Like many architects who are interested in building performance, I’m interested in the concept of Passivhaus, Like many architects, I’m also interested in ideas. Most of our buildings have aimed for the particular, and have aimed to more than just have low energy bills and use resources wisely. I mentioned to Olly Wainwright that my worry about Passivhaus was that it was a one size fits all approach, and was jumped on by a few zealots who have signed up to the cause because, well, if you’re a true believer, and this how you make your living, there’s no room for doubt is there? Passivhaus Zealots, I’m not attacking you – just wondering whether in your beliefs, there’s room for a conversation? We want the same thing, ultimately, don’t we?
What I meant is this. Architecture – the design of a building for a given brief, a given context and given client is a very particular thing, and we’ve always used each building as a mini manifesto with which to explore a particular issue and a particular way of being in one place, for one particular group of people. Glenn Murcutt used to say that a building needs to do more than just perform well, and I’m with him. My nervousness about Passivhaus is the potential distraction that the performance is the end game.
I’ll explain what I mean with three of our houses, each which has a very different design approach, and each which explores a different idea about building envelope and performance.
First up, Moonshine. In many ways it’s a very naïve building, but the big idea, the big guiding concept, works. We wanted absolute transparency in the living spaces on the ground floor, partly to let the idea of landscape run through the building, and partly to let the building have a flexible skin, which we could adjust depending on the weather, light and wind pattern, and spill outside accordingly. Upstairs, we wanted to feel like we were camping in the treetops – to be able to slide back big boors in our bedroom at night and hear the forest noises, and see the canopy from the big ash tree almost as if it was in the room.
It’s an uber lightweight building (everything had to be carried down a track in order to construct it), and the solid bits are super insulated, but it’s a very leaky building. I was over influenced by those great antipodean shacks where everything opens up and shuts down, and where the concept of a building is a finely tuned yacht that you constantly adjust in response to weather. The best thing about is the solar gain on bright winter days that mean that we don’t need any heating until after dark. The fuel for heating is all from the woodland around the house, that we cut, stack and dry the previous year.
Could this have been a Passivhaus? No way – we enjoy opening windows too much, and we like the house being able to physically respond to the adjacent mircroclimate. Moonshine isn’t a particularly good building, but it does do some things well.
Moonshine is deficient because there’s far too much glass, and it’s far too lightweight. We tried to remedy this in Starfall – the next building we did in the same valley, for a family much like our own with a bunch of rumbustious growing children who would leave the doors and windows open. The big idea in terms of building envelope is thermal mass. I wanted – to the point of obsession – a super-insulated thermal envelope with as much exposed thermal mass as possible, and far less glass. So, we focused on placing windows were necessary to gain views or the first chinks of morning light, and, importantly (a repeated mantra of ours) to allow the landscape to run through the building and cooking area to be right between two large sliding screens that could disappear into the walls.
This family wanted, like ours, an ambiguous relationship with the outside, one where the surroundings felt like part of the house and an extension too it. And what’s great is that they can do this – they can leave the doors and screens open in chilly spring or autumn weather, and because of all the heat retained in the thermal mass, the temperature hardly drops. Of course it isn’t as efficient as a Passivhaus, but it is still uber efficient, and, critically, it reinforces the notion that a house isn’t a sealed little box that you go into or out of, but instead an intelligent envelope that allows occupants to dwell in a responsive way to one particular place.
Nowhere more true is that than the Caretaker’s House. This time, we wanted a super-insulated ultra lightweight responsive well-sealed envelope, and we wanted to make it from wood from the forest in which it sat. Pretty much every significant part of it is. We used 5 different species of timber for the house – for the frame, the cladding, the floors, the worktops etc. There’s no wet trades in the building, which sits on tiny mini steel piles.
But, in terms of Passivhaus principles, that’s as far as it goes. It’s heated entirely with waste wood from other manufacturing processes that exist on site, and, like the other houses, the occupants wanted the house to have a symbiotic connection with the surrounding woodand – one where it could extend or retreat into the surrounding landscape, depending on weather, mood or occasion.
