Can passive ever be viable?

hge19

I've been thinking about the financial viability of the passive model over the past few weeks and can't see how it can work out. Say we take a 2000sqft house with construction costs of €80/sqft for standard and €150/sqft for passive, that's a difference of €140000 initially. If we assume that the cost of heating this house is a generous €2000/yr and the cost of oil doubles, over a 30 yr payback period it's going to cost €120000 to heat the house. That means there's still a 20k deficit ever before we go into mortgage repayments, interest etc. I just think it's an interesting point. I'd like to hear what others think!

dfader

hge19 wrote: »

I've been thinking about the financial viability of the passive model over the past few weeks and can't see how it can work out. Say we take a 2000sqft house with construction costs of €80/sqft for standard and €150/sqft for passive, that's a difference of €140000 initially. If we assume that the cost of heating this house is a generous €2000/yr and the cost of oil doubles, over a 30 yr payback period it's going to cost €120000 to heat the house. That means there's still a 20k deficit ever before we go into mortgage repayments, interest etc. I just think it's an interesting point. I'd like to hear what others think!

What are you basing your cost per square foot figures on. The cost difference between building to regs and building passive is not as different as you say. can you back up tyese figures for us. Otherwise your arguement holds no water

beyondpassive

hge19 wrote: »

...... with construction costs of €80/sqft for standard and €150/sqft for passive, that's a difference of €140000 initially. ......

I think you need to rephrase that question. Your build cost numbers are off. Standard build now in the ROI is Part L 2011 compliant standard, which is pretty damn close to Passivhaus. So your figures for €80/sqft are not comparable. You should also realise that the biggest issue in costing the building is finishes. The extra investment of 4 to 12% isn't solely for energy efficiency, it's primarily for better quality components, more robust ironmongery, quieter ventilation.

Change your base case to €110 and Passivhaus to €135. For your calc. You should aim for a 15 yr return on investment without including energy inflation and discount (cost of finance).

Also consider that the compactness and orientation can have a huge impact on cost of Passivhaus. Getting the most usable floor area into the tightest envelope is the cheapest intervention and is done at concept design stage. Shoehorning a McMansion into Passivhaus will be hidiously expensive.

Also note that as builders and trades tool up and gain experience of thermal bridge free and airtightness detailing, it becomes cheaper. Also our designers are finding ways to get certified Passivhaus without certified components and with simplified traditional methods such as wide cavity. Two contributors to this forum have Passivhaus Builds and may confirm or correct my view
What is the procurement method?

sydthebeat

hge19 wrote: »

I've been thinking about the financial viability of the passive model over the past few weeks and can't see how it can work out. Say we take a 2000sqft house with construction costs of €80/sqft for standard and €150/sqft for passive, that's a difference of €140000 initially. If we assume that the cost of heating this house is a generous €2000/yr and the cost of oil doubles, over a 30 yr payback period it's going to cost €120000 to heat the house. That means there's still a 20k deficit ever before we go into mortgage repayments, interest etc. I just think it's an interesting point. I'd like to hear what others think!

Current building regulations are damn close to passive standards.
'direct labour' builds are in the majority problematic and not up to standard.
Some (a lot) of contractors are not up to speed with current building regulation and the workmanship required to comply.

so what youve described above is not comparable. Passive standard is dynamically designed, specific to the individual build, and onerous to meet.
Irish 'direct labour' standards are bad, generic and not policed with any authority.

hge19

sydthebeat wrote: »

Current building regulations are damn close to passive standards.
'direct labour' builds are in the majority problematic and not up to standard.
Some (a lot) of contractors are not up to speed with current building regulation and the workmanship required to comply.

so what youve described above is not comparable. Passive standard is dynamically designed, specific to the individual build, and onerous to meet.
Irish 'direct labour' standards are bad, generic and not policed with any authority.

