Garage and new border

Indeed, its probably the inverse square law, or something like that. So double the insulation thickness to halve the heat transfer through it.

Start with, say, £100 heating/cooling cost and cut that in half by installing, say, 100mm of insulation. You've saved £50 and spent £X on insulation. To save another £25 you have to install another 100mm of insulation, cost £X. To save the next £12.50 you have to install 200mm of insulation, cost £2X ... But when building new one could use a different formula. The Bricks cost £10,000 and the insulation costs £100. Increasing the insulation 10x only costs £1,000 - not significant in the cost of the building, but would be ridiculous as a retro-fit cost because the final £500 you spent on insulation may only be saving £10 a year - 50 year payback. Not many individuals will make that choice, hence why I think that government has to by Sponsoring it or Legislating it as a requirement.

My daughter is studying Architectural and Civil Engineer at Uni. She tells me that in their lectures (where passive House features in almost every lecture) her Prof has waxed lyrical about how irrelevant increasingly fuel efficient cars are compared to better insulating buildings. In his opinion there is far more money to be saved insulating buildings well, than in swapping a car for something that does 2x the MPG.

I haven't looked at any figures, but my own experience of trying to retro-fit improvements to a house, is that it is expensive and the payback is terrible. Of course the improvement is there for the lifetime of the building, so probably 100 years or more, but as an individual I have zero interest in the economics of that sort of timescale. Government could take a view on that - and use Tax £'s to insulate every building on the planet ... All I can say is that given the choice I would new-build as it is so much easier to insulate well from the ground up.

 

In a passive way, I assume?

 

I completely agree that the return on investment retrofitting a complete house to make it more thermally efficient is not great in the short to medium term, however one could always upgrade certain things like the loft, windows and so forth.

Going by the drawing below from http://www.aeinsulation.net/




The walls contribute 33% of heat loss which is a huge percentage and the loft 26% again a very big percentage to simply waste.
So if one was to properly insulate the loft (if applicable) and upgrade some or all of the windows, that would add up to 44% and may pay for itself much quicker.
Of course it's best to tackle the walls too, but in a lot of cases especially with the older buildings it's simply not an option.

This is where the government could play a pivotal role by perhaps introducing sliding tax breaks for those that upgrade their houses, the more "components" you upgrade the higher the tax break and for a longer period.
It of course amounts to the same thing as paying out incentives but with the added benefit that government does not have to come up with the money upfront.

 

We periodically have incentives to do lofts - cheap insulation offers, or grants for elderly / disadvantaged and so on. But they install the minimum requirement. I suppose that is the "right" thing to do, but then a few years later we decide to raise the minimum thickness recommendation - and then pay out grants all over again. It would cost peanuts to put twice as much in, in the first place, the labour / scaffolding / whatever is most of the cost.

Windows not so beneficial, so it seems. Payback much longer, and they are regarded as providing comfort, rather than insulation. But you need to get the windows to the point where inside glass temperature is only 4C colder than room air temperature, any more than that and the air by the window will fall [cold convection current], and then you get a draught, feel uncomfortable, and turn the heating up to compensate! (The 4C differential is an aim of Passive House design, dunno if it is achievable in replacement windows in regular houses though ...).

Dunno in a hot country, I suppose that a draught when it is hot is actually pleasant, so perhaps double glazing just needs to do its best to keep heat out in hot countries? External shading maybe does a better / equal job? There also seem to be some fancy glass coatings around that should help, and seem to improve every few years.

Depends how much heat is travelling through it I suspect that a passive house is losing the same relative percentages for roof/windows/walls etc, its just that hardly any heat escapes in the first place Sunlight [not that that is brilliant in UK Winters], body heat, and appliance heat are sufficient "heat sources" until temperature is well below 0C outside. Well, that's the theory! ask me in a year when the extension is finished, and we've lived in it for a winter, and I'll tell you if it has worked!

