12 Oct 2010

£6k v £60k

Spent yesterday at the UK's first PassivHaus Conference, ably hosted by Alexis Rowell of Cutting the Carbon, who had hired Islington Town Hall Assembly Rooms, and also arranged a number of site visits in the afternoon session. Well organised, too, with around 250 people in attendance. Lots of familiar faces there, and buckets of enthusiasm for PassivHaus as a concept.

We also had a visit from Chris Huhne, the Coalition's minister for Energy and Climate Change, who made a 15 minute speech and answered a few questions from the floor. I thought he spoke quite well, but I heard one or two rather more negative comments from fellow participants. He bigged up the Green Deal, saying that it would be coming into effect with the forthcoming Energy Bill, which he expected to pass into law by next summer, and that he wanted every home in the UK to benefit from it between now and 2050 in "just one visit."

No figures were put on the Green Deal, but the indications are that it will be a soft loan of around £6,000, which can be paid off via the anticipated savings from lower fuel bills. The question is, will it work?

Now you can do a certain amount for £6,000, but it doesn't deliver a low-energy retrofit. Earlier in the day, I had visited 89 Culford Road, a Victorian terrace house nearby which has been given the PassivHaus treatment. This involved gutting the place, putting in a steel cage and rehanging all the floors, adding copious amounts of internal insulation, replacing all the windows, and threading in an MVHR system. The clients ended up with a stunning conversion (really lovely house, guys), but it had cost them an arm and a leg. Robert Cohen (the owner) told us that he thought the costs were around £60,000 just for the energy efficiency measures: seeing the house is just 120m2 in floor area, that's a gob smacking amount of money.

I don't know whether Chris Huhne was aware of this project, but he did refer to a similar scheme he had recently visited in Liverpool which had cost, in total, over £100,000. I expect this was one of the Retrofit for the Future projects which are being carried out all over the country at the moment, average spend about £120,000 per unit. No way, said Huhne, is that a realistic amount to spend on a retrofit. For once, my sympathies were with the politician.

But, on the other hand, £6k doesn't buy very much in terms of energy saving. Indeed, it may cause more problems than it solves for, without a coherent ventilation strategy, many amateur attempts at dry lining and draft proofing simply end up with pools of condensation and black mould. £6k puts us into that territory.

Now it may be that when the Green Deal is finally revealed, it will have one or two added elements that address these problems. Chris Huhne kept referring to a series of disasters which had happened to the Australian version of the Green Deal, where cowboy builders had been caught nailing through electricity cables and, as a result, the scheme has been derided in the Australian press. "We don't want that happening here," he said. At this point, he sounded like a true politician: afraid, very afraid.

But if £6k is too little, and £60k is too much, then the challenge must be to work out how to make robust alterations that cost somewhere in between. For a start, it might help us to define exactly what the hoped-for outcome should be. PassivHaus is great at using minimal energy to deliver even temperatures and really comfortable surroundings — shirtsleeves all winter — but in reality very few UK homes can achieve this level of comfort, even with a heat load ten times the PassivHaus standard. So it may be that we have to aim lower: say, looking for retrofits that manage to avoid condensation and mould problems and can guarantee residents a basic temperature, like 16°C, through most of the building, on a minimal heat load. Hair shirt heating. Anything above that would be classed as a luxury.

PassivHaus is already addressing these problems — to an extent — by introducing a lower standard for retrofits, known as EnerPHit, which is based on a much easier to achieve heating metric of 25kWh/m2/a. Whether this hits the sweet spot for the UK retrofit market remains to be seen, but EnerPHit still requires dramatic airtightness improvement and MVHR, so the likes of Chris Huhne will probably not be banging on the door just yet. MVHR can be difficult to incorporate into a new build, but in a retrofit it can be next to impossible to find the space to run all the ducting, without going through a total gutting process at costs which make demolition and rebuilding begin to look like the cheaper option.

