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.
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.