Maybe I’m just instinctively prejudiced against regulations and legislation. Maybe I’m an over enthusiastic hopeless romantic, but as far as I can tell, this symbiosis with context, this delight in the particular, this desire to have a flexible responsive skin that is operated intelligently by the occupants would be banished if we’d tried to go for Passivhaus conformity – and yet all of these houses have tiny running costs and very low emissions.
I may be wrong, but that’s great, tell me I’m wrong, and let’s work together to find a way that environmentally responsible buildings that perform well can also do the other stuff – in embracing the particular and the delightful, and respond directly to site, context and use.
You are not wrong.
Piers! You’re being suckered into the idea that performance criteria leads to conformity! Would you be annoyed that a car you bought used more fuel than you hoped it would? Do fuel- efficient cars have to look alike? The winner of the Passivhaus awards a few years ago was, like moonshine, all glass and transparent, and beautifuuly detailed- a real bit of architecture with its own big idea. It also had a measured energy use for space heating of less than 15kWhr/m2yr. That’s all Passivhaus is; it cuts out the greenwash and gives us actual performance rather than another target a building fails to reach. It recognises the gap between theoretical energy loss and actual performance. It doesn’t dictate what the building looks like, how much glass there is, and certainly doesn’t stop you opening windows. So on your NEXT building, keep the big idea, keep the glass and the thermal mass and the timber and the lightweight frame and whatever makes THAT building unique and brilliantly idiosyncratic, and make it work.
There seems to be a common assumption by many non-Passivhaus-aware architects that Passivhaus ‘zealots’ (interesting choice of word – bit like the Zero Carbon Hub brigade labelling the Passivhaus route to carbon compliance ‘extreme’!) have no interest in architecture with a capital ‘A’, no understanding of ’connecting with nature’, no capability of appreciating the joy of morning sun or the sway of branches in a tree canopy. My experience of most Passivhaus designers is that the importance of good design ideas, in response to people and place, are just as paramount but we just choose to achieve, or at least aspire to achieve, these ideals in a manner that also addresses the need to minimise our impact on the planet, with particular attention paid to the worst polluter of all, energy use. Disappointingly, this rather insulting stance can only have come from a position of ignorance and perhaps an unwillingness to properly understand Passivhaus design – I’m looking forward to you engaging with that aspect. the Passivhaus movement can only benefit from higher-profile designers like yourself embracing its principles.
I agree with you that the press has to date focused on the more mundane or socially-driven examples in this country but to dismiss the likes of Ty Foel, Plummerswood, Crossway et al as having no ‘connection’ with nature just seems lazy. Early next year, I will be fortunate enough to judge the 2014 International Passivhaus Awards – unlike our Stirling Prize, we will be able to judge each building on its architectural merits safe in the knowledge that each one has been quality-assured to be amongst the most energy efficient buildings in the world. I compare that rigour with your statement that your admittedly leaky building must be ‘uber-efficent’ because it has thermal mass etc – is this kind of assumption still acceptable if you can’t back it up with some real data on performance?
Interestingly, another online debate has sprung up recently with respect to another ‘eco-house’ design seeking to connect with nature. Rather than repeating some of that technical discussion here I recommend you give it a read – http://www.houseplanninghelp.com/hph034-balancing-environmental-design-and-low-energy-design-with-wilf-meynell/ There are some interesting points about ‘connection with outside’ that are relevant here I suggest. These aspirations are all very obvious and straightforward to achieve for wealthy clients in idyllic rural sites such as in your highlighted projects – yet they are equally possible with Passivhaus and can be also translated to urban sites. Good luck and I hope to see you at future Passivhaus events.
Link here to the last iPHA Awards in 2010 – http://www.passivehouse-international.org/index.php?page_id=209
Perhaps for these beautifully designed, detached houses, ‘Passivhuas’ may not have been the best solution. It’s certainly difficult for the cash strapped self builder to justify the increased cost and technical difficulty that ‘Passivhaus’ certification adds to the build. The use of often ugly triple glazing also seems restrictive and unnecessary when building throughout most of the UK, but surely the decision to seek ‘Passivhaus’ certification should just be another of the many considerations weighed when researching any project. But I think ‘Passivhaus’ really comes into its own when used for social housing in our towns and cities. I’m sure the residents of St Mary’s close in Oldam aren’t too worried about the restrictions that their triple glazed windows may bring when as a trade off they get the basic comfort that being warm at a reasonable cost brings. A dilapidated brick terrace house with plastic film taped to the leaky windows doesn’t do much for connection to the immediate context either.
