We're just about to start a complete renovation of our early nineteenth century farmhouse in Perthshire - it's B listed (Scotland) so external insulation is not an option. We're looking to insulate floors, wall and ceiling (the lot!) in a manner that's as effective, environmentally sound, and space-efficient as possible. For the walls and roof we're looking at everything from the dreaded tri-iso to aerogels and various laminate boards and (of course) are seeing vastly conflicting advice and opinions - so can anyone point us at a good place to start with assessing the options, preferably before we crack completely and resort to the default ecooption of a steady buildup of cat fur, of which we have a plentiful supply... ;-)

Thanks
Richard

It's late, so here's a stream of consciousness:

I imagine your house is a sort of Georgian style foursquare building. If so, good, as a compact shape can be made quite warm.

Walls: phenolic foam (e.g. from ebay) or celotex etc. Use the best high-tech insulants you can get: living space is money. Aerogel is not currently worth it IMO. Consider insulated coving/cornice (commercial polystrene or homemade) for the thermal bridge where wall joins ceiling. Remember to insulate window returns on all four sides. You may need longer/thinner windowledges. Consider returning a thin layer of insulation up interior walls where appropriate (tricky one this as you could lose a lot of floor space and you lose heat capacity to some extent). I personally would aim for a U value of .25 as this is the current "standard", but you have to decide for yourself, obviously.

Try to buy the plasterboard in bulk and look for the best price. Try to seal the wall as best you can before you put the insulation up and ideally try to seal the insulation boards themselves and then the plasterboard. You want to have as many goes as possible at airtightness. Hopefully one of the layers will actually end up airtight. Use as few battens as possible: ideally none.

Ceiling: lots of mineral wool (local classified ads?) Make sure you at least have one good layer completely over the joists as this actually has more effect than the layer between them, which loses heat through the timber itself. If replacing a top-floor ceiling, consider a layer of foam underneath the joists to give a lost frame. Insulate loft hatches with insulation boards.

Floor: if solid, don't bother, just carpet. Ideally carpeting should have an airtight layer underneath that joins to the airtight layer in the wall with tape. If timber, draught seal the bottom with insulation boards and tape, or mylar or double-bubble if cheap (don't bother with multifoil). You may get a little condensation pooling at the bottom: so what. Put mineral wool in between the joists if you can, especially if you don't use insulation boards.

Fenestration: less important, but if changing any glazing, try to go double glazed with soft coat, krypton fill and warm edge. That is if the fascists will let you! Alternatively: secondary glazing. It can be affordable to get inward opening double glazed windows from France and use these, but it would depend on many factors. Glazing changes in renovation are more for comfort in the vicinity of the window than reduced energy use.

Can you put insulation boards on doors and cover with leather/baize? This could also be combined with an overlay for airtightness. I have never done this, but I think it would work and look quite good.

You may have already done this, but can't tell from the description:

The first thing to do, if I were doing it, would be to look at what you have and then work out:

1: For each component (windows, doors, walls, roof, floor), what do you have and what area of that is exposed
2: For each component find out what the U value is (how much heat does that component lose per metre multiplied by area exposed)
some typical U values can be found in the Green Building Bible
3: Warm air rises so give more importance to your ceiling then the floor
again read the GBB so that you understand the issues

When you've worked out how important each existing component set is, you can then set to work on evaluating the financial and embodied costs of changing that set: In some circumstances, you may find that delaying installation or allowing for future installation is more worthwhile than doing it now

Good luck

Posted By: JamesAsealing a house which was designed to breath normally causes huge problems

You've got to distinguish between air permeability/leakiness/airtightness on the one hand, and water vapour resistance/permeability/transparency on the other hand. They are two quite independent things - a building material can have either, both or neither. 'Breathing' should refer only to water vapour permeability.

fostertoms got the right direction as usual but nobody seems to appreciate that you will need lised building consent for the sort of internal changes being discussed and probably won't get it !
in historic buildings you need to take a much more holistic approach which on the one hand might look at planting a wind 'screen' on the side of the house facing the dominant wind, and on the other looks at carbon reduction rather than concentrating on energy reduction per se i.e nothing wrong with burning wood!
any internal improvements should be on the basis on minimal intervention and maximum reversibility e.g as much loft insulation as possible, insulate below ground against external walls, removeable secondary glazing sitting within existing openings, seasonal wall linings, shutters, foils (under carpets)over suspended floors, efficient heating systems, solar panels on adjacent outbuildings or against garden walls, ground source heat pumps (electricity supply from wind, mini-hydro, pv, or bio-fuel diesel generator) etc, etc

richardh,

Are the beams you mention the rafters?
You won't get a very good U value unless you have insulation either on the inside or the outside of the rafters. Just putting it between the beams won't work well (unless these are 13"X1" I-beams or something!), because the conduction through the wood itself will always be high. I doubt you can put much insulation them and the tiles even if you are re-roofing so I would ask whether it's actually necessary to be able see the rafters. Problem if so! You could probably leave purlins exposed without much effect, though.

fostertom, if you want more heat capacity, put more material on the inside of the insulation! 75mm of hempcrete just won't have a very good u value. The reason people like hempcete is mainly political. That said, trying to get good airtightness is important, and wet materials are good for this.