Moving into a new ( passive) house & running costs

The solar tubes on the roof have been extremely effective in the supply of nearly all our hot water for a number of months. The tank did not get as hot as I had expected , probably due to a terrible summer in Wicklow and the fact its a large buffer tank (1500 litres). However the buffer tank is extremely effective in carrying over heat gathered from a sunny day into following days. Further more it is a stratified tank meaning that the water is colder at the bottom than the top, usually the top is around 50-55C whereas the bottom is around 25-30C. Will continue to monitor the amount of heat harvested from the panels over the winter so see their overall contribution is over the heating season. It has just hit the end of September which is the start of the traditional heating season & the temperature in the building is amazingly stable considering the change in seasons outside

Its been an interesting few months & am finally starting to get round to the many ( far more than I thought there would be!) list of jobs / unfinished work / finishing touches. To be honest the vast majority of these are what has to happen anyways when you move into a new house or build one.

• Putting in a base for a patio
• Installing land drains for any places water was ponding
• Putting in bushes, shrubs & flower bulbs
• Optimising heating , solar tubes and domestic hot water (DHW)controls
• Getting the heat recovery system (MHRV) set up to match our requirements
• Preparing the lawn & putting down grass seed
• Changing any locks for which tradesmen may not have returned keys
• Re-affixing any roof slates that have come loose
• Completing the set up of the rainwater system
• Organising the dozens of keys for doors.
• Paint & filler touch ups
• Emptying the garage of surplus construction materials ( gave away quite a bit on freetradeireland.ie which is excellent)
• Finishing drains, paving & paths around house
  The list goes on......& are just part of owning any house!

As regards the costs of services ( i.e. Gas and electricity in our case) , we have been monitoring these on a weekly basis and the bills are pretty close to what we expected & modelled by the PHPP software for a house this size. The biggest & most immediate change was to change services providers away from the incumbent suppliers - this is all very easily done on the likes of www.bonkers.ie and bill saving are around 15% immediately.

Final piece of news, we are opening the house for International Passive House open day, where owners /builders / designers open up passive houses around the world, for no cost, for a number of days each year.

Overview : http://www.passivehouse-international.org/index.php?page_id=262

Visit Details : http://www.passivhausprojekte.de/projekte.php?detail=2309

Getting Passive House / Passivhaus certification

Well, our certificate from the PHI in Germany arrived in the post this morning which we are delighted at & it comes with a plaque which we will have to find a spot for.

There were a few final questions over the last few weeks around solar gain & making sure that the humidity in the house did not drop below 40%. To answer these questions we need to show that
(1) we had fitted some large roller blinds on the south & west to reduce the solar gain; these have done a terrific job & are in regular use
(2) had a large amount of house plants which greatly increase the humidity in the house; the ideal RH is about 45%, but in Ireland the outside RH regularly hits 90% so it tends to be less of an issue than in mainland europe where the climate is much drier and the MHRV may make the inside air too dry. Needless to say in the last 6 months the RH has never dropped inside below 45% in this house

These may seem like little details but show the PHI interest in demonstrating that the building will be both comfortable & healthy to live in. Below is a quick snap of how the house looks today with still a lot of work to do on the garden!

Passive House Design & Construction Decisions - part 5

The last 18months of the blog have been very interesting. We are getting about 400 hits per month with the most read post has been ' How much does a passive house cost to build' which really shows that there is a lack of good information out there about what (1) what a house costs to build and (2) how much extra a passive house would cost.

Well we've been in the house now for about 5 months now and it have been an interesting time in terms of wrapping things up and perhaps areas where we would do things differently.

Paint

The main  lesson learnt on paint is to buy the best you can. Secondly it takes twice as long as you think it will, & even more if you have the final floor coverings down. We went for water based paint from Colortrend ( International Paints) based in Celbridge Co Kildare. They distribute through a limited number of suppliers who make up the colour in a mixing machine in the quantity you need, the paint is amazingly hard wearing . A stunning range of colours and better value than other high end suppliers like Farrow & Ball. We rolled the entire house in an obliterating white emulsion as soon as the plaster was dry. We did all the woodwork in a Colortrend water based mid satin off white; if I were doing it again I might more seriously consider a gloss for the woodwork given the proliferation of little mucky hands everywhere.

