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I'm faced with the prospect of wanting to improve the insulation of a 4-storey Victorian (c1890) house in the UK that has solid stone walls and a top floor that is within the non-insulated roof space.

Given that this work could take a period of some years as we refurbish the interior (exterior cladding is not an option) is it better to start with insulating the lower floors or the upper floors? From an amateur's perspective it would seem:

  • Starting at the top would reduce the heat escape, but if heat input is still needed at the bottom that might just make the top floors uncomfortably hot.

  • Starting at the bottom would reduce the need for heat input there, but the energy would be easily lost from the top.

Which approach would be better?


More detail in response to points raised by answers:

  • A significant part of the layout (say 20% of the footprint) is an open staircase top to bottom, but most rooms onto it have doors that could be closed.
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First, draught-proofing

Close the gaps around windows, doors, between floorboards, gaps where pipes go into walls and floors. It's a cheap and relatively easy way to stop a lot of heat escaping, and to cut down on the convection currents that will take a lot of heat from the bottom to the top of the house.

Curtains around the stairwell?

Can you put a curtain around the bottom of the stairwell, and one just past the top of it? They should be floor-to-ceiling, and wall-to-wall. That will help reduce vertical convection. Do take into account safety; and, as with any work, check with Building Regulations.

Glazing

As you've currently got single glazing, then double- or triple-glazing offer lots of energy savings, as well as making it much quieter, and more secure. Not all double-glazing is equal: look for very low U-values, and try to avoid the national branded installers advertised on TV, which tend to be complete sharks. If the building is listed or in a conservation area, you may need to consider secondary glazing, which can offer the same improvements to air-tightness, quietness and physical security, but typically with higher U-values (i.e. higher heat loss).

Thermal imaging camera

I agree with Darren Cook that going round with a thermal imaging camera would be a great way to diagnose the biggest problems, and that in the absence of that, the roof is prime suspect (once you've got rid of the worst draughts). Do it in winter. You may be able to borrow a thermal imaging camera from your local library (some do this), or see if your council offers the service through other routes. If you've got a local college that teaches architecture or building-energy, see if they want to use your house as a research project: ideally, they'd come round in winter and do a blower-door test (to measure air-tightness) and go round with the thermal camera during decompression: that will suck in air from the outside through all cracks, and you'll see blue plumes on the camera where the leaks are. Run around putting post-it notes on the leaky bits, to go back and fix later.

Look for mould or condensation

If you see mould, or an area that repeatedly gets condensation on it (most noticeable after cooking or bathing) that will become mouldy, start there. The condensation is indicating that those places are colder than anywhere else in the house (i.e. fastest rate of heat loss per unit surface area), and mould can be a threat to health too.


All other things being equal, start at the top

If you start at the bottom, you'll still have cold draughts coming down the stairwell anyway, and heat will just go straight up and out the downstairs living area. Insulating lofts is fairly easy (compared to insulating walls or double/triple glazing windows), cheap, and has big big savings. You might be able to turn off heating at the very top of the house, and just let rising heat do the job.

Attic room

In this case, there's no loft to insulate, so insulating the roof becomes an altogether messier job. Assuming it's plasterboard on rafters, you could make a couple of small holes in the plasterboard and shine a light through, to look at the state of the insulation between the rafters. If it's not good, you might have to take the ceiling down, pack new insulation in (eg Kingspan K7 [pdf]), then stick some insulated plasterboard over the top (e.g. Kingspan K18 [pdf]).


Do floors when you replace the carpets.

If you're going to put down new carpets, get the floor under them insulated first. Once you've got new carpets in, you probably won't want to pull them up for years, so insulate before they get laid.


But be warned!

A lot of old British houses contain decades of botch jobs, which creates lots and lots of work when you start renovation, as Jack Kelly found out (warning - contains images that anyone contemplating retrofitting a UK Victorian dwelling may find harrowing)

  • Great overview. In this case, with the top floor being in the roof the usual trivial case of adding a think layer of insulation to the loft is not quite that easy. Insulating floors is something I need to learn more about. – Cheeseminer Feb 28 '14 at 9:19
  • @Cheeseminer edited to include a bit about attic rooms – EnergyNumbers Feb 28 '14 at 10:17
  • +Accept, for being the most comprehensive answer after a week, and for "All things being equal start at the top" - Many thanks. – Cheeseminer Mar 3 '14 at 13:05
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I think EnergyNumbers' answer is pretty comprehensive! Basically, do 'low hanging fruit first' - i.e. the things that have a quick result such as draught proofing (sealing around gaps/cracks/skirtings/windows etc); install heavy curtains and if you can loft insulation, which you should be able to do yourself fairly easily and cheaply. Then you can start with the top more thoroughly. Having said that, even if you cannot afford to do all of the works now, I think it will still pay of to have someone give you professional advice for a ' whole house ' solution/approach so that if you do things one-by-one you don't neglect any important overlapping or interconnecting issues.( if you are going much more airtight, you might need to look at ventilation issues etc). We are after all going on very basic information and a site-visit from someone may immediately throw up better strategies/more low hanging fruit and would give you a good list of priorities and 5 year plan to work towards,...This would also be helpful if you want to do some internal re-modelling of the layout,...And if you cannot afford professional fees, you may be able to pay less to a less experienced new graduate,....

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The scientific approach would be to turn on all the heating and use heat cameras to see where most heat is escaping. Otherwise just guess it is the roof.

I would start with the roof/top floor, then do the ground floor. Then the middle floors last. If you do find that heating living areas makes the top floors unbearably hot, consider moving your living area upstairs; you might need to do this anyway while renovating the ground floor.

  • Thanks for that reminder. It's probably a safe bet that the roof and the single-glazing are the major factors, but certainly following that up with a camera check makes much sense. – Cheeseminer Feb 28 '14 at 9:16
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I'm not an expert in this area, but:

I think this depends a little on the layout of the house. Certainly insulating the top first will improve the overall efficiency much sooner than starting at the bottom, but as you identify it does mean increasing the temperature difference between floors, which might not be desirable.

If you have an open staircase anywhere, this leaves you little choice. In this case warmth downstairs will disappear straight up the stairs and leave you just as cold. If this isn't the case - if you are able to heat downstairs rooms and close the doors - then there is more flexibility, and hopefully people with more expertise can chime in on how to judge things then.

  • Good point - I've added detail to the question. – Cheeseminer Feb 26 '14 at 12:05

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