PASSIVHAUS technology report jack petch
Originating in Europe, The passivhaus principles are considered to be the world’s leading design standard in energy efficient construction. Passivhaus relies on airtightness, super-insulation and mechanical ventilation to operate. All these of these work together to retain heat in the most efficient way. If followed correctly, the system can save at least 80% of energy compared to building regulations. The space heat requirement is reduced to the point when conventional heating system isn’t required, and instead an air supply system is used to circulate already generated heat. Heat from solar gain is predominant in designing passive houses, with about a third of generated heat from correct positioning for solar gain. Heat is also generated by the people living there, lights, TVs and other electrical equipment. The heat is exchanged in the air supply system, which works with the sealed envelope. All factors of the Passivhaus standards work in temporal balance to provide a typical energy consumption of 15kWh/sqM per year, which is roughly the cost of just running the air handling unit. The UK Passivhaus website mentions just needing a simple heated towel rail to give the entire house enough heat. In 2008, there were over 14,000 passive houses in Europe, with very few built in the UK. In 2010 there were 25,000. The UK steadily is rapidly increasing its numbers up to 250 in 2013. Passivhaus is one of the fastest-growing energy standards of the modern era, with many European regulations beginning to implement its principles into standard regulation. The map of UK certified passive houses is viewable on http://passivhausbuildings.org.uk/passivhaus.php. Building the passivhaus standards requires sealing the Building Envelope, high-performing glazing and a Mechanical Ventilation Heat Recovery System, or MVHR. Any building can be built to a passivhaus standard and any construction method can be incorporated. In terms of aesthetic changes, the passivhaus is no different on it’s exterior from any other building. A passivhaus really can be any building, but it requires detailing, knowledge of the scheme, and strict testing. The energy cost savings will no doubt increase every year, as energy prices slowly increase, but initial installation, materials and required knowledge may be more expensive. On larger scale buildings, however, the difference is negligible.
Dr Feist’s Darmstadt Kranichstein. Image from http://nvirohaus.wordpress.com/passivhaus/
In this report, I have looked at local precedents which I have visited and the construction methods behind them: the information for retrofitting a building to EnerPHit standards, as well as the technical specifications to design to passivhaus principles; the Passivhaus Planning Package, a tool used by architects and designers; as well as an interview with Derrie O’Sullivan and the history of passivhaus. Additional material is included in the appendix regarding details for the Cre8 Barn, the original transcript of the interview, and a reference list. I have not looked into the specifics of how the MVHR system works, or passivhaus in the global context. I have focused the report on our UK climate and how it is integrated in our own buildings and as MVHRs are often specified by external companies such as The Green Building Store. PASSIVHAUS EXPLAINED IN 90 SECONDS: The concept of passivhaus is so simple, a diagrammatic 90-second video has been made to explain to anyone the passivhaus principles. If your house uses a central heater or air conditioning to make itself cool, you might wonder if this amount of energy waste is necessary. In 1991, physicist Dr Feist built the first passivhaus and created passivhaus principles as follows:
Proper Insulation - just like “wearing a winter coat”, you don’t need additional heating to stay warm. No Air Leakages - no holes, small or large, to let warm air out of the house. No Thermal Bridges - “Thermal Highways” are apparent in everyday houses, reducing these means heat can’t travel as easily. Plus, the house needs proper windows, often triple glazed; to be orientated properly, to gain the most heat from the sun; and shade itself effectively in the summer. Lastly, the MVHR, which provides the fresh air in, without letting the generated heat out.
Add all these up and “it turns out you don’t need heating anymore”. A Passivhaus uses 90% less energy, and it can be generated by a combination of body heat, solar gain, electrical appliances and even smaller items such as the TV or lighting. These help save you money on your electricity bill and saves the environment.
Passivhaus explained in 90 seconds, http://vimeo.com/74294955
Denby Dale, visited late 2013.
I sat down with Huddersfield University lecturor Derrie O’Sullivan for a short interview on Passivhaus, his work, and how he believes the future of sustainability will be implamented in the UK. Derrie O’Sullivan Architects, in collaboration with the Green Building Store, produced the 3-bedroomed Denby Dale Passivhaus, the first to be built using traditional British cavity-wall construction at £141,000. By using traditional cavity construction, they reduced costs of labour, fitted into Yorkshire planning regulations, (stone exterior) and provided thermal mass. Additional, specialist materials were ordered from The Green Building Store themseleves. Jack Petch, Interviewer: [Good Afternoon]
Derrie O’Sullivan: Good Afternoon Jack.