Building Drying Out

There is a tendency when wrapping up a build to rush the finishing, especially the installation of doors , skirting, architraves etc. Well, whatever you do dont rush it. The building when the second fix carpentry is installed should be very dry , in particular any plaster be well pink. Secondly, the timber should planed / treated / knotstopped before installation but also let sit in the building for a few weeks so that the moisture content stabilises to that of the building. If the moisture content is higher then than the building, the the timber will crack as it contracts as it dries out. Your tradesmen will want to rush to get finished, so order in time & its well wort waiting.!

Buying on the internet

We bought a number of items on the net, in particular the branded sanitaryware & taps from a German website ( mainly http://www.reuter-badshop.com). Given that the products are branded ( mainly Duravit) with international warranties ( check this before buying) then once we ordered the correct items then there was actually little risk. Furthermore if you pay using credit card then you have protection should faulty good be delivered , for up to six months. The prices were 40% less than here in Ireland but there was an 8 week lead-time on some item but in stock items were delivered in a week. They were excellent with questions We did buy some mid level taps from a UK website and that experience was less positive as the quality of the goods was simply lower than the German products. So in summary, buy good quality branded goods on the net, for mid level products then buy in the trade outlets locally.

Choosing Tradesmen

We have has a really mixed experience with our tradesmen. My lesson is document what you have agreed in advance & either email it or both sign it. Such a document means that an alterations from it will need to be documented so else you end up in a ' he say....she says....' situation eventually. No matter how convivial it all is at the start, there will be moments were selective memory will kick in. Always ask for references & check them out. In general, I would suggest buying the material for tradesmen and getting them in on day rates for the work & then monitor the quality. This is generally cheaper than a lump sum where you don't have transparency on pricing or material quality Finally, I would always suggest using tradesmen that are local, meaning within a 1 hour drive, in particular the plumber, roofer & electrician. These should be people who value their good name & have a vested interest....too often these days the work is ' hit & run' All of the above seems like common sense, but it is something that is often forgotten. To say that we were let down by many of our trademen would be an understatement, inlcuding the roofers. At the other end of the spectrum has been the electrician, Tommy & Maurice Whelan of Marathon Electrical, who have done a great job and stand over their work.

Documenting Your Build

This is absolutely key and should involve buying a small handheld HD video camera & a good high rez camera with a flash ( not a phone). The price of both would be around €200 on amazon. You should aim to regularly walk all the building walls, exterior, roof, scaffolding, skips etc... twice per week to show (1) progrees (2) technical details as they are being constructed (3) materials on site with batch / quality marks. We have had cause to produce some of these photos already & they were simply invaluable.

Gardening

Even though we're in the house a few months, some parts of the garden were planted over a year ago. If youve a large area to plant then its best to use bare root plants or whips ( little bare root trees). These take a while to develope but are a fraction of the price. Likewise now that the construction boom is over, there are many plant nurseries ( not gardencentres!) that have root balled trees - many of which can be 6m tall – which can be planted & have an immediate visual impact. All these type of trees / shrubs need to be planted by the start of April and well watered in their first season. Trees like silver birch are typically used in passive houses to give solar shading during the summer months to reduce building overheating. Gardening lesson over!

Paths Around the House

We put a 750mm concrete path around the house with a small quantity of smashed glass & pebbles pushed below the surface when it was drying. We will grind this back a few millimeters to give a polished concrete finish & the fall is away from the building of course. Between the build and the path there is a large gap with a land drain below the surface with a covering of grey pea gravel. We put the structure / pad in for a patio down too as this involved some heavy equipment and if done in the future would have shredded the lawn that is about to be planted.

Lighting

The best value & designs are to be had by going to the trade lighting outlets who will stock enormous ranges from the likes of Philips & Massive. These sellers do not have retail outlets but have good catalogues with all the dimensions. I would say these suppliers are 60% less than the usual lighting centres we all know. Have just done an exercise of replacing a few halogens with LEDs. Got these online from futureled.ie and whilst the quality of the bulbs if great, the light from LEDs is a harsher white. I did order warm white LEDs which are supposed to mimic the yellow of halogens but even then the 3 types I did order, each have a very difference ' warm white' colour, so do definitely order the LEDs in small quantities first as they do cost about €6 each. Switching the bulbs is a very straighforward job. The electical power saving is incredible; for example I replaced 50W halogens with 3W LEDs & the latter are actually brighter than the halogens.

