The point of PassivHaus is to reduce energy consumption. That’s it. It is a design and construction method developed by Dr Wolfgang Feist over the past 20 years in Germany to reduce the amount of energy a house uses. It is not concerned with CO2 emissions, with sustainable materials, with embodied energy or embodied CO2. It sets two energy benchmarks — 15kWh/m2/yr for space heating and 120kWh/m2/yr to include space heating, domestic hot water, lighting, fans, pumps and main appliances. But this begs the question, is energy efficiency really all that matters?

It’s Not Mandatory

PassivHaus is a choice. Compliance with the Code for Sustainable Homes (CSH), however, is mandatory across most of the country. So if the self-builder chooses to adopt PassivHaus it will be as well as meeting the prevailing Code standard, not instead of.

CSH is ratcheting up from the current Level 3 (already Level 4 in some parts of the country) to Level 6 in 2016. PassivHaus, in terms of CO2 emissions, will do better than Level 3 and could scrape Level 4, but will not get to 5 or 6. We still need to develop the methods to meet those CSH standards and PassivHaus may lead us to believe we are already there.

Sustainability Matters, Too

Sustainability means considering materials, longevity and now, crucially, CO2 emissions. It means building houses that suit young and old alike, that can be adapted to meet changing needs over generations, that use replaceable materials. For the sustainable builder, energy efficiency is a factor within the overall design. Energy can come from a zero-carbon source and efficiency does not need to be the altar upon which all other things are sacrificed.

Lifestyle Has to Change

The energy split in a house built to 2010 Building Regulations standards is broadly 53% space heating, 19% hot water and 28% power. In a PassivHaus it’s broadly 12% space heating, 32% hot water and 56% power.

Electricity becomes the dominant energy source, with its huge CO2 overhead. It’s said that energy-efficient living is 20% technology and 80% lifestyle. PassivHaus addresses space heating but not hot water and power demands. It is only lifestyle that affects these.

It’s More Expensive

The consensus seems to be that PassivHaus will increase build costs by 15% to 25%. The extra design work will be a big factor, but it flows through every element of the build. A triple-glazed, PassivHaus-grade window will cost around £350/m2 while a double-glazed window with a U-value of 1.4 will cost around £220/m2. PassivHaus doors will cost 60% more than conventional doors. PassivHaus requires an obsessive attention to airtightness detail and that impacts on glues, mastic, tape, grommets — the things we would not normally think about.

Then there is certification — a similar process to CSH compliance where evidence of conformity must be produced. The certification itself will cost £2,000. Testing and evidence gathering could add another £4,000. And that’s on top of any CSH requirements. There are some 8,000 certified PassivHauses across Europe and said to be three or four times that number of ‘nearly passive’ houses — built to the standard but not certified, perhaps because fuel bills have more impact on sale value than a certificate could ever have.

Code Level 5 is Stricter

Consider a 200m2 house built to CSH Level 3 standard. The build will need airtightness between 7m3/hr and 5m3/hr, use low-energy lighting, solar thermal and a gas boiler with underfloor heating; energy consumption will be around 83kWh/m2, which translates into CO2 emissions of 5.6 tonnes per year.

If that same house is built to PassivHaus standards, probable real energy consump tion is around 140kWh/m2 (the 120kWh/m2 plus those other power usages not included in PassivHaus standard). But the calculation is more complicated as the 120kWh/m2 standard refers to primary energy. That is, energy going into a power station, not to the house. If we assume the PassivHaus is all electric then the energy entering the house is only 27% of that figure — the other 73% being power station and Grid losses. That translates into CO2 emissions of 3.9 tonnes per year — a reduction of 30% but still some way short of CSH Level 5 or zero carbon.

What it means is that the CSH provides stiffer targets than PassivHaus — and that is the way the legislation is taking us. And, it might be said, the CSH addresses all issues relating to sustainability — rather than the perhaps narrow nature of our current PassivHaus obsession.

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  • Tom Mason

    Lifestyle has to change:
    PassivHaus aims to set a standard that provides comfort and efficiency. You can then attach whatever complicated systems to your house to enable it to conform to whatever code you like. This is the great thing about Passivhaus- it sets a standard for the building fabric and not the managing of the occupation – ie you are not making people live in a specific way – it is up to the occupants whether they want to re-use all their grey water/produce electricity via PV’s etc etc In this way it is the perfect implementation of building regulations – regulating the building fabric only.

    The most expensive retrofitting you can perform on a house is the building fabric upgrades – fitting PV’s or whatever additional system is relatively easy comparatively. These could then be easily implemented by government incentives – and would be perfect for the ‘Green Deal’ – these things are essentially political, the PassivHaus is a blank canvas.

    It’s more expensive:
    On many levels this is hugely incorrect – CSH is much more expensive in the short and long terms. PassivHaus’ have been built for the similar cost of a uk building regs house. This is possible with trained contractors, cost estimates without trained contractors may attract around a 10% uplift in cost.
    http://www.building.co.uk/passivhaus-diaries-what-the-denby-dale-home-costs/3141749.article
    ref p.51 http://housingandbuiltenvironmentforum.files.wordpress.com/2012/02/csh-costs-2011-dclg.pdf

    Code 5 is stricter:
    Real consumption in PassvHaus’ depends on occupants – if they are ‘green’ it can be much lower – you should use the 120 average – as it is indeed, an average. Not only do your figures state that the PassivHaus produces less CO2 than your CSH3 building (this is another kettle of fish – this is worth a read: http://www.bdonline.co.uk/comment/blogs/zero-intelligence/5036954.article ), but if you added all the techno fixes to your property that CSH6 implies – with PassivHaus fabric you would be smashing the CSH6 CO2 levels out of the water.

