How do greenhouse growers keep heating costs down

[blondie]

Hi

So I had a wonder full letter from the electric company saying our electric bill coil be going up buy £1000 increase, over this year.

Well before this I was planing on renovanting the greenhouse and way and try in tomake the greenhouse more energy efficient and cheep all round. Now even more so. The main catalyst was to give the greenhouse a deep clean, after finding the main insulation was knackered.

So now I am going to be spending a few hundred pounds on the greenhouse. I am using something called airtec as the first layer which is a, silver double bubble insulation to keep heart in and in summer keep what out. ThatI shall have around the sides upto the high of the benching, but then on the one side it will go up to hieght of the roof and on the end of the greenhouse will be completely covered in it.
The second layer will b 250mm celotex insulation boarding they will be the same height, as the benching all the way around. Then the third layer will be UV treated bubble wrap that will cover all the side and not get taken down. I am also hoping the insulation with it being silver will reflect more light in the winter months.
I will still be bubble wrapping the roof by that gets removed each year so I can but up a layer of netting.

I shall also be building all new benching in the greenhouse as the only bench is ready to fall apart I think in some places, it's only the rust holding it together.

So how are other people heat in there greenhouses and keep the costs down and becoming as energy efficient as possible.

 

[NYEric]

Ask Dot, besides insulation there are heat sinks and other methods. Good luck.

 

[JAB]

One of the sole reasons businesses fail and personal collections can no longer be maintained. Insulation. Smart install. Really all depends on the initial setup. After market upgrades are tough to maintain efficiency.

 

[tomkalina]

Start by replacing all of your glazing with 8 ml. twin-wall polycarbonate.

 

[blondie]

Start by replacing all of your glazing with 8 ml. twin-wall polycarbonate.

That shall be ny next step but that is a costly task so need to save up for that.

 

[Ray]

Believe me, it'll be better if you "bite the bullet" and do it sooner, if you can. With so-so insulation, you'll be paying considerably more to heat the thing, making it a longer-term savings effort. Put the better cover on immediately, and the energy cost savings will pay it off much sooner.

The thicker, and with more walls you can get, the better.

 

[blondie]

Afternoon

Just doing some quick calcuations and if I went down the 8mm twin wall pollycarb im lookin at very roughtly £1947.44 to do my greenhouse, plus indont know if ill be able to clip that size into my glazing bars.

I could buy three greenhouse that size lol.

Most of the pollycarb sold in the UK for a greenhouse is 6mm.

This options would have to be a long haul as it is way out my budget this year in all honestly, or it might have to be done in stages each year.

Rome wasnt built in a day as they say.

 

[abax]

A cheaper way than polycarb is dead air spaces between
layers of 6mm greenhouse plastic and fiberglass. I also
have a heavily insulated knee wall. Other than that, I just
pay the damn bill and roll my eyes every month.

 

[blondie]

Yes the hole reason this has come up is the orginal insulation has been there for 10yrs now, and is very tasty and dissintergrating so it time to change.

Plus the greenhouse has not really had a full clean in years, well since I turned it over to the orchids.

I have been able to bring the price down year on year, but this coast increase is over allon electric price so if I can minminimise I want to.

Also I though as I am doing the hole greenhouse over hall benching and all, I would be stupid not to ask the question as to what others do.

My over all goal is to be the base area under then benching as insulated as possible. Then when I have the money to slowly move towards the pollycarb route.

 

[Bjorn]

Living in a moderately cold area, I have chosen to insulate with heavily insulated knee-wall as Angela, plus two or three layers of 10mm double walled poly. This sounds quite excessive but it pays off. Now the heat from the lights is enough to keep up the temperature. And btw. A thermostat shuts off the light when temp is high enough.
One very important thing to do if you have an aluminium structure, is to break the heat transfer through the ribs. This can account for more than 50% of your total heatloss. I did that by putting a layer of poly outside the entirely greenhouse covering all metal and everything that conducts heat. Also the vents are blocked, cooling in summer is done by fans blowing in fresh air if necessarily. The latter is unfortunately not always the case in my climate though. Even in summer. My point is that you will have to adopt to your lical climate with these things.
Good luck

 

[Ray]

We need to be clear on this one (no pun intended): in the industry, "poly" typically refers to polyethylene film, typically 6 mil thickness, UV protected, and often with infrared-trapping-, and/or drip-preventing coatings. Two layers are inflated with a small fan, and that becomes an effective insulating layer. Something you might consider, Blondie.

The multi wall, rigid stuff - polycarbonate - is referred-to as "polycarb" or just "PC."

 

[blondie]

The Pollycarb is a root I will be going down at the moment it is just unaffordable at the moment.

I have been play with ideas and you guy's have give me some extra ideas I shall what I'm playing as I will be increasing insulation and keeping the price down. The coldest I do at in normal winter is -7C. Overall the electric bill is going up as a hole but I want to try and maximise the best chance of reducing the electric in the greenhouse.

I know there will never be a full solution growing under glass will always cost, and will always have to tweak to make it work in all situations.

I shall be saving up to pollycarb the roof first, as long as I can fit it in the glazing strips.

 

[Bjorn]

We need to be clear on this one (no pun intended): in the industry, "poly" typically refers to polyethylene film, typically 6 mil thickness, UV protected, and often with infrared-trapping-, and/or drip-preventing coatings. Two layers are inflated with a small fan, and that becomes an effective insulating layer. Something you might consider, Blondie.

The multi wall, rigid stuff - polycarbonate - is referred-to as "polycarb" or just "PC."

Thank you Ray, I meant polycarbonate:sob: sorry for the misunderstandings that might have caused

 

[Ray]

Blondie, as an interim thing, consider a single layer of polyethylene over the exterior of the existing cover. Put some spacers on the existing cover to create a dead-air space, (I have used double-sided cellophane tape to temporarily hold narrow strips of styrofoam), and use tape to seal it to the edges (there is a greenhouse tape available, but good old duct tape works, too).

 

[TyroneGenade]

Hello,

See page 9 of https://web.archive.org/web/2008120....org/newsletters/2007_04AtOSNewsletterWeb.pdf .

 

[blondie]

Very interesting read thanks

 

[JAB]

Million dollar question right? I mean this single query has been the sole reason many an orchid business fail, and the cost to do it properly is so prohibitive that historically only the very well to do can afford to get into orchids on most any level outside a windowsill.

good luck. Keep us posted on what you decide

 

[Bjorn]

Thanks a lot Tyrone, good reading! Actually I have done similar things, placed a number of water filled containers under the benches, this cools during hot days and release heat during night (= save heating bill) Not a big impact, but measurable. As said before nowadays I use artificial lightnig (mostly due to lack of light in Winter) as the sole heating during daytime.

 

[TyroneGenade]

As said before nowadays I use artificial lightnig (mostly due to lack of light in Winter) as the sole heating during daytime.

How many watts of light in how large a green house? What temperatures do you maintain with this setup?

 

[Bjorn]

How many watts of light in how large a green house? What temperatures do you maintain with this setup?

The house is some 27 sqm, and the total wattage lights installed might be around 4000W MH and HPS lighting. Additionally comes a number of LED units (self built and designes approx 200W each)
But when that is said, this amount of lighting is much more than is necessary to lift temperature to approx 20-25C during daytime. In order to avoid "frying" the plants the lights are connected to thermostat that breaks the power when temperature is attained. This thermostat has failed one or two times with ugly results, scorched leaves on the cattleyas etc. Using the lights as heat source works fine, no problem with reduced life of the lights etc.