[When did you and Passivhaus meet?] Probably eight years ago I think. Gosh, when did I first come across it? I think I saw a mention of it at the time of the tenth or ninth passivhaus Conference. I’ve been at every single one ever since, And I’m going in a few weeks time to the eighteenth. I’ve probably been involved with passivhaus for ten years, Actually. [Do you regularly perform at the conference or a mix of the two?] A mix of the two. [How does Passivhaus and Traditional Construction Marry?] That’s what we set out to do in Denby Dale, to actually demonstrate that you can build a passivhaus from commonplace materials. Traditionally, in the UK - and I think in some European countries, notably Denmark - they build in cavity wall construction. Traditionally in Europe, going back five hundred years, from the fifteen hundreds right through to now, cavity walls tend to be full fill; Half a metre, tend to have stone on the outside, stone on the inside and rubble in the middle. Some cases in Scotland, Ireland and Wales, they render them, but around here we tend to dress them up in stone. This building, all these buildings [Gestures] are all nineteenth century buildings, built with good quality stone on the outside, maybe brick on the inside or more than likely a ratty old stone on the inside. The rubble is resultant from the dressing of the stone and it’s called a ‘rubble filled cavity’. Sometime, probably in the Edwardian or Victorian times, they started to have a proper cavity, and in some cases in Huddersfield there are houses with a double cavity. The cavity wall was made for a very good reason, it separated the brick on the inside from the stone on the outside, but they tended to bond them together with through-stones. All of these buildings - if they’re not rubble fill - they’ve got a clear cavity, the cavity tie will be the through-stone. The reason they generally built them like that is because the rain here, certainly in west Yorkshire, it rains uphill. The wind drives the rain up the valley and it pushes it up, coming horizontally and it’s coming underneath, the wall gets absolutely saturated. You can see it coming over the hills! My daughter lives in a house which was built in Eighteen Thirty, right at the top of the town, and every Christmas or November-time she rings up: “Papa, my wall is leaking!” It’s a full-fill, rubble filled cavity, and it’s a listed building. The rain is driven right through, you can almost see it coming in. It gushes down the back and it comes in on the stone windowsill, so she’s beginning to tolerate it. [What was working on Denby Dale like in relation to your other projects?] In some ways it was quite similar: it was a small house, and a lot of my work is around small houses, it was for a family, a couple, again a lot of my clients tend to be house-owners, but the read difference was working and truly collaborating. Not just a ‘builder’ but a builder who is a co-designer. At times, we tousle over who’s the author of the design, I don’t think it matters, the important thing is to achieve a product that functions. Architecture in the British isles, more so say than in Europe or America, (I get a feel that the American system and the European system is quite different to ours) is more adversarial. You’d be forgiven for thinking “Wait a minute, everyone sues everyone else in America” and while there is that culture, but in terms of construction, the builder is introduced into the process much earlier on. Traditionally, the architect does everything or the design team does everything, and then gives it over to the builder! Denby Dale, it wasn’t a true design build, but it was the nearest thing to one with a JCT contract - with collaboration right from the outset. It went in for planning saying:
“look, planners, this is a Passivhaus! This is something special! (So, you know, be nice to us.)”
They said they would, but they didn’t, they refused about four times because they don’t get passivhaus… they still don’t get it actually, and we’re on passivhaus number ten. Kirklees in West Yorkshire will probably have more passivhauses than any other borough, but, they still don’t treat it as anything special, which is odd. They will if you say that you’re designing it to ‘Code 6 for the sustainable homes’, because that is a ‘home-grown, semi-legitative’ approach, but the code for sustainable homes is actually disbanded and is going to be given another name.
Denby Dale was quite interesting, because the clients were very much involved. The clients said “We want an Ecohouse” but we said “Aha! You need a Passivhaus!” because at the beginning of the design stage, Bill and myself went to our second passivhaus conference. The Clients said “We want to see one of these ‘passivhauses’”, and they took themselves off to Austria. They experienced the passivhaus first-hand. Good architecture, generally, comes from a collaboration between; a client, you need a patron; a good design team and a good builder. We had all of those, you think about the great architecture in the world, and then you look at good architecture, those who commissions architects, and it’s regularly the good clients. I could name people like, Cummins Engineering, who make superb hearty diesel engines. It’s an American firm, but it’s also down in Huddersfield, they make turbochargers and they commission good architecture. When you look at their factories in Lancashire, in northern France, in places like Philadelphia, all their buildings are pieces of architecture. Can you get good architecture without good clients? … hmm, good question. That’s another discussion for another day, really! [Have your clients and subsequent schemes been affected by previous works?] Yes, the passivhaus that’s on site at the moment [Golcar Passivhaus] was essentially a repeat of Denby Dale. The details are, though it’s got some added details and added problems because no two buildings are the same. Those clients, actually went to Denby Dale, and met the couple and they’re very similar, they’re committed. Completely committed. In my experience, the client is key every time. I’ve lost a lot of work by insisting on passivhaus! Sometimes, clients have said to me, “I’m sorry I’m not comfortable with the passivhaus.. so I think I’ll use another architect” and I say “… that’s a shame. Ok.” It’s a difficult one. I will say to people “I’d like you to have a passivhaus, but you don’t have to.” But people can misread things and they can over-think and at that point you have to think if it’s a neat get-out for them. The last one I looked at was going to be a passivhaus barn. The couple liked the idea from the start, and they went to see the