I believe that honesty is an important aspect of any building project, whether an industrial building or a domestic retreat, especially with respect to energy/carbon sustainability. I feel that in some cases the ‘intention’ to design and construct a sustainable building is seen to be enough. In reality the inconvenience of design limitations, costs and subsequent project team ‘buy in’ can dilute the influence of sustainable principles, that is until project completion when, for marketing purposes, the subject of sustainability is catapulted to the forefront once more.
As intimated in Lukes comments above, adhering to stringent performance criteria such as Passivhaus could and maybe should be embraced on suitable projects, but one should not forget the often competing criterion of embodied carbon within the materials and construction processes. As highlighted by Piers, designing and building with longevity and locally sourced products in mind can go some way towards producing a sustainable building that does not adhere to the ‘in use’ performance doctrine.
I feel there is room to express ‘sustainable design’ in many ways, but we must be transparent and not overstate the sustainable virtues of a project, whether it is a high tech (potentially higher embodied carbon) low-energy building or a draughty locally sourced project. Improved carbon accounting should also help fight the cause of low embodied projects.
Piers, I think we share passion for good environmental design. If I take Meredith’s analogy to cars and run with it: no one thinks good fuel economy and reliability of an average car are boring. This is what’s expected from them. The disappointment comes when these promises are not delivered. You seem to imply (and please correct me if I’m wrong) that the freedom of design and passivhaus are somehow mutually exclusive – they’re not. We use the passivhaus standard as a tool (amongst other tools) that helps inform the design rather than dictate the form, concept etc. In the end, we just want to design and deliver better and more resilient buildings. We owe it to our future generations.
PS: hope the debate will continue face to face
The full text of this comment is as post on my blog at http://markstephensarchitects.com
Let’s start with explaining what the Passivhaus standard is about:
1. It’s the design and construction of ANY building (not just a house) that has a comfortable temperature for every room, day an night throughout the building for every day of the year with very low heating bills. A building needs to meet an exacting standard in terms of design and construction in order to meet this standard. You can get your building certified as a Passivhaus via an accredited Passivhaus certifier through the Passivhaus Institute.
The temperature for every room is designed, calculated and built to be 20 degC
It’s a common misconception that a Passivhaus requires no heating; this isn’t the case – for a largish, detached house the heating costs are in the region of hundreds of euro rather than thousands per year.
2. The house is designed and constructed to be very comfortable to live in; no condensation on windows (internally), no mould growth and ventilated with lovely clean air.
And that’s more or less it.
I’ve also written a blog post on Passivhaus fallacies HERE
Let’s look at the words in bold and if you ask ANY person, would you like a house that has very low heating bills and is very comfortable to live in you’d obviously say YES.
And that’s it, it’s just a bunch of physics, maths and construction methods that achieve these two things.
With the Passivhaus methodology you can design, model and test different designs, configurations and construction methods in order to EXACTLY determine whether you are meeting these two key goals before you build without any guesswork. The calculations are just another weapon in the architects armoury to help achieve a better building for your client.
The trick for architects is to use the physics/maths in a way that doesn’t compromise the delight of good design and I’ve already written my worries on this matter in my post on: A few observations on being a certified passive house designer and since I’ve written this post the situation has changed and the certification is split into Certified ‘Consultants’ and Certified ‘Designers’ (interestingly the exam is the same but to be a certified Designer you need to also give proof of design qualifications.
The gorgeous projects by Piers Taylor could have been designed to be Passivhaus projects, you as the architect have the choice to decide whether you want to meet the standard that meets the goals described and equally you have the choice not to. That’s what Passivhaus is giving you, a choice. The choice you make can determine EXACTLY what your heating bills will be for any particular month or for the whole year. Now you can choose to ignore the results and pay a little bit more for your heating or you can take the results on board and reduce your heating costs – I know which one I (and I guess most people) would choose if they could afford it. Equally you can also choose whether you have your project certified or not; currently in Germany some architects certify the first couple of houses but the ones after that (meeting the same standard) tend not to be certified Passivhaus’ – again you have the choice.
