Eco spherical objects, or...

[Nemesis]

Well, read and argue amongst yourselves.

http://www.housebuildersupdate.co.uk/2007/07/eco-bollocks-award-dept-communities-and.html

 

[NT]

Better than most govt advice on the subject.

 

[chuckey]

The savings on double glazing are nonsense because they ignore the cost penalty of having to paint wooden frames every 2/3 years with a burn off and total repaint every 20 years or so. Also most wooden windows are not 100% draught free.
With out knowing what size house was taken as the standard, the cost of solid internal insulation is way too low, to restore a house to full decorative order would cost something more like £10,000, by the time all the window/door reveals have been plastered, power points moved, skirting boards re-fitted ands re painted.
That is another good thing about double glazing, the amount of internal remedial work can be zero (it was in my case).

The point the politicians have not got (perhaps because they don't want to) is that, to substantially decrease the carbon footprint of our existing housing stock, requires the house to be vacant for say 3 weeks and to have a lot of money invested in it during this period. This is a luxury that most people actually cannot afford. A much better thing for politicians to do, is to concentrate on are the power generators with their misereable 34% chemical to electrical energy conversion. Its a historical thing and its got a name, basically, the larger the power station, the cheaper the electricity, how ever converting Didcot or Ferrybridges power station to a combined heat and electricity generator would leave us with the problem of transporting gigawatts of heat ( in hot water) to their domestic consumers - say 25 miles away. If we had stuck with smaller power stations in the heart of our conurbations, they would all be CHP by now. But this may still be cheaper then upgrading 22 million houses, as they are relatively few in number.


Frank

P.S. A domestic coal fire has an efficiency of about 60%.

 

[NT]

A world in which politicians, who show least understanding of the subject, make rules for the rest of us to follow. A case of the idiots taking over the asylum


NT

 

[Nemesis]

My house certainly hasn't had a complete burn off in rather more than twenty years! Nor indeed a coat of paint for several more years than two.

I think that draughtprofing can be readily achieved to a satisfactory standard in timber windows, but some small draught is a good idea - and trickle vents give that in modern windows.

I'm sticking with my single glazed historic windows, which I reckon is the cheapest and best option really.

 

[Flyfisher]

Well insulated houses are all very well but who wants to live in a sealed box?

I wish I could remember where I read a recommendation that household ventilation should allow the air in a room to be changed three times per hour. Is this correct? If not, what is the recommended current practice?

Assuming 3 times per hour is correct, it means that every 20 minutes you are dumping all the expensively heated air in your comfortable room to the outside atmosphere and replacing it with the cold that needs heating again. So why all the fuss about thermal losses through the fabric of the building ?

I've read about heat exchanger systems expressly designed to recover internal air-borne heat, but they don't seem to be particularly well publicised. Probably too expensive for most households I guess.

Have I got the wrong end of the stick here?

 

[Nemesis]

Em - I'm worried, I think I might have to agree with you...


Time for a large glass of something.

This is interesting:

http://www.stovesonline.co.uk/stove-ventilation.html

This may answer some questions, and the building regs should answer more (but will have to be waded through):

http://www.vent-axia.com/knowledge/buildingregs/partf.asp

 

[Lime]

For the sake of discussion, would it be possible to copy exactly the construction of a wooden sash window in uPVC?

Would that then make one of the chief objections to normal uPVC windows, namely the alteration of a property's appearance, no longer valid?

Well insulated houses are all very well but who wants to live in a sealed box?

The building regulations appear to have a dichotomy within them regarding design for draughtproofing and ventilation.


As for the painting every few years argument, that is a modern phenomena created by modern paints.
Paints of yesteryear had more staying power.

 

[Flyfisher]

According to this article from a Jersey public health website it would seem that 3 changes of air per hour is a bare minimum . . . . which makes all this onus on insulation even more curious.

How long before the building regs make domestic air heat exchangers compulsory?

 

[worms]

This is a luxury that most people actually cannot afford.

Of course, if they removed VAT from the materials...

 

[NT]

Personally I think good health is a lot more value than saving £100 on heating. Ventilation makes a huge difference to levels of bacteria, mould, spore and pollutant level build up in houses, and these have a significant impact on lung health.

I'd bet that some day in the future these ubertight buildings going up now will be deemed unhealthy practice.

This is nothing new either, the basic info on bacteria & mould were taught back in the 30s, and probably go much further back than that. Awarenes of indoor air pollution and its effect on health is more recent but has been around for several years now.


NT

 

[Nemesis]

Totally agree - although also agree that it would be useful to recover the heat before it vanished into the garden.

