugs and containers are used as practical storage solutions for water in the greenhouse. The video describes how these containers, once filled and painted black, can absorb and hold heat, further contributing to the thermal mass and aiding in temperature regulation.

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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