Will keep working through my list of observations on the design and construction of the house. If there are certain topics you would like to see addressed, then let me know.

Technical FAQs on building a passive house No. 1

Have received a lot of questions via the website, house visitors and looking at the search words for this blog, so have decided to answer the first tranche via an FAQ:

How many passive houses are there in Ireland?

I reckon at the moment there are about 10 certified in this country but many more in the pipeline.

Search function on PHI website: http://www.passivhausprojekte.de/projekte.php?lang=en

UK Passive House Map: http://www.passivhaustrust.org.uk/projects/

What is the PassivHaus Institut?

The Passivhaus Institut (PHI)was founded in 1996, by Dr. Wolfgang Feist, as an independent research institution. It employs physicists, mathematicians and civil, mechanical and environmental engineers, performing research and development on highly efficient energy use. Based in Darmsdadt in Germany, they are the though leaders in the field of lowe energy building design. The PHI certify the design and construction of ' Certified' passive houses and sets the exams for professionals training in the area. The use of the term ' passive house' or 'passivhaus' is not trademarked so so whilst the term is often used casually, just like the term 'Hoover' or 'Tupperware', it is only buildings that have official certification that have genuinely & officially reached the quality standard demanded by the PassivHaus Institut

Wed address: http://www.passiv.de/

What is a passive house certificate & how does it differ from a conventional build

In Ireland, & maybe in other jurisdictions, the design of any house is undertaken by an architect with regards layout, planing permission, massing etc & the structural design undertaken by a structural engineer. These professionals with then come up with design details that the contractor should use. The construction process is then 'monitored' ( whatever that means) – perhaps via 4 or 5 site visits - by an engineer / architect and 'self certified' ( hard to believe...but true) as meeting the quality standard required by the building regulations and Technical Guidance Documents. There is little inspection of builds by building control or local enforcement function.

The process of certifying a house is an additional leg to the process whereby the energy demands of the building are modelled, via an excel tool call the PHPP ( Passive House Planing Package) to meet strict requirements. Then to confirm that the build meets the requirements, photos, details of material, junction details and airtightness test results are detailed. These are send to the PHI in Germany or the local approved certified for certification as meeting PHI Passivhaus design and construction requirements.

The Passive House Enyclopedia : http://passipedia.passiv.de/passipedia_en/start

Self building a passive house a good idea?

Not sure I can answer this question in anything less than 5000 words! In short, any self build should not be undertaken lightly; a self build of a passive house requires a whole different level of attention to detail in design and construction – much of which is new to the vast majority of site personnel & tradesmen. As mentioned earlier in the blog , in a tight market everyone is selling something & it pays to be a sceptical & informed client. Bottom line is that savings of going self build may cover the additional costs of a passive house over a more standard build.

Disadvantages of a passivehouse

The single biggest challenge is the additional capital cost of the build.The second biggest one – according to my wife – that there is no open fire!

Does a passive house have a heating system

Yes, unless there are sufficient solar gain, heat losses from other sources ,enough people and activities to make the building a 'comfortable' temperature. The key term here is ' comfortable'; there are people who think 21C is toasty & necessary; other say that anything above 17C is far too warm & stuffy. In addition, bedrooms should typically run a few degrees cooler. In summary, one man ( or woman's) hothouse is another man's ice house.

What sort of heating system does a passivehouse have?

There is no one answer to this & very much depends on your location & requirement. The key thing is that it should be a small & efficient unit, given that the building will overheat very quickly Options out there include

• Preheating the air on the way using a water to air radiator
• Sealed fires
• Radiators
• Radiant panels
• UFH - water or electric

What materials are used for air tightness?