Well put Mark – just a couple of comments I’d add:
You say “the temperature of every room (in a Passivhaus) is designed, calculated and built to be 20 deg C”. I’m not sure if you really meant that Passivhaus occupants are in some way obliged by the building to live at 20 degrees, around the clock? However you do seem to imply that. I don’t see why Passivhaus occupants can’t live at whatever temperature they choose – I thought the point of the fabric design principles in Passivhaus was to increase people’s choice of living temperature, by making it easier and cheaper to achieve the temperature they want.
I wouldn’t pick this up, only this very misconception that Passivhaus in some way ‘dictates’ a fixed living temperature seems to have (mis)led some to criticise Passivhaus fairly publicly, and it’s a shame to risk perpetuating the confusion?
The other point I wanted to make was about the cost of Passivhaus. You (Mark) say you expect ‘most people would choose Passivhaus if they could afford it’ and from what I’ve seen and heard, I’d heartily agree. What I wanted to question is how unaffordable Passivhaus is. Yes, the capital costs may well be higher – the usual ‘over-costs’ of Passivhaus are quoted at between 15% and 0%, though increasingly settling at the lower end (0-8%).
However, energy is not exactly free, so the critical question is – what will the whole-life costs and benefits be? One set of calculations I’ve seen suggests that the ‘whole-mortgage-life’ costs of finance-plus-fuel (over a 25-year term) is about equal between a 3-bed-detached Passivhaus and same-shaped non-Passivhaus – meaning Passivhaus is just as “affordable” but as you suggest, a lot more comfortable – and after the mortgage is paid off, of course, the occupants are quids in. Others suggest a ‘pay-back times’ can be a lot shorter than this – making Passivhaus sound like a pretty good buy.
Although the house is designed, calculated and constructed so that the house is at a constant 20degC internally, yes the occupants are free to open windows and have the temperature at whatever they like; ideally to promote sleep bedrooms should be a little lower (18C). Again Passivhaus comes down to choice – if your rooms at at 14C in a poorly designed/constructed house then you don’t have the choice of opening windows/doors.
I’m working in Ireland where the Building Regs is currently higher standard than the UK and in terms of fabric the costs between a ‘standard build’ and Passivhaus are largely the same; we have a slightly more rigorous standard for airtightness but this is an ‘on site’ standard rather than a capital cost.
We’re just about to do the payback calculations on course – watch this space…
It is easy to define Passivhaus as an energy performance standard, but to my mind what is key is the ability to actually deliver that performance in practice. In fact I’d say the actual kWh standard itself come second – it is only because Passivhaus closes the “performance gap” that it is worth building to such a standard.
So how does Passivhaus do this when others have only just realised there is a problem?
Two stages: first we build a numerical model of the heat movement in and out of the building. This isn’t a fancy dynamic model, just a monthly energy balance, but some areas such as windows are accounted for in surprising amounts of detail. This is because they have a significant bearing on the result – the trick here is to not omit anything important, even if it’s inconvenient or makes your design look less efficient that you hoped.
The second stage is to build the building the same as the model. This means working out details properly, and ensuring they are built as designed; knowing how to build airtight, and testing for leakage; checking that the insulation specified is installed, and installed properly. Follow the recipe and the results are good: co-heating – actual physical measurement of building heat loss – demonstrates that Passivhaus reliably delivers buildings which are as well insulated as the model says they will be, whereas the results with other “low energy” builds reveal heat loss up to double the design figure. (Leeds Metropolitan University: ‘Bridging’ the Fabric ‘Performance Gap’)
Now that we have the tools to build like this, it makes sense to build to the Passivhaus energy standard and ensure high levels of comfort, air quality, and energy efficiency.
It’s great to have this conversation – even though I have had it numerous times before. The Passive House performance standard does not preclude aesthetics, nor usage patterns. You may notice that the family in the Guardian article had their windows open – and still enjoyed comfortable indoor temperatures. You can open up your Passive House as much as you like. Indoor-outdoor flow: no problemo. Wood fire: definitely possible. I think it was in 1999 when I ran a workshop titled: Is Passive House an excuse for boring design? Even then there were some very interesting projects, like e.g. this http://www.pressebuero-pfaeffinger.de/images/oehlerbretten.jpg around to demonstrate that creativity is not restricted by performance requirements, neither structurally nor thermally. Yes, it is a bit more difficult to design a building that meets certain criteria, like: withstanding earthquakes, being accessible to the physically impaired and so forth. But: every design necessarily operates within constraints. That is the art. Passive House does not change any of this. I urge anyone to actually do the research rather than regurgitating well-loved, but long-busted myths when it comes to Passive Houses.
