PowerSwitch Main Page
PowerSwitch
The UK's Peak Oil Discussion Forum & Community
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Cheap building
Goto page 1, 2  Next
 
Post new topic   Reply to topic    PowerSwitch Forum Index -> Preparations
View previous topic :: View next topic  
Author Message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Wed Feb 16, 2011 12:06 pm    Post subject: Cheap building Reply with quote

A friend of a friend has recently sought my advice regarding the electrical arrangements for a house they are building.
Nothing very unusual regarding the electrics, but I thought others might be interested in the building itself.

They work for a builders merchants and can obtain damaged, defective or substandard building materials very cheaply, sometimes for free.
A large single floor home is being built.
The floor is solid concrete, cast in situ with a double thickness of second grade insulation underneath.
Pipes are cast into the base for underfloor heating.
Outside walls are built of blocks made on site, consisting of local stone and cement, then lined with insulating board, and an inner face of concrete blocks.
Broken blocks are obtained for nothing and are fine for this as they are laid the "wrong" way round, such that the longest dimension of the block is the thickness of the wall. A wall thus built wont be as strong as with intact blocks, but is ample in view of the extra thickness.
Very substantial thermal mass is thereby obtained.
All internal walls are also built of broken blocks, for thermal mass, fire resistance, and soundproofing.
Ceilings are timber joists lined with plasterboard, and insulated, and then boarded above for storage.
As the internal walls are load bearing, the joists span a much shorter distance than is normal, allowing short lengths of cheap timber to be used.
Heavy water tanks or doomer supplies may be stored in the loft without concern.
The roof will be timber framed and covered in slates.

Heating to be from a woodstove, centally placed.
Underfloor heating from either the woodstove or LPG
Cooking to be LPG.
Lighting to be a mixture of LPG and PV powered electric light.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
DominicJ



Joined: 18 Nov 2008
Posts: 4387
Location: NW UK

PostPosted: Wed Feb 16, 2011 12:25 pm    Post subject: Reply with quote

Quote:
Pipes are cast into the base for underfloor heating.

That Always creeps me out.
I know its not particularly common, but pipes break and joints fail.
A broken pipe 3 inches below in the middle of a concrete floor would be a nightmare.

Just a thought, can they put a "break" between the internal walls and the external walls.

Code:

 _____________
|////////////|
|//////_|_///|
|///////|////|
|____________|


The slashes are open space.

The Woodstove would heat the internal walls, but the internal walls wouldnt be able to heat the external walls (except by conduction through joists and the like), that way your only really losing the heat through your chimney stack,
***

My pic hasnt worked, its a square with an X in the middle
[Bandidoz - fixed?]
_________________
I'm a realist, not a hippie


Last edited by DominicJ on Wed Feb 16, 2011 1:05 pm; edited 1 time in total
Back to top
View user's profile Send private message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Wed Feb 16, 2011 12:43 pm    Post subject: Reply with quote

The underfloor heating SHOULD be reliable as it consists of a large bore semi rigid plastic pipe with smaller flexible pipe within.
Acces is possible to the ends of each section via manholes or inspection covers, these are covered with concrete slabs normally.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
postie



Joined: 06 Nov 2010
Posts: 445
Location: Bishop's Stortford

PostPosted: Wed Feb 16, 2011 4:17 pm    Post subject: Reply with quote

Not that I'm planning on a self-build, but out of interest, what kind of end cost do they think they'll have for the build?
_________________
Learn to whittle now... we need a spaceship!
Back to top
View user's profile Send private message
PS_RalphW



Joined: 24 Nov 2005
Posts: 5493
Location: Cambridge

PostPosted: Wed Feb 16, 2011 4:41 pm    Post subject: Reply with quote

How much volume is lost to the extra mass being employed? You get less space inside for a given land area, and the roof still has to cover the lot.

Is the underfloor heating suitable for electric airsource heating ?

What windows are being fitted?
Back to top
View user's profile Send private message
kenneal - lagger
Site Admin


Joined: 20 Sep 2006
Posts: 11126
Location: Newbury, Berkshire

PostPosted: Wed Feb 16, 2011 4:49 pm    Post subject: Reply with quote

I hope they had it designed properly Adam or did they scrimp on that?