These depends on the surface

• Floor :A screed cement / concrete layer is accepted as airtight
• Walls : 18mm Orientated Strand Board ( OSB) – it looks like a plywood – as the internal sheathing board is generally accepted as being airight in the long term. The joints between the boards are sealed using airtight tapes e.g. Siga tapes. Thinner boards are much less airtight but are cheaper & easier to work with.
• Roofs : working at height with OSB is very difficult due to their weight. The more common approach is to use various proprietary membranes. These membranes are also used at some of the junction details to ensure air tightness

Windows in a passive house

In general where possible, at a design stage the room layouts is optimised so that rooms that need natural light , e.g. Living rooms, kitchens, are south facing ( to capture the benefit of solar gain) and those that don't e.g. Utility rooms, bathrooms are north facing. There are many windows are certified by the PHI as meeting their specific energy loss requirements ( this usually refers to the frame which is generally manufacturer specific). Other important components though include the glazing panels, spacer that separates the glazing & the fill gas. The frames are made from the usual materials : woods & PVC. There are a number of questions about the longevity of PVC frames given that the triple glazed panels are extremely heavy and I would look for a manufacturer to have a long track record in case the PVC sagged over time. Passive certified windows are significantly more expensive & bigger than standard windows we are all used. That being said, they are exceptionally solid & sound proof .

Foundations ina passive house

There are a large number of proprietary insulated foundation & slab designs on the market but as previously mentioned they are extremely expensive. It is definitely possible to achieve the same levels of insulation and thermal bridging using readily available materials such as EPS. There is a book of accepted Passive House design details available on Amazon which will suggest some options. As a measure many modern houses have floor U values of about 0.16 W/m2K; for a passive house you are looking for about 0.1W/m2K

Why did you use panelvent on the roof?

As a sarking board to reduce the impact of wind on the roof level insulation as we used a warm roof construction. Panelvent is a 9mm wood fibre board which is rigid but moisture permeable.

Running services in a passive house

Really no different to any services layout – keep it simple when possible & keep the runs short. Any good design should stack bathrooms on top of each other to minimise runs. Levels of insulation of all services very high by comparison to usual Irish workmanship standards.

If you have a question that I can help resolve , would be happy to answer & post in the FAQ section.

First observations from moving into a passive house

Well we've moved into the new house now about six weeks and its been an interesting few weeks, have noted below be first observations on the house and how it differed from the previous house we lived in. Firstly its worth saying that the previous house was 60 years old, antiquated heating and single glazing...so comparing the two is like comparing apples and oranges.

Even building temperature

The thermal comfort of the build is so incredibly consistent and even, the building is a dead steady 20C. The air has a freshness / crispness I've really only noticed in passive houses. There are no cold areas, draughts etc...at all. This has some very simple implications ; recently we had a 4 year old birthday party and the kids were happy to play in the hall as it was a warm as every other room. Similarly, you don't have to heat a room if you plan on using it...its just the same temperature as the rest of the house.

Impact of the MHRV system

The MHRV system we are using is a PHI Certified up from Dantherm supplied by Beam Systems. The unit does and excellent job of distributing heat through the building, , removing odours and humidity. The unit is virtually silent and was properly commissioned upon installation. I'll do a detailed review of the system design, installation and operation at a later stage. I had expected that the undercut on the internal doors required by the MHRV would result in noise , but its simply not the case & they make no difference.

Triple glazed doors and windows

The level of thermal comfort and sound insulation from the glazing is amazing – the vast majority of external sound simply can't be heard – that includes cars outside, buses, wind , trees etc...The impact on this is that may of the internal sounds can appear magnified as the background noise were are used to is simply not present. Given the size of the frames, this make the central mullions on split windows quite large, the windows are either fixed ( as 50% are) or are fully operable 9 tilt & turn)

Low building humidity

The previous house we lived in had regular humidity levels between 70-90% which we believe resulted in request colds and chest infections. The new house has relative humidity of between 40-50% and this rises over the course of that day as there is activity in the house.

Natural light

Given the thought that went into the room layouts and orientation at the design stage – this is very much in line with Passiv Haus design principles. In general the rooms where we spent most time are very well naturally light; other rooms such as utility, bathrooms and no or little glazing.

On the flip side, there are a few things that I miss from a more standard house

• An intense heat source such as a fire / stove would be nice to warm up when coming inside; the reality is that a stove would likely overheat the house though & its actually pretty cosy
• An kitchen extractor which expels kitchen odours cannot be used due to air tightness requirements – instead the cooker hood is a recirculation unit with removable dishwasher safe aluminium filter & the cooking area has an MHRV extract point
• Energy efficient bulbs can take a while to heat up / go the right colour...the technology is getting there though

So - in summary the building to date - in mid winter - has been extremely cosy, the kids definitely seem healthier with less cold & sniffles. The quality of the living environment - day light, low humidity, consistent temperature  - is exactly the reason we build the house in the first place.The observations above are just a short summary and I'll deal with the hows and whys in more detail in further updates.