I like the quote by Charles Eames about never having had to make a design compromise but having had many constraints. Along with George, Alan and Kate I would probably be branded as a zealot by you and yet, like them, I am proud to be a sceptic. Sure when people spout bollocks about Passivhaus I feel I have to put the record straight but we all get bored explaining that you can open the windows on a Passivhaus (however you can’t close the windows on a naturally ventilated house). Like my fellow zealots who have already commented, I’d much rather question all aspects of Passivhaus as that is far more intellectually stimulating and should result in even better buildings for less money.
tech Director of the Passivhaus Trust but views are always my own or stolen.
The individuals and organisations that promote Passivhaus are presenting the case that building performance is important and that meeting the Passivhaus standard will ensure that excellent building performance is achieved. If more buildings are built like this, I would think that has to be a good thing. There are only around 150 Passivhaus buildings in the UK to date, so I don’t think you need to feel threatened.
You implicate Psssivhaus in a number of false ways in your post. The worst offender is the reference you make to opening windows: ‘We enjoy opening our windows too much’ and ‘a bunch of rumbustious children who enjoy leaving the windows and doors open’. You either don’t know much about Passivhaus or you are deliberately being misleading. You can of course open your windows in a Passivhaus just as in any other house. In winter you won’t want to open your windows because the outside air is cold and in a Passivhaus you won’t need to open your windows as the ventilation system will remove stale air from kitchens and bathrooms and replace it with fresh air from outside. If you do decide to open your windows in winter this will result in wasted energy as cold air comes in and warm air goes out, whichever type of building you are in.
A theme throughout your piece, which I like about your buildings, is the responsiveness, relationship with the outside and ability to tune the building. In essence you are referring to fittings such as windows, doors, shutters and blinds. There is nothing in the Passivhaus standard which precludes any of these. The only difference is that for these buildings to be Passivhaus certified the quality of these fittings would have to be very high to preserve airtightness, keeping warm air in and cold draughts out when doors and windows are closed. The Passivhaus standard also acknowledges the overheating risk due to large glazed areas and the inefficiencies of shaded glazing which provides little solar gain whilst allowing increased heat loss relative to walls.
You are probably right that none of these houses could be a Passivhaus but not for the right reasons. Passivhauses could achieve almost all the design features the occupiers delight in, whilst being more comfortable to live in and cheaper to run. The area where these buildings would struggle is their size. It is difficult to achieve the Passivhaus standard with small detached buildings . This is because the ratio between building envelope area and floor area is higher (higher heat loss area per unit of living area). This is a bit of a problem with Passivhaus and it is one of the reasons the AECB has come up with the Silver Standard which incorporates Passivhaus design principles but allows a higher annual energy demand.
If you want to know what Passivhaus is really about visit the Passivhaus Trust website.
Nice work! I struggle with the same issues…well, not really. I did the PH training and got certified because it was a great way to understand the issues about some aspects of what makes a building comfortable and durable. The Passive house approach is good for this and actual certification is great for those who want it – I hope to do a certified building someday (if the stars align). I approach my work more as an artist than an engineer and find that the PH approach is simply a part of the palette I have available. Sometimes there are more important things. Where I live, it is easy to build above the minimum energy codes and get a very low energy and durable building that may not meet the 4.75 PH number. It’s all about perspective. My own house, built in 1970 with minimal energy upgrades has no official heating bill. I cut and burn a few cord of wood off my own property for heat. I hope to supply all my electrical needs from PV someday. This is a common regional approach in the rural northeast U.S. I do see the PH approach as being very applicable to multi-family housing and larger scale projects. We in the U.S. are trying too hard, perhaps, to apply it to detached, single family houses.
[…] response is following on from the post by Piers Taylor on Passivhaus: ‘Passivhaus – Is it the Future?’. The post is especially relevant as today’s Guardian has a full page on the concept and […]