I think that's a bit generalised. In that case we will never have the quality of workmanship to build to passive standards. Maybe I've been picked up wrong but my point is that you could, realistically, build with standard construction and live in the same comfort as passive for a far lower cost. I'm not taking the latest regs into account as I believe that they will not be taken into account by the ordinary customer. That's not to say it will not be constructed to a satisfactory standard. Therefore can the ethics of passive outweigh the conscience of using oil for the lifetime of the building and have a cheaper whole life cost.

cuculainn

But equally his estimation of heating cost for a 2000 sqft house is way off......if you are meeting the 2011 building regs the cost to heat a 2000 sqft house should be closer to €600*

Taking Beyond passives costings the difference in build would be €50000. the pay back on this difference would again makes a good argument for not going passive

*obviously depending on heat source/use/solar gain etc

sydthebeat

hge19 wrote: »

I think that's a bit generalised. In that case we will never have the quality of workmanship to build to passive standards. Maybe I've been picked up wrong but my point is that you could, realistically, build with standard construction and live in the same comfort as passive for a far lower cost. I'm not taking the latest regs into account as I believe that they will not be taken into account by the ordinary customer. That's not to say it will not be constructed to a satisfactory standard. Therefore can the ethics of passive outweigh the conscience of using oil for the lifetime of the building and have a cheaper whole life cost.

As a professional in the industry, what i see as "generalised" is pretty much on the mark. There are very good contractors out there who are educated and trained in best practises, but there are also many who are stuck in the celtic tiger era, "throw it up" mindset.

the costs that youve outlined above, to me would describe the latter celtic era direct labour standard. Proposed educated contractor costs for current building standards would be higher.
Ask your direct labour guys how they intend on achieve an air tightness value of 7?
I dont know why you wouldnt take current regs into account in this argument... perhaps its not applicable to you, but it is applicable to the general argument.

Also the costs youve outlined for passive would be on the high side comparatively.
Im not sure what 'ethics' you refer to as the passive standard? If you are referring to the reduction of carbon use, there are better "low carbon" standards out there to refer to. For me, the passive standard has too many "bolt on" specifics that do not take 'whole life' carbon use into account. For example a timber frame, green eco-build with a wood stove etc, may not come anywhere near meeting passive standards, but may use substantially less carbon over its life than passive.

Truthfully, ive never heard of 'ethics' being used as a pro-passive argument. The whole idea behind passive is to lower your energy demand.
Theres no 'ethics' involved in that goal in my opinion.

hge19

cuculainn wrote: »

But equally his estimation of heating cost for a 2000 sqft house is way off......if you are meeting the 2011 building regs the cost to heat a 2000 sqft house should be closer to €600*

Taking Beyond passives costings the difference in build would be €50000. the pay back on this difference would again makes a good argument for not going passive

*obviously depending on heat source/use/solar gain etc

I'm using that cost as a very very liberal figure taking into account the cost of energy. That's why I'm putting forward that it can't be viable...

cuculainn

Yes I appreciate that. But if, the Counter arguments are closing the build cost between passive and standard builds you have to use a more realistic heat cost to support the point that passive may not be viable.

hge19

sydthebeat wrote: »

As a professional in the industry, what i see as "generalised" is pretty much on the mark. There are very good contractors out there who are educated and trained in best practises, but there are also many who are stuck in the celtic tiger era, "throw it up" mindset.

the costs that youve outlined above, to me would describe the latter celtic era direct labour standard. Proposed educated contractor costs for current building standards would be higher.
Ask your direct labour guys how they intend on achieve an air tightness value of 7?
I dont know why you wouldnt take current regs into account in this argument... perhaps its not applicable to you, but it is applicable to the general argument.

Also the costs youve outlined for passive would be on the high side comparatively.
Im not sure what 'ethics' you refer to as the passive standard? If you are referring to the reduction of carbon use, there are better "low carbon" standards out there to refer to. For me, the passive standard has too many "bolt on" specifics that do not take 'whole life' carbon use into account. For example a timber frame, green eco-build with a wood stove etc, may not come anywhere near meeting passive standards, but may use substantially less carbon over its life than passive.