How much does a passive house cost to build?

In looking at the cost of any build, a passive house or not, there are at least 4 main cost drivers, in no particular order:

Size : The biggest driver of cost is the size - every square metre adds costs proportionally
Building Complexity : is it a standard enough looking building or a modernists dream, complexity = additional cost
Self build or using a contractor : the  premium of going a main contractor route is about 15-20%; this is the cost that you incur by passing off the risk , hassle etc.
Location - costs in metropolitain areas ) e.g. Dublin would be about 20% higher than less urban areas e. g Cork, Tipperary

So, its worth stating that if you have a site and an idea of what you want from your home, much of the above has already been decided be default. My own estimate that having now completed the build, that going the certified passive house route has added 15-20% to the final cost against the good quality house that we would gave built otherwise.

In our case when it came to it , there is a lot of missleading information out there. You hear stories of people who 'completed' (i.e. whatever that means) a house for €800/sqm using free labour over a long period etc.. At the other end of the spectrum some of the German ‘kit’ ( ie factory built) turnkey houses ( i.e. you walk in & the heating is on!) with a reasonable specification have budget costs of €2500/sqm. Are these really comparing apples with apples? In one word...No. These two examples are not realistic for many people & most houses are built, passive or not,  in between these numbers, the majority of the cost having been predetermined by the 4 points raised at the start

In the end it really comes down to ones own definition of quality, preferences & attention to detail. This addition cost be be simple things like preferred floor covering, wall breathability, carbon footprint, slates , lighting or quality of sound proofing etc... In our case a non passive house that looks similar to what we finished with could have been completed for about  20% less (15% passive premium and 5% quality premium). 

So, to answer the question posed at the start is to answer the imponderable. The best route is look at where the additional cost , this 15% cost premium, ends up. The list below is in descending order.


Windows - these need to PHI certified triple glazed, in the Irish market there are not that many companies operating. Windows for the PHI certified house  will cost 50-100% more than a good /reasonable window from one of the large window producers. This is not exactly comparing like with like but gives an idea of the scale of this line item
The Structure - if its timberframe than there is additional material and workmanship required, if its block / concrete then there may be specialist blocks required - [25% premium]
Wall insulation - there is a lot more insulation needed, its a multiple( x2 or 3) of a standard run of the mill building
Building Airtighness - the process of taping and sealing all building junctions [€5-10k]
Mechanical Heat Recovery Unit - the units essentially needs to be PHI certified ( there are some exceptions) [€5-8k]
Certification of the building through PHI - there is a fee for the modelling / complilation of the final package & also a fee to the institute [ €5k]
Floor insulation - depending on the approach this be a quite an expensive approach  if you run with one of the insulated raft specialists, in which case the additional cost would be around €15k. Otherwise the requirements for floor insulation are not dramatically different from the Irish Building Regulations
Airtightness testing [€500]


So, to conclude the major drivers for any build, a passive house or not, lie in the initial specification , location and procurement route. There is a higher level of attention to detail on a passive house building site and the various trades do need to work closely - but this need not result in additional cost. However from a budgeting perspective the main additional costs over a good quality conventional build are fairly clear. Moreover, a recession as we’re experiencing at the moment  in Ireland means that there are a lot of great tradesmen out there and work can be quite competitively priced.

Passive House Design & Construction Decisions - part 4

In previous posts we've concentrated on technical design & construction decisions & issues. However as a self builder one of the principal issue you face is that you are not a repeat customer for the suppliers you are using. If you contrast  this position with that of a normal building contractor where there is an onus on the supplier to act true to their word as there is likely going to be repeat business in the future. In the current construction climate especially, many suppliers are hungry for business and willing to make commitments that may prove difficult or impossible to actually deliver on. Before going through a case study of one of the issues we've faced, its worth clearly stating that the vast majority of suppliers, tradesmen & professionals we've used have been excellent - delivering on commitments, have a good eye for detail & most importantly willing to stand over their work & word.

 At the end of the day, in a passive build or any other build, its not possible to write everything down contractually and there is an element of trust that what has been committed to by a supplier will be delivered. This is particularly so when a company is supplying a product which will subsequently be installed by others you hire - this means that all payment is due on delivery or indeed in advance. Put simply, that  means that once the delivery truck leaves the site then you have little bargaining power with the supplier.