passivhaus barn we’ve done up in Stirley Farm [Cre8 Barn], but something spooked them about it. Perhaps they thought it a step too far, it does take a very determined attitude. I even did a house half-way to passivhaus for a client because they wanted marble floors instead of triple-glazed windows, which they now regret, but they do appreciate the cavity wall is still three times better than the building regs! Passivhaus is about ten times better: “Ten Times? Never” Yes. Ten. “Ten? Can’t be. … you can’t.” It is. It is! If you build a five-bedroomed home to the building regs, expect to pay £1500 a year on your gas bill. If you build that same house as a passivhaus; Denby Dale’s the first year’s bills were £150 for the gas. In a ratty old house they were paying £1500, and they were cold. They’re much more cosy in the new one! [What information is Mandatory for designing Passivhaus Projects?] The Rough Guide to Sustainability, Fourth edition by Brian Edwards is a great book. Great writer, I’ve got the first edition and now I’ve got into the fourth edition! This edition looks at passivhaus seriously. Brian [Author, A Rough Guide to Sustainability, 4th Ed, 2014] was not convinced about passivhaus, and he still written stuff in here which I wrestle with, but I still think he’s a good writer. [see overleaf] That ‘Hundred and Twenty killo-watts..’, these are real figures. You should be able to go and ask what the primary energy load is for any building, but most people don’t know because it gets ‘fudged’. BREEAM and ‘Code for Sustainability’ doesn’t give or ask of you this level of raw information, and they don’t test their buildings properly, too. There is a lot of ‘BREEAM excellence’ buildings that have never been, it’s sadly a paper exercise. I haven’t quite answered your question properly because Brian puts the answer beautifully. If you went to ask how many architects, and most of the your tutors are architects, too: “If they were building a new house in the morning, what and how would they build?” I’m sure, very few would say it would be to passivhaus principals. It would be an interesting question, in a leading or in a subliminal way, but I think you would get resistance as well. Lots of architects believe it to be too restrictive and that It’s going to compromise ‘architecture with a capital A’. … Poor lambs, I say! Building regulations will compromise, a difficult site will compromise, all legislation, all the other interfering busy-bodies will compromise! Look, get over it, architecture is a tough thing it’s not easy to do, and you just have to battle all the way.
Passivhaus is aimed at producing energy efficient buildings. Focused towards energy saving, there is no regulation on additional implementations of other environmental techniques. Particular attention is paid towards Siting, Building Design, Specification Detailing and Management of Operation. Both Residential and Non-residential buildings can be built to the standard, but must be approved and tested as the performance standards require third-party verification before true Passivhaus Certification. Regional climate data has to be used in calculations, which vary greatly depending on the space occupied and the users inside. The origins are from research in Sweden in the 1970s, developed in Austira and Germany in subsequent years. Cited as a global standard, with a growing impact in the UK. “To meet the passivhaus standard, a building has to reach the following: - Space Heating demand of 15kWh/m2/year - Heating load of 10W/m2 - Pressure test of 0.6 air changes per hour at 50 pascals - Space cooling demand of 15kWH/m2/yr - Total primary energy demand (heating, lighting, ventialtion, appliances etc.) of 120kWh/m2/yr. ” ORIENTATION: The principal façade should be 30º either side of south. Hence the building should have an east-west axis, with major rooms facing south to take advantage of solar gains. Heat demand can be reduced by 30-40 percent by a favourable orientation alone, and further reduced by optimum window area. BUILDING FORM: Compact shapes are recommend with a surface area to volume (A/V) ratio of 0.7. Small building in particular compact spaces, if Passivhaus standards are to e met. Irregular forms are energy inefficient. U-Values. All elements of construction (walls, frames, window glass) should have good U-Values. Recommended stares are 0.15 W/m2K for wall, floors and roofs, and 0.85 W/m2K for complete window installations. (Glazing and frame). CONSTRUCTION TYPES: Most construction types can achieve Passivhaus standards, with external insulation often preferred. The Passivhaus Primer Designer’s Guide provides a variety of wall construction strategies for timber framee, masonry, steel or other structural systems, aimed at achieving the required U-Values. THERMAL BRIDGES: Particular attention is needed at junctions of wall and roof, wall and floor and wall and ground to avoid heat loss via thermal bypasses. Passivhaus building should be free of thermal bridges - a condition tested by inferred imaging and air permeability testing. AIRTIGHTNESS: High airtightness, a condition of Passivhaus design, is required to prevent heat loss and prevent moisture entering the fabric of the building. External render, vapour barriers and taping of junctions around door and window frames is normally required. Pressure testing on site is needed to ensure the standard of 0.6 air changes at 50 Pascals is met. GLAZING, SOLAR GANES AND SHADING: Useful solar gains are explained in Passivhaus design. Typically, gazing on southern façades is around 30-35 percent of wall area, although in earlier passivhauses a fight of 50 per cent was more typical in northern climates. The change reflects the difficulties hat large windows pose for energy efficiency. Houses should be planned so that the main windows face south, with kitchens, bathrooms and minor bedrooms facing north. In the UK, triple glazing is normally employed, especially on windows facing north. Glazing with good solar transmittance is required, although external shading and internal blinds may be employed to avoid summertime over-heating. MVHR: To avoid ventilation heat losses, MVHR is commonly employed in Passivhaus buildings. Hence natural ventilation through opening windows is discouraged. Most MVHR systems use small heating coils to prevent frost damage and provide occasional winter heating. HEATING: As much heating as possible is provided by solar means and via incidental gains from lighting and appliances. (TV, computers, cookers); boilers and radiators are rarely needed. However, in very cold weather, a supplementary heat source may be required in the form of a small fan heater.