This is all good stuff, close to the nitty gritty of what this blog is all about. My feeling is that this government (just like the last one) is all at sea on the retrofit debate, and is about to throw a large amount of money at it without really understanding the issues. As yet, I am not convinced that the PassivHaus standard is the solution for the UK retrofit market, but I am bowled over by the enthusiasm of the UK standard bearers. If anyone is going to sort out this conundrum, it's this lot. Count me in.


  1. Nice post.
    Strine for cowboy building is 'shonky'. We are likely to see a lot of shonky for £6000 a dwelling.
    We have just extended and refurbished a 1900 detached 140 sq m 'cottage'. This has cost £140k. I estimate that about £50k of that has gone on energy efficiency, including new windows and doors, solar heating, condensing boiler, high efficiency lighting, a porch/vestibule plus insulation in the new build parts and cavity wall infill in the older parts. Nothing fancy, mind, and nothing remotely close to Passivhaus, which would not be appropriate anyway. It is eye-wateringly expensive to do the basics properly. £60k for the energy efficiency features of 89 Culford Road sounds very optimistic to me. How are these costs separated out?

  2. I wonder how much original period features got ripped out and destroyed in the 60k refurb.

    I own an Edwardian property, and judging from the various measures that can be taken, I cant do much with it to improve its energy inefficiency without vandalising the place irretrevably. Which is a shame!

  3. (I suppose I could do something with 'rainwater harvesting' though... snort)

  4. I wonder (when we have lots of carbon-free energy generation - nuclear of course) if we'll look back on these refurbs the way we look back on the chopping down of all those railings during WWII...

  5. In order to really improve buildings in this country where many of which have 60mm or less cavity wall void space, it is necessary to use some form of external or internal insulation. Filling these small cavities with cheap rockwool or beads is totally inadequate for the really big savings on heat. External insulation would solve the problem easily without resorting to gutting the interior but this would still be quite expensive - I would think at least 15k for an average house. Internal insulation is far far harder to get right - condensation problems if got wrong! - so many junctions to navigate around so many thermal bridges to mitigate. Government as usual is being highly unrealistic but at least the debate has started on how to get these big improvements over today's old drafty housing stock.

  6. I think realistic goals are a must, you can't expect a perfectly insulated house on a budget.

  7. Alan ClarkeOctober 12, 2010

    I am working on a couple of these TSB retrofits and of course one reason they cost £120K is that there is £150K to spend (inc VAT and fees). However these projects are prototypes, and aimed at a very challenging target to meet the TSB criteria.
    Even so, one RSL I'm working with is retrofitting a pair of semi detached houses for this budget, rather than just one house.
    Still, even with economies of scale and mass production of kit, £6K won't go far - maybe it can go some way to upping a basic retrofit to a low-energy one, but a dedicated retrofit to energy use by 80% has got to cost significantly more than that.

    On the subject of ventilation, I think the powers-that-be don't get the ventilation issues. Once you start making a house airtight it's hard to stop at precisely say 5ach@50Pa, and 1ach@50Pa isn't difficult in a full-on retrofit (this is our experience after measurement in a number of cases). If you don't include proper ventilation you will have serious problems. For retrofit a system of continuous mechanical extract may be the better option - less ductwork, maybe only 25% the cost of full MVHR but still controlling ventilation heat loss and ensuring good air quality.

  8. I'd like to propose a Culford-style refit for one of London's worst performing buildings - Buckingham Palace. What a great demonstration project that would be, though not sure that 6k would cover it.

  9. Culford Road would have cost far more than £60k, as it involved a roof extension, and many other changes as well. The owner reckoned that £60k would have covered just the energy efficiency improvements. Because it is in a conservation area, the externals had to remain identical at the front and sympathetic at the rear. Housing built in this era was that was highly adaptable internally - they don't come with masses of internal features that have to be preserved at all cost.

  10. As i understand it you can just wack in some rigid foam backed plasterboard, and you providing you dont leave gaps you wont get internal humidity issues (any gaps = mould).

    But this loses room space, and so most people therefore won't want this, especially those already living in boxes.