    Your Code6 house’s permeability at 5or7m3/hr@50Pascals is like keeping your coffee warm with a power hungry perculator powered by a solar panel as opposed to the PassivHaus’ approach of keeping your coffee warm with a thermos cafetiere. And arguably, the coffee is better from a cafetiere.

  • Peter Chisnall

    You’ve missed the point, Passivhaus is an energy and comfort standard.

    You can build it sustainably if you want to.

    You can add eco-bling to achieve the code if you want to, that extra point for laying a concrete path to the compost bin is really sustainable.

  • Richard Tibenham

    I would agree with the comments raised above. This article is utterly misleading.

    The energy rating quoted above for the purposes of CSH are calculated using SAP. This is acknowledged to significantly under estimate energy demand and CO2 emissions through the omission of accurately calculated thermal losses through fabric junctions and the use of internal geometry dimensions, to name two areas of issue.

    The suggestion that a CSH level 5 homes will result in lower CO2 emissions is misleading.

    The key benefits of passivhaus are completely over-looked; These include;

    – low cost, low energy design through effecient form, orientation and air tightness.
    – Construction fabric which offers enduring performance (longer than renewable equipment lifespan)
    – Mandatory high levels of internal thermal comfort and air quality.

  • David Richardson

    I came to this article and comments (now a bit old) while looking for problems with Passivhaus. And there are some let’s face it. I do have some concerns about their use of huge areas of glass for solar gain for instance. Winter 2012/13 will have been a bit instructive for Germans where the Sun did not shine much for weeks. It does not take much common sense to realise that even when the Sun does shine in Winter, that it is dark 16 hours of the day when you need heating the most, and windows are an order of magnitude worse U value-wise than your walls.

    BUT

    This article seeks to compare apples and oranges. CSH was faulty from the start as it uses SAP calculations. More "browny points" are given in CSH for use of expensive add-ons rather than looking at the true use of energy in a property. The use of %ages makes valid comparisons even more difficult. In other words it is better to use expensive ways of generating energy than not to use that energy in the first place. Some very bizarre poor SAP ratings for houses using very little energy just underline this point.

    Harping on about how much CO2 is involved is surely so yesterday anyway – climate science is slowly realising that the world isn’t warming (15 years now) and that CO2 is not a major driver of climate. The "science is settled" has been replaced by an increasing admission that they have no clue. Some parts of the Northern Hemisphere (including the southern UK) are actually cooling a little over the last decade. Europe has had its third bitterly cold winter in a row. We need to consider how to keep warm in our energy efficient houses.

    Therefore what is important is energy efficiency and a Passivhaus and other similar standards (for all their faults) seek to minimise energy use.

  • Peter Chisnall

    Well I can really sleep easy now that I have been told that man made climate change isn’t happening. You read the Daily Mail too much!!

  • David Richardson

    Hello Peter – Thanks for your comment.

    I don’t read the newspaper you elude to. I don’t need my opinions forming for me. Believe me there is too much of that around trying to stoke up a dead theory.

    I am a meteorologist and can assure you there is no evidence that climate is changing due to man made CO2 emissions. Belief in AGW is faith based not science based. Many scientists now are questioning the failure of climate models to predict the first couple of decades never mind the next century. AGW was a theory and the real world data does not support it. We are in the potentate has no clothes on period now, but more and more scientists are noticing the lack of garments. If the most eminent theoretical physicist (Freeman Dyson) tells you it’s wrong – you should at least have an open mind. As Richard Feynman famously said "if your data don’t fit your theory – your theory is wrong". Here is the reality –

    http://www.drroyspencer.com/2013/04/global-warming-slowdown-the-view-from-space/

    BUT – This doesn’t mean we shouldn’t be seeking to look after our environment or build houses with high energy efficiency. I have had an interest in low energy housing for 35 years or so, but what we do should be based on reality not fantasy. Much current policy (like large scale biomass) is very misguided as I said earlier.

  • Peter Chisnall

    I am not a meteorologist or a scientist but I cannot believe that burning millions and millions and millions of of tonnes of carbon based fossil fuels in a few hundred years does not lead to something happening.

    Whilst we have had a few relatively colder years the trend has still been upward and by adjusting the climate models it can take this blip into account and still show that man has had an influence.

    I find it strange that I am accused of faith rather than a scientific base when I thought it was the vast majority of the world’s climate scientists that still hold the view that the changes in our climate are man made.

    Whilst you may not read the Daily Mail, Climate Change is not happening is the headline that they love as it gives their readers a reason not to change their habits and that has meant we are taking our foot off the gas in reducing our foot on the gas, if you excuse the inverse pun.

  • Raffaele De Angelis

    I could not agree more.
    Passivahs, with all due respect, is sustaianbility for dummies. It is a spreadsheet calculation.
    We have been working on several desing schemes using proper calculation and DSM, and we are producing higher standards than Passivhaus without having to undergo all the insensible strict conditions posed by that scheme. And we had the opportunity of comparing with the Passivhaus option
    But we could actually address realistic perfomance issues and really optimise design in order to obtain our results: save money and produce a better quality and performance with plenty of design freedom.

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