(Information from A Rough Guide to Sustainability, Fourth Edition by Brian Edwards.)
A passivhaus has got to get the Orientation right: ideally you want few windows on the north side and optimum glazing on the south side. The Building Form: there’s something called ‘Form-Factor’, a very long, thin house is going to loose a lot more heat than a cube. So, you try and have a cube. U-values: you’re looking at, super insulation, U-values of .1, .15. The Building regs is .35, that gives you an idea. Construction types: you can build a passivhaus from anything, you can build it from traditional materials like Denby Dale, you can build it in a factory and ship it to site, you can build it from any material you wish. You can use straw bale, hemp, you can grow all the materials for a passivhaus, it’s about the strategy. Thermal Bridges: you avoid those, because that is a real deal-breaker. It’s something which architects have been dealing with since the 60’s. Actually, we’re getting good at thermal bridging. Air tight-ness: we’re not good at airtightness, we don’t understand it, no-one understands airtightness. If you look at a square metre of ‘wall’ in a passivhaus, it’s so airtight that a 1.5mm hole is the only amount of air leakage you would expect, if you build it to the building regs, you’re probably looking at a hole, something like 75mm diameter. You can visualise that, you can imagine it, but you still don’t really get it. I always show the airtightness layer with a green line, now, so you can trace around the building and really check. Glazing: If you’re building a passivhaus in Portugal you probably can use a good double-glazing, but the rest of Europe, and as you go north, you’re looking at triple glazing. If you go to a really cold climate, like Siberia, you’re probably looking at quadruple glazing. It’s balancing all of those heat losses. Mechanical Heat Recovery System : because it is an air tight building, an MVHR is a very efficient way of giving you plenty of fresh air, and if you’ve got a lot of people in you switch it to ‘party-mode’. It’s a very simple piece of kit, really simple, it takes the heat out of the exhaust air, and passes it on to the supply air. The number of architects who say they’re not not convinced about passivhaus because they natural ventilation… [Sighs] give me peace! You open the windows! If the MVHR breaks down, open a window. An MVHR is natural ventilation just through a fan. You can, actually, put a whole lot of filters in and screen out all the dust particles, microns and pollens and all the stuff that gives people hay-fever, and that’s fine, but somebody still has to go outside and change the filter. Hay-fever sufferers still have to go outside once-in-awhile, except it plagues you at this time of year when the pollens are high and things, so that’s sort of an oxymoron, but it is a big stumbling block. I honestly think a lot of architects use it as an excuse not to embrace MVHR, because there is a huge amount of resistance to it. [What are some of the Downsides to Passivhaus projects?] It’s often a bit more expensive to build, but that’s not altogether true. If you commissioned me for a school for 350 pupils, I would definitely say that you can have a passivhaus for the budget. If you have a passivhaus school you’ve got an MVHR system, which you’d have most of it in a school anyhow; you would have a heating system, which you needn’t in a passivhaus, apart from back-up heating; and there are a number of passivhaus schools in the country already. Architects have said “We’ve looked at the norms for schools, it’s in between £150 per square metre, and we can give you a passivhaus for that” and they have done. I don’t see downsides, I don’t see any downsides to passivhaus, frankly. [Do you believe that we’ll ever get to the Passivhaus standard in the UK?] Well, Wow, that’s an interesting question. Frankfurt, was the first city in Germany to say “We are building to a passivhaus standard” but what they really meant was that any building to be built on public money would have to be passivhaus standard. They’re doing it, though. Housing Offices, Schools, but why haven’t the Germans adopted it full, fullstop? It’s a very big political thing. There is a wonderful, strong passivhaus movement in Belgum, and from 2016 all the buildings built, specifically around Brussels, will be passivhaus. There’s a very funny promotion film, b-r-e-f dot passiv. It’s a short clip of this guy coming to this Brothel, and the Lady of the house is a well-known journalist in Belgum, wearing red with silk stockings. She takes him around and holds his hand, but she’s essentially extolling the virtues of passivhaus to him! It’s full of double-entendre, which it would be! [Laughs] The English translation’s hilarious, but you get the nuances in humour, it’s funny. The architects who promoted that movie built five passivhauses in and around brussels. Actually, they built them to passivhaus and also to BREEAM standards, and they said that building to passivhaus did not add nor cost anymore than to build to BREEAM. If you look at BREAAM, there are about ten points, and it looks at management, at aspects which are beyond the architect’s control; it looks at transport, that’s got nothing to do with a building after it’s built. Passivhaus is about fabric, and fabric first. The problem in passivhaus from the outside as being anti-sustainable. Brian [Rough Guide to Sustainability] wrote this in his book which annoys me:
“However, unlike BREEAM, or Code for Sustainable Home, there is no standard beyond those of energy use. Hence, passivhaus is of little use to those who seek sustainable design as against low energy design.”