Truthfully, ive never heard of 'ethics' being used as a pro-passive argument. The whole idea behind passive is to lower your energy demand.
Theres no 'ethics' involved in that goal in my opinion.

Personally, I would have seen the ethical soundness of the passive model as a clear marketing tool in comparison to a house fueled by fossil means.

Take this back to a simpler domain; Joe Bloggs who knows nothing about construction contracts ABC Contracting to build his house designed by Ordinary Architects Ltd... I.e., a very ordinary house and more than likely "thrown up" to quote you earlier. It will work out cheaper over the 30 yr life on which the oassive model is based. So I cited the ethical values as being the only advantage I can think of to build passive in this case.

beyondpassive

cuculainn wrote: »

Taking Beyond passives costings the difference in build would be €50000. the pay back on this difference would again makes a good argument for not going passive.

This is not a discussion that benefits from reducing it to back of the envelope calcs. Its quite complex due to the different modelling tools and client profiles.

The difference in build cost attributed to energy efficient interventions alone is about €20,000, the other €30,000 is down to better quality materials and finishes.

Bear in mind that Energy aside, Passivhaus and Reg compliant houses are very different animals in at least two significant areas.

1.) Most Passivhaus clients have higher expectations of design quality and build finishes than your average one-off dweller. Look at the unit price difference between Kountry Pine and Irika Teak, Aluclad vs plastic windows, porceline tiles vs natural stone and mosaic, Lots of glazing, rooflights and vaulted ceilings vs poky rooms and long dark corridors. You can't compare because your 'standard' house is generally planned by an engineer or draftsman with no requirement for beauty or delight.

2.) In terms of running cost savings paying back the extra investment. Note the recent study in the link indicating thats almost half of houses looked at don't comply fully with Part L and of those compliant houses, on average they require twice the energy in practice than predicted when modelled in DEAP (even accounting for abnormal usage patterns and occupancy. http://www.constructireland.ie/News/Government/Unpublished-SEAI-report-showed-systemic-building-control-failure.html)

A Passivhaus is designed and built to perform as predicted. Building to regs is simply a guideline. Deap is not an accurate tool for estimating running costs.

beyondpassive

hge19 wrote: »

It will work out cheaper over the 30 yr life on which the oassive model is based. So I cited the ethical values as being the only advantage I can think of to build passive in this case.

Most Passivhauses use the same fossil fuel based systems and renewables as an ordinary house built to post 2008 regs. Most Irish Passivhaus are built 10 miles from the nearest town for 2 car dependant families. So they are only 'ethical' in the measurement of reduced fuel use on site. Renovating a house in town is significantly more environmentally benign.

Passivhaus is not democratic. A 2 storey south facing Passivhaus buillt in kerry could get passivhaus certified with the only intervention over Part L 2011 being the enhanced airtightness from 7 to 0.6 (+€3,000.) Where as the same house in Birr would need an extra 2 inches of insulation to walls and thermally broken frames, €15,000.

So you have to be careful what you mean by Passivhaus. The passivhaus approach is proven at this stage. For some projects the cost/benefit sweet spot might be a space heat demand of 20kWh/m2.an where for a more favourable shape and site it might be 13kWh/m2. The Passivhaus benchmark is really quite arbitrary. It is simply the heat demand point at which space heating cam be delivered solely by the ventilation system. Most houses built using the passive approach use hydrophic radiant heating systems, so the 15kWh/m2.an benchmark isn't relevant. The main benefit of certified Passivhaus is the quality assurance that the badge offers. But often that pretty plaque on the wall can carry an extra €10-15k of cost that has a longer payback than would be easily justified for your 'ordinary' client.

I do agree with the general point being well made by contributers, that the noise from some quarters "that anything less than certified Passivhaus is heresy"is a bit fundamentalist. But Passivhaus is primarily an approach and applied to the new regulations, results in a very efficient good quality build.