    And with some constructions this could move the condensation point into the structure, particularly older properties with no cavities.

    I can't see external insluation coming in under that figure, you have to change all the opening details and deal with the roof and wall junctions to avoid really bad cold briding (and lots and lots of mould) you can't just wack on any old insulation.

    I am already seeing a rise in companies adding in innapropriate or poorly installed insulation causing the property to become un-morgatable.

    I would like to see a set of standard details drawn up covering the most common buildings needing upgrading, and the methods of doing so safely. I know we do them for timber frame, but i know nothing about older brick and concrete buildings and what the viable methods for those are.

    I can't see this being anything but a disaster if the goverment get involved. I just spoke to someone who only found out their house was timber frame (it's brick clad) when they went to sell it, and the surveyor pointed out that someone had blown insulation into the cavity, no morgage company will touch it now, and they are going to have to pull of the brick cladding to chip away at the blown in foam.

    Your dealing with householders who are very uninformed, and companies who are either incompetent or dodgy.

  11. "Green Deal to create green jobs (Press Release)"

    "Up to a quarter of a million jobs by 2030, says Energy Secretary"

  12. Sorry about that, here's the whole thing.

    Very interesting article- thank you. You wrote:

    "My feeling is that the government (just like the last one) is all at sea on the retrofit debate, and is about to throw a large amount of money at it without really understanding what the principles involved are. "

    I think it's worse than that. I think they are all over the place with energy policy generally and seem determined to muddle energy saving with 'benefits to the economy'.

    They seem desperate to show that energy saving measures always result in money saving despite this being obviously untrue. It is a shame they do because it obscures a very useful debate about just how much insulation it is reasonable to put into old houses, how it should best be done and yes, how much that would cost.

    My guess is they don't do this because, for them, it is not really the main point of the policy. Following you link to the Green Deal leads to these two headlines:

    "Green Deal to create green jobs"

    "Up to a quarter of a million jobs by 2030, says Energy Secretary"

    It's not about energy it's the fabled 'Green Economy'. This scheme is about the doing, not the outcome. It's out of the same bag as the RHI and FITs, what a shame.

  13. Putting insulation externally avoids most bad points of cold bridging that is why it's a superior method but unfortunately more expensive than internal wall lining. Insulated plasterboard is totally inadequate. The target should be realistic to modernise the old stock to something near the building regs of today. So 50mm+ celotex/kingspan/Xtratherm dry lining or 50mm+ external with brick slips or render finish & fill any cavities with a weak concrete mix - that will give big savings without aiming for what the government thinks sounds good but will achieve little due to the limits of money, practicality and know how.

  14. "Insulated plasterboard is totally inadequate."

    Inadequate compared to what>?

    External insulation just isnt practicle in a number of cases, you either spend lots of money doing it properly, or you don't do it at all. With current tech there just isnt a go between for alot of stock housing that won't cause major damp issues.

    Insulated plasterboard if properly installed will make a significant difference to alot of housing with poor to no insulation. It's only inadequate if your target is passive house.

    A target i feel is so far fetched for most housing on a low budget, i don't see it worth contemplating.

  15. As with any project you have to take the good with the bad. Sure spending 60K to 'green' up your house will make you feel a lot better about your self but you will never see the return on that within your lifetime.
    We recently spent 7k fixing up our place and apart from the fact the house is now draft proof and 30% of our electricity is produced from our roof installed solar panels. We are not likely to make that money back within the next 10 years.

  16. I don't understand how the 60k Culford Road energy efficiency 'improvement' figures are arrived at, given that a large amount of internal work has been done. Surely these costs are bound in with the much bigger sums for the total build cost. Where are the boundaries drawn? 'Improvement' with respect to what?

  17. I can't really tell you much about the Culford Road project - I am only going on what Robert told us as we passed through on a flying visit. But you are right - it must have cost way more than £60k in total - it's a total internal rebuild.

  18. @ Anonymous

    >Insulated plasterboard is totally >inadequate."

    Inadequate compared to what>?

    Inadequate to address the topic of this discussion.