I think that a basic heat recovery system was one of the things done on the telly prog about going green - but it wasn't terribly attractive.

It's waste though which annoys me - so much energy is needlessly wasted by people not switching things off, for example, and what's wrong with wearing warm clothes and not turning up the heating?

(Ann Widdecombe speaks again... I really am getting worried... much of Grumpy Old Women is actually filmed in a nearby town. It must be something in the water, apart from the flouride)

 

[biffvernon]

The savings on double glazing are nonsense because they ignore the cost penalty of having to paint wooden frames every 2/3 years with a burn off and total repaint every 20 years or so.

So you've not heard of linseed oil paint then?

 

[Nemesis]

Double glazing or single - wood needs similar treatment surely?

At least quality timber lasts, unlike uPVC.

 

[sarahj]

'For the sake of discussion, would it be possible to copy exactly the construction of a wooden sash window in uPVC? '

A house in our village has sliding UPVc windows and they still look awful!

 

[Nemesis]

I agree - you can spot them very readily!

I can't see what's wrong with wood, really.

 

[Aidan]

Well insulated houses are all very well but who wants to live in a sealed box?

I wish I could remember where I read a recommendation that household ventilation should allow the air in a room to be changed three times per hour. Is this correct? If not, what is the recommended current practice?

Assuming 3 times per hour is correct, it means that every 20 minutes you are dumping all the expensively heated air in your comfortable room to the outside atmosphere and replacing it with the cold that needs heating again. So why all the fuss about thermal losses through the fabric of the building ?

I've read about heat exchanger systems expressly designed to recover internal air-borne heat, but they don't seem to be particularly well publicised. Probably too expensive for most households I guess.

Have I got the wrong end of the stick here?

There's usually an allowance made for infiltration, fortuitous ventilation, in domestic heating design which I think works out at about a quarter or a third of the total heat loss. This is uncontrolled ventilation caused by leaks, due to wind/air pressure differences across a building and convection. I think you'd assume 1 or 2 air changes per hour for most rooms for design purpose and more for bathrooms and kitchens.

The air temperature is not the only factor involved in heating a building; the air transfers heat by convection, but there's also heat transfer by radiation and so the temperatures of the room surfaces have an influence on one's feeling of comfort. The ventilation heat losses are not the largest factor involved, as one might think.

Mechanical ventilation to maintain the indoor air quality (IAQ) usually depends on the occupancy. I think the CIBSE recommendation is about 16 litres per second of fresh air per person. There are lots of methods for recovering heat from extracted air ( run-around coils, thermal wheel, croos-flow plate heat exchangers, recirculation, heat pumps) but the domestic ones are usually plate heat exchangers.

I've been underwhelmed by the quality of many of the domestic offerings; manufacturers selling to clueless domestic consumers. The major advantage of a properly designed and specified ventilation system is that it maintains a positive air pressure; air leaks out. The air supplied is filtered and the air infiltration is reduced, greatly reducing the ingress of airborne dirt and particles.

 

[Nemesis]

Em - with my houskeeping it's possibly a matter of more muck being in than out...

 

[Flyfisher]

The ventilation heat losses are not the largest factor involved, as one might think.

I can understand that insulation will lead to warmer walls and increase one's sense of well-being within the house, but I'm surprised that ventilation heat losses are not the largest factor. Even using a change-of-air factor of 2 means emptying the entire volume heated air within a house every 30 minutes, and the Jersey website link I posted suggests 3-6 changes per hour for a living room and more for kitchens/bathrooms etc.

Having said all that, I freely admit I have no specific experience in this area so I'm perfectly willing to believe I'm wrong - but I do like to understand things and I'm struggling a bit with this one. Changing all the heated air in a house every 10-20 minutes seems like an awful lot of heat loss to me, surely much more than would be lost through the roof and walls?

Regardless of all this, I agree with NT about the quality of air being far more important than a few pounds saved on heating costs. In fact I've never been able to sleep comfortably without the bedroom window open and I think stable doors are a wonderful invention!

 

[alice]

Flyfisher, here's my guess. Wouldn't a good bit of the heat (as energy) be transfered and stored in the very walls, floors, furniture, etc of a house? Although I could see quite a bit of the heat (which is energy) leaving the house as the air circulates out, I can see quite a bit staying behind, too, stored in the walls, etc. The house itself acts as a heat sink.

After all, when a house is allowed to get dead cold (say, after a holiday) and you move back in and turn the heat back on, it takes a long run of the heater before you knock the chill out and the heater can go back to it's maintenence phase. It has to heat up all the stuff IN the house before equilibrium is obtained.

alice