No6

hge19 wrote: »

I've been thinking about the financial viability of the passive model over the past few weeks and can't see how it can work out. Say we take a 2000sqft house with construction costs of €80/sqft for standard and €150/sqft for passive, that's a difference of €140000 initially. If we assume that the cost of heating this house is a generous €2000/yr and the cost of oil doubles, over a 30 yr payback period it's going to cost €120000 to heat the house. That means there's still a 20k deficit ever before we go into mortgage repayments, interest etc. I just think it's an interesting point. I'd like to hear what others think!

Your calculations are flawed in that you can't calculate the cost of oil @ 2k per year for 30 year 60k and then double it to 120K and say that what it will take to heat the house for a year.

Oil / Energy costs are rising a a varying % cost per year, if you take 2000K per year with 5 % average price inflation then the cost of oil over 30 years will be 132k, so the difference is down to 8k, however as energy inflation has average around 7% per year for the last 10 years of so using this figure the cost of heating your house would be 188k for 30 years so now your passive house has saved you money, and thats before you look at the build costs, the cost of building passive is not 90% more than standard build costs.

sinnerboy

Divide any constant annual % rise into 70 and you get the doubling period

eg
7% constant rise means something will double in 10 years
10% constant rise means something will double in 7 years

Just bear that in mind when spokespersons for companies or bodies try to present single digit price rises as reasonable.

Certified

hge19 wrote: »

I'm using that cost as a very very liberal figure taking into account the cost of energy. That's why I'm putting forward that it can't be viable...

Sorry but your figures are wider than a barn door away from being near the correct ball park.

fclauson

hge19 wrote: »

....and live in the same comfort as passive ....

Having just completed our Passive build - I want to pick up on the above

Our previous accomodation was built 2003 - and was drafty as anything - burnt 2 to 3 tanks of oil per year - and on a drafty night was impossible to heat.

Our new house - on a very exposed site - during the recent storms it stayed at 20 degrees (the whole house currently sits at this day and night via a combination of solar gain and an ASHP - we are still tuning how this all works)
Today there is a thick frost outside - and still it sits at 20 degrees - I walked to the kitchen bear footed - no cold

Was it worth building to this level - Part L 2011 requires it - and this is not and Irish standard but a rolled down european standard - ITS NOT AN OPTION NOT TO BUILD TO REGS in my opinion

You cannot build to the "same comfort" unless you address insulation and air-tightness (we got 0.54 ACH on a wide cavity block build)

there are NO DRAFTS in our house - thats comfort

braftery

hge19 wrote: »

I've been thinking about the financial viability of the passive model over the past few weeks and can't see how it can work out. Say we take a 2000sqft house with construction costs of €80/sqft for standard and €150/sqft for passive ...

I think you need to start by defining the term "standard".

sas

braftery wrote: »

I think you need to start by defining the term "standard".

I think in this case "standard" means "whatever the builder normally does"

braftery

sas wrote: »

I think in this case "standard" means "whatever the builder normally does"

..... and what is that "the builder" normally does ?

I see alot of sites and there is no "standard" construction quality and no "normal" across them.

The variation in quality and knowledge of "the builder" in Ireland is vast and is usually directly proportional to the €/sq ft that is charged.

sas

braftery wrote: »

..... and what is that "the builder" normally does ?

Usually it's whatever he can get away with.

sydthebeat

braftery wrote: »

..... and what is that "the builder" normally does ?

I see alot of sites and there is no "standard" construction quality and no "normal" across them.

The variation in quality and knowledge of "the builder" in Ireland is vast and is usually directly proportional to the €/sq ft that is charged.

perhaps post of the day!!!

just wish some clients could see beyond the bottom line

braftery

sas wrote: »

Usually it's whatever he can get away with.

... I rest my case

I firmly believe that most people building in Ireland will put into the building everything they can afford. I have never met a client that does not feel they are pushing their financial limits during a build.

Based on this, it is not really about the viability of an energy efficient building but more where do you spend your limited budget to get the best home you can afford.

Good preparation in advance and timely quality control during the build is the most cost effective way to an energy efficient building.

Don't spend your hard earned money on high quality components and then have poor detailing and construction make it money down the drain !