A case in point to the date has been the supply of our monocouche render system by Parex Lanko ( a French company), supplied by REP Ltd. in Ireland as part of our wall buildup. Technically, the outer skin of the building consists of a ventilated cavity battened out out, a 9mm magnesium renderboard which is then coated in an approx 8mm monocouche render which is a self coloured plaster. Such a system is somewhat unusual in residential applications, virtually maintenance free, comes with a long colour warranty and should not require painting. We selected the product as one of the best on the market & proven in Irish conditions. The application of a coloured render / monocouche  is becoming more popular with the introduction of external insulation systems ( EIFS) in residential retrofits as a means of protecting the insulation & as a bonus is maintenance free as long as you are happy with the colour of the render.

First of all REP supplied and had  installed a different Parex Lanko  renderboard product to that what had been agreed during site visits and for which certification / agreement has been supplied. This was resolved to some extent as the documentation on what was committed to ( versus what was supplied to the site) was very clear. To be very honest, with hindsight,  this should have forewarned us.

Secondly, having visited a number of sites we chose a brilliant white and grey monocouche colour for the building ( bearing in mind that monocouche is a permanent coloured finish!). When the Parex Lanko monocouche was applied we suggested during site visits and in writing that the colour supplied was not that agreed & were dismissed as  needing to dry out / scaffolding shading / wind / aspect etc....Needless to say, 4 months later & numerous meetings/discussions later  REP agree(1)  that the colour of the house is not white and , (2) that we indeed ask for what white BUT.....having tested the bags of colour in France that it really wasn't their problem & they did their very  best. In short, we are left with a colour that we did not order & no bargaining power over REP to deliver on their commitment. None of this would matter at all if we wanted to paint the building afterwards, but given that the incremental cost of the Parex Lanko / REP monocouche is the price of a new car - then it really is a blow to us.

In summary , because we are not a repeat customers you get messed about. To be honest we are not sure how this issue will resolve itself with Paex Lanko/REP.Perhaps we should simply have demanded that the work be stopped on site  - i.e. down tools! -  until we were 100% sure that what was delivered was actually was ordered. The lesson is that it become difficult to remedy once installed & the  site guys just want to get cracking & finish up. Bottoms line is that cracking on is possibly not in your best interest.

In addition, this should clearly highlight the importance of keeping a good site diary, taking lots of photos / videos, making sure that issues are noted/ responded to in email & raised as early as possible.  Most importantly, if at all possible, retaining some of the invoiced amount ( or maybe even pay by credit card) until you are sure that what you have ordered & was committed, was actually delivered ( along with all its sub-components / accessories).

The experience with Parex Lanko/REP has not been a positive one despite the clear terms of payment & our order. As a self builder you are likely in transaction mode rather than repeat custom. It is likely that were we using a regular building contractor that the complaint would be taken more seriously / less readily dismissed. Again, given the current bidding / tendering climate, it pays to be a skeptical consumer no matter what seemingly well intentioned commitments you are given on site by a sales rep & get it down in writing where possible. Again, the vast majority of suppliers, tradesmen & professionals we've used have been excellent & would happily stand as references for them.

Passive House Design & Construction Decisions - part 3

Just to continue what I started in June of looking at various decision points along the way & the conclusions we've come to. The bottom line is that the area of Passive House design & construction is new in many markets, not just here. There are real reasons to be skeptical, or just plain inquisitive, as regards both the services the professionals sell you and material / equipment you buy from rather  young companies. In part 3 of Passive House Design & Construction decisions I will be highlighting the following areas: Acoustics, Breathable Wall Systems, Insulation types & Windows.


Acoustics - this is an area that timber frame buildings have usually let themselves down and give timber frame building a poor quality image - especially in semi-detached suburban housing estates. It comes down to inadequate measure being taken during construction to reduce sound transmission between properties and even with properties. Measures that are suitable for your build are unlikely to suit another for reasons of cost, cosmetics, floor types. Practical solutions we have employed include double slabbing ( with plasterboard) some rooms / space, 90mm acoustic insulation between all rooms, 150mm insulation between the floor , the use of I beams between the floors. Other options include the use of underlays and screed in the first floor floor buildup. As the doors in a passive house need to be slightly undercut for airflow & there is MHRV ducting, remedial action at a construction stage can avoid expensive retrofitting at a latter stage.
Pros : reduced noise in building                                 Cons : expense

