Heated Multispan Polytunnels?

[Chris F]

So this one was a new one on me. I was at Energy now and there was a company there offering a complete package to start your own growing business, with a 5000m2 heated multispan polytunnel.

Said the income would be up to £3.4 million utilising the Renewal Heat Incentive for heating in addition to production profits or rental income (I think that was over 25 years).

All was based on using a Ground Source Heat pump for the heating system.

Has anyone else heard or installed such a system - unless you want to grow a lot of produce or can rent it out for sure, would it work? How much maintenance do the polytunnels require? Could you keep animals inside them?

 

[Doing it for the kids]

Didn't think polytunnels were allowed under RHI, only glass?

 

[Chris F]

Didn't think polytunnels were allowed under RHI, only glass?

They offered glass too, but said polytunnel was ok for RHI. Its slightly cheaper to put up polytunnels than glasshouses.

 

[renewablejohn]

Didn't think polytunnels were allowed under RHI, only glass?

i thought they where specifically excluded.

 

[Chris F]

i thought they where specifically excluded.

Like I say, I’d not heard of this one before.

 

[Doing it for the kids]

Just checked, they aren't. Typical salesman!

 

[Chris F]

So falls into the too good to be true category then - shame. Sorry folks.

 

[Daniel Larn]

Are polytunnels specifically excluded or are '...poly tunnels erected on a temporary basis...' excluded?

As for keeping animals in them, that's a whole different ballgame. There are a number of suppliers of tensile fabric structures, the coverall or clearspan type you may have seen before (popular in the US and Canada), but they can be quite expensive.

I wouldn't recommend a regular polytunnel designed for growing plants, for keeping livestock in, as there are a whole host of complications that arise.

We have a solution you could use for either option, plants or livestock, which is specifically designed to be able to do both. We are going through the process of assessing the suitability of RHI for each specific case, as it is quite a complicated issue.

If you can consider 5000m^2, I'd say it is definitely worth considering a bull beef system, as it would likely pay much better.

 

[renewablejohn]

Are polytunnels specifically excluded or are '...poly tunnels erected on a temporary basis...' excluded?

As for keeping animals in them, that's a whole different ballgame. There are a number of suppliers of tensile fabric structures, the coverall or clearspan type you may have seen before (popular in the US and Canada), but they can be quite expensive.

I wouldn't recommend a regular polytunnel designed for growing plants, for keeping livestock in, as there are a whole host of complications that arise.

We have a solution you could use for either option, plants or livestock, which is specifically designed to be able to do both. We are going through the process of assessing the suitability of RHI for each specific case, as it is quite a complicated issue.

If you can consider 5000m^2, I'd say it is definitely worth considering a bull beef system, as it would likely pay much better.

And what chance do you think you have of getting planning permission for a permanent polytunnel of a size which you could justify a biomass boiler.

 

[Daniel Larn]

At that size, the planners are unlikely to consider anything as being temporary. If the salesman anticipates you having it for 25 years, I doubt they will be selling it to you as a temporary structure either.

There have been a number of test cases over the years that have challenged arguments for, and against, the permanence of polytunnels. It comes down to a case by case ruling as to whether they will be considered as temporary or permanent structures.

...and to clarify, I didn't explicitly mention a biomass boiler. Unless you want it to get totally tropical in there, you would be better served using a ground source heat pump.

 

[renewablejohn]

At that size, the planners are unlikely to consider anything as being temporary. If the salesman anticipates you having it for 25 years, I doubt they will be selling it to you as a temporary structure either.

There have been a number of test cases over the years that have challenged arguments for, and against, the permanence of polytunnels. It comes down to a case by case ruling as to whether they will be considered as temporary or permanent structures.

...and to clarify, I didn't explicitly mention a biomass boiler. Unless you want it to get totally tropical in there, you would be better served using a ground source heat pump.

You are actually joking I hope.

 

[Daniel Larn]

nope, deadly serious.

I am not going to pretend to be an expert on polytunnels or the planning issues that surround them, but I will say that have explored all of these sorts of discussions with a number of local authorities for our systems. We have the option of placing our structures as temporary or permanent, and there are pro's and con's to both.

We ruled out polytunnels for our systems as they aren't robust enough, and didn't offer the level of environmental control we needed, but not before we looked at options for planning.

I'd be interested to hear if you have some other take on it, as it could be transferable.

 

[Daniel Larn]

Forgive the double post, but this was the particular case that put the nail in the coffin for us. I am calling it a night here.

http://www.bailii.org/cgi-bin/marku...482.html&query=hall+and+hunter&method=boolean

Sections of particular interest are 21, 23 and 25.