This is my grumble - that it is so blinking difficult to retro fit good wall insulation. I will be fascinated to hear from my Daughter, over the coming semesters, what they are teaching her at Uni in this regard; she seems to be taken with the idea that that might form the basis of a career for her. Either you insulate around the outside, and cover that with render or some sort of additional brick skin. Then you have to move all the windows further out (so they are inline with the insulation "layer"), and somehow join the new wall insulation seamless to the loft insulation - under the edge of the roof!!. Big job. Or you insulate each room, perhaps as & when you decorate it, and then you lose some room size, have to extend all your electric sockets etc., and move all the radiator plumbing on outside walls. Also that leaves you with your internal walls still connected to the outside walls (i.e. with no thermal break) and also the joists that hold up the floor and ceiling, so they act as much more significant cold bridges, and you have to make them air tight. It is far from easy. You could use Aerogel to insulate the walls - really thin, really efficient, "wonder material" insulation. Guess what? Yeah, it costs a fortune and is a nightmare to work with! But I am optimistic that we are on a journey, and Science will make further breakthroughs that will provide better solutions. We need lots of people doing it, to enable that industry to move forwards. Come on governments, more sponsorship please!

I like you tax break idea. We have plenty of "home renovators" here. Either individuals, or small building companies. They buy housing stock, speculatively, do it up and sell it. When they sell it there is Stamp Duty to pay (a tax on buying a house). If the renovator did X, Y and Z then the government could reduce / cancel stamp duty on the next sale - so renovator can either sell higher, or more easily. But at the bottom end of the market Government are always fiddling with Stamp Duty - right now they need the housing market to move, to get us out of recession, so their are various help-to-buy schemes, and Stamp Duty those tricks. Bit tough if you renovated with lots of Green Tech to get the stamp duty on sale, and then government scraps it for 3 years to kickstart the housing market!

Government fiddle too blinking much. If they just paid out, instead of dreaming up all these workarounds, then people would get on with it - rather than trying to figure out what the best way to jump will be, government isn't smart enough - the speculator parasites always clean-up.

 

Well I had to Google it!

UK Building Regulations requirements / recommendations for insulation. This is specified in terms of "U-Value", which is basically the amount of heat that flows through a given area of material, when there is a temperature difference between once side and the other. Lower values mean less heat loss. A U-value of 2 means have as much heat flows through compared to a U-value of 4 (apologies if that is obvious)

Year Walls / Roof / Loft insulation thickness
1965 1.7 / 1.4 / 25mm
1976 1.0* / 0.6 / 60mm (* 1.7 still for semi exposed walls)
1986 0.6* / 0.35 / 100mm (* 1.0 for semi exposed walls)
1990 0.45* / 0.25 / 150mm (* 0.6)
1995 200mm
2002 0.35 / 0.2 / 250mm Windows & doors 2.0/2.2, Floors 0.25
2003 270mm
Tomorrow ??mm

So walls now lose 5 times less heat than 50 years ago, and roofs 7 times less.

Passive House 0.1 / 0.066

Anyone who has a house build before 1976 is losing 5 - 7 times as much heat as a house built today. Or 17 - 21 times as much heat as a passive house.

I would vote for a government that was "bold" enough to make Passive House the requirement ...

 

Sorry Loofah ... your garage has got derailed ... further apologies for the mixed metaphore!

 

The "norm" here is still single glazing (yes single) and would guess that less than 20% of homes have double glazing, even for new builds.
Interestingly, standard windows have 3mm glass except where the windows are below a certain height or on doors, then 6.35mm (minimum) safety glass must be used.
Apparently there is talk that the spec is to be updated but nothing finalized yet, certainly nothing that I'm aware of.
There are regions that get cold in winter (still a joke compared to the UK and the rest of Europe) and thus have double glazing but it's still the exception rather than the rule.

In my new house, I am lucky that every single room (lounge and dinning room included) have one wall that is completely made of glass by way of big sliding doors and windows and must say the benefits in light levels and the (free) breeze far outweigh the few cold evenings we get in winter.
The single aluminum frame for these doors and windows do have neoprene rubber linings to keep out most of the draught when closed but they have no thermal breaks and the glass is all 6.35mm thick.
Actually it's two panes of 3mm glass with a "plastic" layer (0.35mm) sandwiched between them.
The house is only 10 years old.
Imagine that in the UK.

Window shades are quite popular here and glass coatings are becoming more and more widely used.

 

I'm guessing, but I would have thought more important in hot countries would be good thermal mass (to absorb the heat during the day) and then some sort of chimney-effect convection ventilation (openings low down in the walls, and an outlet high up in the top of the house) to drag the cold air through the house at night and "store" that cold into the thermal-mass ready to combat tomorrow's heat.

Not sure if double glazing would help you - it would keep the heat, captured during the day, "in" at night I think? Single glazing presumably re-radiates it back out at night.