The sufficiency of the spec you've detailed will depend on the types of board insulation, it's thickness and the type of block. If they were getting insulation very cheaply and put enough in they wouldn't have needed to put underfloor heating in.

Hopefully they've used continuous lengths of PEX pipe for that so there shouldn't be any joints in it. I've specified loads of houses like that and not had any problems at all. The first one, I built myself in 1975, had some copper pipes, which we greased, with special treatment at the bends to allow for movement and is still going strong. Two thirds of it was done using PEX a couple of years later though, as it became available.

With the spec he's used the U/F heating won't work very well, if at all. You need a good contact between the water bearing pipe and the floor so that conduction takes place to transfer the heat. He's relying on a bit of conduction and a lot of convection to transfer heat from one plastic pipe to another and plastic is a good insulator. The delay in heat transfer from pipe to room will be very long, a couple of hours or more, compared with half an hour for a commercial system. If he's got thick concrete and the pipe well down in the slab he may have to wait half a day before the heat comes through and will have to heat the system 24/7 for it to work.

Tell him to get some advice before he wastes any more money.
_________________
Action is the antidote to despair - Joan Baez
Back to top
View user's profile Send private message Send e-mail Visit poster's website
vtsnowedin



Joined: 07 Jan 2011
Posts: 5223
Location: New England ,Chelsea Vermont

PostPosted: Wed Feb 16, 2011 4:53 pm    Post subject: Reply with quote

adam2 wrote:
The underfloor heating SHOULD be reliable as it consists of a large bore semi rigid plastic pipe with smaller flexible pipe within.
Acces is possible to the ends of each section via manholes or inspection covers, these are covered with concrete slabs normally.

My daughter's new house('09) has radiant heating in the basement slab as well as under each living area floor. The tubes are a resilient plastic and are cast direct into the concrete or stapled tight to the underside of the wooden sub flooring. The concrete floor tubes are as close as one foot apart and each tube makes one loop out from the furnace and back to the collection manifold. If a leak was to develop turning two valves will isolate that loop and there is adequate redundancy in the system for closures of up to fifty percent. The propane fired boiler for this two and a half story three bedroom house is about two thirds the size of a standard washing machine. The wall panel with all the distribution manifolds and zone valves is a piece of copper art work that is a plumbers favorite dream.


Last edited by vtsnowedin on Wed Feb 16, 2011 4:56 pm; edited 1 time in total
Back to top
View user's profile Send private message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Wed Feb 16, 2011 4:54 pm    Post subject: Reply with quote

postie wrote:
Not that I'm planning on a self-build, but out of interest, what kind of end cost do they think they'll have for the build?


About £10,000 for materials, and about the same for paid labour, they already had the land.
Some of the labour is being done for free by family members.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Wed Feb 16, 2011 4:59 pm    Post subject: Reply with quote

RalphW wrote:
How much volume is lost to the extra mass being employed? You get less space inside for a given land area, and the roof still has to cover the lot.

Is the underfloor heating suitable for electric airsource heating ?

What windows are being fitted?


Quite considerable space is lost, but they consider this to be worthwhile for a durable and inexpensive building with good thermal mass.

The water for the underfloor heating could be heated by a heatpump, but wont be as there is no mains electricity.
The ultimate plan is electric resistance heating from a wind turbine.

Windows are all double glazed, some wood and some UPVC . Obtained very cheaply owing to transit damage.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Wed Feb 16, 2011 5:18 pm    Post subject: Reply with quote

kenneal wrote:
I hope they had it designed properly Adam or did they scrimp on that?

The sufficiency of the spec you've detailed will depend on the types of board insulation, it's thickness and the type of block. If they were getting insulation very cheaply and put enough in they wouldn't have needed to put underfloor heating in.

Hopefully they've used continuous lengths of PEX pipe for that so there shouldn't be any joints in it. I've specified loads of houses like that and not had any problems at all. The first one, I built myself in 1975, had some copper pipes, which we greased, with special treatment at the bends to allow for movement and is still going strong. Two thirds of it was done using PEX a couple of years later though, as it became available.