Breathable Wall System - this means the ability of a wall to dissipate any moisture it collects over the year during the warmer months.  It doesn't mean the ability of the wall to let air pass through it. At one end of the spectrum this can mean a hemp building which is highly vapour permeable ( like a good wool coat). At the other end are building with OSB sandwich constructions which should never letter water in & if it does get in, then it certainly aint getting out ( much like a plastic bag). The latter issue has been the subject of much investigation in the US, with the conclusion that any moisture build up, in particular the OSB sandwich walls , can result in Sick Building Syndrome (SBS). This can be hugely complicated area, many experts differ & in the end we chose a breathable wall system, using Panelvent a woodfibre board on the outside  which will allow moisture out if / when it gets in but has the cost and strength advantages of using OSB for racking strength. There is a calculation tool caled WUFI that many professionals use to determine how a wall will perform as regards interstitial condensation over time.
Pros : reduced chance of SBS & mould developing; more durable structure             Cons : expense 

Insulation Types - every insulation manufacturer has a myriad of product at various price points. Products range from hemp to sheeps wool to polystyrene to glass wool. Each product has pros and cons including cost / issues with water or condensation / carbon footprint, ease of installation. However , in the end we went for fibreglass batts installed by Baker Insulation & supplied by Superglass in Scotland . The reason being that as they are a rigid sheet, they are self supporting  in our wall cavities and not likely to sag. These are similar to ubiquitous the rolls of fibreglass we are used to seeing, but it comes in a more rigid slab form
Pros : wont sag, proven trackrecord       Cons : more expensive than some alternative, not as eco as other products, less eco-bling!

Windows - The windows on a passive house are generally tripple glazed and very highly insulated. There are few window manufacturers in this country so to date we have been largely reliant on imported product installed by local agents. As this is a new area, experience is somewhat thin on the group and a number of installers have ceased trading recently. We chose an aluclad triple glazed window. You will need to make sure that the windows , as installed, take cognizance of local building regulations ( with its idiosyncrasies)  as some of these issue will not make sense in the German or Austrian context. Generally speaking, the windows for a certified passive house, need to carry PHI certification & use high quality plastic/ rubber spacers (e.g. Thermix  / Swiss spacers) in the glazing panels itself . Just make sure that your window supplier has sufficient ( & real!) after sales support in your area to deal with any issues that crop up.
Pros : PHI certified windows meet a high independent quality threshold for technical performance     Cons : PHI certified windows are expensive & the lead time is about 8-10 weeks if imported; make sure local expertise is available ;lack of track record of some agents or manufacturers in your local area; lack of flexibility in PHI windows mean they may not suit all types of construction;  idiosyncrasies of local building regulations may be  'foreign' for some importers / producers

Just to recap, this a new and emerging field of passive house construction and design in many markets, not just Ireland. Many sales people and professionals are now cottoning on that. For that reason, there are a lot of people and companies with slick marketing, great logos, great technical product, PHI certificates etc.... All of this is lovely and great, BUT, do they really have the practical knowledge, skills, experience and attitude to deliver the high quality engineered components you will need to get  your home performing as it should. A construction site is not the place for on the job training, first installations or theories.  For exactly this reason there are real reasons to be skeptical, or just plain inquisitive, as regards both the services the professionals sell you and material / equipment you buy.  It really pays to be a smart customer.

Passive House Design & Construction Decisions - part 2

Just to continue what I started in June of looking at various decision points along the way & the conclusions we've come to.In part w  of Passive House Design & Construction decisions I will be highlighting the following areas: Window Cills, Heat Recovery ventilations ( MHRV) , Boiler Plant Room Location & Skimmings vs Tape & Fill.