In Arab countries the tendency is to build with narrow alleyways, so the sun cannot "reach" into them, so there is not much thermal-gain during the day. Everything painted white to reduce heat absorption.

 

What are you going to use it for? That may effect how best to adapt/improve it?

Has it got a [usable] South facing side that might be worth adding glass to and putting plants inside (or even people!)

 

@Kristen

Agree with you about the convection cooling and thermal mass.
My lounge and dinning room are double volume so I installed small windows close to the ceiling to create the convection effect.
(The only disadvantage is I need a long pole with a hook at the end to open and close these windows, not sure what the proper name for the pole is).

The "colder" air comes in via the windows and doors and pushes the hotter air out via the top windows.
The bedrooms have a much lower ceiling so could not do the same thing and the temperature difference is very evident.

As for double glazing, yes not really needed except for houses near busy roads and I guess it would help when a room is being cooled by air con.

Cast concrete roofs are quite common here and are normally made water tight by melting on a thick mastic on top then painted silver to not only reflect the sun rays but also protect the mastic from becoming hard and brittle due to the very high UV content.
Normally one has to repaint every 3 to 4 years.
You would be surprised at how many of these roofs are neglected and never get painted resulting in not only water proofing problems but elevated indoor temperatures.
What do the occupants do? install more air con.

 

Could you use an automatic greenhouse vent opener? Like the Bayliss ones? Possible disadvantage is that they open based on heat - so they would open during the day and might close too early in the evening (maybe you don't want them to open at all until dusk, and then to stay open well into the night to get the max benefit from cooler outside air). perhaps just install them "the wrong way round"?

http://www.baylissautovents.co.uk/

No opportunity to get a "chimney effect" into the roof space above? I presume you have a flat roof - perhaps a pitched roof would allow that to be built in? but if I am hearing you right they don't build them like that where you are?

Good point, hadn't considered that.

I remember landing in Khartoum at 3am in the morning. It was 120F, even at that time, and the International Terminal Lounge had ari con units built into the windows (which was a bit unwieldy). Trouble was they had thrown all the windows open, so the Air Con units were pumping cold air into the desert!! and generating heat out the back of the windows, of course, which being open was probably finding its way back inside!!

Don't tell me any more ... its far too depressing :(

 

Not a bad idea will investigate, thank you.

No chance in the bedrooms as they have a flat, cast concrete roof.
I could do it in the lounge and dinning rooms as that part of the house has pitched tiled roof so I installed the windows right at the top near the apex, it was easier than messing about with the tiled roof.

The three most popular roof types here (and I presume in most countries) are pitched tiled roofs, flat cast concrete roofs and galvanized sheet metal roofs (IBR).
The tiled roofs being by far the most popular, followed by the cast ones and then the galvanized ones which are normally used mainly for more industrial buildings.

Had a good laugh about the air cons with the windows open (I know I shouldn't).
It's surprising how many people do this, thinking that it's better as then it creates a mixture of "fresh" and "canned" air.

 

Something else that Passive House does well. Excellent air quality, because of the mechanical ventilation, but without much energy/heat loss. I imagine easy enough to couple an Air Con unit to that - but the point of Passive House is to remove the need for heat, here, and presumably remove the need for cooling in hot countries.

 

Totally agree.
It drives me bonkers when I see an air con unit mounted just below a window and that window is left wide open, very common in office parks.
I'm not sure about over there, but here very few buildings (except the big shopping centers and high rise offices) have a central air con unit, instead the individual units are used.

 

We only have air con in Offices / Shopping Malls (generally speaking).

I think more common in USA where they have both hot summers and cold winters, and I think it is common over there to have a central "furnace" with ducted air for heating, and then an air-con unit connected to the same ducting for the summer.

Strikes me the problem where you are is that these are retro-fit units. Nightmare to retrospectively plumb-in ducting for Air Con? Especially if you have no loft space ...

My solution would be to get government to require that centralised air-con ducting is included in New Builds, and then people can use a far more efficient central unit, rather than individual room units. A central unit could also draw in external air, for better air quality. I presume your individual room units are recirculating room-air? perhaps introducing some outside air? ... or maybe not introducing any? and let me guess - that's on the cheaper units? so folk save some capital cost but incur increased running cost by having to open windows to get rid of stale air :(