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.
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.