He’s saying it’s low energy viruses sustainability, but no, it isn’t. Sustainability is a very wide field and low energy is a real part of sustainability. Solve the building out, then look at the gizmos. If you want to build a passivhaus out of straw bales great - I would love to do it. I’m doing a passivhaus Yoga-Studio at the moment, it’s got a zinc roof, it’s timber clad and it will be a timber box, built on-site by joiners, and I had a meeting yesterday with the two guys who are going to build it and they’re really up for it. They’re high-class joiners, but they’re never done a passivhaus before, and they don’t know anything about it. Bill will act as sort of Project Manager, Co-Ordinater, Designer. Yes, Bill has encroached into the territory of an architect, because he thinks about passivhauses, he lives and breaths them! Not all of my work is passivhaus, but most of it is and it’s getting more and more like that, and it’s great to collaborate in this way. It’s about working with good quality people, you’re not constantly being told fibs, by builders who think they can save the client money, but really saving themselves. It comes back to trust, but ‘trust’ doesn’t exist in the legal profession, it’s a dirty word, but the whole world gets by, but we don’t value trust at all. We’re mistrustful of trust. “However the use of passivhaus, PHPP, gives architects the tools needed to achieve exemplary energy standards” and when I read that, I know who wrote this, I know what he’s thinking, and I know he’s sceptical of it, but fair dues to Brian Edwards, he’s put passivhaus in his book and he’s asked me to do a Testimonial, too, which I was very happy to do. I wrote my testimonial extolling the virtues of passivhaus, but I wobbled when I read it back. I thought… “Can I do this? How am I going to couch it?” [Testimonial on back cover] [Lastly, Do you think we, as designers, are going to all build to Passivhaus Standards?] I think you will. I’ve been drumming on about passivhaus for years and I see light at the end of the tunnel with you, your co-hort. I’ve seen it for the first time, some of the third years as well… you’ve probably got it from the third years, to be fair. I think this year’s graduates and from all down as long as I’m around, you guys will be adopting it. You will be, because it’s the right thing to do. It’s an impossible question if we’ll accept it in the UK, but we are getting much closer to adopting it, with more and more architects in the country building them. A-J [Architects Journal] does a wonderful map of the country of where they all are. You see the concentrations and the RIBA have wrestled with it for a long time. But, in the RIBA magazine the other month there was 40 affordable homes built in London to passivhaus standards. If you go to any German city, there are buildings everywhere, and you can’t tell which are passivhauses, but they are! I mean, for the people who live in them don’t believe it, because if you live in them you pay very little in energy costs, but that’s what it’s about, fuel security and fuel poverty. It’s amazing how long it’s taking to get to that stage. But you guys are sold up, you can see it, it will be, with you guys. You’ll be saying “Why wouldn’t you?” and there is no issue around it.
THE CRE8 BARN at Stirley Farm was a part of the passivhaus trust open days in 2013. An example of retrofitting an existing structure, the barn is described as a timber box inside a stone outer leaf; a building within a building. Retrofitting a building to passivhaus standards is a different process, as unlike normal construction, there are factors of the existing structure which are outside of the architect’s control, and there are many new challenges to work around. The Stirley Farm Project is to promote an environmentally aware community of growers. The Cre8 Barn is an annexe to the scheme, and creates a space for education around growing and preparation of meals. The inside is left predominantly open, with large, king-post trusses spanning the width of the structure. Additional bracing was needed on the original beams, as well as new supports where the old ones had rotted. One of the most impressive parts of the building is the two MVHRs on show. These stand proud, positioned squarely with the beams and trusses, with the wires almost delicately wrapped around as mirror-images of each other. A perfect diagram to explain the movement of air inside the building, to visitors. Passivhaus is not made secret or hidden like conventional services can be. In supplement to the MVHRs, there is a small, residential-scale electric boiler, which was required to heat up the water for the multiple sinks. The walls of the barn are significantly larger than in similar scale buildings, as the inner leaf is stand-alone, the exterior ‘shell’ is traditional stone with a rubble fill. Chamfered edges are used to to aid light to travel into the building. This, in turn, psychologically reduces the effect of wall thickness, and it’s only when you see the outer leaf that you are aware of the depth of the walls and the light-coloured windowsills (which again help bring light inside). Bill Butcher, in an interview with Lucy Tindall in 2013, noted that the main problems with the stability in the existing masonry structure was the inadequate foundations and the excessive movement of the walls over the years. The thermal envelope inside helps the stabilisation of the barn, without compromising thermal performance; this ‘building within a building’ helps keep the exterior shell from becoming derelict. The MVHR system had to be designed to cope with occupancy changes, from “one or two people to 20 children experimenting with cooking on numerous Baby Bellings”. He asked for more time to be able to finalise the design, to combat costs more effectively; recent versions of the PHPP could have helped to weigh up the different “build-ability of different designs”. Commenting on EnerPHit retrofitting of buildings and the problems they cause, he noted that internal insulation of external walls and moisture movement is a large problem when thinking of the future. “The vapour openness of traditional masonry walls is severely compromised by vapour barriers and insulation materials” which can lead to structural damage and even mould growth. Natural materials, building correctly and fore-knowledge, can be used to combat the issue. Retrofitting and refurbishment currently has no regulation standard regarding energy in the UK, but with a reduction of space, the Passivhaus Handbook expects over 80% of buildings will stilll be here by 2050. It therefore pays to plan and design properly to reduce costs later on and ‘future-proof’ buildings as well as possible, with the limits of today’s technology. Between 2010 and 2011, the passivhaus official standard, known as “EnerPHit”, was launched at the Passivhaus Conference in 2011. EnerPHit allows a maximum annual heat demand of 25kWh/m2 and an upper airtightness of 1.0 air changes per hour (though only if the 0.6 ac/h are not attainable.) More complex than the traditional passivhaus standard, there are additional regulations and tests to achieve the EnerPHit certification. The Cre8 barn, with its many complications, received an airtightness of 0.2 ac/h. (Bill Butcher, cited in Lucy Tindall, “Can Passivhaus be Incorporated into Existing Buildings in the UK?”, 2014) (Passivhaus Handbook)