    Even 25mm of kingspan board is inadequate to reach anywhere near the current building regs standards. A lot more thickness is required - getting to passivhaus thicknesses is certainly not sensible, practical or cost effective on retrofits of current stock. (think 50mm celotex or 75-100mm glass wool as a sensible starting point)

    Would you consider putting 10mm of polystyrene down for your loft insulation??

    You don't seem to understand that by externally insulating a house that all the structures are then put on the warm side and thus the condensation risk is vastly reduced. That superior result comes in at around £100 per m2 so not cheap at all.

  19. Mark SiddallOctober 14, 2010

    I'm working on three TSB retrofits with Alan Clarke (two houses for the RFF pot of cash).
    Right now in the UK thick insulation is not as cheap as it could be. MVHR also costs more than it would in a fully functional market.

    What we have is the old supply and demand conundrum. (This did not seem to be appreciated by Huhne at the conference.) Once the scales of economy kick I feel confident that the costs will have the opportunity to fall significantly.

    A 2-3 bed house, according to EST, spends ~£600-800/yr on heating and hot water. The lifecycle costs also have to be considered.

    I did some rough numbers - at today’s prices - things almost stack up (esp when taking into account the non energy benefits). In essence, over time and with the market working properly (even without subsidy), affordability is possible. For now you won't get rich but it is an affordable way of reducing CO2 emissions.

  20. Interesting comments, Mark. I guess the sums adding up all depends on what answers you are looking for. My feeling is that we need to move away from insulation-based solutions (i.e. how thick should the insulation be) towards a PHPP metric which defines a delivered temperature, and then work out how best to achieve it with the minimal energy input.

    But it's still probably way out line with what is being proposed by the Green Deal which, as someone has already pointed out, is as much to do with job creation as anything else.

  21. "Even 25mm of kingspan board is inadequate to reach anywhere near the current building regs standards."

    Yes, but my point is i don't think that alot of housing can be upgraded to meet those requirements without going into double figures.

    "You don't seem to understand that by externally insulating a house that all the structures are then put on the warm side and thus the condensation risk is vastly reduced. That superior result comes in at around £100 per m2 so not cheap at all."

    Sigh. Read my posts, i understand it fully. I deal with buildings where it has been done improperly leading to moisture issues and morgagability issues.

    You have to change all the window reveal details for weathertightness, and all the eaves details so that you properly wrap the building and not just the walls. (i see alot of issues where the ceiling junction of top floors are covered in mould due to cold bridging)

    Also some structures have insulation between the structural members (steel, timber frame and some in particular). And you can still get dew point issues by putting insulation on the outside.

    I fully understand the issues as i deal with the bad results of improper installations or improper materials for the construction.

    The point i am making is that with current tech, there is no way of doing anything worthwhile externally with 6k, and even suggesting it is treading down a path that will lead to widespread issues.

    adding internal insulation won't add much, and it won't be popular* but it's easy and risk free in a number of places in conjuction with cavity insulation (where appropriate) and the typical windows/loft upgrades.

    *One of my rooms is literally wide enough to fit a bed, just adding 1 layer of backed plasterboard would mean i would struggle to fit a bed in that bedroom.

  22. Yes, I would agree with most of that, Anonymous. Externally insulated houses still need an air tightness barrier on the inside to prevent interstitial condensation issues and the problems around windows and eaves is a pain to sort - but done properly will give a very satisfactory result.

    Internal will always be a bit of a struggle unless the houses is cleared out, but yes it is cheaper and more for your DIY folk.

  23. Mark SiddallOctober 18, 2010

    Fully agree that PHPP based approach should be at the heart of the decision making process. We are using PHPP to assist our decisions on retrofit.
    A whole systems approach is certainly what is requiredas it enables the economics of a retrofit to work more effectively and affordably. (It is this approach is what enabled us to retrofit two homes where others are just tackling one.)

  24. Anonymous have you read this irish web article?? Suggests internal insulation is far from risk free and external is less risk (if done properly of course)