Window Cills - usually in Ireland these are concrete or granite, and are supported by the external blockwork. However the catch is that we'r using a renderboard so that load bearing structure is not there. In short this leaves 2 viable options - either metal or a lightweight plastic. We choose powder coated cills in the same colour as the windows.
Pros : no maintenance, drip from cill extends beyond building      Cons : get scratched during construction, cannot be stood on

Heat Recovery Ventilation - houses generally have vents in the walls, trickle vents on windows or a central MHRV unit. The use of these units draw quite strong opinion from people based on their experience or not. The topic has been well flogged on many forums but is basically a requirement for a certified Passive Haus. The trick here is not to turn it on until the house is dust free lest dust be draw into the ducting. Space has to be left for the ducting in the building structure in order to keep it big ( & therefore with low velocities and noise). These systems need to be properly sized, designed, installed & commissioned. Many cheaper units are not as efficient and hence use more electricity to run.
Pros : better air quality apparently ( its filtered entering & leaving the house)., lower heating bills                                 Cons : expense

Boiler / Plant room location - In many houses this is simply a back room where the equipment ( boiler / tank ) etc... are jammed in. In many countries the basement is used. In our case we've chosen to go with putting much of this in the garage. In addition I've heard it recommended to put the tumble dryer ( if you have one that is) out in the garage as they are a significant source of fires / smoke damage in domestic houses.
Pros : garage space per square meter is about 65% cheaper ;   Cons : longer pipe runs

Skimming ( plastering) vs tape & fill - this is another chestnut where people have either had great or awful experience. The usual approach in this a wet plaster skim over plasterboard - in the future if you want to put up a picture frame or similar then you have to find the stud behind as the plasterboard is not weight bearing. The results is highly dependent on the skill of the plasterer obviously. The tape & fill approach ( not widespread in Ireland) uses sheets of a dense load bearing material such as fermacell with the joints between sheets filled. I have heard that this not as skilled a job & the results a lot more variable / inconsistent. We ended up going for skimming.
Pros : with a good plasterer the finish is perfect.    Cons : more expensive,  regular plasterboard is not load bearing, wet plaster introduces water to the building  which has to dry over about 4 weeks.


In further blog postings we'll at other design & construction decisions in more detail, bearing in mind that many of these are indeed relevant to any new house build, not just a passive house.

Passive House Design & Construction decisions - Part 1

Its been another steady few weeks where the plastering has been completed & the scaffolding taken down. Have included a few photos below that show the next step since the photos in the last post.In part 1 of Passive House Design & Construction decisions I will be highlighting the following areas: Foundations, Rainwater Harvesting, Rainwater Goods & Fascia / Soffit.

Have gotten a few question from people on various material / techniques / approaches we've taken & in each post going forward will describe our solution for a number of items.

Slates - this is a oldie! For planning reason we were limited to blue black or a derivative thereof. There are many , hundreds actually, of manmade & natural options. Some people swear by the colour fastness & strength of the manmade. As many vote the other way. We ended up choosing a large brazilian natural slate from Capco, which we also fixed with stainless steel hooks given our hilltop location. They have been up for 4 months, through some heavy storms & only a few were damaged.
Pros: amazing colour, expected longer life, great size;  Con: more brittle than man made, more labour installing

Foundation - As you may gather from the older posts we did not go with a raft system from one of the 'insulated foundation systems' companies. The solution we came up with , in consultation with the structural engineer uses polystyrene ( rather than closed cell insulation) overlapping to give the thermal breaks, using rising walls.
Pros: 50% saving over system type foundation ; Con: if you have already engaged an engineer they may not accept it

Rainwater Use- Have installed a large tank under the garage for use for all household water which will be filtered & UV treated, with the exception of cold water taps
Pros: House not as dependent on the mains system & potential shortages , reducing consumption by about 60% ; Con: No return on investment (ROI) in the absence of water metering, this is a fairly fundamental negative

Rainwater Goods - There are a myriad of profiles & materials - just need to select one that fits our budget & requirements. Our guttering is square aluminium with plastic downpipes( to minimise noise / dripping during rainfall,) all painted/powdercoated  in a similar gray to the windows; had to take care that all the fixing are corrosion resistant as they are being secured into the monocouche rather than a paintable surface. We have limited the number of downpipes on the structure  - its just one of these things I notice when its not done well, its a finishing detail.

Fascia / Soffit - there is none like in many traditional house, the fascia / soffit we are used to seeing is apparently an import from the UK British Standards  transposed in the 1960s. Regardless, you need to have this understood as the start of the build so that this is allowed for, its too late to decide half way through.
Pros: Need to decide early, additional labour, sharper building lines ; Con: Less room for error in workmanship & tolerances


In further blog postings we'll at other design & construction decisions in more detail, bearing in mind that many of these are indeed relevant to any modern house build, not just a passive house or a self build.