They key specifications of EnerPHit are:
Annual specific heat demand below 25kwh/m2.a Airtightness of 0.6 air changes an hour (though can be up to 1.0 ac/h with “additional evidence provided”) Evidence and Calculations of moisture management issues. Only can be done on existing buildings which are proved unable to be fitted to the passivhaus standard. Heat recovery efficiency at or above 75%. Electrical efficiency at or below 0.45Wh/m3
U-Values:
Wall: below 0.15W/m2K for external insulation, 0.35W/m2K for internally insulated walls. Roof: At or Below 0.12 W/m2K Floors: At or Below 0.12W/m2K Windows: Full Window at or below 0.85W/m2K External Doors: Whole Door at or Below 0..80 W/m2K
The energy performance standard is around twice as demanding of the Fabric Energy Efficiency Standard (FEES) in the Code for Sustainable Homes, and three times more air-tight than zero-carbon standards in CSH’s Level 5/6. However, it is noted that it’s much easier to achieve EnerPHit in the UK’s mild climate, than in central Europe, where it was originally piloted. (Information from the Passivhaus Handbook) Additional Construction Details from Derry O’Sullivan provided in appendix:
Stone exterior (rubble fill)
Ventilated Cavity Passivhaus inner leaf
THE GOLCAR PASSIVHAUS was a fantastic trip to visit a building site, but also to see the raw bones of passivhaus. Built with traditional construction, the house is no different from any other building in the UK built using cavity wall construction. Peeking behind the glass-fibre curtain, the site gave a greater understanding of what undertaking is necessary to build to this high standard. Positioned predominantly south-facing, towards the great view of the sprawling valley, visiting the building site of the Golcar Passivhaus with a group of peers was a great way to experience technology first-hand. Passing under the scaffolding, we went through the traditional stone outer rain-screen at first floor level. This took us into a double-height atrium space, where the TJI (Timber I-Beams, with OSB in the middle of the flanges) are still visible. The building site looks just like any other, but it’s clean, tidy, and has a lot of insulation around. One interesting part of the design is the exterior retaining wall, which is set back from the main passivhaus. Separating the building and retaining wall helps with drainage placement and solves moisture problems. The passivhaus balance is really so delicate that extra ‘breathing room’, where taken, can help solve complications before they arise. Predominantly made of bloc-work on the inside, we passed under the slightly sunken space for the MVHR and moved into the open plan kitchen-dining room. This is a very different construction to the Cre8 barn, which was predominantly timber. There were no internal finishes, and sadly we couldn’t see the airtightness layers being applied. However, the Denby Dale passivhaus was sealed with wet plaster, which again is a traditional building method, and wouldn’t require specialist teaching to convert a practised builder. The Cre8 barn was taped and fitted with an airtight barrier in front of the wooden joists. The living space was separated with a split-level, where the large, south-facing windows are. Similar to the ‘greenhouse’ area of Denby Dale, there are additional problems and details which need to be considered when building larger passivhauses. For the planning application, the design of the exterior cladding reflects the traditional with a mock extension, old with new, which is less viewable from the road edge. The internal arrangements are ‘upside down’, with the bedrooms on the ground-floor, living space above, a large attic space for a guest bedroom, and storage (extra roof space which the Denby Dale Passivhaus doesn’t have!) From the attic space, we could see the steel frame, bloc-work and TJI rafters all working together, which when combined with 2-Dimensional drawings gave a much greater sense of the scale and effort required to build houses in general. However, it never felt like the passivhaus elements were additional, that it was ‘out-of-the-ordinary’; it was built and integrated into the design. As students, we picked up on a few of the details: a padstone which had cracked from the weight of the steel beam, and the unique intermediate floor construction. These we had seen images of before, but hadn’t experienced first-hand. We then left the open roof and went down towards the south side of the building, where the large expanses of glazing would be placed. One of the issues with the Golcar Passivhaus design is the small, thin slivers of insulation between glazing, which, with the amount of glass fibre, has little integrity without being placed between two structural members and needed to be replaced a few times. This wasn’t necessarily an issue with it being passivhaus; it was instead the imposed design from Planning to aid in the look of the building. Under the intermediate floor there were some examples of pipes and ducts, with holes in the TJIs made for additional services. Pipes and waste water are a cold bridge you cannot get around, but using carbon-fibre wall ties and using the PHPP, you can weigh up what effect they will have on the entire scheme. Seeing services being placed inside the building gave us a better understanding of how to integrate technology, especially in residential properties where it’s often easy to forget that wires and pipes live hidden inside walls. Seeing technology of passivhaus first-hand definitely gave me a broader understanding of how buildings are made. It did seem that using this technology was something that everyone could easily do in their own buildings, and it made me wonder why it hasn’t been more widespread in it’s acceptance in the UK.