21: states that even an area of 3200m^2 is not 'inconsequential', and as it falls outside of the 465m^2 of permitted development, it requires full planning permission to be in place prior to construction despite the defence made under section 23 and especially considering section 25.

23: States that the structures do not require any foundations, and do not physically have any impact on the land when they are removed, therefore do not constitute development (this is what most people rely on as a defence when they are contested).

25: States that despite the structures moving around frequently in this particular case, some of the structures were in place for more than 3 months, which is sufficient period to require planning as even a temporary structure.

This case means there is now a president, set in law, that means any polytunnel can be said to be a permanent structure (whether that decision is upheld will need to be considered case by case).

If you are going to install a ground source heat pump, you are not going to be moving your tunnels every few months.

 

[renewablejohn]

Not on about the planning which everyone knows is a postcode lottery as to whether it slips under the planning radar or not. What I was referring to was your thought of using a ground source heat pump to heat a polytunnel. You just have to be kidding.

 

[Doing it for the kids]

Not on about the planning which everyone knows is a postcode lottery as to whether it slips under the planning radar or not. What I was referring to was your thought of using a ground source heat pump to heat a polytunnel. You just have to be kidding.

Quite, i though he got that from your last post but clearly not!

I woulder what the insulation properties are of a poly tunnel are!? To think they can get RHI on poly tunnels does seem bonkers.

 

[Daniel Larn]

IPT technology use groundsource heating for polytunnels being used for raising seasonal poultry. They are able to claim RHI and are able to achieve temperatures of 30°C or more.

...with a ground source heat pump.

It isn't going to work for your basic super thin single membrane setup, but again, If it is being sold as eligible for RHI then I am saying that it is possible.

Also, upon reading the original post again it says the seller was offering a ground source pump solution. So I think it would likely work.

Going back and looking again at what you said, it seems obvious what you were driving at.

My apologies for the confusion.

 

[renewablejohn]

IPT technology use groundsource heating for polytunnels being used for raising seasonal poultry. They are able to claim RHI and are able to achieve temperatures of 30°C or more.

...with a ground source heat pump.

It isn't going to work for your basic super thin single membrane setup, but again, If it is being sold as eligible for RHI then I am saying that it is possible.

Also, upon reading the original post again it says the seller was offering a ground source pump solution. So I think it would likely work.

Going back and looking again at what you said, it seems obvious what you were driving at.

My apologies for the confusion.

This is rubbish. Poultry tunnels are like Mushroom tunnels and are twin skin with a layer of insulation between the skins. With recovery of heat from the chickens it would be quite easy to heat with a GSHP but that is not what was being suggested in the first post. It is specifically stating a growing tunnel which would only be single skin and heated by a GSHP. Snake oil springs to mind.

 

[Daniel Larn]

It may be a growing tunnel, and it could be snake oil. But it is wrong to say that it is not possible to claim RHI on a poly tunnel. If the system is being sold as being eligible, then it probably is, and it wouldn't be difficult to find out with more information.

We don't use any insulation, and use almost exactly the same materials. With a twin layer of film and a sufficient air gap you have more than enough insulation.

Without the use of any recirculation, straight from a GSHP we can achieve 21°. Although we have never had to go any higher I am sure we could be touching 30° without much trouble.

 

[renewablejohn]

It may be a growing tunnel, and it could be snake oil. But it is wrong to say that it is not possible to claim RHI on a poly tunnel. If the system is being sold as being eligible, then it probably is, and it wouldn't be difficult to find out with more information.

We don't use any insulation, and use almost exactly the same materials. With a twin layer of film and a sufficient air gap you have more than enough insulation.

Without the use of any recirculation, straight from a GSHP we can achieve 21°. Although we have never had to go any higher I am sure we could be touching 30° without much trouble.

Please stop kidding people. My polytunnels easily achieve 30C without any heating in the middle of winter. That is not the point its a question of keeping the polytunnel frost free when its -15C outside. Or maintain a growing temperature of 15C when its freezing outside.

 

[Daniel Larn]

I didn't say we made polytunnels.

I didn't say we could maintain it year round, or at 30°. We have to supplement in the winter, and we use more and more recirculation air. In effect we only heat the 10% make up air we bring in, the rest has the heat recovered.

My only point here, is that the idea proposed by the original post is not in anyway shape or form unbelievable. I would say that it is entirely possible, and that the salesman was probably quite right in his assumptions.

I also wanted to make the case that I don't think 3.4M is the best return that can be had from a structure that size. Unless the capital cost of the system is far lower than I think it will be.