With the spec he's used the U/F heating won't work very well, if at all. You need a good contact between the water bearing pipe and the floor so that conduction takes place to transfer the heat. He's relying on a bit of conduction and a lot of convection to transfer heat from one plastic pipe to another and plastic is a good insulator. The delay in heat transfer from pipe to room will be very long, a couple of hours or more, compared with half an hour for a commercial system. If he's got thick concrete and the pipe well down in the slab he may have to wait half a day before the heat comes through and will have to heat the system 24/7 for it to work.

Tell him to get some advice before he wastes any more money.


I dont think that it was designed at all !
Though they do understand the importance of insulation and thermal mass.
The insulation under the concrete floor is about 300mm thick, with a similar thickness of concrete.
The extra thermal resistance of a pipe within a pipe is a decided drawback, but the concrete will eventually get warm.
A simple and fairly brief test with a 3KW water heater showed that the water went into the system hot and came out cold, so the heat must be going somwhere, and were else except into the concrete ?
In the near term it has not been decided how to heat the water, the longer term aim is to use a wind turbine. Holding the heat for calm days is more important than a rapid response.

A not very detailed calculation by others suggests that the heating demand will be about 8KW at zero outside and 20 centigrade inside.
The woodstove is designed for 6 KW into the room and 3KW for water heating.
LPG lights will contribute a KW or two.
Too late to alter much as the floor slab and walls are complete, but not permanent roofing or internal fitting out.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
biffvernon



Joined: 24 Nov 2005
Posts: 18541
Location: Lincolnshire

PostPosted: Wed Feb 16, 2011 5:41 pm    Post subject: Reply with quote

This film, Garbage Warrior, http://www.youtube.com/watch?v=b1cUa4yWQp4 is quite an inspiration.
_________________
http://biffvernon.blogspot.co.uk/
Back to top
View user's profile Send private message Send e-mail Visit poster's website
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Wed Feb 23, 2011 11:09 am    Post subject: Reply with quote

UPDATE
Roofing now well underway.
North elevation is a conventional slated roof and intended to last for decades.
South elevation is assorted rigid plastic over plywood, only temporary pending installation of PV and solar thermal. When these have been installed, the rest of the rooof will be slated.
Wood stove installed and working.
Battery installed, borrowed inverter in use.
Power from diesel generator at present being run for 12 hours a day, with the cooling system of the engine connected indirectly to the underfloor heating.
Electrical installation underway.

No LPG tank or appliances yet.

Rendering the building weather tight and partialy habitable became very urgent as the hut in which the owner was living was destroyed by fire.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
adam2
Site Admin


Joined: 02 Jul 2007
Posts: 7152
Location: North Somerset

PostPosted: Tue Mar 15, 2011 3:13 pm    Post subject: Reply with quote

True building work, as distinct from fitting out now complete.
Interior temperatures average about 19 degrees and increasing at about 1 or 2 degrees a week, without any use of the wood stove.
Diesel generator now in use 8 hours a day with the cooling water used for the undefloor heating.
880 watts of PV installed and running, more to follow when money permits.
LPG cylinders (not a bulk tank as originaly proposed) in a purpose built secure hut. LPG used for cooking, some lighting, and water heating.
Most lighting is 12 volt from the battery bank. 12 volt flourescent lighting and LED light strip very succesfull.
Solar thermal to follow for water heating.

Damp was a problem initialy, but is suspected to be water used in construction, not ongoing water ingress. An industrial de-humidifier was removing 20 litres per 8 hour day.
_________________
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Back to top
View user's profile Send private message
DominicJ



Joined: 18 Nov 2008
Posts: 4387
Location: NW UK

PostPosted: Tue Mar 15, 2011 3:48 pm    Post subject: Reply with quote

Quote:
with the cooling system of the engine connected indirectly to the underfloor heating.

Wink
_________________
I'm a realist, not a hippie
Back to top
View user's profile Send private message
RenewableCandy



Joined: 12 Sep 2007
Posts: 12654
Location: York

PostPosted: Wed Mar 16, 2011 8:40 pm    Post subject: Reply with quote

Fuel rods??
_________________
Soyez réaliste. Demandez l'impossible.
Stories
The Price of Time
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    PowerSwitch Forum Index -> Preparations All times are GMT + 1 Hour
Goto page 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group