The Exterior retaining wall and scaffolding, with the existing house in the background.
Where we entered, underneath the MVHR room. This room needed to be slightly lower than the others, due to total space in the roof. (Also the point of entry for air ducts.)
The Glass Fibre insulation. Every wall was bursting to the brim of lovely soft, fluffy insulation. (Would have been better if it was Sheep’s Wool, though!)
The Rooftop view. This opening will house a Quadruple-Glazed unit, to combat the effect of warm air rising, a ‘standard’ triple glazing unit wouldn’t be effective.
Derry explaining issues with such short walls, and the details he walked through with us.
A detail often shown in books, but to see the diagonal DPM in person, a whole new perspective is given. Real materials, Real site.
The Odd, small areas where walls meet and require additional attention to pack in insulation. Also the way the floor sits on top of the steel beam, bracketed into the wall.
Openings in the TJI’s OSB section for air ducts on the ground floor. These lightweight Floor beams are held by a bracket on the wall, which prevents a thermal bridge from occurring.
The Passivhaus planning package (PHPP) is a tool for passivhaus construction, developed in 1998; it’s a clearly structured tool for designers and builders to use passivhaus standards to calculate the complete energy ‘balance’ of a building. “Taking the guesswork out of the design process” it can accurately determine a proposal’s energy performance and heat losses (both through transmission and ventilation). It also allows for accurate calculations of solar and internal heat gains, which, when offset against losses, can create an energy ‘demand’ for a building. The PHPP can determine for the architect, before the building is even built, an accurate representation of how much heat will be required to heat the space. This can be used iteratively, working with clients and architects to see different options, decide which areas need attention, and therefore save a large amount of money. The PHPP includes tools for calculating U-Values and energy balances, designing comfort ventilation, evaluating summer comfort calculations, and more. Lots of information regarding how to use the package is available in both the PHPP manual and the Passivhaus Handbook. To obtain the results, it distinguishes between ‘significant and insignificant factors’. The PHPP includes standard values of household appliances and inhabitants’ thermal outputs, for example. The package can be purchased from carbonlite.org.uk; the PHPP works best in real-world situations compared to other models because of it’s use of real world figures and it has an “excellent track record” in creating useful, accurate data. One of the largest debates with the PHPP is the view that the tool can be used supplementary to creativity; using the tool to generate the ‘most efficient’ design will render the building dull and overly functional. However, by giving architects the ability to create a range of designs, and then test them with real figures, design and science can really work together to create new forms of architecture. Pushing higher performance, the passivhaus brings a lot of criteria and demand to a design, which isn’t as apparent in other forms of construction. The tool helps keep this open and flexible, letting architects focus on other challenges of the site. The Passivhaus Handbook argues that there is no conflict between performance and design in a passivhaus; interconnectivity of science and art is key. Version 7 (released in 2012) of the package contained three spreadsheets and a 217-page supporting manual. Version 8.5 is the most current, however the PHPP is designed to be continually updated with information, re-evaluated and refined; new measurements are added to improve the software. The main spreadsheets are complex, with 36 interlinked worksheets and a ‘Final Protocol’ supplementary spreadsheet for design and commissioning the MVHR. New to version 7, and included in version 8.5, is the ability to import and export the PHPP data with other CAD software via plug-ins. The PHPP can easily run alongside conventional practices already operating modelling programs, and can be used in-tandem to create energy efficient designs. The spreadsheets work on Microsoft Excel, and any other program which can operate these files. The Passivhaus Handbook mentions that the free-sourced Open Office can be used, and presumably it would work on both Microsoft’s and Apple’s online versions of Office and Numbers, respectively, though untested. The decision to use a freely available source for the information was to be transparent in use and to ease updating efficiency. The spreadsheets display the raw method of calculations, which also can help architects ‘programme’ their buildings more effectively. The cells are colour-coded: yellow for inputting data; calculations/default values and other reference material is in white; results and important final figures are in green. The last verification worksheet is to summarise the key results of the model, though only becomes useful once the other spreadsheets are completed. These currently are: U-Values, Ground, WinType and Windows, Shading, Ventilation, Annual Heating Demand, Summer, Shading in Summer (Shading-S, an extension of Windows & Shading), Domestic Hot Water & Distribution (DHW), Solar Thermal Hot Water Systems (Solar DHW), Climate. New spreadsheets and data are added regularly with updates. The overall effectiveness of the final result is in the “Specific Demands with Reference to the Treated Floor Area” table, though at an internal temperature of 20ºC. The Verification and Design modes are used together to judge the requirements of the necessary MVHR unit and what internal heat gains would be generated. Every stage of the PHPP has lots of specific information to be addressed and in-putted to achieve the most accurate real-world resut.
(Images from the Green Building Store’s Blog Passivhausblog.co.uk, where they used the PHPP to test and evaluate the best way of detailing the Cre8 Barn to combat the beams and vapour issues.)
Starting as just a conversation in 1988 between Bo Adamson and Wolfgang Feist in the institute for Housing and the Environment in Germany, the passivhaus concept was developed through research projects and aided by financial assistance from the Hessian Ministry for Economics and Technology (HMWT). The two developed the project until Adamson retired. Feist’s thesis “Passive Houses in Central Europe” used computerised simulations of the energy consumed by buildings, and how to reduce this with his passive principles. Energy optimisation for buildings shouldn’t be limited to heating energy; the whole energy use needs to be minimised; even inefficient lighting affects heating with incandescent light bulbs. At the time, the exact amount of internal heat gains in typical houses was not recorded, but even today most national energy standards aren’t accurate enough. The first prototype, The Passive House in Kranichstein, was four row-houses. Made over twenty-five years ago, they were part of the study to see how effective the concept would be. To monitor energy use, they were equipped with very precise data recording devices. They performed almost exactly as planned; the residents were “not only satisfied but truly excited by the outcome”. However, the components to reach this standard were incredibly expensive because they had to be individually handmade. When the measurements from the original passive house in Darmstadt Kranichstein were confirmed, accurate conclusions could be made of how to implement this data into subsequent buildings. Because of how impossibly small the energy readings were, they were often misquoted in the professional world, which somewhat hindered its adoption. Most of the time, they didn’t understand that the figures were for four of the buildings. Derrie’s “10 times? never!” seems very realistic here, the connection between the product and reality often get lost in translation. Questions began to arise, if mass production and mass acceptance could lower the initial cost, “The Economical Passivhaus” could change energy forever. Describing the “Passivhaus Handbook” as “long overdue”, Feist, was impressed with the “swift uptake” of passivhaus in the UK. Passivhaus has always been open source. With all principles, tools, details and design aids, the outcome is designed to be “100% transparent”. Recorded data then gets imputed in the PHPP through updates, the cycle continues. “Anyone may choose to build a passivhaus” and there is a diversity of functional, built examples and routes to achieving the final quality. Passivhaus as an idea is part of a real “paradigm shift” in the costing of the energy in our buildings; ‘traditional’ energy sources (oil, coal, natural gas and others) can be put into longer-lasting products, effective glazing, insulation and ventilation systems, which are one-off payments and do not tie you down to the everfluctuating eventuality that resources will run out. From the original passivhaus concept, the pricing difference had “gone down by a factor of 7” in 2006: €50,000 to €6,000. Since then, triple glazing, education and constructional breakthroughs have developed the way we can see passivhaus being adopted in our traditional construction in the UK.
(Foreword by Wolfgang Feist in Passivhaus Handbook) (2006 Essay on Passivhaus: http://www.passivhaustagung.de/Kran/First_Passive_House_Kranichstein_en.html) Image from Feist, retrieved from www.passivhaustagung.de.
BIBLIOGRAPHY Images referenced under/beside picture. All other images, unless referenced, from Authors Own - 2013 / 2014. Key Sources of information: Cotterell, J., & Dadeby, A. (2012). The passivhaus handbook: A practical guide to constructing and retrofitting buildings for ultra-low energy performance. Totnes: UIT Cambridge Ltd. Nicholls, R., & Hall, K. (2008). The green building bible: The low energy design technical reference. Llandysul: Green Building. Edwards, B., & Royal Institute of British Architects. (2014). Rough guide to sustainability: A design primer. London: RIBA in association with Earthscan. BRE trust (n.d.). Passivhaus UK. Retrieved from http://www.passivhaus.org.uk. Passivhaus Initiative - Dr. Wolfgang Feist (2006). 15th Anniversary of the Darmstadt - Kranichstein Passive House . Retrieved from http://www.passivhaustagung.de/Kran/First_Passive_House_Kranichstein_en.html. Tindall, L. (2014). Can Passivhaus be incorporated into existing buildings in the UK? (Degree Dissertation). BA Architecture, University of Huddersfield. Broome, J. (2008). The green self-build book: How to design and build your own eco-home. Totnes: Green Books. Bird, C. (2010). Local sustainable homes : How to make them happen in your community. New York: UIT Cambridge Ltd. Hans-JÜrn Eich, . (2013). Passive House Explained in 90 Seconds (Online video). Retrieved from http://vimeo. com/74294955. Interview with Derrie O’Sullivan, March 2014. Visit to Denby Dale Passivhaus, Golcar Passivhaus and Cre8 Barn 2013, 2014.